LINER LT1761ES5-3 100ma, low noise, ldo micropower regulators in tsot-23 Datasheet

LT1761 Series
100mA, Low Noise,
LDO Micropower
Regulators in TSOT-23
FEATURES
DESCRIPTION
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The LT®1761 series are micropower, low noise, low
dropout regulators. With an external 0.01μF bypass
capacitor, output noise drops to 20μVRMS over a 10Hz to
100kHz bandwidth. Designed for use in battery-powered
systems, the low 20μA quiescent current makes them an
ideal choice. In shutdown, quiescent current drops to less
than 0.1μA. The devices are capable of operating over an
input voltage from 1.8V to 20V, and can supply 100mA of
output current with a dropout voltage of 300mV. Quiescent
current is well controlled, not rising in dropout as it does
with many other regulators.
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Low Noise: 20μVRMS (10Hz to 100kHz)
Low Quiescent Current: 20μA
Wide Input Voltage Range: 1.8V to 20V
Output Current: 100mA
Very Low Shutdown Current: <0.1μA
Low Dropout Voltage: 300mV at 100mA
Fixed Output Voltages: 1.2V, 1.5V, 1.8V, 2V, 2.5V,
2.8V, 3V, 3.3V, 5V
Adjustable Output from 1.22V to 20V
Stable with 1μF Output Capacitor
Stable with Aluminum, Tantalum or
Ceramic Capacitors
Reverse-Battery Protected
No Reverse Current
No Protection Diodes Needed
Overcurrent and Overtemperature Protected
Available in Tiny 5-Lead TSOT-23 Package
APPLICATIONS
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Cellular Phones
Pagers
Battery-Powered Systems
Frequency Synthesizers
Wireless Modems
The LT1761 regulators are stable with output capacitors as
low as 1μF. 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 device is available in fixed output
voltages of 1.2V, 1.5V, 1.8V, 2V, 2.5V, 2.8V, 3V, 3.3V and
5V, and as an adjustable device with a 1.22V reference
voltage. The LT1761 regulators are available in the 5-lead
TSOT-23 package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
TYPICAL APPLICATION
10Hz to 100kHz Output Noise
5V Low Noise Regulator
VIN
5.4V TO
20V
IN
1μF
OUT
LT1761-5
SHDN
BYP
0.01μF
+
5V AT100mA
20μVRMS NOISE
10μF
VOUT
100μV/DIV
20μVRMS
1761 TA01
GND
1761 TA01b
1761sff
1
LT1761 Series
ABSOLUTE MAXIMUM RATINGS (Note 1)
IN Pin Voltage .........................................................±20V
OUT Pin Voltage ......................................................±20V
Input to Output Differential Voltage .........................±20V
ADJ Pin Voltage ...................................................... ±7V
BYP Pin Voltage .....................................................±0.6V
SHDN Pin Voltage ................................................. ±20V
Output Short-Circuit Duration ........................ Indefinite
Operating Junction Temperature Range
E, I Grade (Note 2) ............................. –40°C to 125°C
MP Grade (Note 2) ............................. –55°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
LT1761-BYP
LT1761-SD
TOP VIEW
IN 1
5 OUT
GND 2
BYP 3
LT1761-X
TOP VIEW
IN 1
5 OUT
IN 1
GND 2
4 ADJ
SHDN 3
TOP VIEW
5 OUT
GND 2
SHDN 3
4 ADJ
4 BYP
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 250°C/W
SEE APPLICATIONS INFORMATION SECTION
TJMAX = 150°C, θJA = 250°C/W
SEE APPLICATIONS INFORMATION SECTION
TJMAX = 150°C, θJA = 250°C/W
SEE APPLICATIONS INFORMATION SECTION
ORDER INFORMATION
LEAD FREE FINISH
LT1761ES5-BYP#PBF
LT1761IS5-BYP#PBF
LT1761ES5-SD#PBF
LT1761IS5-SD#PBF
LT1761ES5-1.2#PBF
LT1761IS5-1.2#PBF
LT1761ES5-1.5#PBF
LT1761IS5-1.5#PBF
LT1761ES5-1.8#PBF
LT1761IS5-1.8#PBF
LT1761MPS5-1.8#PBF
LT1761ES5-2#PBF
LT1761IS5-2#PBF
LT1761ES5-2.5#PBF
LT1761IS5-2.5#PBF
LT1761ES5-2.8#PBF
LT1761IS5-2.8#PBF
LT1761ES5-3#PBF
LT1761IS5-3#PBF
LT1761ES5-3.3#PBF
LT1761IS5-3.3#PBF
LT1761MPS5-3.3#PBF
TAPE AND REEL
LT1761ES5-BYP#TRPBF
LT1761IS5-BYP#TRPBF
LT1761ES5-SD#TRPBF
LT1761IS5-SD#TRPBF
LT1761ES5-1.2#TRPBF
LT1761IS5-1.2#TRPBF
LT1761ES5-1.5#TRPBF
LT1761IS5-1.5#TRPBF
LT1761ES5-1.8#TRPBF
LT1761IS5-1.8#TRPBF
LT1761MPS5-1.8#TRPBF
LT1761ES5-2#TRPBF
LT1761IS5-2#TRPBF
LT1761ES5-2.5#TRPBF
LT1761IS5-2.5#TRPBF
LT1761ES5-2.8#TRPBF
LT1761IS5-2.8#TRPBF
LT1761ES5-3#TRPBF
LT1761IS5-3#TRPBF
LT1761ES5-3.3#TRPBF
LT1761IS5-3.3#TRPBF
LT1761MPS5-3.3#TRPBF
PART MARKING *
LTGC
LTGC
LTGH
LTGH
LTCDS
LTCDS
LTMT
LTMT
LTJM
LTJM
LTDCH
LTJE
LTJE
LTGD
LTGD
LTLB
LTLB
LTGE
LTGE
LTGF
LTGF
LTGF
PACKAGE DESCRIPTION
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
5-Lead Plastic TSOT-23
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
1761sff
2
LT1761 Series
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING *
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1761ES5-5#PBF
LT1761ES5-5#TRPBF
LTGG
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-5#PBF
LT1761IS5-5#TRPBF
LTGG
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761MPS5-5#PBF
LT1761MPS5-5#TRPBF
LTGG
5-Lead Plastic TSOT-23
–55°C to 125°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING *
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1761ES5-BYP
LT1761ES5-BYP#TR
LTGC
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-BYP
LT1761IS5-BYP#TR
LTGC
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-SD
LT1761ES5-SD#TR
LTGH
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-SD
LT1761IS5-SD#TR
LTGH
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-1.2
LT1761ES5-1.2#TR
LTCDS
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-1.2
LT1761IS5-1.2#TR
LTCDS
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-1.5
LT1761ES5-1.5#TR
LTMT
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-1.5
LT1761IS5-1.5#TR
LTMT
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-1.8
LT1761ES5-1.8#TR
LTJM
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-1.8
LT1761IS5-1.8#TR
LTJM
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761MPS5-1.8
LT1761MPS5-1.8#TR
LTDCH
5-Lead Plastic TSOT-23
–55°C to 125°C
LT1761ES5-2
LT1761ES5-2#TR
LTJE
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-2
LT1761IS5-2#TR
LTJE
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-2.5
LT1761ES5-2.5#TR
LTGD
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-2.5
LT1761IS5-2.5#TR
LTGD
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-2.8
LT1761ES5-2.8#TR
LTLB
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-2.8
LT1761IS5-2.8#TR
LTLB
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-3
LT1761ES5-3#TR
LTGE
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-3
LT1761IS5-3#TR
LTGE
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761ES5-3.3
LT1761ES5-3.3#TR
LTGF
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-3.3
LT1761IS5-3.3#TR
LTGF
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761MPS5-3.3
LT1761MPS5-3.3#TR
LTGF
5-Lead Plastic TSOT-23
–55°C to 125°C
LT1761ES5-5
LT1761ES5-5#TR
LTGG
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761IS5-5
LT1761IS5-5#TR
LTGG
5-Lead Plastic TSOT-23
–40°C to 125°C
LT1761MPS5-5
LT1761MPS5-5#TR
LTGG
5-Lead Plastic TSOT-23
–55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
1761sff
3
LT1761 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
Minimum Input Voltage (Notes 3, 11)
ILOAD = 100mA
MIN
TYP
MAX
1.8
2.3
V
Regulated Output Voltage (Note 4)
LT1761-1.2
VIN = 2V, ILOAD = 1mA
2.3V < VIN < 20V, 1mA < ILOAD < 50mA
2.3V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
1.185
1.170
1.150
1.2
1.2
1.2
1.215
1.230
1.240
V
V
V
LT1761-1.5
VIN = 2V, ILOAD = 1mA
2.5V < VIN < 20V, 1mA < ILOAD < 50mA
2.5V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
1.478
1.457
1.436
1.5
1.5
1.5
1.522
1.538
1.555
V
V
V
LT1761-1.8
VIN = 2.3V, ILOAD = 1mA
2.8V < VIN < 20V, 1mA < ILOAD < 50mA
2.8V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
1.775
1.750
1.725
1.8
1.8
1.8
1.825
1.845
1.860
V
V
V
LT1761-2
VIN = 2.5V, ILOAD = 1mA
3V < VIN < 20V, 1mA < ILOAD < 50mA
3V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
1.970
1.945
1.920
2
2
2
2.030
2.045
2.060
V
V
V
LT1761-2.5
VIN = 3V, ILOAD = 1mA
3.5V < VIN < 20V, 1mA < ILOAD < 50mA
3.5V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
2.465
2.435
2.415
2.5
2.5
2.5
2.535
2.565
2.575
V
V
V
LT1761-2.8
VIN = 3.3V, ILOAD = 1mA
3.8V < VIN < 20V, 1mA < ILOAD < 50mA
3.8V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
2.762
2.732
2.706
2.8
2.8
2.8
2.838
2.868
2.884
V
V
V
LT1761-3
VIN = 3.5V, ILOAD = 1mA
4V < VIN < 20V, 1mA < ILOAD < 50mA
4V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
2.960
2.930
2.900
3
3
3
3.040
3.070
3.090
V
V
V
LT1761-3.3
VIN = 3.8V, ILOAD = 1mA
4.3V < VIN < 20V, 1mA < ILOAD < 50mA
4.3V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
3.250
3.230
3.190
3.3
3.3
3.3
3.350
3.370
3.400
V
V
V
LT1761-5
VIN = 5.5V, ILOAD = 1mA
6V < VIN < 20V, 1mA < ILOAD < 50mA
6V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
4.935
4.900
4.850
5
5
5
5.065
5.100
5.120
V
V
V
ADJ Pin Voltage (Note 3, 4)
LT1761
VIN = 2V, ILOAD = 1mA
2.3V < VIN < 20V, 1mA < ILOAD < 50mA
2.3V < VIN < 20V, 1mA < ILOAD < 100mA
l
l
1.205
1.190
1.170
1.220
1.220
1.220
1.235
1.250
1.260
V
V
V
Line Regulation
LT1761-1.2
LT1761-1.5
LT1761-1.8
LT1761-2
LT1761-2.5
LT1761-2.8
LT1761-3
LT1761-3.3
LT1761-5
LT1761 (Note 3)
ΔVIN = 2V to 20V, ILOAD = 1mA
ΔVIN = 2V to 20V, ILOAD = 1mA
ΔVIN = 2.3V to 20V, ILOAD = 1mA
ΔVIN = 2.5V to 20V, ILOAD = 1mA
ΔVIN = 3V to 20V, ILOAD = 1mA
ΔVIN = 3.3V 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
ΔVIN = 2V to 20V, ILOAD = 1mA
l
l
l
l
l
l
l
l
l
l
1
1
1
1
1
1
1
1
1
1
10
10
10
10
10
10
10
10
10
10
l
UNITS
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
1761sff
4
LT1761 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
Load Regulation
LT1761-1.2
LT1761-1.5
LT1761-1.8
LT1761-2
LT1761-2.5
LT1761-2.8
LT1761-3
LT1761-3.3
LT1761-5
LT1761 (Note 3)
Dropout Voltage
VIN = VOUT(NOMINAL)
(Notes 5, 6, 11)
MIN
VIN = 2.3V, ΔILOAD = 1mA to 50mA
VIN = 2.3V, ΔILOAD = 1mA to 50mA
VIN = 2.3V, ΔILOAD = 1mA to 100mA
VIN = 2.3V, ΔILOAD = 1mA to 100mA
VIN = 2.5V, ΔILOAD = 1mA to 50mA
VIN = 2.5V, ΔILOAD = 1mA to 50mA
VIN = 2.5V, ΔILOAD = 1mA to 100mA
VIN = 2.5V, ΔILOAD = 1mA to 100mA
VIN = 2.8V, ΔILOAD = 1mA to 50mA
VIN = 2.8V, ΔILOAD = 1mA to 50mA
VIN = 2.8V, ΔILOAD = 1mA to 100mA
VIN = 2.8V, ΔILOAD = 1mA to 100mA
VIN = 3V, ΔILOAD = 1mA to 50mA
VIN = 3V, ΔILOAD = 1mA to 50mA
VIN = 3V, ΔILOAD = 1mA to 100mA
VIN = 3V, ΔILOAD = 1mA to 100mA
VIN = 3.5V, ΔILOAD = 1mA to 50mA
VIN = 3.5V, ΔILOAD = 1mA to 50mA
VIN = 3.5V, ΔILOAD = 1mA to 100mA
VIN = 3.5V, ΔILOAD = 1mA to 100mA
VIN = 3.8V, ΔILOAD = 1mA to 50mA
VIN = 3.8V, ΔILOAD = 1mA to 50mA
VIN = 3.8V, ΔILOAD = 1mA to 100mA
VIN = 3.8V, ΔILOAD = 1mA to 100mA
VIN = 4V, ΔILOAD = 1mA to 50mA
VIN = 4V, ΔILOAD = 1mA to 50mA
VIN = 4V, ΔILOAD = 1mA to 100mA
VIN = 4V, ΔILOAD = 1mA to 100mA
VIN = 4.3V, ΔILOAD = 1mA to 50mA
VIN = 4.3V, ΔILOAD = 1mA to 50mA
VIN = 4.3V, ΔILOAD = 1mA to 100mA
VIN = 4.3V, ΔILOAD = 1mA to 100mA
VIN = 6V, ΔILOAD = 1mA to 50mA
VIN = 6V, ΔILOAD = 1mA to 50mA
VIN = 6V, ΔILOAD = 1mA to 100mA
VIN = 6V, ΔILOAD = 1mA to 100mA
VIN = 2.3V, ΔILOAD = 1mA to 50mA
VIN = 2.3V, ΔILOAD = 1mA to 50mA
VIN = 2.3V, ΔILOAD = 1mA to 100mA
VIN = 2.3V, ΔILOAD = 1mA to 100mA
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
ILOAD = 1mA
ILOAD = 1mA
l
ILOAD = 10mA
ILOAD = 10mA
l
ILOAD = 50mA
ILOAD = 50mA
l
ILOAD = 100mA
ILOAD = 100mA
TYP
MAX
1
6
12
12
50
mV
mV
mV
mV
20
35
30
55
mV
mV
mV
mV
20
35
30
60
mV
mV
mV
mV
20
35
35
65
mV
mV
mV
mV
20
35
40
80
mV
mV
mV
mV
20
38
40
86
mV
mV
mV
mV
20
40
40
90
mV
mV
mV
mV
20
40
40
100
mV
mV
mV
mV
30
60
65
150
mV
mV
mV
mV
6
12
12
50
mV
mV
mV
mV
1
10
14
10
15
10
15
10
20
10
20
10
20
10
20
15
25
1
1
UNITS
0.10
0.15
0.19
V
V
0.17
0.22
0.29
V
V
0.24
0.28
0.38
V
V
0.30
0.35
0.45
V
V
1761sff
5
LT1761 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 = 10mA
ILOAD = 50mA
ILOAD = 100mA
MIN
Output Voltage Noise
COUT = 10μF, CBYP = 0.01μF, ILOAD = 100mA, BW = 10Hz to 100kHz
ADJ Pin Bias Current
(Notes 3, 8)
Shutdown Threshold
VOUT = Off to On
VOUT = On to Off
l
l
SHDN Pin Current
(Note 9)
VSHDN = 0V
VSHDN = 20V
l
l
Quiescent Current in Shutdown
VIN = 6V, VSHDN = 0V
Ripple Rejection (Note 3)
VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P , fRIPPLE = 120Hz,
ILOAD = 50mA
Current Limit
VIN = 7V, VOUT = 0V
VIN = VOUT(NOMINAL) + 1V or 2.3V (Note 12), ΔVOUT = –5%
l
Input Reverse Leakage Current
VIN = –20V, VOUT = 0V
l
Reverse Output Current
(Note 10)
LT1761-1.2
LT1761-1.5
LT1761-1.8
LT1761-2
LT1761-2.5
LT1761-2.8
LT1761-3
LT1761-3.3
LT1761-5
LT1761 (Note 3)
l
l
l
l
l
VOUT = 1.2V, VIN < 1.2V
VOUT = 1.5V, VIN < 1.5V
VOUT = 1.8V, VIN < 1.8V
VOUT = 2V, VIN < 2V
VOUT = 2.5V, VIN < 2.5V
VOUT = 2.8V, VIN < 2.8V
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 LT1761 regulators are tested and specified under pulse load
conditions such that TJ ≈ TA. The LT1761E is 100% production tested
at TA = 25°C. Performance at –40°C and 125°C is assured by design,
characterization and correlation with statistical process controls. The
LT1761I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT1761MP is 100% tested and guaranteed over
the –55°C to 125°C operating junction temperature range.
Note 3: The LT1761 (adjustable versions) are 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 LT1761
(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.
TYP
MAX
UNITS
20
55
230
1
2.2
45
100
400
2
4
μA
μA
μA
mA
mA
20
0.25
55
μVRMS
30
100
nA
0.8
0.65
2
V
V
0
1
0.5
3
μA
μA
0.01
0.1
μA
65
dB
200
mA
mA
110
10
10
10
10
10
10
10
10
10
5
1
mA
20
20
20
20
20
20
20
20
20
10
μA
μA
μA
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
(whichever is greater) and a current source load. This means the device
is tested while operating in its dropout region or at the minimum input
voltage specification. 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 LT1761, LT1761-1.2, LT1761-1.5, LT1761-1.8 and
LT1761-2 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 VIN = 2.3V, whichever is greater.
1761sff
6
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
Guaranteed Dropout Voltage
500
450
450
350
TJ = 125°C
300
250
TJ = 25°C
200
150
= TEST POINTS
450
400
TJ ≤ 125°C
350
300
TJ ≤ 25°C
250
200
150
350
250
150
50
50
50
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
1.220
OUTPUT VOLTAGE (V)
25
VSHDN = VIN
20
15
10
1.528
IL = 1mA
1.215
1.521
1.210
1.514
1.205
1.200
1.195
1.190
1.185
5
0
–50
VSHDN = 0V
–25
0
25
50
75
100
125
1.180
–50
–25
0
25
50
75
1.507
1.500
1.493
1.486
100
125
1.472
–50
2.04
2.54
IL = 1mA
2.02
2.52
1.78
1.77
OUTPUT VOLTAGE (V)
1.82
OUTPUT VOLTAGE (V)
2.53
1.79
2.01
2.00
1.99
1.98
1.97
–25
0
25
50
75
100
125
TEMPERATURE (°C)
75
1.96
–50
100
125
IL = 1mA
2.51
2.50
2.49
2.48
2.47
–25
0
25
50
75
100
125
TEMPERATURE (°C)
1761 G06
50
LT1761-2.5
Output Voltage
2.03
1.80
25
1761 G51
LT1761-2
Output Voltage
1.81
0
TEMPERATURE (°C)
1.83
1.76
–50
–25
1761 G05
1761 G03
IL = 1mA
125
IL = 1mA
TEMPERATURE (°C)
LT1761-1.8
Output Voltage
100
1.479
TEMPERATURE (°C)
1.84
50
25
0
75
TEMPERATURE (°C)
LT1761-1.5
Output Voltage
OUTPUT VOLTAGE (V)
VIN = 6V
RL = ∞ (250k FOR LT1761-BYP, -SD)
IL = 0 (5μA FOR LT1761-BYP, -SD)
30
–25
1761 G01.1
LT1761-1.2
Output Voltage
Quiescent Current
35
IL = 1mA
1761 G01
1761 G00
40
IL = 10mA
0
–50
0
0
IL = 50mA
200
100
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
IL = 100mA
300
100
0
QUIESCENT CURRENT (μA)
400
100
0
OUTPUT VOLTAGE (V)
Dropout Voltage
500
DROPOUT VOLTAGE (mV)
400
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
Typical Dropout Voltage
500
2.46
–50
–25
0
25
50
75
100
125
TEMPERATURE (°C)
1761 G07
1761 G08
1761sff
7
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1761-2.8
Output Voltage
3.060
IL = 1mA
LT1761-3.3
Output Voltage
3.360
IL = 1mA
3.045
3.345
2.82
3.030
3.330
2.81
2.80
2.79
2.78
2.77
OUTPUT VOLTAGE (V)
2.83
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2.84
LT1761-3
Output Voltage
3.015
3.000
2.985
2.970
2.955
2.76
–50
0
–25
25
50
75
100
0
–25
TEMPERATURE (°C)
25
50
75
100
3.270
125
3.240
–50
1.235
5.04
1.230
5.00
4.98
4.96
4.94
0
25
50
75
100
125
1.225
1.220
1.215
1.210
0
–25
25
50
75
100
100
75
50
VSHDN = VIN
75
50
3 4 5 6 7
INPUT VOLTAGE (V)
VSHDN = VIN
VSHDN = 0V
0
1
2
8
10
1761 G53
8
200
TJ = 25°C
175 RL = ∞
150
125
100
75
50
VSHDN = VIN
1
2
10
3 4 5 6 7
INPUT VOLTAGE (V)
8
150
125
100
75
50
VSHDN = VIN
25
VSHDN = 0V
0
9
LT1761-2
Quiescent Current
TJ = 25°C
175 RL = ∞
0
9
3 4 5 6 7
INPUT VOLTAGE (V)
1761 G10b
200
25
VSHDN = 0V
2
100
0
125
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
125
1
125
LT1761-1.8
Quiescent Current
TJ = 25°C
175 RL = ∞
0
150
1761 G10
200
0
175
TEMPERATURE (°C)
1761 G12
25
200
25
1.200
–50
LT1761-1.5
Quiescent Current
125
100
TJ = 25°C
225 RL = ∞
IL = 1mA
TEMPERATURE (°C)
150
75
LT1761-1.2
Quiescent Current
1.205
–25
50
1761 G11
QUIESCENT CURRENT (μA)
5.06
5.02
25
250
1.240
IL = 1mA
4.92
–50
0
–25
TEMPERATURE (°C)
LT1761-BYP, LT1761-SD
ADJ Pin Voltage
ADJ PIN VOLTAGE (V)
OUTPUT VOLTAGE (V)
3.285
1761 G09
LT1761-5
Output Voltage
QUIESCENT CURRENT (μA)
3.300
TEMPERATURE (°C)
1761 G52
5.08
3.315
3.255
2.940
–50
125
IL = 1mA
VSHDN = 0V
0
9
10
1761 G18
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1761 G19
1761sff
8
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1761-2.5
Quiescent Current
LT1761-2.8
Quiescent Current
200
200
125
100
75
50
VSHDN = VIN
25
3 4 5 6 7
INPUT VOLTAGE (V)
125
100
75
50
VSHDN = VIN
0
9
8
0
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
9
8
100
75
50
VSHDN = VIN
9
125
100
75
50
VSHDN = VIN
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
RL = 12Ω
IL = 100mA*
1.50
1.25
RL = 24Ω
IL = 50mA*
1.00
0.75
RL = 1.2k
IL = 1mA*
0.50
0.25
RL = 120Ω
IL = 10mA*
1
2
VSHDN = 0V
9
8
0
10
3 4 5 6 7
INPUT VOLTAGE (V)
8
1.75
RL = 15Ω
IL = 100mA*
1.50
1.25
RL = 30Ω
IL = 50mA*
1.00
0.75
RL = 1.5k
IL = 1mA*
0.25
9
10
1761 G17b
0
2
4
6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
1761 G17
LT1761-1.8
GND Pin Current
2.00
0.50
0
0
10
5
2.50
TJ = 25°C
*FOR VOUT = 1.5V
2.25
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
2.50
10
15
1761 G16
TJ = 25°C
*FOR VOUT = 1.2V
9
8
VSHDN = VIN
20
LT1761-1.5
GND Pin Current
2.00
3 4 5 6 7
INPUT VOLTAGE (V)
TJ = 25°C
RL = 250k
IL = 5μA
VSHDN = 0V
0
10
LT1761-1.2
GND Pin Current
2.25
2
1761 G14
25
1761 G15
2.50
1
LT1761-BYP, LT1761-SD
Quiescent Current
150
0
8
VSHDN = 0V
30
25
VSHDN = 0V
3 4 5 6 7
INPUT VOLTAGE (V)
VSHDN = VIN
0
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
125
1.75
10
TJ = 25°C
175 RL = ∞
150
2
50
0
200
TJ = 25°C
175 RL = ∞
1
75
LT1761-5
Quiescent Current
200
0
100
1761 G54
LT1761-3.3
Quiescent Current
0
125
25
1761 G13
25
150
VSHDN = 0V
TJ = 25°C
*FOR VOUT = 1.8V
2.25
GND PIN CURRENT (mA)
2
150
25
VSHDN = 0V
0
TJ = 25°C
175 RL = ∞
QUIESCENT CURRENT (μA)
150
1
200
TJ = 25°C
175 RL = ∞
QUIESCENT CURRENT (μA)
QUIESCENT CURRENT (μA)
TJ = 25°C
175 RL = ∞
0
LT1761-3
Quiescent Current
2.00
1.75
RL = 18Ω
IL = 100mA*
1.50
1.25
RL = 36Ω
IL = 50mA*
1.00
0.75
RL = 1.8k
IL = 1mA*
0.50
RL = 150Ω
IL = 10mA*
0.25
0
RL = 180Ω
IL = 10mA*
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1761 G55
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1761 G02
1761sff
9
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1761-2.5
GND Pin Current
2.50
2.25
2.00
RL = 20Ω
IL = 100mA*
1.75
1.50
1.25
RL = 40Ω
IL = 50mA*
1.00
0.75
RL = 2k
IL = 1mA*
0.50
0.25
RL = 25Ω
IL = 100mA
2.00
1.75
1.50
1.25
RL = 50Ω
IL = 50mA*
1.00
0.75
RL = 2.5k
IL = 1mA*
0.50
RL = 200Ω
IL = 10mA*
0.25
0
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
2.00
RL = 30Ω
IL = 100mA*
1.25
RL = 60Ω
IL = 50mA*
0.75
RL = 3k
IL = 1mA*
0.50
0.25
8
9
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
1.75
1.50
1.25
RL = 66Ω
IL = 50mA*
1.00
0.75
RL = 3.3k
IL = 1mA*
10
2.50
2.50
1.25
RL = 24.4Ω
IL = 50mA*
1.00
0.75
RL = 1.22k
IL = 1mA*
0.50
0.25
RL = 122Ω
IL = 10mA*
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
1.50
1.25
8
0.75
10
1761 G24
RL = 5k
IL = 1mA*
RL = 500Ω
IL = 10mA*
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1761 G23
SHDN Pin Threshold
(On to Off)
1.0
0.9
2.00
1.75
1.50
1.25
1.00
0.75
0.25
9
RL = 100Ω
IL = 50mA*
1.00
10
0.50
0
10
RL = 50Ω
IL = 100mA
1.75
0.25
SHDN PIN THRESHOLD (V)
1.50
9
2.00
0.50
VIN = VOUT(NOMINAL) + 1V
2.25
GND PIN CURRENT (mA)
1.75
8
TJ = 25°C
*FOR VOUT = 5V
2.25
GND Pin Current vs ILOAD
RL = 12.2Ω
IL = 100mA*
3 4 5 6 7
INPUT VOLTAGE (V)
1761 G22
TJ = 25°C
*FOR VOUT = 1.22V
2.00
2
0
0
LT1761-BYP, LT1761-SD
GND Pin Current
2.25
1
1761 G56
RL = 330Ω
IL = 10mA*
1761 G21
2.50
RL = 280Ω
IL = 10mA*
LT1761-5
GND Pin Current
RL = 33Ω
IL = 100mA*
0.25
9
RL = 2.8k
IL = 1mA*
0
0
1
0.75
10
2.00
0.50
RL = 300Ω
IL = 10mA*
0
0
RL = 56Ω
IL = 50mA*
1.00
0.25
TJ = 25°C
*FOR VOUT = 3.3V
2.25
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
2.50
TJ = 25°C
*FOR VOUT = 3V
1.00
1.25
LT1761-3.3
GND Pin Current
2.25
1.50
1.50
1761 G20
LT1761-3
GND Pin Current
2.50
RL = 28Ω
IL = 100mA
1.75
0
0
1761 G04
1.75
2.00
0.50
RL = 250Ω
IL = 10mA*
GND PIN CURRENT (mA)
1
TJ = 25°C
*FOR VOUT = 2.8V
2.25
0
0
GND PIN CURRENT (mA)
2.50
TJ = 25°C
*FOR VOUT = 2.5V
2.25
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
2.50
TJ = 25°C
*FOR VOUT = 2V
LT1761-2.8
GND Pin Current
GND PIN CURRENT (mA)
LT1761-2
GND Pin Current
IL = 1mA
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
1761 G25
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1761 G26
1761sff
10
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
SHDN Pin Input Current
1.0
0.9
0.9
IL = 100mA
0.8
0.7
0.6
IL = 1mA
0.5
0.4
0.3
0.2
SHDN Pin Input Current
1.4
SHDN PIN INPUT CURRENT (μA)
1.0
SHDN PIN INPUT CURRENT (μA)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.1
0
–50
0
50
25
0
75
TEMPERATURE (°C)
–25
100
125
0
1
2
3 4 5 6 7 8
SHDN PIN VOLTAGE (V)
9
ADJ Pin Bias Current
350
60
50
40
30
20
10
50
25
0
75
TEMPERATURE (oC)
100
300
300
250
200
150
100
50
0
1
4
3
2
5
INPUT VOLTAGE (V)
1
2
REVERSE OUTPUT CURRENT (μA)
REVERSE OUTPUT CURRENT (μA)
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
200
150
100
1761 G33
–25
50
25
0
75
TEMPERATURE (°C)
100
Input Ripple Rejection
LT1761-BYP,-SD
7.5
70
LT1761-BYP
60
LT1761-5
LT1761-1.2,-1.5,-1.8,-2,
-2.5,-2.8,-3,-3.3,-5
IL = 100mA
VIN = VOUT(NOMINAL) +
1V + 50mVRMS RIPPLE
CBYP = 0
50
COUT = 10μF
40
30
20
5.0
0
–50
125
1761 G32
80
VIN = 0V
22.5 VOUT = 1.22V (LT1761-BYP, -SD)
VOUT = 1.2V (LT1761-1.2)
20.0 VOUT = 1.5V (LT1761-1.5)
VOUT = 1.8V (LT1761-1.8)
17.5 VOUT = 2V (LT1761-2)
VOUT = 2.5V (LT1761-2.5)
15.0 VOUT = 2.8V (LT1761-2.8)
VOUT = 3V (LT1761-3)
12.5 VOUT = 3.3V (LT1761-3.3)
VOUT = 5V (LT1761-5)
10.0
2.5
10
125
250
Reverse Output Current
LT1761-5
100
VIN = 7V
VOUT = 0V
0
–50
7
6
25.0
LT1761-3.3
50
25
0
75
TEMPERATURE (°C)
1761 G31
Reverse Output Current
TJ = 25°C
LT1761-BYP
LT1761-SD
90 VIN = 0V
CURRENT FLOWS
80 INTO OUTPUT PIN
LT1761-1.2
70 VOUT = VADJ
(LT1761-BYP, -SD)
60
LT1761-1.5
LT1761-1.8
50
LT1761-2
LT1761-2.5
40
LT1761-2.8
30
LT1761-3
20
–25
50
0
125
100
0
0.2
Current Limit
1761 G30
0
0.4
350
CURRENT LIMIT (mA)
SHORT-CIRCUIT CURRENT (mA)
ADJ PIN BIAS CURRENT (nA)
70
10
0.6
1761 G29
VOUT = 0V
TJ = 25°C
90
–25
0.8
Current Limit
100
0
–50
1.0
1761 G28
1761 G27
80
VSHDN = 20V
1.2
0
–50
10
RIPPLE REJECTION (dB)
SHDN PIN THRESHOLD (V)
SHDN Pin Threshold
(Off to On)
COUT = 1μF
10
0
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1761 G34
10
100
1k
10k
FREQUENCY (Hz)
100k
1M
1761 G35
1761sff
11
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1761-5
Input Ripple Rejection
80
80
CBYP = 0.01μF
70
CBYP = 1000pF
RIPPLE REJECTION (dB)
60
50
CBYP = 100pF
40
30
20
IL = 100mA
VIN = VOUT(NOMINAL) +
1V + 50mVRMS RIPPLE
COUT = 10μF
10
100
60
50
40
30
20
VIN = VOUT (NOMINAL) +
1V + 0.5VP-P RIPPLE
AT f = 120Hz
IL = 50mA
10
0
–50
0
10
2.5
100k
1k
10k
FREQUENCY (Hz)
1M
MINIMUM INPUT VOLTAGE (V)
70
RIPPLE REJECTION (dB)
LT1761-BYP, LT1761-SD
Minimum Input Voltage
Input Ripple Rejection
0
–25
50
25
75
100
IL = 100mA
1.5
IL = 50mA
1.0
0.5
0
–50
125
50
25
0
75
TEMPERATURE (°C)
–25
TEMPERATURE (°C)
1761 G36
1761 G37
Load Regulation
ΔIL = 1mA to 50mA
100
125
1761 G38
Load Regulation
ΔIL = 1mA to 100mA
0
LT1761-BYP, -SD, -1.2
LT1761-1.5
LT1761-1.8
LT1761-2
LT1761-2.5
LT1761-2.8
LT1761-3
LT1761-3.3
–5
–10
–15
–20
–25
–30
LT1761-5
LOAD REGULATION (mV)
0
LOAD REGULATION (mV)
2.0
–10
LT1761-BYP, -SD, -1.2
–20
LT1761-1.5
LT1761-1.8
LT1761-2
LT1761-2.5
LT1761-2.8
LT1761-3
LT1761-3.3
–30
–40
–50
–60
–70
LT1761-5
–80
–35
–90
–25
0
25
50
75
100
TEMPERATURE (°C)
–100
–50
125
1761 G39
OUTPUT NOISE SPECTRAL DENSITY (μV/√Hz)
OUTPUT NOISE SPECTRAL DENSITY (μV/√Hz)
LT1761-3.3
LT1761-2.8,-3
LT1761-2.5
LT1761-5
1
LT1761-BYP,
-SD, 1.2
LT1761-1.5
LT1761-1.8
0.1
LT1761-2
COUT = 10μF
CBYP = 0
IL = 100mA
1k
10k
FREQUENCY (Hz)
25
75
50
100k
1761 G41
100
125
1761 G40
RMS Output Noise vs
Bypass Capacitor
Output Noise Spectral Density
10
100
0
TEMPERATURE (°C)
Output Noise Spectral Density
0.01
10
–25
10
140
LT1761-5
120
LT1761-5
CBYP = 1000pF
1
CBYP = 100pF
LT1761-BYP
0.1
CBYP = 0.01μF
LT1761-3.3
COUT = 10μF
IL = 100mA
f = 10Hz TO 100kHz
LT1761-3
100
LT1761-2.8
LT1761-2.5
80
60
40
LT1761-1.8, -2
20
COUT = 10μF
IL = 100mA
0.01
10
OUTPUT NOISE (μVRMS)
–40
–50
LT1761-1.5
LT1761-BYP, -1.2
0
100
1k
10k
FREQUENCY (Hz)
100k
10
100
1k
CBYP (pF)
10k
1761 G43
1761 G42
1761sff
12
LT1761 Series
TYPICAL PERFORMANCE CHARACTERISTICS
LT1761-5
10Hz to 100kHz Output Noise
CBYP = 0pF
RMS Output Noise vs
Load Current (10Hz to 100kHz)
LT1761-5
10Hz to 100kHz Output Noise
CBYP = 100pF
160
COUT = 10μF
CBYP = 0
CBYP = 0.01μF
LT1761-5
120
VOUT
100μV/DIV
VOUT
100μV/DIV
100
80
LT1761-BYP
60
40
LT1761-5
20
COUT = 10μF
IL = 100mA
LT1761-BYP
10
0.1
1
LOAD CURRENT (mA)
1761 G45
1ms/DIV
COUT = 10μF
IL = 100mA
1ms/DIV
1761 G46
100
1761 G44
LT1761-5
10Hz to 100kHz Output Noise
CBYP = 1000pF
LT1761-5
10Hz to 100kHz Output Noise
CBYP = 0.01μF
VOUT
100μV/DIV
VOUT
100μV/DIV
COUT = 10μF
IL = 100mA
1761 G46
1ms/DIV
COUT = 10μF
IL = 100mA
VIN = 6V
CIN = 10μF
COUT = 10μF
0.2
0.1
0
–0.1
LOAD CURRENT
(mA)
–0.2
100
50
0
0
400
800
1200
TIME (μs)
1600
1761 G48
1ms/DIV
LT1761-5 Transient Response
CBYP = 0.01μF
OUTPUT VOLTAGE
DEVIATION (V)
LT1761-5 Transient Response
CBYP = 0pF
OUTPUT VOLTAGE
DEVIATION (V)
0
0.01
LOAD CURRENT
(mA)
OUTPUT NOISE (μVRMS)
140
2000
1761 G49
VIN = 6V
CIN = 10μF
COUT = 10μF
0.04
0.02
0
–0.02
–0.04
100
50
0
0
20 40 60 80 100 120 140 160 180 200
TIME (μs)
1761 G50
1761sff
13
LT1761 Series
PIN FUNCTIONS
IN (Pin 1): 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 LT1761 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.
GND (Pin 2): Ground.
SHDN (Pin 3, Fixed/-SD Devices): Shutdown. The SHDN
pin is used to put the LT1761 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 not function
if the SHDN pin is not connected. For the LT1761-BYP, the
SHDN pin is internally connected to VIN.
BYP (Pins 3/4, Fixed/-BYP Devices): Bypass. The BYP
pin is used to bypass the reference of the LT1761 regulators to achieve low noise performance from the regulator.
The BYP pin is clamped internally to ±0.6V (one VBE) from
ground. 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 4, Adjustable Devices Only): Adjust Pin. For the
adjustable LT1761, 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 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.
OUT (Pin 5): Output. The output supplies power to the load.
A minimum output capacitor of 1μF 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.
1761sff
14
LT1761 Series
APPLICATIONS INFORMATION
The LT1761 series are 100mA low dropout regulators with
micropower quiescent current and shutdown. The devices
are capable of supplying 100mA 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 (20μA)
drops to less than 1μA in shutdown. In addition to the
low quiescent current, the LT1761 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 LT1761-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 LT1761 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 1. 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 1. The value of R1 should be no greater than 250k
to minimize errors in the output voltage caused by the
OUT
IN
VIN
+
R2
LT1761
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.
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
to 1.22V: VOUT/1.22V. For example, load regulation for an
output current change of 1mA to 100mA is –1mV typical
at VOUT = 1.22V. At VOUT = 12V, load regulation is:
(12V/1.22V)(–1mV) = –9.8mV
Bypass Capacitance and Low Noise Performance
The LT1761 regulators may be used with the addition of a
bypass capacitor from OUT 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
100mA 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 stay within 1% for a 10mA to
100mA load step (see LT1761-5 Transient Response in
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.
VOUT
¥ R2 ´
VOUT 122V ¦ 1
µ
§ R1¶
IADJ R2
VADJ 122V
ADJ
GND
R1
IADJ 30nA AT 25oC
OUTPUT RANGE = 1.22V TO 20V
1761 F01
Figure 1. Adjustable Operation
1761sff
15
LT1761 Series
APPLICATIONS INFORMATION
The LT1761 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 1μF with an ESR of
3Ω or less is recommended to prevent oscillations. The
LT1761-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 LT1761-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, 2.2μF of output capacitor is recommended. With a 330pF bypass capacitor or
larger, a 3.3μF output capacitor is recommended. The
shaded region of Figure 2 defines the region over which
the LT1761 regulators are stable. The minimum ESR
needed is defined by the amount of bypass capacitance
used, while the maximum ESR is 3Ω.
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior across
temperature and applied voltage. The most common
dielectrics used are specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but they tend to have strong voltage
and temperature coefficients as shown in Figures 3 and 4.
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
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.
20
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
0
CHANGE IN VALUE (%)
Output Capacitance and Transient Response
X5R
–20
–40
–60
Y5V
–80
–100
0
2
4
14
8
6
10 12
DC BIAS VOLTAGE (V)
16
1761 F03
Figure 3. Ceramic Capacitor DC Bias Characteristics
4.0
40
3.5
20
STABLE REGION
ESR (Ω)
2.5
2.0
CBYP = 0
CBYP = 100pF
CBYP = 330pF
CBYP > 3300pF
1.5
1.0
0.5
CHANGE IN VALUE (%)
3.0
–20
–40
1
3
2
4 5 6 7 8 9 10
OUTPUT CAPACITANCE (μF)
1761 F02
Figure 2. Stability
Y5V
–60
–80
0
X5R
0
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–100
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1761 F04
Figure 4. Ceramic Capacitor Temperature Characteristics
1761sff
16
LT1761 Series
APPLICATIONS INFORMATION
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 5’s trace in response to light tapping from a pencil.
Similar vibration induced behavior can masquerade as
increased output voltage noise.
The ground 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 LT1761 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.
The following table lists 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.
VOUT
500μV/DIV
Table 1. Measured Thermal Resistance
LT1761-5
COUT = 10μF
CBYP = 0.01μF
ILOAD = 100mA
100ms/DIV
1761 F05
Figure 5. Noise Resulting from Tapping on a Ceramic Capacitor
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
COPPER AREA
THERMAL RESISTANCE
BOARD AREA (JUNCTION-TO-AMBIENT)
TOPSIDE*
BACKSIDE
2500mm2
2500mm2
2500mm2
125°C/W
1000mm2
2500mm2
2500mm2
125°C/W
225mm2
2500mm2
2500mm2
130°C/W
100mm2
2500mm2
2500mm2
135°C/W
50mm2
2500mm2
2500mm2
150°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 50mA
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
1761sff
17
LT1761 Series
APPLICATIONS INFORMATION
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) = 50mA
VIN(MAX) = 6V
IGND at (IOUT = 50mA, VIN = 6V) = 1mA
So,
P = 50mA(6V – 3.3V) + 1mA(6V) = 0.14W
The thermal resistance will be in the range of 125°C/W to
150°C/W depending on the copper area. So the junction
temperature rise above ambient will be approximately
equal to:
0.14W(150°C/W) = 21.2°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 + 21.2°C = 71.2°C
Protection Features
The LT1761 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 LT1761-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 typically 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.
1761sff
18
LT1761 Series
APPLICATIONS INFORMATION
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. 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 6.
When the IN pin of the LT1761-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
LT1761-BYP
LT1761-SD
90 VIN = 0V
CURRENT FLOWS
80 INTO OUTPUT PIN
LT1761-1.2
70 VOUT = VADJ
(LT1761-BYP, -SD)
60
LT1761-1.5
LT1761-1.8
50
LT1761-2
LT1761-2.5
40
LT1761-2.8
30
LT1761-3
20
LT1761-3.3
10
LT1761-5
0
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
10
1761 F06
Figure 6. Reverse Output Current
1761sff
19
LT1761 Series
PACKAGE DESCRIPTION
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
0.62
MAX
0.95
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.4 MIN
3.85 MAX 2.62 REF
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1.90 BSC
S5 TSOT-23 0302 REV B
1761sff
20
LT1761 Series
REVISION HISTORY
(Revision history begins at Rev F)
REV
DATE
DESCRIPTION
PAGE NUMBER
F
5/10
Added MP-grade
2, 3
Added Typical Application
22
1761sff
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.
21
LT1761 Series
TYPICAL APPLICATION
Noise Bypassing Provides Soft-Start
Startup Time
100
IN
VIN
5.4V TO 20V
5V
AT 100mA
OUT
LT1761-5
1μF
CBYP
10μF
OFF ON
STARTUP TIME (ms)
BYP
SHDN
GND
1761 TA02a
10
1
0.1
10
100
1000
10000
CBYP (pF)
1761 TA02b
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DESCRIPTION
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1761sff
22 Linear Technology Corporation
LT 0510 REV F • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
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