LINER LT1763CS8-1.8 500ma, low noise, ldo micropower regulator Datasheet

LT1763 Series
500mA, Low Noise, LDO
Micropower Regulators
FEATURES
DESCRIPTION
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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.
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Low Noise: 20μVRMS (10Hz to 100kHz)
Output Current: 500mA
Low Quiescent Current: 30μA
Wide Input Voltage Range: 1.8V to 20V
Low Dropout Voltage: 300mV
Very Low Shutdown Current: < 1μA
No Protection Diodes Needed
Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3V, 3.3V, 5V
Adjustable Output from 1.22V to 20V
Stable with 3.3μF Output Capacitor
Stable with Aluminum, Tantalum or Ceramic
Capacitors
Reverse Battery Protection
No Reverse Current
Overcurrent and Overtemperature Protected
8-Lead SO and 12-Lead (4mm × 3mm) DFN
Packages
APPLICATIONS
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Cellular Phones
Battery-Powered Systems
Noise-Sensitive Instrumentation Systems
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
regulators are available in 8-lead SO and 12-lead, low
proﬁle (4mm × 3mm × 0.75mm) DFN packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All
other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 6144250, 6118263.
TYPICAL APPLICATION
Dropout Voltage
3.3V Low Noise Regulator
400
VIN
3.7V TO
20V
IN
1μF
OUT
+
SENSE
LT1763-3.3
10μF
0.01μF
SHDN
BYP
GND
1763 TA01
DROPOUT VOLTAGE (mV)
350
3.3V AT 500mA
20μVRMS NOISE
300
250
200
150
100
50
0
0
100
300
400
200
OUTPUT CURRENT (mA)
500
1763 TA02
1763fe
1
LT1763 Series
ABSOLUTE MAXIMUM RATINGS
(Note 1)
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
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
TOP VIEW
NC
1
12 NC
OUT
2
11 IN
OUT
3
10 IN
NC
4
9
NC
SENSE/ADJ*
5
8
SHDN
BYP
6
7
GND
13
TOP VIEW
OUT 1
8
IN
SENSE/ADJ* 2
7
GND
GND 3
6
GND
BYP 4
5
SHDN
S8 PACKAGE
8-LEAD PLASTIC SO
DE PACKAGE
12-LEAD (4mm s 3mm) PLASTIC DFN
TJMAX = 150°C, θJA = 70°C/W, θJC = 35°C/W
TJMAX = 125°C, θJA = 40°C/W, θJC = 5°C/W
EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB
*PIN 2: SENSE FOR LT1763-1.5/LT1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5
ADJ FOR LT1763
*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.
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
LT1763CDE-1.5#PBF
LT1763CDE-1.5#TRPBF
76315
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-1.8#PBF
LT1763CDE-1.8#TRPBF
76318
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-2.5#PBF
LT1763CDE-2.5#TRPBF
76325
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-3#PBF
LT1763CDE-3#TRPBF
17633
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-3.3#PBF
LT1763CDE-3.3#TRPBF
76333
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-5#PBF
LT1763CDE-5#TRPBF
17635
12-Lead (4mm × 3mm) Plastic DFN
–40°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
1763fe
2
LT1763 Series
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
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
LT1763CDE-1.5
LT1763CDE-1.5#TR
76315
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-1.8
LT1763CDE-1.8#TR
76318
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-2.5
LT1763CDE-2.5#TR
76325
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-3
LT1763CDE-3#TR
17633
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-3.3
LT1763CDE-3.3#TR
76333
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LT1763CDE-5
LT1763CDE-5#TR
17635
12-Lead (4mm × 3mm) Plastic DFN
–40°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 speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed 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 speciﬁcations, go to: http://www.linear.com/tapeandreel/
1763fe
3
LT1763 Series
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
l
l
TYP
MAX
UNITS
1.8
1.8
2.3
2.35
V
V
Minimum Operating Voltage
C, I Grade: ILOAD = 500mA (Notes 3, 11)
MP Grade: ILOAD = 500mA (Notes 3, 11)
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
LT1763-1.8
LT1763-2.5
LT1763-3
LT1763-3.3
LT1763-5
LT1763 (Note 3)
LT1763 (Note 3)
ΔVIN = 2V to 20V, ILOAD = 1mA
ΔVIN = 2.3V to 20V, ILOAD = 1mA
ΔVIN = 3V to 20V, ILOAD = 1mA
ΔVIN = 3.5V to 20V, ILOAD = 1mA
ΔVIN = 3.8V to 20V, ILOAD = 1mA
ΔVIN = 5.5V to 20V, ILOAD = 1mA
C, I Grade: ΔVIN = 2V to 20V, ILOAD = 1mA
MP Grade: ΔVIN = 2.1V to 20V, ILOAD = 1mA
l
l
l
l
l
l
l
l
1
1
1
1
1
1
1
1
5
5
5
5
5
5
5
5
mV
mV
mV
mV
mV
mV
mV
mV
Load Regulation
LT1763-1.5
VIN = 2.5V, ΔILOAD = 1mA to 500mA
VIN = 2.5V, ΔILOAD = 1mA to 500mA
l
3
8
15
mV
mV
LT1763-1.8
VIN = 2.8V, ΔILOAD = 1mA to 500mA
VIN = 2.8V, ΔILOAD = 1mA to 500mA
l
4
9
18
mV
mV
LT1763-2.5
VIN = 3.5V, ΔILOAD = 1mA to 500mA
VIN = 3.5V, ΔILOAD = 1mA to 500mA
l
5
12
25
mV
mV
LT1763-3
VIN = 4V, ΔILOAD = 1mA to 500mA
VIN = 4V, ΔILOAD = 1mA to 500mA
l
7
15
30
mV
mV
LT1763-3.3
VIN = 4.3V, ΔILOAD = 1mA to 500mA
VIN = 4.3V, ΔILOAD = 1mA to 500mA
l
7
17
33
mV
mV
LT1763-5
VIN = 6V, ΔILOAD= 1mA to 500mA
VIN = 6V, ΔILOAD = 1mA to 500mA
l
12
25
50
mV
mV
2
6
12
12
mV
mV
mV
0.13
0.19
0.25
V
V
0.17
0.22
0.32
V
V
0.20
0.24
0.34
V
V
0.30
0.35
0.45
V
V
Dropout Voltage
VIN = VOUT(NOMINAL)
(Notes 5, 6, 11)
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
ILOAD = 10mA
ILOAD = 10mA
l
ILOAD = 50mA
ILOAD = 50mA
l
ILOAD = 100mA
ILOAD = 100mA
l
ILOAD = 500mA
ILOAD = 500mA
l
1763fe
4
LT1763 Series
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
GND Pin Current
VIN = VOUT(NOMINAL)
(Notes 5, 7)
ILOAD = 0mA
ILOAD = 1mA
ILOAD = 50mA
ILOAD = 100mA
ILOAD = 250mA
ILOAD = 500mA
MIN
Output Voltage Noise
COUT = 10μF, CBYP = 0.01μF, ILOAD = 500mA, BW = 10Hz to 100kHz
20
ADJ Pin Bias Current
(Notes 3, 8)
30
100
nA
Shutdown Threshold
VOUT = Off to On
VOUT = On to Off
0.8
0.65
2
V
V
l
l
l
l
l
l
l
l
0.25
TYP
MAX
UNITS
30
65
1.1
2
5
11
75
120
1.6
3
8
16
μA
μA
mA
mA
mA
mA
SHDN Pin Current
(Note 9)
VSHDN = 0V
VSHDN = 20V
0.1
1
Quiescent Current in Shutdown
VIN = 6V, VSHDN = 0V
0.1
Ripple Rejection
VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz,
ILOAD = 500mA
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
Input Reverse Leakage Current
VIN = –20V, VOUT = 0V
l
Reverse Output Current
(Note 10)
LT1763-1.5
LT1763-1.8
LT1763-2.5
LT1763-3
LT1763-3.3
LT1763-5
LT1763 (Note 3)
VOUT = 1.5V, VIN < 1.5V
VOUT = 1.8V, VIN < 1.8V
VOUT = 2.5V, VIN < 2.5V
VOUT = 3V, VIN < 3V
VOUT = 3.3V, VIN < 3.3V
VOUT = 5V, VIN < 5V
VOUT = 1.22V, VIN < 1.22V
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.
50
μVRMS
μA
μA
1
65
μA
dB
520
520
mA
mA
10
10
10
10
10
10
5
1
mA
20
20
20
20
20
20
10
μA
μA
μA
μA
μA
μA
μA
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.
1763fe
5
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
TJ = 125°C
350
300
250
TJ = 25°C
200
150
100
50
0
= TEST POINTS
450
450
400
400
DROPOUT VOLTAGE (mV)
GUARANTEED DROPOUT VOLTAGE (mV)
450
DROPOUT VOLTAGE (mV)
500
500
400
TJ b 125°C
350
300
TJ b 25°C
250
200
150
200
150
50
50 100 150 200 250 300 350 400 450 500
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
40
20
15
125
IL = 1mA
1.521
1.83
1.514
1.82
OUTPUT VOLTAGE (V)
45
100
1.84
IL = 1mA
25
50
25
0
75
TEMPERATURE (°C)
LT1763-1.8
Output Voltage
1.528
30
–25
IL = 10mA
1763 G03
LT1763-1.5
Output Voltage
VSHDN = VIN
IL = 50mA
1763 G02
50
35
IL = 1mA
0
–50
0
Quiescent Current
QUIESCENT CURRENT (μA)
250
50
1763 G01
IL = 100mA
300
100
0
IL = 500mA
IL = 250mA
350
100
50 100 150 200 250 300 350 400 450 500
OUTPUT CURRENT (mA)
0
1.507
1.500
1.493
1.486
1.81
1.80
1.79
1.78
10
VIN = 6V
5 RL = d, IL = 0 (LT1763-1.5/-1.8/-2.5/-3/-3.3/-5)
RL = 250k, IL = 5μA (LT1763)
0
0
25
50
75 100 125
–50 –25
1.77
1.479
1.472
–50
–25
0
25
50
75
100
1.76
–50
125
LT1763-2.5
Output Voltage
2.54
3.030
3.330
OUTPUT VOLTAGE (V)
2.52
OUTPUT VOLTAGE (V)
3.345
3.015
3.000
2.985
2.970
0
25
50
75
100
125
TEMPERATURE (°C)
2.940
–50
–25
0
25
50
75
100
125
3.300
3.285
3.270
3.240
–50
–25
0
25
50
75
100
125
TEMPERATURE (°C)
TEMPERATURE (°C)
1763 G07
3.315
3.255
2.955
–25
125
IL = 1mA
3.045
2.47
100
3.360
2.53
2.48
75
LT1763-3.3
Output Voltage
IL = 1mA
2.49
50
1763 G06
3.060
IL = 1mA
2.50
25
TEMPERATURE (°C)
LT1763-3
Output Voltage
2.51
0
1763 G05
1763 G04
2.46
–50
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
Dropout Voltage
Guaranteed Dropout Voltage
Typical Dropout Voltage
500
1763 G08
1763 G09
1763fe
6
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-5
Output Voltage
LT1763
ADJ Pin Voltage
5.100
250
1.240
IL = 1mA
1.235
5.050
1.230
5.025
5.000
4.975
4.950
IL = 1mA
1.225
1.220
1.215
1.210
4.925
1.205
4.900
–50
1.200
–50
0
–25
25
50
75
100
125
0
–25
25
50
75
100
150
125
100
75
VSHDN = VIN
3 4 5 6 7
INPUT VOLTAGE (V)
175
150
125
100
75
50
8
9
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
125
100
75
VSHDN = VIN
1
2
150
125
100
75
50
3 4 5 6 7
INPUT VOLTAGE (V)
8
10
1763 G16
VSHDN = 0V
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1763 G15
LT1763
Quiescent Current
40
175
150
125
100
75
50
VSHDN = VIN
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
VSHDN = VIN
30
25
20
15
10
5
VSHDN = 0V
0
TJ = 25°C
RL = 250k
35
200
0
9
VSHDN = VIN
0
TJ = 25°C
RL = d
25
VSHDN = 0V
10
175
10
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
150
9
TJ = 25°C
RL = d
1763 G14
225
175
8
200
LT1763-5
Quiescent Current
200
3 4 5 6 7
INPUT VOLTAGE (V)
0
250
0
2
25
VSHDN = 0V
0
10
TJ = 25°C
RL = d
0
1
1763 G12
VSHDN = VIN
0
250
25
VSHDN = 0V
225
200
LT1763-3.3
Quiescent Current
225
VSHDN = VIN
250
25
VSHDN = 0V
50
50
0
TJ = 25°C
RL = d
1763 G13
QUIESCENT CURRENT (μA)
125
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
175
2
75
LT1763-3
Quiescent Current
225
200
1
100
0
250
TJ = 25°C
RL = d
0
125
LT1763-2.5
Quiescent Current
250
0
150
1763 G11
LT1763-1.8
Quiescent Current
25
175
TEMPERATURE (°C)
1763 G10
50
200
25
TEMPERATURE (°C)
225
TJ = 25°C
RL = d
225
QUIESCENT CURRENT (μA)
5.075
ADJ PIN VOLTAGE (V)
OUTPUT VOLTAGE (V)
LT1763-1.5
Quiescent Current
VSHDN = 0V
0
9
10
1763 G17
0
2
4
6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
1763 G18
1763fe
7
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-1.8
GND Pin Current
LT1763-1.5
GND Pin Current
1200
1200
1200
800
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.5V
600
RL = 150Ω
IL = 10mA*
400
RL = 1.5k
IL = 1mA*
200
0
1
2
1000
RL = 36Ω
IL = 50mA*
800
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
600
RL = 180Ω
IL = 10mA*
400
200
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
0
10
RL = 1.8k
IL = 1mA*
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
1763 G19
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3V
600
400
RL = 300Ω
IL = 10mA*
200
RL = 3k
IL = 1mA*
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3.3V
600
400
RL = 330Ω
IL = 10mA*
200
RL = 3.3k
IL = 1mA*
0
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
RL = 1.22k
IL = 1mA*
200
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
9
10
1763 G25
10
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 5V
RL = 500Ω
IL = 10mA*
400
RL = 5k
IL = 1mA*
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
12
RL = 5Ω
IL = 300mA*
6
4
RL = 15Ω
IL = 100mA*
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
10
RL = 3Ω
IL = 500mA*
8
0
9
1763 G24
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.5V
2
8
8
RL = 100Ω
IL = 50mA*
600
0
10
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
GND PIN CURRENT (μA)
RL = 122Ω
IL = 10mA*
3 4 5 6 7
INPUT VOLTAGE (V)
LT1763-1.8
GND Pin Current
10
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.22V
2
200
12
800
1
800
LT1763-1.5
GND Pin Current
RL = 24.4Ω
IL = 50mA*
0
1763 G23
1200
400
RL = 2.5k
IL = 1mA*
1000
RL = 66Ω
IL = 50mA*
800
LT1763
GND Pin Current
600
200
LT1763-5
GND Pin Current
1763 G22
1000
RL = 250Ω
IL = 10mA*
1763 G21
GND PIN CURRENT (μA)
GND PIN CURRENT (μA)
GND PIN CURRENT (μA)
800
400
1200
1000
RL = 60Ω
IL = 50mA*
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 2.5V
600
0
10
1200
1000
800
LT1763-3.3
GND Pin Current
1200
0
9
RL = 50Ω
IL = 50mA*
1763 G20
LT1763-3
GND Pin Current
0
GND PIN CURRENT (μA)
1000
RL = 30Ω
IL = 50mA*
GND PIN CURRENT (μA)
GND PIN CURRENT (μA)
1000
0
LT1763-2.5
GND Pin Current
RL = 3.6Ω
IL = 500mA*
8
RL = 6Ω
IL = 300mA*
6
4
RL = 18Ω
IL = 100mA*
2
8
9
10
1763 G26
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1763 G27
1763fe
8
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-2.5
GND Pin Current
LT1763-3
GND Pin Current
12
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 2.5V
10
GND PIN CURRENT (mA)
RL = 5Ω
IL = 500mA*
8
6
RL = 8.33Ω
IL = 300mA*
4
RL = 25Ω
IL = 100mA*
2
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
RL = 6Ω
IL = 500mA*
8
6
RL = 10Ω
IL = 300mA*
4
RL = 30Ω
IL = 100mA*
2
0
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
1763 G28
12
GND PIN CURRENT (mA)
4
RL = 50Ω
IL = 100mA*
2
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
4
RL = 12.2Ω
IL = 100mA*
IL = 1mA
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
SHDN PIN THRESHOLD (V)
0.2
0.1
0
–50
50
25
0
75
TEMPERATURE (°C)
100
125
1763 G34
10
6
4
0
50 100 150 200 250 300 350 400 450 500
OUTPUT CURRENT (mA)
1763 G33
SHDN Pin Input Current
1.4
0.8
IL = 500mA
0.7
0.6
0.5
IL = 1mA
0.4
0.3
0.2
0.1
–25
9
8
0
10
0.9
0.3
8
2
1.0
0.4
3 4 5 6 7
INPUT VOLTAGE (V)
1763 G32
1.0
0.5
2
1763 G30
SHDN Pin Threshold
(Off-to-On)
0.6
1
VIN = VOUT(NOMINAL) + 1V
RL = 4.07Ω
IL = 300mA*
6
0
10
0.7
0
10
RL = 2.44Ω
IL = 500mA*
8
SHDN Pin Threshold
(On-to-Off)
SHDN PIN THRESHOLD (V)
0
10
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.22V
2
0.8
RL = 33Ω
IL = 100mA*
GND Pin Current vs ILOAD
1763 G31
0.9
9
SHDN PIN INPUT CURRENT (μA)
GND PIN CURRENT (mA)
RL = 16.7Ω
IL = 300mA*
6
4
12
10
8
RL = 11Ω
IL = 300mA*
2
12
10
6
LT1763
GND Pin Current
RL = 10Ω
IL = 500mA*
RL = 6.6Ω
IL = 500mA*
8
1763 G29
LT1763-5
GND Pin Current
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 5V
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3.3V
10
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
10
12
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3V
GND PIN CURRENT (mA)
12
LT1763-3.3
GND Pin Current
0
–50
1.2
1.0
0.8
0.6
0.4
0.2
0
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1763 G35
0
1
2
3 4 5 6 7 8
SHDN PIN VOLTAGE (V)
9
10
1763 G36
1763fe
9
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
SHDN Pin Input Current
ADJ Pin Bias Current
1.6
Current Limit
1.0
140
1.0
0.8
0.6
0.4
0.8
100
CURRENT LIMIT (A)
1.2
80
60
40
0
–50
–25
0
25
50
75
100
50
25
0
75
TEMPERATURE (°C)
–25
TEMPERATURE (°C)
100
Current Limit
0
0.8
0.6
0.4
0.2
100
TJ = 25°C, VIN = 0V
CURRENT FLOWS
INTO OUTPUT PIN
VOUT = VADJ (LT1763)
90
80
70
50
30
LT1763-1.5
LT1763
LT1763-1.8
60
40
LT1763-2.5
LT1763-3
LT1763-3.3
20
LT1763-5
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
1763 G40
9
VIN = 0V, VOUT = 1.22V (LT1763)
18 VOUT = 1.5V (LT1763-1.5)
= 1.8V (LT1763-1.8)
V
16 VOUT = 2.5V (LT1763-2.5)
OUT
14 VOUT = 3V (LT1763-3)
VOUT = 3.3V (LT1763-3.3)
12 VOUT = 5V (LT1763-5)
10
8
4
0
–50
10
Input Ripple Rejection
70 CBYP = 0.01μF
66
60
64
RIPPLE REJECTION (dB)
IL = 500mA
VIN = VOUT(NOMINAL) +
1V + 50mVRMS RIPPLE
CBYP = 0
20
10
50 CBYP = 1000pF
CBYP = 100pF
40
30
20
IL = 500mA
VIN = VOUT(NOMINAL) +
1V + 50mVRMS RIPPLE
COUT = 10μF
COUT = 4.7μF
10
0
RIPPLE REJECTION (dB)
70
30
100
1k
10k
FREQUENCY (Hz)
100k
1M
1763 G43
10
100
1k
10k
FREQUENCY (Hz)
100
125
62
60
58
56
54
0
10
50
25
0
75
TEMPERATURE (°C)
Ripple Rejection
68
40
–25
1763 G42
80
50
LT1763
2
80
COUT = 10μF
LT1763-1.5/-1.8/
-2.5/-3/-3.3/-5
6
1763 G41
Input Ripple Rejection
7
6
Reverse Output Current
0
125
60
4
3
2
5
INPUT VOLTAGE (V)
20
10
50
25
0
75
TEMPERATURE (°C)
1
1763 G39
REVERSE OUTPUT CURRENT (μA)
REVERSE OUTPUT CURRENT (μA)
CURRENT LIMIT (A)
0.3
0
125
100
VIN = 7
VOUT = 0V
1.0
RIPPLE REJECTION (dB)
0.4
Reverse Output Current
1.2
–25
0.5
1763 G38
1763 G37
0
–50
0.6
0.1
0
–50
125
0.7
0.2
20
0.2
VOUT = 0V
0.9
120
ADJ PIN BIAS CURRENT (nA)
SHDN PIN INPUT CURRENT (μA)
VSHDN = 20V
1.4
100k
1M
52
–50
VIN = VOUT (NOMINAL) +
1V + 0.5VP-P RIPPLE
AT f = 120Hz
IL = 500mA
–25
0
25
50
75
100
125
TEMPERATURE (°C)
1763 G44
1763 G45
1763fe
10
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763
Minimum Input Voltage
Load Regulation
5
2.50
IL = 500mA
2.00
1.75
IL = 1mA
1.50
1.25
1.00
0.75
LT1763-1.8
–5
LT1763-3
–10
LT1763-3.3
LT1763-5
–15
0.50
–20
0.25
VIN = VOUT(NOMINAL) + 1V
$IL = 1mA TO 500mA
VOUT = 1.22V
0
–50
50
25
0
75
TEMPERATURE (°C)
–25
LT1763-1.5
0
LOAD REGULATION (mV)
MINIMUM INPUT VOLTAGE (V)
LT1763-2.5
LT1763
2.25
100
–25
–50
125
–25
0
25
50
75
100
1763 G47
1763 G46
Output Noise Spectral Density
CBYP = 0
Output Noise Spectral Density
LT1763-3
LT1763-3.3
1
LT1763
LT1763-2.5
LT1763-1.5
LT1763-1.8
0.1
COUT = 10μF
IL = 500mA
0.01
10
100
1k
10k
FREQUENCY (Hz)
10
OUTPUT NOISE SPECTRAL DENSITY (μV/Hz)
OUTPUT NOISE SPECTRAL DENSITY (μV/Hz)
10
LT1763-5
100k
COUT = 10μF
IL = 500mA
CBYP = 1000pF
LT1763-5
1
CBYP = 100pF
LT1763
0.1
CBYP = 0.01μF
0.01
10
100
1k
10k
FREQUENCY (Hz)
RMS Output Noise
vs Bypass Capacitor
RMS Output Noise
vs Load Current (10Hz to 100kHz)
160
160
COUT = 10μF
IL = 500mA
f = 10Hz TO 100kHz
140
LT1763-5
120
LT1763-3.3
100
LT1763-3
80
LT1763-2.5
60
LT1763
LT1763-1.8
LT1763-1.5
20
100
COUT = 10μF
CBYP = 0
CBYP = 0.01μF
120
LT1763-5
100
80
60
LT1763
40
LT1763-5
20
LT1763
0
10
140
OUTPUT NOISE (μVRMS)
OUTPUT NOISE (μVRMS)
100k
1763 G49
1763 G48
40
125
TEMPERATURE (°C)
1000
10000
CBYP (pF)
1763 G50
0
0.01
0.1
10
100
1
LOAD CURRENT (mA)
1000
1763 G51
1763fe
11
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 0
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 100pF
VOUT
100μV/DIV
VOUT
100μV/DIV
COUT = 10μF
IL = 500mA
1763 G52
1ms/DIV
COUT = 10μF
IL = 500mA
VOUT
100μV/DIV
VOUT
100μV/DIV
COUT = 10μF
IL = 500mA
1763 G54
1ms/DIV
COUT = 10μF
IL = 500mA
0.2
OUTPUT VOLTAGE
DEVIATION (V)
VIN = 6V
CIN = 10μF
COUT = 10μF
0.4
0
–0.2
600
400
200
0
200
400
600
TIME (μs)
1763 G55
800
1000
1763 G56
VIN = 6V
CIN = 10μF
COUT = 10μF
0.10
0.05
0
–0.05
–0.10
LOAD CURRENT
(mA)
–0.4
0
1ms/DIV
LT1763-5
Transient Response
CBYP = 0.01μF
LT1763-5
Transient Response
CBYP = 0
OUTPUT VOLTAGE
DEVIATION (V)
1763 G53
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 0.01μF
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 1000pF
LOAD CURRENT
(mA)
1ms/DIV
600
400
200
0
0
10 20 30 40 50 60 70 80 90 100
TIME (μs)
1763 G57
1763fe
12
LT1763 Series
PIN FUNCTIONS
(DE12/S8)
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.
supply system where the regulator load is returned to a
negative supply) and still allow the device to start and
operate.
OUT (Pins 2, 3/Pin 1): Output. The output supplies power
to the load. A minimum output capacitor of 3.3μF is required to prevent oscillations. Larger output capacitors
will be required for applications with large transient loads
to limit peak voltage transients. See the Applications Information section for more information on output capacitance
and reverse output characteristics.
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.
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 voltage 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 regulation
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
resistance (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).
8
IN
OUT
1
RP
LT1763
+
VIN
5
SHDN
SENSE
GND
+
2
LOAD
3
RP
1763 F01
Figure 1. Kelvin Sense Connection
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
GND (Pins 7/Pins 3, 6, 7): Ground.
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 impedance
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.
Exposed Pad (Pin 13) DE12 Only: Ground. The Exposed
Pad must be soldered to the PCB ground for rated thermal
performance.
1763fe
13
LT1763 Series
APPLICATIONS INFORMATION
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.
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
IN
VIN
OUT
VOUT
+
R2
LT1763
GND
ADJ
R1
1763 F02
⎛ R2⎞
VOUT = 1.22V ⎜ 1 + ⎟ + (IADJ )(R2)
⎝ R1⎠
VADJ = 1.22V
IADJ = 30nA AT 25°C
OUTPUT RANGE = 1.22V TO 20V
Figure 2. Adjustable Operation
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.
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
1763fe
14
LT1763 Series
APPLICATIONS INFORMATION
4.0
Output Capacitance and Transient Response
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
3.0
STABLE REGION
ESR (Ω)
2.5
2.0
CBYP = 0
CBYP = 100pF
1.5
CBYP = 330pF
CBYP r 1000pF
1.0
0.5
0
3
2
4 5 6 7 8 9 10
OUTPUT CAPACITANCE (μF)
1763 F03
1
Figure 3. Stability
20
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
0
CHANGE IN VALUE (%)
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.
3.5
X5R
–20
–40
–60
Y5V
–80
–100
0
2
4
6
8
10
14
12
DC BIAS VOLTAGE (V)
16
1763 F04
Figure 4. Ceramic Capacitor DC Bias Characteristics
40
20
CHANGE IN VALUE (%)
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 capacitors. 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 capacitor is recommended. With a 1000pF bypass capacitor or
larger, a 6.8μF output capacitor is recommended.
X5R
0
–20
–40
Y5V
–60
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–100
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1763 F05
Figure 5. Ceramic Capacitor Temperature Characteristics
1763fe
15
LT1763 Series
APPLICATIONS INFORMATION
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.
Thermal Considerations
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.
1. Output current multiplied by the input/output voltage
differential: (IOUT)(VIN – VOUT), and
LT1763-5
COUT = 10μF
CBYP = 0.01μF
ILOAD = 100mA
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:
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 Characteristics 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 generated by power devices.
VOUT
500μV/DIV
100ms/DIV
1763 F06
Figure 6. Noise Resulting from
Tapping on a Ceramic Capacitor
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
TOPSIDE*
BACKSIDE
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500mm2
2500mm2
2500mm2
40°C/W
1000mm2
2500mm2
2500mm2
45°C/W
225mm2
2500mm2
2500mm2
50°C/W
100mm2
2500mm2
2500mm2
60°C/W
* Device is mounted on topside
1763fe
16
LT1763 Series
APPLICATIONS INFORMATION
Protection Features
Table 2. SO-8 Package, 8-Lead SO
COPPER AREA
TOPSIDE*
BACKSIDE
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500mm2
2500mm2
2500mm2
60°C/W
1000mm2
2500mm2
2500mm2
60°C/W
225mm2
2500mm2
2500mm2
68°C/W
100mm2
2500mm2
2500mm2
74°C/W
50mm2
2500mm2
2500mm2
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
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.
1763fe
17
LT1763 Series
APPLICATIONS INFORMATION
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 current 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.
REVERSE OUTPUT CURRENT (μA)
100
TJ = 25°C
90 VIN = 0V
CURRENT FLOWS
80 INTO OUTPUT PIN
70 VOUT = VADJ (LT1763)
LT1763
60
LT1763-1.8
50
LT1763-2.5
LT1763-1.5
LT1763-3
40
30
20
LT1763-5
10
LT1763-3.3
0
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
10
1763 F07
Figure 7. Reverse Output Current
1763fe
18
LT1763 Series
PACKAGE DESCRIPTION
DE/UE Package
12-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
4.00 p0.10
(2 SIDES)
7
0.70 p0.05
3.60 p0.05
2.20 p0.05
0.40 p 0.10
12
R = 0.05
TYP
3.30 p0.05
3.30 p0.10
3.00 p0.10
(2 SIDES)
PIN 1
TOP MARK
(NOTE 6)
1.70 p 0.05
R = 0.115
TYP
1.70 p 0.10
PIN 1 NOTCH
R = 0.20 OR
0.35 s 45o
CHAMFER
PACKAGE
OUTLINE
0.25 p 0.05
6
0.25 p 0.05
0.75 p0.05
0.200 REF
1
(UE12/DE12) DFN 0806 REV D
0.50 BSC
0.50 BSC
2.50 REF
2.50 REF
0.00 – 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING PROPOSED TO BE A VARIATION OF VERSION
5. EXPOSED PAD SHALL BE SOLDER PLATED
(WGED) IN JEDEC PACKAGE OUTLINE M0-229
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
2. DRAWING NOT TO SCALE
ON THE TOP AND BOTTOM OF PACKAGE
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
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
.245
MIN
8
.160 ±.005
.030 ±.005
TYP
7
6
5
.053 – .069
(1.346 – 1.752)
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
1
2
3
4
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
1. DIMENSIONS IN
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
.010 – .020
s 45°
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
SO8 0303
1763fe
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LT1763 Series
TYPICAL APPLICATION
Paralleling of Regulators for Higher Output Current
R1
0.1Ω
+
VIN > 3.8V
IN
C1
10μF
OUT
SENSE
LT1763-3.3
+
C4
0.01μF
SHDN
BYP
GND
3.3V
1A
C2
10μF
R2
0.1Ω
IN
OUT
C5
0.01μF
LT1763
SHDN
R3
2.2k
SHDN
GND
R4
2.2k
3
+
BYP
ADJ
R7
1.21k
8
1/2 LT1490
2
–
4
R6
2k
1
R5
10k
C3
0.01μF
1763 TA03
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PART NUMBER
DESCRIPTION
COMMENTS
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ThinSOT is a trademark of Linear Technology Corporation.
1763fe
20 Linear Technology Corporation
LT 1008 REV E • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1999

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