LT1763 Series
1
1763fg
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 fi xed 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
regulators are available in 8-lead SO and 12-lead, low
profi le (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.
LT1763 Series
2
1763fg
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 ........................ Indefi nite
(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/LT1763-1.8/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
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
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
LT1763 Series
3
1763fg
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
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
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
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1763CDE LT1763CDE#TR 1763 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE LT1763IDE#TR 1763 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE LT1763MPDE#TR 1763 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
LT1763CDE-1.5 LT1763CDE-1.5#TR 76315 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE-1.5 LT1763IDE-1.5#TR 76315 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE-1.5 LT1763MPDE-1.5#TR 76315 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
LT1763CDE-1.8 LT1763CDE-1.8#TR 76318 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE-1.8 LT1763IDE-1.8#TR 76318 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE-1.8 LT1763MPDE-1.8#TR 76318 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
LT1763CDE-2.5 LT1763CDE-2.5#TR 76325 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE-2.5 LT1763IDE-2.5#TR 76325 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE-2.5 LT1763MPDE-2.5#TR 76325 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
LT1763CDE-3 LT1763CDE-3#TR 17633 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE-3 LT1763IDE-3#TR 17633 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE-3 LT1763MPDE-3#TR 17633 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
ORDER INFORMATION
LT1763 Series
4
1763fg
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
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. (Note 2)
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1763CDE-3.3 LT1763CDE-3.3#TR 76333 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE-3.3 LT1763IDE-3.3#TR 76333 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE-3.3 LT1763MPDE-3.3#TR 76333 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
LT1763CDE-5 LT1763CDE-5#TR 17635 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763IDE-5 LT1763IDE-5#TR 17635 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C
LT1763MPDE-5 LT1763MPDE-5#TR 17635 12-Lead (4mm × 3mm) Plastic DFN –55°C to 125°C
LT1763CS8 LT1763CS8#TR 1763 8-Lead Plastic SO –40°C to 125°C
LT1763IS8 LT1763IS8#TR 1763 8-Lead Plastic SO –40°C to 125°C
LT1763MPS8 LT1763MPS8#TR 1763MP 8-Lead Plastic SO –55°C to 125°C
LT1763CS8-1.5 LT1763CS8-1.5#TR 176315 8-Lead Plastic SO –40°C to 125°C
LT1763IS8-1.5 LT1763IS8-1.5#TR 176315 8-Lead Plastic SO –40°C to 125°C
LT1763CS8-1.8 LT1763CS8-1.8#TR 176318 8-Lead Plastic SO –40°C to 125°C
LT1763IS8-1.8 LT1763IS8-1.8#TR 176318 8-Lead Plastic SO –40°C to 125°C
LT1763CS8-2.5 LT1763CS8-2.5#TR 176325 8-Lead Plastic SO –40°C to 125°C
LT1763IS8-2.5 LT1763IS8-2.5#TR 176325 8-Lead Plastic SO –40°C to 125°C
LT1763CS8-3 LT1763CS8-3#TR 17633 8-Lead Plastic SO –40°C to 125°C
LT1763IS8-3 LT1763IS8-3#TR 17633 8-Lead Plastic SO –40°C to 125°C
LT1763CS8-3.3 LT1763CS8-3.3#TR 176333 8-Lead Plastic SO –40°C to 125°C
LT1763IS8-3.3 LT1763IS8-3.3#TR 176333 8-Lead Plastic SO –40°C to 125°C
LT1763CS8-5 LT1763CS8-5#TR 17635 8-Lead Plastic SO –40°C to 125°C
LT1763IS8-5 LT1763IS8-5#TR 17635 8-Lead Plastic SO –40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
ORDER INFORMATION
LT1763 Series
5
1763fg
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
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: ΔVIN = 2V to 20V, ILOAD = 1mA
LT1763-1.5 MP Grade: ΔVIN = 2.1V to 20V, ILOAD = 1mA
LT1763-1.8 ΔVIN = 2.3V to 20V, ILOAD = 1mA
LT1763-2.5 ΔVIN = 3V to 20V, ILOAD = 1mA
LT1763-3 ΔVIN = 3.5V to 20V, ILOAD = 1mA
LT1763-3.3 ΔVIN = 3.8V to 20V, ILOAD = 1mA
LT1763-5 ΔVIN = 5.5V to 20V, ILOAD = 1mA
LT1763 (Note 3) C, I Grade: ΔVIN = 2V to 20V, ILOAD = 1mA
LT1763 (Note 3) MP Grade: ΔVIN = 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 LT1763-1.5 VIN = 2.5V, ΔILOAD = 1mA to 500mA
V
IN = 2.5V, ΔILOAD = 1mA to 500mA l
38
15
mV
mV
LT1763-1.8 VIN = 2.8V, ΔILOAD = 1mA to 500mA
V
IN = 2.8V, ΔILOAD = 1mA to 500mA l
49
18
mV
mV
LT1763-2.5 VIN = 3.5V, ΔILOAD = 1mA to 500mA
V
IN = 3.5V, ΔILOAD = 1mA to 500mA l
512
25
mV
mV
LT1763-3 VIN = 4V, ΔILOAD = 1mA to 500mA
V
IN = 4V, ΔILOAD = 1mA to 500mA l
715
30
mV
mV
LT1763-3.3 VIN = 4.3V, ΔILOAD = 1mA to 500mA
V
IN = 4.3V, ΔILOAD = 1mA to 500mA l
717
33
mV
mV
LT1763-5 VIN = 6V, ΔILOAD= 1mA to 500mA
V
IN = 6V, ΔILOAD = 1mA to 500mA l
12 25
50
mV
mV
LT1763 (Note 3) VIN = 2.3V, ΔILOAD = 1mA to 500mA
C, I Grade: VIN = 2.3V, ΔILOAD = 1mA to 500mA
MP Grade: VIN = 2.35V, ΔILOAD = 1mA to 500mA
l
l
26
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
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
l0.25
0.8
0.65
2V
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
LT1763 Series
6
1763fg
ELECTRICAL CHARACTERISTICS
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 specifi ed 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 specifi ed 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 specifi cation 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 specifi ed 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 specifi ed 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 fl ows into the ADJ pin.
Note 9: SHDN pin current fl ows 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 fl ows 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 specifi cation 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.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Current Limit VIN = 7V, VOUT = 0V
C, I Grade: VIN = VOUT(NOMINAL) + 1V or 2.3V (Note 12), ΔVOUT = –0.1V
MP Grade: VIN = 2.35V (Note 12), ΔVOUT = –0.1V
l
l
520
520
mA
mA
Input Reverse Leakage Current VIN = –20V, VOUT = 0V l1mA
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
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. (Note 2)
LT1763 Series
7
1763fg
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
TJb 125°C
TJb 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
050–25 25 75 125
50
45
40
35
30
25
20
15
10
5
0
VIN = 6V
RL = d, 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
050
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
050
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
050
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
050
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
050
3.360
3.345
3.330
3.315
3.300
3.285
3.270
3.255
3.240
–25 25 75 125
IL = 1mA
LT1763 Series
8
1763fg
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-5
Output Voltage
LT1763
ADJ Pin Voltage
LT1763-1.5
Quiescent Current
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
100
1763 G10
050
5.100
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
050
1.240
1.235
1.230
1.225
1.220
1.215
1.210
1.205
1.200
–25 25 75 12
5
IL = 1mA
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (μA)
250
225
200
175
150
125
100
75
50
25
08
1763 G12
213579
4610
VSHDN = VIN
TJ = 25°C
RL = d
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)
250
225
200
175
150
125
100
75
50
25
08
1763 G13
213579
4610
VSHDN = VIN
TJ = 25°C
RL = d
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (μA)
250
225
200
175
150
125
100
75
50
25
08
1763 G14
213579
4610
VSHDN = VIN
TJ = 25°C
RL = d
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (μA)
250
225
200
175
150
125
100
75
50
25
08
1763 G15
213579
4610
VSHDN = VIN
TJ = 25°C
RL = d
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (μA)
250
225
200
175
150
125
100
75
50
25
08
1763 G16
213579
4610
VSHDN = VIN
TJ = 25°C
RL = d
VSHDN = 0V
INPUT VOLTAGE (V)
0
QUIESCENT CURRENT (μA)
250
225
200
175
150
125
100
75
50
25
08
1763 G17
213579
4610
VSHDN = VIN
TJ = 25°C
RL = d
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
LT1763 Series
9
1763fg
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
RL = 3.6Ω
IL = 500mA*
RL = 6Ω
IL = 300mA*
RL = 18Ω
IL = 100mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
LT1763 Series
10
1763fg
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
012345678910
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
LT1763 Series
11
1763fg
TYPICAL PERFORMANCE CHARACTERISTICS
SHDN Pin Input Current ADJ Pin Bias Current Current Limit
TEMPERATURE (°C)
–50
SHDN PIN INPUT CURRENT (μA)
100
1763 G37
050
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
012345678910
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
050
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
LT1763 Series
12
1763fg
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
050–25 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
LT1763 Series
13
1763fg
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
0203050709010 40 60 80 100
VIN = 6V
CIN = 10μF
COUT = 10μF
LT1763 Series
14
1763fg
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 fl oating.
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 amplifi er. This pin is internally
clamped to ±7V. It has a bias current of 30nA which fl ows
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 fi xed 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 amplifi er. 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 fi lter 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 suffi cient.
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 fl ow 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
LT1763 Series
15
1763fg
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 fl ow. 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, fl ows 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 specifi ed with the ADJ
pin tied to the OUT pin for an output voltage of 1.22V.
Specifi cations 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 benefi t 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 fi nal 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
RIR
VV
InA
OUT ADJ
ADJ
ADJ
=+
⎛
⎝
⎜⎞
⎠
⎟+
()()
=
=°
122 1 2
12
122
30
.
.
AT 25 C
OUTPUT RANGE = 1.22V TO 20V
LT1763 Series
16
1763fg
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 defi nes the range over
which the LT1763 regulators are stable. The minimum ESR
needed is defi ned 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 specifi ed 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 coeffi cients, 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
ESR (Ω)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
310
1763 F03
245
678
9
STABLE REGION
CBYP = 330pF
CBYP r 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
26 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
LT1763 Series
17
1763fg
Figure 6. Noise Resulting from
Tapping on a Ceramic Capacitor
Y5V and Z5U capacitors, but can still be signifi cant 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 verifi ed.
Voltage and temperature coeffi cients 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
LT1763 Series
18
1763fg
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:
I
OUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX))
where,
I
OUT(MAX) = 250mA
V
IN(MAX) = 6V
I
GND 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:
T
JMAX = 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 fl ow 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 fi xed voltage versions, the output will act like a
large resistor, typically 500k or higher, limiting current fl ow
to less than 100μA. For adjustable versions, the output
will act like an open circuit; no current will fl ow 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.
LT1763 Series
19
1763fg
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 fl ow 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
012345678910
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
LT1763 Series
20
1763fg
PACKAGE DESCRIPTION
DE/UE Package
12-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)s 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.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)
4.00 p0.10
(2 SIDES)
3.00 p0.10
(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 p 0.10
BOTTOM VIEW—EXPOSED PAD
1.70 p 0.10
0.75 p0.05
R = 0.115
TYP
R = 0.05
TYP
2.50 REF
16
127
PIN 1 NOTCH
R = 0.20 OR
0.35 s 45o
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 p0.05
0.70 p0.05
3.60 p0.05
PACKAGE
OUTLINE
3.30 p0.10
0.25 p 0.05
0.50 BSC
1.70 p 0.05
3.30 p0.05
0.50 BSC
0.25 p 0.05
LT1763 Series
21
1763fg
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
(Revision history begins at Rev G)
LT1763 Series
22
1763fg
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1999
LT 0510 REV G • PRINTED IN USA
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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
