Linear Technology LT1120A Datasheet

FEATURES

■

20µA Supply Current

■

8-Lead SOIC

■

125mA Output Current

■

2.5V Reference

■

Reference Output Sources 4mA and Sinks 4mA

■

Open Collector

■

Comparator Sinks 10mA

■

Logic Shutdown

■

0.2V Dropout Voltage

■

Thermal Limiting

U

APPLICATIONS

■

Battery Systems

■

Battery Backup System

■

Portable Terminals

■

Portable Instruments

■

Memory Keep Alive

LT1120A

Micropower Regulator with

Comparator and Shutdown

U

DESCRIPTION

The LT1120A is a combination micropower positive regu­lator and free collector comparator on a single monolithic
chip. With only 20µA supply current, the LT1120A can
supply over 125mA of output current. Input voltage range
is from 4.5V to 36V and dropout voltage is 0.6V at 125mA.
Dropout voltage decreases with lower load currents. Also
included on the chip is a class B output 2.5V reference that
can either source or sink current. This allows it to be used
as a supply splitter or auxiliary output. A shutdown pin
allows logic shutdown of the output.

The comparator can be used for system or battery moni­toring. For example, the comparator can be used to warn
of low system voltage. Frequency compensation of the
comparator for amplifier applications can be obtained by
adding external output capacitance.

TYPICAL APPLICATION

VIN > 5.2V

= 20µA

I

Q

10µF

54

V

IN

++

SHUTDOWN

LT1120A

V

OUT

2

FB

GND

13

U

0.001µF

1M

1M

5V

25µF

1120A TA01

Dropout Voltage and Supply Current5V Regulator

1.00

0.10

DROPOUT VOLTAGE (V)

0.01
0.1

1 1000
OUTPUT CURRENT (mA)

10

SUPPLY CURRENT (mA)

1

10

100

0.1

1120A TA02

1

LT1120A

WW

W

ABSOLUTE MAXIMUM RATINGS

Input Voltage ........................................................... 36V

NPN Collector Voltage ............................................. 36V

Output Short-Circuit Duration.......................... Indefinite

Power Dissipation............................... Internally Limited

Operating Temperature Range

LT1120AC.............................................. 0°C to 100°C

Storage Temperature Range

LT1120AC.......................................... –65°C to 150°C

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS
Reference

Reference Voltage 4.5V ≤ VIN ≤ 36V 2.46 2.50 2.54 V
Line Regulation 4.5V ≤ VIN ≤ 36V 0.01 0.015 %/V
Load Regulation –2.0mA ≤ I
Output Source Current VIN = 5V 2 4 mA
Output Sink Current VIN = 5V 2 4 mA
Temperature Stability 1%

Regulator

Supply Current VIN = 6V, I

V

IN

V

IN

Output Current (VIN – V
Load Regulation (VIN – V
Line Regulation 6V ≤ VIN ≤ 36V 0.01 0.015 %/V
Dropout Voltage I

Feedback Sense Voltage VIN = 12V 2.44 2.5 2.56 V
Shutdown Pin Voltage Normal 0.4 V

Shutdown Pin Current VIN = 1.4V 10 µA
Feedback Bias Current 15 40 nA
Minimum Load Current VIN = 36V 1 5 µA
Short Circuit Current VIN = 36V 250 400 mA

Comparator

Offset Voltage VIN = 36V 3 7 mV
Bias Current VIN = 36V 15 40 nA
Gain ∆V
Power Supply Rejection 4.5V ≤ VS ≤ 36V 80 96 dB
Output Sink Current VIN = 4.5V 10 18 mA
Saturation Voltage I
Input Voltage Range 0 VIN – 1 V
Response Time 5 µs
Leakage Current VIN = 36V, V(Pin 7) = 36V 2 µA

I

V

OUT
OUT

OUT

OUT

REF

OUT

= 36V, I

OUT

= 12V, I

OUT

) ≥ 1V, VIN ≥ 6V 125 mA

OUT

) ≥ 1V, VIN ≥ 6V 0.2 0.5 %

OUT

= 100µA 0.02 0.05 V
= 125mA 0.40 0.65 V

≤ 0.5V Shutdown 2.2 1.4 V

= 29V, RL = 20k 2000 10000 V/V

OUT

= 1mA 0.4 0.6 V

U

U

W

U

PACKAGE/ORDER INFORMATION

ORDER PART

TOP VIEW

1GND

FEEDBACK

SHUTDOWN

8-LEAD PLASTIC DIP

Consult factory for Industrial and Military grade parts.

2
3

V

OUT

N8 PACKAGE

T

= 110°C, θJA = 130°C/ W (N)

JMAX

= 110°C, θJA = 190°C/ W (S)

T

JMAX

LT1120A

8-LEAD PLASTIC SOIC

–INPUT

8
7

COMP OUT

6

REF

54

V

IN

S8 PACKAGE

1120A POI01

TJ = 25°C

≤ 2mA, VIN = 12V 0.3 0.6 %

≤ 100µA2025µA

≤ 100µA3040µA
= 125mA 11 20 mA

NUMBER

LT1120ACN8
LT1120ACS8

S8 PART

MARKING

1120A

2

LT1120A

TEMPERATURE (°C)

–50

0

SHORT-CIRCUIT CURRENT (mA)

350

150

1120A G03

300

250

200

150

100

50

110

–10

30 70

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS
Reference

Reference Voltage 4.5V ≤ VIN ≤ 36V ● 2.40 2.50 2.55 V
Line Regulation 4.5V ≤ VIN ≤ 36V ● 0.01 0.02 %/V
Load Regulation –2.0mA ≤ I
Output Source Current VIN = 5V ● 2mA
Output Sink Current VIN = 5V ● 2mA

Regulator

Supply Current VIN = 6V, I

= 36V, I

V

IN

VIN = 12V, I
Output Current (VIN – V
Load Regulation (VIN – V
Line Regulation 6V ≤ VIN ≤ 36V ● 0.02 %/V
Dropout Voltage I

= 100µA ● 0.06 V

OUT

I

= 125mA ● 0.85 V

OUT

Feedback Sense Voltage VIN = 12V ● 2.38 2.5 2.57 V
Feedback Bias Current ● 50 nA
Minimum Load Current VIN = 36V ● 50 µA
Short Circuit Current VIN = 36V ● 240 400 mA

Comparator

Offset Voltage VIN = 36V ● 10 mV
Bias Current VIN = 36V ● 15 60 nA
Gain ∆V

OUT

Output Sink Current (Note 1) VIN = 4.5V ● 510 mA
Leakage Current VIN = 36V, V(Pin 7) = 36V ● 8 µA

The ● denotes specifications which apply over the operating temperature range.
Note 1: For TA ≤ –40°C output sink current drops to 2.5mA.

≤ 2mA, VIN = 12V ● 0.4 0.8 %

REF

≤ 100µA ● 30 40 µA

OUT

≤ 100µA ● 40 50 µA

OUT

= 125mA ● 11 20 mA

OUT

) ≥ 1V, VIN ≥ 6V ● 125 mA

OUT

) ≥ 1V, VIN ≥ 6V ● 1%

OUT

= 29V, RL = 20k ● 1000 V/V

TYPICAL PERFORMANCE CHARACTERISTICS

Regulator Load Regulation Supply Current

0.3

PRE-LOAD = 100 µA

0.2

0.1

0

–0.1

OUTPUT VOLTAGE CHANGE (%)

–0.2

–0.3

0.1

TJ = –55°C

TJ = 25°C

TJ = 125°C

1
OUTPUT CURRENT (mA)

10 1000

100

W

1120A G01

U

SUPPLY CURRENT (mA)

0.01

100

10

1

0.1

0.1

1 1000

REGULATOR OUTPUT CURRENT (mA)

Regulator Short-Circuit Current

10

100

1120A G02

3