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LT1763 Datasheet

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Datasheet

For more information www.linear.com/LT1763
LT1763 Series
1
1763fh
Typical applicaTion
DescripTion
500mA, Low Noise, LDO
Micropower Regulators
The LT
®
1763 series are micropower, low noise, low dropout
regulators. The devices are capable of supplying 500mA of
output current with a dropout voltage of 300mV. Designed
for use in battery-powered systems, the low 30µA quiescent
current makes them an ideal choice. Quiescent current is
well controlled; it does not rise in dropout as it does with
many other regulators.
A key feature of the LT1763 regulators is low output noise.
With the addition of an external 0.01µF bypass capacitor,
output noise drops to 20µVRMS over a 10Hz to 100kHz
bandwidth. The LT1763 regulators are stable with output
capacitors as low as 3.3µF. Small ceramic capacitors can
be used without the series resistance required by other
regulators.
Internal protection circuitry includes reverse battery
protection, current limiting, thermal limiting and reverse
current protection. The parts come in fixed output voltages
of 1.5V, 1.8V, 2.5V, 3V, 3.3V and 5V, and as an adjustable
device with a 1.22V reference voltage. The LT1763 regu-
lators are available in 8-lead SO and 12-lead, low profile
(4mm × 3mm × 0.75mm) DFN packages.
3.3V Low Noise Regulator
FeaTures
applicaTions
n Low Noise: 20µVRMS (10Hz to 100kHz)
n Output Current: 500mA
n Low Quiescent Current: 30µA
n Wide Input Voltage Range: 1.8V to 20V
n Low Dropout Voltage: 300mV
n Very Low Shutdown Current: < 1µA
n No Protection Diodes Needed
n Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3V, 3.3V, 5V
n Adjustable Output from 1.22V to 20V
n Stable with 3.3µF Output Capacitor
n Stable with Aluminum, Tantalum or Ceramic
Capacitors
n Reverse Battery Protection
n No Reverse Current
n Overcurrent and Overtemperature Protected
n 8-Lead SO and 12-Lead (4mm × 3mm) DFN
Packages
n Cellular Phones
n Battery-Powered Systems
n Noise-Sensitive Instrumentation Systems
Dropout Voltage
IN
SHDN
0.01µF
10µF
1763 TA01
OUT
SENSE
VIN
3.7V TO
20V
BYP
GND
LT1763-3.3
3.3V AT 500mA
20µVRMS NOISE
1µF +
OUTPUT CURRENT (mA)
0
DROPOUT VOLTAGE (mV)
400
350
300
250
200
150
100
50
0400
1763 TA02
100 200 300 500
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents including 6144250, 6118263.
For more information www.linear.com/LT1763
LT1763 Series
2
1763fh
absoluTe MaxiMuM raTings
IN Pin Voltage ........................................................ ±20V
OUT Pin Voltage ..................................................... ±20V
Input to Output Differential Voltage ........................ ±20V
SENSE Pin Voltage ............................................... ±20V
ADJ Pin Voltage ...................................................... ±7V
BYP Pin Voltage .....................................................±0.6V
SHDN Pin Voltage ................................................ ±20V
Output Short-Circuit Duration ........................ Indefinite
(Note 1)
12
11
10
9
8
7
13
GND
1
2
3
4
5
6
NC
IN
IN
NC
SHDN
GND
NC
OUT
OUT
NC
SENSE/ADJ*
BYP
TOP VIEW
DE PACKAGE
12-LEAD (4mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 40°C/W, θJC = 5°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
*PIN 5: SENSE FOR LT1763-1.5/L
T1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5
ADJ FOR LT1763
SEE THE APPLICATIONS INFORMATION SECTION.
TOP VIEW
IN
GND
GND
SHDN
OUT
SENSE/ADJ*
GND
BYP
S8 PACKAGE
8-LEAD PLASTIC SO
1
2
3
4
8
7
6
5
TJMAX = 150°C, θJA = 70°C/W, θJC = 35°C/W
*PIN 2: SENSE FOR LT1763-1.5/LT1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5
ADJ FOR LT1763
SEE THE APPLICATIONS INFORMATION SECTION.
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1763CDE#PBF LT1763CDE#TRPBF 1763 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763IDE#PBF LT1763IDE#TRPBF 1763 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE#PBF LT1763MPDE#TRPBF 1763 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CDE-1.5#PBF LT1763CDE-1.5#TRPBF 76315 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763IDE-1.5#PBF LT1763IDE-1.5#TRPBF 76315 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE-1.5#PBF LT1763MPDE-1.5#TRPBF 76315 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CDE-1.8#PBF LT1763CDE-1.8#TRPBF 76318 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
Operating Junction Temperature Range (Note 2)
C, I Grade ...........................................40°C to 125°C
MP Grade ...........................................55°C to 125°C
Storage Temperature Range
S8 Package ........................................65°C to 150°C
DFN Package ......................................65°C to 150°C
Lead Temperature (Soldering, 10 sec)
S8 Package ....................................................... 300°C
pin conFiguraTion
For more information www.linear.com/LT1763
LT1763 Series
3
1763fh
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1763IDE-1.8#PBF LT1763IDE-1.8#TRPBF 76318 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE-1.8#PBF LT1763MPDE-1.8#TRPBF 76318 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CDE-2.5#PBF LT1763CDE-2.5#TRPBF 76325 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763IDE-2.5#PBF LT1763IDE-2.5#TRPBF 76325 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE-2.5#PBF LT1763MPDE-2.5#TRPBF 76325 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CDE-3#PBF LT1763CDE-3#TRPBF 17633 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763IDE-3#PBF LT1763IDE-3#TRPBF 17633 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE-3#PBF LT1763MPDE-3#TRPBF 17633 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CDE-3.3#PBF LT1763CDE-3.3#TRPBF 76333 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763IDE-3.3#PBF LT1763IDE-3.3#TRPBF 76333 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE-3.3#PBF LT1763MPDE-3.3#TRPBF 76333 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CDE-5#PBF LT1763CDE-5#TRPBF 17635 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763IDE-5#PBF LT1763IDE-5#TRPBF 17635 12-Lead (4mm × 3mm) Plastic DFN 40°C to 125°C
LT1763MPDE-5#PBF LT1763MPDE-5#TRPBF 17635 12-Lead (4mm × 3mm) Plastic DFN 55°C to 125°C
LT1763CS8#PBF LT1763CS8#TRPBF 1763 8-Lead Plastic SO 40°C to 125°C
LT1763IS8#PBF LT1763IS8#TRPBF 1763 8-Lead Plastic SO 40°C to 125°C
LT1763MPS8#PBF LT1763MPS8#TRPBF 1763MP 8-Lead Plastic SO 55°C to 125°C
LT1763CS8-1.5#PBF LT1763CS8-1.5#TRPBF 176315 8-Lead Plastic SO 40°C to 125°C
LT1763IS8-1.5#PBF LT1763IS8-1.5#TRPBF 176315 8-Lead Plastic SO 40°C to 125°C
LT1763CS8-1.8#PBF LT1763CS8-1.8#TRPBF 176318 8-Lead Plastic SO 40°C to 125°C
LT1763IS8-1.8#PBF LT1763IS8-1.8#TRPBF 176318 8-Lead Plastic SO 40°C to 125°C
LT1763CS8-2.5#PBF LT1763CS8-2.5#TRPBF 176325 8-Lead Plastic SO 40°C to 125°C
LT1763IS8-2.5#PBF LT1763IS8-2.5#TRPBF 176325 8-Lead Plastic SO 40°C to 125°C
LT1763MPS8-2.5#PBF LT1763MPS8-2.5#TRPBF 176325 8-Lead Plastic SO 55°C to 125°C
LT1763CS8-3#PBF LT1763CS8-3#TRPBF 17633 8-Lead Plastic SO 40°C to 125°C
LT1763IS8-3#PBF LT1763IS8-3#TRPBF 17633 8-Lead Plastic SO 40°C to 125°C
LT1763CS8-3.3#PBF LT1763CS8-3.3#TRPBF 176333 8-Lead Plastic SO 40°C to 125°C
LT1763IS8-3.3#PBF LT1763IS8-3.3#TRPBF 176333 8-Lead Plastic SO 40°C to 125°C
LT1763CS8-5#PBF LT1763CS8-5#TRPBF 17635 8-Lead Plastic SO 40°C to 125°C
LT1763IS8-5#PBF LT1763IS8-5#TRPBF 17635 8-Lead Plastic SO 40°C to 125°C
LT1763MPS8-5#PBF LT1763MPS8-5#TRPBF 17635 8-Lead Plastic SO 55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
orDer inForMaTion
For more information www.linear.com/LT1763
LT1763 Series
4
1763fh
elecTrical characTerisTics
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage C, I Grade: ILOAD = 500mA (Notes 3, 11)
MP Grade: ILOAD = 500mA (Notes 3, 11)
l
l
1.8
1.8
2.3
2.35
V
V
Regulated Output Voltage
(Note 4)
LT1763-1.5 VIN = 2V, ILOAD = 1mA
2.5V < VIN < 20V, 1mA < ILOAD < 500mA
l
1.485
1.462
1.5
1.5
1.515
1.538
V
V
LT1763-1.8 VIN = 2.3V, ILOAD = 1mA
2.8V < VIN < 20V, 1mA < ILOAD < 500mA
l
1.782
1.755
1.8
1.8
1.818
1.845
V
V
LT1763-2.5 VIN = 3V, ILOAD = 1mA
3.5V < VIN < 20V, 1mA < ILOAD < 500mA
l
2.475
2.435
2.5
2.5
2.525
2.565
V
V
LT1763-3 VIN = 3.5V, ILOAD = 1mA
4V < VIN < 20V, 1mA < ILOAD < 500mA
l
2.970
2.925
3
3
3.030
3.075
V
V
LT1763-3.3 VIN = 3.8V, ILOAD = 1mA
4.3V < VIN < 20V, 1mA < ILOAD < 500mA
l
3.267
3.220
3.3
3.3
3.333
3.380
V
V
LT1763-5 VIN = 5.5V, ILOAD = 1mA
6V < VIN < 20V, 1mA < ILOAD < 500mA
l
4.950
4.875
5
5
5.050
5.125
V
V
ADJ Pin Voltage
(Notes 3, 4)
LT1763 VIN = 2.2V, ILOAD = 1mA
C, I Grade: 2.3V < VIN < 20V, 1mA < ILOAD < 500mA
MP Grade: 2.35V < VIN < 20V, 1mA < ILOAD < 500mA
l
l
1.208
1.190
1.190
1.220
1.220
1.220
1.232
1.250
1.250
V
V
V
Line Regulation LT1763-1.5 C, I Grade: ∆VIN = 2V to 20V, ILOAD = 1mA
LT1763-1.5 MP Grade: ∆VIN = 2.1V to 20V, ILOAD = 1mA
LT1763-1.8VIN = 2.3V to 20V, ILOAD = 1mA
LT1763-2.5VIN = 3V to 20V, ILOAD = 1mA
LT1763-3VIN = 3.5V to 20V, ILOAD = 1mA
LT1763-3.3VIN = 3.8V to 20V, ILOAD = 1mA
LT1763-5VIN = 5.5V to 20V, ILOAD = 1mA
LT1763 (Note 3) C, I Grade: ∆VIN = 2V to 20V, ILOAD = 1mA
LT1763 (Note 3) MP Grade: ∆VIN = 2.1V to 20V, ILOAD = 1mA
l
l
l
l
l
l
l
l
l
1
1
1
1
1
1
1
1
1
5
5
5
5
5
5
5
5
5
mV
mV
mV
mV
mV
mV
mV
mV
mV
Load Regulation L
T1763-1.5 VIN = 2.5V, ∆ILOAD = 1mA to 500mA
VIN = 2.5V, ∆ILOAD = 1mA to 500mA
l
3 8
15
mV
mV
LT1763-1.8 VIN = 2.8V, ∆ILOAD = 1mA to 500mA
VIN = 2.8V, ∆ILOAD = 1mA to 500mA
l
4 9
18
mV
mV
LT1763-2.5 VIN = 3.5V, ∆ILOAD = 1mA to 500mA
VIN = 3.5V, ∆ILOAD = 1mA to 500mA
l
5 12
25
mV
mV
LT1763-3 VIN = 4V, ∆ILOAD = 1mA to 500mA
VIN = 4V, ∆ILOAD = 1mA to 500mA
l
7 15
30
mV
mV
LT1763-3.3 VIN = 4.3V, ∆ILOAD = 1mA to 500mA
VIN = 4.3V, ∆ILOAD = 1mA to 500mA
l
7 17
33
mV
mV
LT1763-5 VIN = 6V, ∆ILOAD= 1mA to 500mA
VIN = 6V, ∆ILOAD = 1mA to 500mA
l
12 25
50
mV
mV
LT1763 (Note 3) VIN = 2.3V, ∆ILOAD = 1mA to 500mA
C, I Grade: VIN = 2.3V, ∆ILOAD = 1mA to 500mA
MP Grade: VIN = 2.35V, ∆ILOAD = 1mA to 500mA
l
l
2 6
12
12
mV
mV
mV
Dropout Voltage
VIN = VOUT(NOMINAL)
(Notes 5, 6, 11)
ILOAD = 10mA
ILOAD = 10mA
l
0.13 0.19
0.25
V
V
ILOAD = 50mA
ILOAD = 50mA
l
0.17 0.22
0.32
V
V
ILOAD = 100mA
ILOAD = 100mA
l
0.20 0.24
0.34
V
V
ILOAD = 500mA
ILOAD = 500mA
l
0.30 0.35
0.45
V
V
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
For more information www.linear.com/LT1763
LT1763 Series
5
1763fh
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
GND Pin Current
VIN = VOUT(NOMINAL)
(Notes 5, 7)
ILOAD = 0mA
ILOAD = 1mA
ILOAD = 50mA
ILOAD = 100mA
ILOAD = 250mA
ILOAD = 500mA
l
l
l
l
l
l
30
65
1.1
2
5
11
75
120
1.6
3
8
16
µA
µA
mA
mA
mA
mA
Output Voltage Noise COUT = 10µF, CBYP = 0.01µF, ILOAD = 500mA, BW = 10Hz to 100kHz 20 µVRMS
ADJ Pin Bias Current (Notes 3, 8) 30 100 nA
Shutdown Threshold VOUT = Off to On
VOUT = On to Off
l
l
0.25
0.8
0.65
2 V
V
SHDN Pin Current
(Note 9)
VSHDN = 0V
VSHDN = 20V
0.1
1
µA
µA
Quiescent Current in Shutdown VIN = 6V, VSHDN = 0V 0.1 1 µA
Ripple Rejection VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz,
ILOAD = 500mA
50 65 dB
Current Limit VIN = 7V, VOUT = 0V
C, I Grade: VIN = VOUT(NOMINAL) + 1V or 2.3V (Note 12), ∆VOUT = –0.1V
MP Grade: VIN = 2.35V (Note 12), ∆VOUT = –0.1V
l
l
520
520
mA
mA
Input Reverse Leakage Current VIN = –20V, VOUT = 0V l1 mA
Reverse Output Current
(Note 10)
LT1763-1.5 VOUT = 1.5V, VIN < 1.5V
LT1763-1.8 VOUT = 1.8V, VIN < 1.8V
LT1763-2.5 VOUT = 2.5V, VIN < 2.5V
LT1763-3 VOUT = 3V, VIN < 3V
LT1763-3.3 VOUT = 3.3V, VIN < 3.3V
LT1763-5 VOUT = 5V, VIN < 5V
LT1763 (Note 3) VOUT = 1.22V, VIN < 1.22V
10
10
10
10
10
10
5
20
20
20
20
20
20
10
µA
µA
µA
µA
µA
µA
µA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT1763 regulators are tested and specified under pulse
load conditions such that TJ @ TA. The LT1763 (C grade) is 100% tested
at TA = 25°C; performance at –40°C and 125°C is assured by design,
characterization and correlation with statistical process controls. The
LT1763 (I grade) is guaranteed over the full –40°C to 125°C operating
junction temperature range. The LT1763 (MP grade) is 100% tested and
guaranteed over the –55°C to 125°C operating junction temperature range.
Note 3: The LT1763 (adjustable version) is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.
Note 4: Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will not apply
for all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current, the input voltage
range must be limited.
Note 5: To satisfy requirements for minimum input voltage, the LT1763
(adjustable version) is tested and specified for these conditions with an
external resistor divider (two 250k resistors) for an output voltage of
2.44V. The external resistor divider will add a 5µA DC load on the output.
Note 6: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
output voltage will be equal to: VIN – VDROPOUT.
Note 7: GND pin current is tested with VIN = VOUT(NOMINAL) or VIN = 2.3V
(C, I grade) or 2.35V (MP grade), whichever is greater, and a current
source load. This means the device is tested while operating in its dropout
region. This is the worst-case GND pin current. The GND pin current will
decrease slightly at higher input voltages.
Note 8: ADJ pin bias current flows into the ADJ pin.
Note 9: SHDN pin current flows into the SHDN pin.
Note 10: Reverse output current is tested with the IN pin grounded and the
OUT pin forced to the rated output voltage. This current flows into the OUT
pin and out the GND pin.
Note 11: For the LT1763, LT1763-1.5 and LT1763-1.8 dropout voltage will
be limited by the minimum input voltage specification under some output
voltage/load conditions. See the curve of Minimum Input Voltage in the
Typical Performance Characteristics.
Note 12: To satisfy requirements for minimum input voltage, current limit
is tested at VIN = VOUT(NOMINAL) + 1V or 2.3V (C, I grade) or 2.35V
(MP grade), whichever is greater.
For more information www.linear.com/LT1763
LT1763 Series
6
1763fh
Typical perForMance characTerisTics
Typical Dropout Voltage Guaranteed Dropout Voltage Dropout Voltage
OUTPUT CURRENT (mA)
500
450
400
350
300
250
200
150
100
50
0
DROPOUT VOLTAGE (mV)
1763 G01
0 50 100 150 200 250 300 350 400 450 500
TJ = 125°C
TJ = 25°C
OUTPUT CURRENT (mA)
500
450
400
350
300
250
200
150
100
50
0
GUARANTEED DROPOUT VOLTAGE (mV)
1763 G02
0 50 100 150 200 250 300 350 400 450 500
TJ 125°C
TJ 25°C
= TEST POINTS
TEMPERATURE (°C)
–50
DROPOUT VOLTAGE (mV)
050 75
1763 G03
–25 25 100 125
500
450
400
350
300
250
200
150
100
50
0
IL = 500mA
IL = 1mA
IL = 10mA
IL = 50mA
IL = 250mA
IL = 100mA
Quiescent Current
LT1763-1.5
Output Voltage
LT1763-1.8
Output Voltage
LT1763-2.5
Output Voltage
LT1763-3
Output Voltage
LT1763-3.3
Output Voltage
TEMPERATURE (°C)
–50
QUIESCENT CURRENT (µA)
100
1763 G04
0 50–25 25 75 125
50
45
40
35
30
25
20
15
10
5
0
VIN = 6V
RL = , IL = 0 (LT1763-1.5/-1.8/-2.5/-3/-3.3/-5)
RL = 250k, IL = 5µA (LT1763)
VSHDN = VIN
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1763 G05
0 50
1.528
1.521
1.514
1.507
1.500
1.493
1.486
1.479
1.472
–25 25 75 125
IL = 1mA
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1763 G06
0 50
1.84
1.83
1.82
1.81
1.80
1.79
1.78
1.77
1.76
–25 25 75 125
IL = 1mA
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1763 G07
0 50
2.54
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
–25 25 75 125
IL = 1mA
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1763 G08
0 50
3.060
3.045
3.030
3.015
3.000
2.985
2.970
2.955
2.940
–25 25 75 125
IL = 1mA
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1763 G09
0 50
3.360
3.345
3.330
3.315
3.300
3.285
3.270
3.255
3.240
–25 25 75 125
IL = 1mA
For more information www.linear.com/LT1763
LT1763 Series
7
1763fh
Typical perForMance characTerisTics
LT1763-5
Output Voltage
LT1763
ADJ Pin Voltage
LT1763-1.5
Quiescent Current
2
TEMPERATURE (°C)
–50
100
1763 G10
0 50
5.075
5.050
5.025
5.000
4.975
4.950
4.925
4.900
–25 25 75 125
IL = 1mA
TEMPERATURE (°C)
–50
ADJ PIN VOLTAGE (V)
100
1763 G11
0 50
1.240
1.235
1.230
1.225
1.220
1.215
1.210
1.205
1.200
–25 25 75
125
IL = 1mA
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
250
225
200
175
150
125
100
75
50
25
08
1763 G12
21 3 5 7 9
4610
VSHDN = VIN
TJ = 25°C
RL =
VSHDN = 0V
LT1763-1.8
Quiescent Current
LT1763-2.5
Quiescent Current
LT1763-3
Quiescent Current
LT1763-3.3
Quiescent Current
LT1763-5
Quiescent Current
LT1763
Quiescent Current
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
225
200
175
150
125
100
75
50
25
08
1763 G13
21 3 5 7 9
4610
VSHDN = VIN
TJ = 25°C
RL =
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
250
225
200
175
150
125
100
75
50
25
08
1763 G14
21 3 5 7 9
4610
VSHDN = VIN
TJ = 25°C
RL =
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
225
200
175
150
125
100
75
50
25
08
1763 G15
21 3 5 7 9
4610
VSHDN = VIN
TJ = 25°C
RL =
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
250
225
200
175
150
125
100
75
50
25
08
1763 G16
21 3 5 7 9
4610
VSHDN = VIN
TJ = 25°C
RL =
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
250
225
200
175
150
125
100
75
50
25
08
1763 G17
21 3 5 7 9
4610
VSHDN = VIN
TJ = 25°C
RL =
SHDN
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (µA)
40
35
30
25
20
15
10
5
016
1763 G18
42 6 10 14 18
812 20
VSHDN = VIN
TJ = 25°C
RL = 250k
VSHDN = 0V
For more information www.linear.com/LT1763
LT1763 Series
8
1763fh
Typical perForMance characTerisTics
LT1763-1.5
GND Pin Current
LT1763-1.8
GND Pin Current
LT1763-2.5
GND Pin Current
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G19
0123456 7 8 9 10
RL = 30Ω
IL = 50mA*
RL = 150Ω
IL = 10mA*
RL = 1.5k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.5V
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G20
0123456 7 8 9 10
RL = 36Ω
IL = 50mA*
RL = 180Ω
IL = 10mA*
RL = 1.8k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G21
0123456 7 8 9 10
RL = 50Ω
IL = 50mA*
RL = 250Ω
IL = 10mA*
RL = 2.5k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 2.5V
LT1763-3
GND Pin Current
LT1763-3.3
GND Pin Current
LT1763-5
GND Pin Current
LT1763
GND Pin Current
LT1763-1.5
GND Pin Current
LT1763-1.8
GND Pin Current
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G22
0123456 7 8 9 10
RL = 60Ω
IL = 50mA*
RL = 300Ω
IL = 10mA*
RL = 3k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3V
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G23
0123456 7 8 9 10
RL = 66Ω
IL = 50mA*
RL = 330Ω
IL = 10mA*
RL = 3.3k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3.3V
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G24
0123456 7 8 9 10
RL = 100Ω
IL = 50mA*
RL = 500Ω
IL = 10mA*
RL = 5k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 5V
INPUT VOLTAGE (V)
1200
1000
800
600
400
200
0
GND PIN CURRENT (µA)
1763 G25
0123456 7 8 9 10
RL = 24.4Ω
IL = 50mA*
RL = 122Ω
IL = 10mA*
RL = 1.22k
IL = 1mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.22V
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G26
0123456 7 8 9 10
RL = 3Ω
IL = 500mA*
RL = 5Ω
IL = 300mA*
RL = 15Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.5V
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G27
0123456 7 8 9 10
RL = 3.6Ω
IL = 500mA*
RL = 6Ω
IL = 300mA*
RL = 18Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
For more information www.linear.com/LT1763
LT1763 Series
9
1763fh
Typical perForMance characTerisTics
LT1763-2.5
GND Pin Current
LT1763-3
GND Pin Current
LT1763-3.3
GND Pin Current
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G28
0123456 7 8 9 10
RL = 5Ω
IL = 500mA*
RL = 8.33Ω
IL = 300mA*
RL = 25Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 2.5V
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G29
0123456 7 8 9 10
RL = 6Ω
IL = 500mA*
RL = 10Ω
IL = 300mA*
RL = 30Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3V
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G30
0123456 7 8 9 10
RL = 6.6Ω
IL = 500mA*
RL = 11Ω
IL = 300mA*
RL = 33Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3.3V
SHDN Pin Threshold
(On-to-Off)
SHDN Pin Threshold
(Off-to-On) SHDN Pin Input Current
TEMPERATURE (°C)
–50
SHDN PIN THRESHOLD (V)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0050 75
1763 G34
–25 25 100 125
IL = 1mA
TEMPERATURE (°C)
–50
SHDN PIN THRESHOLD (V)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0050 75
1763 G35
–25 25 100 125
IL = 500mA
IL = 1mA
SHDN PIN VOLTAGE (V)
SHDN PIN INPUT CURRENT (µA)
1763 G36
0123456 7 8 9 10
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
LT1763-5
GND Pin Current
LT1763
GND Pin Current GND Pin Current vs ILOAD
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G31
0123456 7 8 9 10
RL = 10Ω
IL = 500mA*
RL = 16.7Ω
IL = 300mA*
RL = 50Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 5V
INPUT VOLTAGE (V)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G32
0123456 7 8 9 10
RL = 2.44Ω
IL = 500mA*
RL = 4.07Ω
IL = 300mA*
RL = 12.2Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.22V
OUTPUT CURRENT (mA)
12
10
8
6
4
2
0
GND PIN CURRENT (mA)
1763 G33
0 50 100 150 200 250 300 350 400 450 500
VIN = VOUT(NOMINAL) + 1V
For more information www.linear.com/LT1763
LT1763 Series
10
1763fh
Typical perForMance characTerisTics
SHDN Pin Input Current ADJ Pin Bias Current Current Limit
TEMPERATURE (°C)
–50
SHDN PIN INPUT CURRENT (µA)
100
1763 G37
0 50
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–25 25 75 125
VSHDN = 20V
TEMPERATURE (°C)
–50
ADJ PIN BIAS CURRENT (nA)
050 75
1763 G38
–25 25 100 125
140
120
100
80
60
40
20
0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
INPUT VOLTAGE (V)
0
CURRENT LIMIT (A)
245
1763 G39
1367
VOUT = 0V
Current Limit Reverse Output Current Reverse Output Current
Input Ripple Rejection Input Ripple Rejection Ripple Rejection
TEMPERATURE (°C)
–50
CURRENT LIMIT (A)
1.2
1.0
0.8
0.6
0.4
0.2
0050 75
1763 G40
–25 25 100 125
VIN = 7
VOUT = 0V
OUTPUT VOLTAGE (V)
100
90
80
70
60
50
40
30
20
10
0
REVERSE OUTPUT CURRENT (µA)
1763 G41
0123456 7 8 9 10
TJ = 25°C, VIN = 0V
CURRENT FLOWS
INTO OUTPUT PIN
VOUT = VADJ (LT1763)
LT1763
LT1763-5
LT1763-1.5
LT1763-3.3
LT1763-3
LT1763-2.5
LT1763-1.8
20
18
16
14
12
10
8
6
4
2
0
REVERSE OUTPUT CURRENT (µA)
1763 G42
VIN = 0V, VOUT = 1.22V (LT1763)
VOUT = 1.5V (LT1763-1.5)
VOUT = 1.8V (LT1763-1.8)
VOUT = 2.5V (LT1763-2.5)
VOUT = 3V (LT1763-3)
VOUT = 3.3V (LT1763-3.3)
VOUT = 5V (LT1763-5)
LT1763-1.5/-1.8/
-2.5/-3/-3.3/-5
LT1763
TEMPERATURE (°C)
–50 0 50 75
–25 25 100 125
FREQUENCY (Hz)
RIPPLE REJECTION (dB)
80
70
60
50
40
30
20
10
0
10 1k 10k 1M
1763 G43
100 100k
IL = 500mA
VIN = VOUT(NOMINAL) +
1V + 50mVRMS RIPPLE
CBYP = 0
COUT = 4.7µF
COUT = 10µF
FREQUENCY (Hz)
RIPPLE REJECTION (dB)
80
70
60
50
40
30
20
10
0
10 1k 10k 1M
1763 G44
100 100k
IL = 500mA
VIN = VOUT(NOMINAL) +
1V + 50mVRMS RIPPLE
COUT = 10µF
CBYP = 0.01µF
CBYP = 100pF
CBYP = 1000pF
TEMPERATURE (°C)
–50
RIPPLE REJECTION (dB)
100
1763 G45
0 50
68
66
64
62
60
58
56
54
52
–25 25 75 125
VIN = VOUT (NOMINAL) +
1V + 0.5VP-P RIPPLE
AT f = 120Hz
IL = 500mA
For more information www.linear.com/LT1763
LT1763 Series
11
1763fh
Typical perForMance characTerisTics
Output Noise Spectral Density
CBYP = 0
LT1763
Minimum Input Voltage Load Regulation
TEMPERATURE (°C)
–50
MINIMUM INPUT VOLTAGE (V)
050 75
1763 G46
–25 25 100 125
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
IL = 1mA
VOUT = 1.22V
IL = 500mA
TEMPERATURE (°C)
–50
LOAD REGULATION (mV)
100
1763 G47
0 50–25 25 75 125
5
0
–5
–10
–15
–20
–25
VIN = VOUT(NOMINAL) + 1V
IL = 1mA TO 500mA
LT1763
LT1763-5
LT1763-3
LT1763-3.3
LT1763-1.5
LT1763-1.8
LT1763-2.5
FREQUENCY (Hz)
10 1k 10k 100k
1763 G48
100
10
1
0.1
0.01
OUTPUT NOISE SPECTRAL DENSITY (µV/
Hz)
COUT = 10µF
IL = 500mA
LT1763
LT1763-5
LT1763-1.5
LT1763-2.5
LT1763-1.8
LT1763-3.3
LT1763-3
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 1000pF
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 0
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 100pF
1ms/DIV
VOUT
100µV/DIV
COUT = 10µF
IL = 500mA
1763 G52 1ms/DIV
VOUT
100µV/DIV
COUT = 10µF
IL = 500mA
1763 G53 1ms/DIV
VOUT
100µV/DIV
COUT = 10µF
IL = 500mA
1763 G54
Output Noise Spectral Density RMS Output Noise
vs Bypass Capacitor
RMS Output Noise
vs Load Current (10Hz to 100kHz)
FREQUENCY (Hz)
10 1k 10k 100k
1763 G49
100
10
1
0.1
0.01
OUTPUT NOISE SPECTRAL DENSITY (µV/Hz)
LT1763
LT1763-5 CBYP = 1000pF
CBYP = 0.01µF
CBYP = 100pF
COUT = 10µF
IL = 500mA
CBYP (pF)
10
OUTPUT NOISE (µVRMS)
160
140
120
100
80
60
40
20
0
100 1000 10000
1763 G50
COUT = 10µF
IL = 500mA
f = 10Hz TO 100kHz
LT1763-5
LT1763-3.3
LT1763
LT1763-1.5
LT1763-3
LT1763-2.5
LT1763-1.8
LOAD CURRENT (mA)
0.01
OUTPUT NOISE (µVRMS)
160
140
120
100
80
60
40
20
0
0.1 1
1763 G51
10 100 1000
COUT = 10µF
LT1763-5
LT1763-5
LT1763
LT1763
CBYP = 0
CBYP = 0.01µF
For more information www.linear.com/LT1763
LT1763 Series
12
1763fh
Typical perForMance characTerisTics
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 0.01µF
LT1763-5
Transient Response
CBYP = 0
LT1763-5
Transient Response
CBYP = 0.01µF
1ms/DIV
VOUT
100µV/DIV
COUT = 10µF
IL = 500mA
1763 G55
TIME (µs)
0.4
0.2
0
–0.2
–0.4
OUTPUT VOLTAGE
DEVIATION (V)
600
400
200
0
LOAD CURRENT
(mA)
1763 G56
0 200 400 600 800 1000
VIN = 6V
CIN = 10µF
COUT = 10µF
TIME (µs)
0.10
0.05
0
–0.05
–0.10
OUTPUT VOLTAGE
DEVIATION (V)
600
400
200
0
LOAD CURRENT
(mA)
1763 G57
0 20 30 50 70 9010 40 60 80 100
VIN = 6V
CIN = 10µF
COUT = 10µF
For more information www.linear.com/LT1763
LT1763 Series
13
1763fh
pin FuncTions
NC (Pins 1, 4, 9, 12) DE12 Only: No Connect. No connect
pins have no connection to any internal circuitry. These
pins may be tied to either GND or VIN, or left floating.
OUT (Pins 2, 3/Pin 1): Output. The output supplies power
to the load. A minimum output capacitor of 3.3µF is re-
quired to prevent oscillations. Larger output capacitors
will be required for applications with large transient loads
to limit peak voltage transients. See the Applications Infor-
mation section for more information on output capacitance
and reverse output characteristics.
ADJ (Pin 5/Pin 2): Adjust. For the adjustable LT1763, this
is the input to the error amplifier. This pin is internally
clamped to ±7V. It has a bias current of 30nA which flows
into the pin (see the curve of ADJ Pin Bias Current vs
Temperature in the Typical Performance Characteristics
section). The ADJ pin voltage is 1.22V referenced to ground
and the output voltage range is 1.22V to 20V.
SENSE (Pin 5/Pin 2): Output Sense. For fixed volt-
age versions of the LT1763 (LT1763-1.5/LT1763-1.8/
LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5), the SENSE
pin is the input to the error amplifier. Optimum regula-
tion will be obtained at the point where the SENSE pin
is connected to the OUT pin of the regulator. In critical
applications, small voltage drops are caused by the re-
sistance (RP) of PC traces between the regulator and the
load. These may be eliminated by connecting the SENSE
pin to the output at the load as shown in Figure 1 (Kelvin
Sense Connection).
BYP (Pin 6/Pin 4): Bypass. The BYP pin is used to bypass
the reference of the LT1763 regulators to achieve low noise
performance from the regulator. The BYP pin is clamped
internally to ±0.6V (one VBE). A small capacitor from the
output to this pin will bypass the reference to lower the
output voltage noise. A maximum value of 0.01µF can
be used for reducing output voltage noise to a typical
20µVRMS over a 10Hz to 100kHz bandwidth. If not used,
this pin must be left unconnected.
GND (Pins 7, Exposed Pad Pin 13/Pins 3, 6, 7): Ground.
The exposed pad of the DFN package is an electrical con-
nection to GND. To ensure proper electrical and thermal
performance, solder Pin 13 to the PCB ground and tie
directly to Pin 7. Connect the bottom of the output volt-
age setting resistor divider directly to the GND pins for
optimum load regulation performance.
SHDN (Pin 8/Pin 5): Shutdown. The SHDN pin is used
to put the LT1763 regulators into a low power shutdown
state. The output will be off when the SHDN pin is pulled
low. The SHDN pin can be driven either by 5V logic or
open-collector logic with a pull-up resistor. The pull-up
resistor is required to supply the pull-up current of the
open-collector gate, normally several microamperes, and
the SHDN pin current, typically 1µA. If unused, the SHDN
pin must be connected to VIN. The device will be in the low
power shutdown state if the SHDN pin is not connected.
IN (Pin 10, 11/Pin 8): Input. Power is supplied to the device
through the IN pin. A bypass capacitor is required on this
pin if the device is more than six inches away from the
main input filter capacitor. In general, the output imped-
ance of a battery rises with frequency, so it is advisable to
include a bypass capacitor in battery-powered circuits. A
bypass capacitor in the range of 1µF to 10µF is sufficient.
The LT1763 regulators are designed to withstand reverse
voltages on the IN pin with respect to ground and the OUT
pin. In the case of a reverse input, which can happen if
a battery is plugged in backwards, the device will act as
if there is a diode in series with its input. There will be
no reverse current flow into the regulator and no reverse
voltage will appear at the load. The device will protect both
itself and the load.
(DE12/S8)
Note that the voltage drop across the external PC traces will
add to the dropout voltage of the regulator. The SENSE pin
bias current is 10µA at the nominal rated output voltage. The
SENSE pin can be pulled below ground (as in a dual supply
system where the regulator load is returned to a negative
supply) and still allow the device to start and operate.
IN
SHDN
1763 F01
RP
OUT
VIN SENSE
GND
LT1763
RP
3
2
1
5
8
+
+LOAD
Figure 1. Kelvin Sense Connection
For more information www.linear.com/LT1763
LT1763 Series
14
1763fh
The LT1763 series are 500mA low dropout regulators with
micropower quiescent current and shutdown. The devices
are capable of supplying 500mA at a dropout voltage of
300mV. Output voltage noise can be lowered to 20µVRMS
over a 10Hz to 100kHz bandwidth with the addition of
a 0.01µF reference bypass capacitor. Additionally, the
reference bypass capacitor will improve transient response
of the regulator, lowering the settling time for transient load
conditions. The low operating quiescent current (30µA)
drops to less than 1µA in shutdown. In addition to the
low quiescent current, the LT1763 regulators incorporate
several protection features which make them ideal for use
in battery-powered systems. The devices are protected
against both reverse input and reverse output voltages.
In battery backup applications where the output can be
held up by a backup battery when the input is pulled to
ground, the LT1763-X acts like it has a diode in series with
its output and prevents reverse current flow. Additionally,
in dual supply applications where the regulator load is
returned to a negative supply, the output can be pulled
below ground by as much as 20V and still allow the device
to start and operate.
Adjustable Operation
The adjustable version of the LT1763 has an output voltage
range of 1.22V to 20V. The output voltage is set by the
ratio of two external resistors, as shown in Figure 2. The
device servos the output to maintain the ADJ pin voltage
at 1.22V referenced to ground. The current in R1 is then
equal to 1.22V/R1 and the current in R2 is the current
in R1 plus the ADJ pin bias current. The ADJ pin bias
current, 30nA at 25°C, flows through R2 into the ADJ pin.
The output voltage can be calculated using the formula in
Figure 2. The value of R1 should be no greater than 250k
to minimize errors in the output voltage caused by the
ADJ pin bias current. Note that in shutdown the output
is turned off and the divider current will be zero. Curves
of ADJ Pin Voltage vs Temperature and ADJ Pin Bias
Current vs Temperature appear in the Typical Performance
Characteristics section.
The adjustable device is tested and specified with the ADJ
pin tied to the OUT pin for an output voltage of 1.22V.
Specifications for output voltages greater than 1.22V will
be proportional to the ratio of the desired output voltage
applicaTions inForMaTion
Figure 2. Adjustable Operation
to 1.22V: VOUT/1.22V. For example, load regulation for an
output current change of 1mA to 500mA is –2mV typical
at VOUT = 1.22V. At VOUT = 12V, load regulation is:
(12V/1.22V)(–2mV) = –19.6mV
Bypass Capacitance and Low Noise Performance
The LT1763 regulators may be used with the addition of
a bypass capacitor from VOUT to the BYP pin to lower
output voltage noise. A good quality low leakage capacitor
is recommended. This capacitor will bypass the reference
of the regulator, providing a low frequency noise pole.
The noise pole provided by this bypass capacitor will
lower the output voltage noise to as low as 20µVRMS
with the addition of a 0.01µF bypass capacitor. Using
a bypass capacitor has the added benefit of improving
transient response. With no bypass capacitor and a 10µF
output capacitor, a 10mA to 500mA load step will settle
to within 1% of its final value in less than 100µs. With
the addition of a 0.01µF bypass capacitor, the output will
settle to within 1% for a 10mA to 500mA load step in less
than 10µs, with total output voltage deviation of less than
2.5% (see the LT1763-5 Transient Response curve in the
Typical Performance Characteristics section). However,
regulator start-up time is proportional to the size of the
bypass capacitor, slowing to 15ms with a 0.01µF bypass
capacitor and 10µF output capacitor.
IN
1763 F02
R2
OUT
VIN
VOUT
ADJ
GND
LT1763
R1
+
VV
R
R
IR
VV
InA
OUT ADJ
ADJ
ADJ
=+
+
()
()
=
1221
2
12
122
30
.
.
AT 25 C
OUTPUT RANGE = 1.22V TO 20V
For more information www.linear.com/LT1763
LT1763 Series
15
1763fh
Output Capacitance and Transient Response
The LT1763 regulators are designed to be stable with a
wide range of output capacitors. The ESR of the output
capacitor affects stability, most notably with small capaci-
tors. A minimum output capacitor of 3.3µF with an ESR
of 3Ω, or less, is recommended to prevent oscillations.
The LT1763-X is a micropower device and output transient
response will be a function of output capacitance. Larger
values of output capacitance decrease the peak deviations
and provide improved transient response for larger load
current changes. Bypass capacitors, used to decouple
individual components powered by the LT1763-X, will
increase the effective output capacitor value. With larger
capacitors used to bypass the reference (for low noise
operation), larger values of output capacitors are needed.
For 100pF of bypass capacitance, 4.7µF of output capaci-
tor is recommended. With a 1000pF bypass capacitor or
larger, a 6.8µF output capacitor is recommended.
The shaded region of Figure 3 defines the range over
which the LT1763 regulators are stable. The minimum ESR
needed is defined by the amount of bypass capacitance
used, while the maximum ESR is 3Ω.
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior across
temperature and applied voltage. The most common
dielectrics used are specified with EIA temperature
characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U
and Y5V dielectrics are good for providing high capacitances
in a small package, but they tend to have strong voltage
and temperature coefficients, as shown in Figures 4
and 5. When used with a 5V regulator, a 16V 10µF Y5V
capacitor can exhibit an effective value as low as 1µF to
2µF for the DC bias voltage applied and over the operating
temperature range. The X5R and X7R dielectrics result in
more stable characteristics and are more suitable for use
as the output capacitor. The X7R type has better stability
across temperature, while the X5R is less expensive and is
available in higher values. Care still must be exercised when
using X5R and X7R capacitors; the X5R and X7R codes
only specify operating temperature range and maximum
capacitance change over temperature. Capacitance change
due to DC bias with X5R and X7R capacitors is better than
applicaTions inForMaTion
OUTPUT CAPACITANCE (µF)
1
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
3 10
1763 F03
2 4 5 67 8 9
STABLE REGION
CBYP = 330pF
CBYP 1000pF
CBYP = 100pF
CBYP = 0
Figure 3. Stability
DC BIAS VOLTAGE (V)
CHANGE IN VALUE (%)
1763 F04
20
0
–20
–40
–60
–80
–100 04810
2 6 12 14
X5R
Y5V
16
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
TEMPERATURE (°C)
–50
40
20
0
–20
–40
–60
–80
–100
25 75
1763 F05
–25 0 50 100 125
Y5V
CHANGE IN VALUE (%)
X5R
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
Figure 4. Ceramic Capacitor DC Bias Characteristics
Figure 5. Ceramic Capacitor Temperature Characteristics
For more information www.linear.com/LT1763
LT1763 Series
16
1763fh
Figure 6. Noise Resulting from
Tapping on a Ceramic Capacitor
Y5V and Z5U capacitors, but can still be significant enough
to drop capacitor values below appropriate levels. Capacitor
DC bias characteristics tend to improve as component
case size increases, but expected capacitance at operating
voltage should be verified.
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates
voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric accelerometer or
microphone works. For a ceramic capacitor, the stress
can be induced by vibrations in the system or thermal
transients. The resulting voltages produced can cause
appreciable amounts of noise, especially when a ceramic
capacitor is used for noise bypassing. A ceramic capacitor
produced Figure 6’s trace in response to light tapping from a
pencil. Similar vibration induced behavior can masquerade
as increased output voltage noise.
Thermal Considerations
The power handling capability of the device will be limited
by the maximum rated junction temperature (125°C). The
power dissipated by the device will be made up of two
components:
1. Output current multiplied by the input/output voltage
differential: (IOUT)(VIN – VOUT), and
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
The GND pin current can be found by examining the GND
Pin Current curves in the Typical Performance Character-
istics section. Power dissipation will be equal to the sum
of the two components listed above.
The LT1763 series regulators have internal thermal limiting
designed to protect the device during overload conditions.
For continuous normal conditions, the maximum junction
temperature rating of 125°C must not be exceeded. It is
important to give careful consideration to all sources of
thermal resistance from junction-to-ambient. Additional
heat sources mounted nearby must also be considered.
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Copper board stiffeners and plated
through-holes can also be used to spread the heat gener-
ated by power devices.
The following tables list thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 3/32" FR-4 board with one ounce
copper.
Table 1. DE Package, 12-Lead DFN
COPPER AREA
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)TOPSIDE* BACKSIDE
2500mm22500mm22500mm240°C/W
1000mm22500mm22500mm245°C/W
225mm22500mm22500mm250°C/W
100mm22500mm22500mm260°C/W
* Device is mounted on topside
applicaTions inForMaTion
100ms/DIV
VOUT
500µV/DIV
1763 F06
LT1763-5
COUT = 10µF
CBYP = 0.01µF
ILOAD = 100mA
For more information www.linear.com/LT1763
LT1763 Series
17
1763fh
applicaTions inForMaTion
Table 2. SO-8 Package, 8-Lead SO
COPPER AREA
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)TOPSIDE* BACKSIDE
2500mm
2
2500mm
2
2500mm
2
60°C/W
1000mm
2
2500mm
2
2500mm
2
60°C/W
225mm
2
2500mm
2
2500mm
2
68°C/W
100mm
2
2500mm
2
2500mm
2
74°C/W
50mm
2
2500mm
2
2500mm
2
86°C/W
* Device is mounted on topside
Calculating Junction Temperature
Example: Given an output voltage of 3.3V, an input voltage
range of 4V to 6V, an output current range of 0mA to 250mA
and a maximum ambient temperature of 50°C, what will
the maximum junction temperature be?
The power dissipated by the device will be equal to:
IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX))
where,
IOUT(MAX) = 250mA
VIN(MAX) = 6V
IGND at (IOUT = 250mA, VIN = 6V) = 5mA
So,
P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W
The thermal resistance will be in the range of 60°C/W to
86°C/W, depending on the copper area. So, the junction
temperature rise above ambient will be approximately
equal to:
0.71W(75°C/W) = 53.3°C
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature, or:
TJMAX = 50°C + 53.3°C = 103.3°C
Protection Features
The LT1763 regulators incorporate several protection
features which make them ideal for use in battery-powered
circuits. In addition to the normal protection features
associated with monolithic regulators, such as current
limiting and thermal limiting, the devices are protected
against reverse input voltages, reverse output voltages
and reverse voltages from output to input.
Current limit protection and thermal overload protection
are intended to protect the device against current overload
conditions at the output of the device. For normal operation,
the junction temperature should not exceed 125°C.
The input of the device will withstand reverse voltages of
20V. Current flow into the device will be limited to less
than 1mA (typically less than 100µA) and no negative
voltage will appear at the output. The device will protect
both itself and the load. This provides protection against
batteries which can be plugged in backward.
The output of the LT1763-X can be pulled below ground
without damaging the device. If the input is left open-circuit
or grounded, the output can be pulled below ground by
20V. For fixed voltage versions, the output will act like a
large resistor, typically 500k or higher, limiting current flow
to less than 100µA. For adjustable versions, the output
will act like an open circuit; no current will flow out of the
pin. If the input is powered by a voltage source, the output
will source the short-circuit current of the device and will
protect itself by thermal limiting. In this case, grounding
the SHDN pin will turn off the device and stop the output
from sourcing the short-circuit current.
The ADJ pin of the adjustable device can be pulled above
or below ground by as much as 7V without damaging the
device. If the input is left open-circuit or grounded, the
ADJ pin will act like an open circuit when pulled below
ground and like a large resistor (typically 100k) in series
with a diode when pulled above ground.
In situations where the ADJ pin is connected to a resistor
divider that would pull the ADJ pin above its 7V clamp
voltage if the output is pulled high, the ADJ pin input current
must be limited to less than 5mA. For example, a resistor
divider is used to provide a regulated 1.5V output from the
1.22V reference when the output is forced to 20V.
For more information www.linear.com/LT1763
LT1763 Series
18
1763fh
Figure 7. Reverse Output Current
The top resistor of the resistor divider must be chosen to
limit the current into the ADJ pin to less than 5mA when
the ADJ pin is at 7V. The 13V difference between output
and ADJ pin divided by the 5mA maximum current into the
ADJ pin yields a minimum top resistor value of 2.6k.
In circuits where a backup battery is required, several
different input/output conditions can occur. The output
voltage may be held up while the input is either pulled
to ground, pulled to some intermediate voltage or is left
open-circuit. Current flow back into the output will follow
the curve shown in Figure 7.
When the IN pin of the LT1763-X is forced below the OUT
pin, or the OUT pin is pulled above the IN pin, input cur-
rent will typically drop to less than 2µA. This can happen
if the input of the device is connected to a discharged
(low voltage) battery and the output is held up by either
a backup battery or a second regulator circuit. The state
of the SHDN pin will have no effect on the reverse output
current when the output is pulled above the input.
OUTPUT VOLTAGE (V)
100
90
80
70
60
50
40
30
20
10
0
REVERSE OUTPUT CURRENT (µA)
1763 F07
0123456 7 8 9 10
TJ = 25°C
VIN = 0V
CURRENT FLOWS
INTO OUTPUT PIN
VOUT = VADJ (LT1763)
LT1763
LT1763-5
LT1763-3.3
LT1763-1.5
LT1763-1.8
LT1763-2.5
LT1763-3
applicaTions inForMaTion
For more information www.linear.com/LT1763
LT1763 Series
19
1763fh
package DescripTion
DE/UE Package
12-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
4.00 ±0.10
(2 SIDES)
3.00 ±0.10
(2 SIDES)
NOTE:
1. DRAWING PROPOSED TO BE A VARIATION OF VERSION
(WGED) IN JEDEC PACKAGE OUTLINE M0-229
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
0.40 ± 0.10
BOTTOM VIEW—EXPOSED PAD
1.70 ± 0.10
0.75 ±0.05
R = 0.115
TYP
R = 0.05
TYP
2.50 REF
16
127
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
0.00 – 0.05
(UE12/DE12) DFN 0806 REV D
2.50 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
2.20 ±0.05
0.70 ±0.05
3.60 ±0.05
PACKAGE OUTLINE
3.30 ±0.10
0.25 ± 0.05
0.50 BSC
1.70 ± 0.05
3.30 ±0.05
0.50 BSC
0.25 ± 0.05
For more information www.linear.com/LT1763
LT1763 Series
20
1763fh
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 REV G 0212
.053 – .069
(1.346 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
For more information www.linear.com/LT1763
LT1763 Series
21
1763fh
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
G 5/10 Updated Order Information to add MP-grade to all versions of DFN package
Revised Line Regulation section of Electrical Characteristics
Consolidated GND and exposed pad descriptions in Pin Descriptions section
Added LT3085 to Related Parts
2 to 4
5
14
22
H 11/14 Updated Order Information Table to add MP-grade to LT1763-2.5 and LT1763-5 in SO-8 package. 2-3
(Revision history begins at Rev G)
For more information www.linear.com/LT1763
LT1763 Series
22
1763fh
LINEAR TECHNOLOGY CORPORATION 1999
LT 1114 REV H • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507 www.linear.com/LT1763
relaTeD parTs
Typical applicaTion
PART NUMBER DESCRIPTION COMMENTS
LT1120 125mA Low Dropout Regulator with 20µA IQIncludes 2.5V Reference and Comparator
LT1121 150mA Micropower Low Dropout Regulator 30µA IQ, SOT-223 Package
LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current
LT1175 500mA Negative Low Dropout Micropower Regulator 45µA IQ, 0.26V Dropout Voltage, SOT-223 Package
LT1521 300mA Low Dropout Micropower Regulator with Shutdown 15µA IQ, Reverse Battery Protection
LT1529 3A Low Dropout Regulator with 50µA IQ500mV Dropout Voltage
LT1613 1.4MHz Single-Cell Micropower DC/DC Converter SOT-23 Package, Internally Compensated
LT1761 Series 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20µA Quiescent Current, 20µVRMS Noise, ThinSOT™
LT1762 Series 150mA, Low Noise, LDO Micropower Regulators 25µA Quiescent Current, 20µVRMS Noise, MS8
LT1764A 3A, Fast Transient Response Low Dropout Regulator 340mV Dropout Voltage, DD, TO220
LT1962 300mA, Fast Transient Response Low Dropout Regulator 270mV Dropout Voltage, 20µVRML, MS8
LT1963A 1.5A, Fast Transient Response Low Dropout Regulator 340mV Dropout Voltage, 40µVRML, DD, TO220, S8, SOT-223
LT3010 50mA, 80V Low Noise, LDO Micropower Regulator 300mV Dropout Voltage, MS8E
LT3021 500mA, Low Voltage, Very Low Dropout Linear Regulator 160mV Dropout Voltage, DFN-8 and SOIC-8 Packages
LT3085 500mA Parallelable, Low Noise, Low Dropout Linear Regulator 275mV Dropout Voltage (2 Supply Operation), MSOP-8 and
2mm × 3mm DFN-6 Packages
Paralleling of Regulators for Higher Output Current
C4
0.01µF
R1
0.1Ω
R2
0.1Ω
R5
10k
R4
2.2k
R7
1.21k
C2
10µF
1763 TA03
VIN > 3.8V
3.3V
1A
C5
0.01µF
8
1
3
2
4C3
0.01µF
IN
SHDN
OUT
SENSE
BYP
GND
LT1763-3.3
IN
SHDN
OUT
BYP
ADJ
GND
LT1763
SHDN
+
C1
10µF
+
+
1/2 LT1490
R6
2k
R3
2.2k

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