LT1120A
Micropower Regulator with
Comparator and Shutdown
FeaTures
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DescripTion
The
LT
®
1120A
is a combination micropower positive regu-
lator 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 moni-
toring. 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.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Analog Devices, Inc. All other trademarks are the property of their
respective owners.
20µA Supply Current
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
8-Lead SO Package
applicaTions
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Battery Systems
Battery Backup System
Portable Terminals
Portable Instruments
Memory Keep Alive
Typical applicaTion
5V Regulator
V
IN
> 5.2V
I
Q
= 20µA
5 V
IN
V
OUT
4
LT1120A
GND
3
SHUTDOWN
1
FB 2
1M
0.001µF
1M
5V
Dropout Voltage and Supply Current
1.00
10
10µF
25µF
DROPOUT VOLTAGE (V)
+
+
SUPPLY CURRENT (mA)
1120A TA01a
0.10
1
0.01
0.1
10
100
1
OUTPUT CURRENT (mA)
0.1
1000
1120A TA01b
1120afb
For more information
www.linear.com/LT1120A
1
LT1120A
absoluTe MaxiMuM raTings
(Note 1)
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
LT1120AI ............................................ –40°C to 100°C
Storage Temperature Range .................. –65°C to 150°C
pin conFiguraTion
TOP VIEW
GND 1
FEEDBACK 2
SHUTDOWN 3
V
OUT
4
N8 PACKAGE
8-LEAD PDIP
T
JMAX
= 110°C,
θ
JA
= 130°C/W
8
7
6
5
–INPUT
COMP OUT
REF
V
IN
GND 1
FEEDBACK 2
SHUTDOWN 3
V
OUT
4
TOP VIEW
8
7
6
5
–INPUT
COMP OUT
REF
V
IN
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 110°C,
θ
JA
= 190°C/W
orDer inForMaTion
LEAD FREE FINISH
LT1120ACN8#PBF
LT1120ACS8#PBF
LT1120AIS8#PBF
TAPE AND REEL
LT1120ACN8#TRPBF
LT1120ACS8#TRPBF
LT1120AIS8#TRPBF
http://www.linear.com/product/LT1120A#orderinfo
PART MARKING
1120ACN8
1120A
1120AI
PACKAGE DESCRIPTION
8-Lead Plastic DIP
8-Lead Plastic SO
8-Lead Plastic SO
TEMPERATURE RANGE
0°C to 100°C
0°C to 100°C
–40°C to 100°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
1120afb
2
For more information
www.linear.com/LT1120A
LT1120A
elecTrical characTerisTics
PARAMETER
Reference
Reference Voltage
Line Regulation
Load Regulation
Output Source Current
Output Sink Current
Temperature Stability
Regulator
Supply Current
V
IN
= 6V, I
OUT
≤ 100µA
V
IN
= 36V, I
OUT
≤ 100µA
V
IN
= 12V, I
OUT
= 125mA
(V
IN
– V
OUT
) ≥ 1V, V
IN
≥ 6V
(V
IN
– V
OUT
) ≥ 1V, V
IN
≥ 6V
6V ≤ V
IN
≤ 36V
I
OUT
= 100µA
I
OUT
= 125mA
V
IN
= 12V
Normal
V
OUT
≤ 0.5V
Shutdown Pin Current
Feedback Bias Current
Minimum Load Current
Short-Circuit Current
Comparator
Offset Voltage
Bias Current
Gain
Power Supply Rejection
Output Sink Current
Saturation Voltage
Input Voltage Range
Response Time
Leakage Current
V
IN
= 36V, V(Pin 7) = 36V
V
IN
= 36V
V
IN
= 36V
∆V
OUT
= 29V, R
L
= 20k
4.5V ≤ V
S
≤ 36V
V
IN
= 4.5V
I
OUT
= 1mA
0
5
2
2000
80
10
3
15
10000
96
18
0.4
0.6
V
IN
– 1
7
40
mV
nA
V/V
dB
mA
V
V
µs
µA
V
IN
= 36V
V
IN
= 36V
V
IN
= 1.4V
Shutdown
2.2
1.4
10
15
1
250
40
5
400
2.44
125
0.2
0.01
0.02
0.40
2.5
0.5
0.015
0.05
0.65
2.56
0.4
20
30
11
25
40
20
µA
µA
mA
mA
%
%/V
V
V
V
V
V
µA
nA
µA
mA
4.5V ≤ V
IN
≤ 36V
4.5V ≤ V
IN
≤ 36V
–2.0mA ≤ I
REF
≤ 2mA, V
IN
= 12V
V
IN
= 5V
V
IN
= 5V
2
2
2.46
2.50
0.01
0.3
4
4
1
2.54
0.015
0.6
V
%/V
%
mA
mA
%
CONDITIONS
T
J
= 25°C.
MIN
TYP
MAX
UNITS
Output Current
Load Regulation
Line Regulation
Dropout Voltage
Feedback Sense Voltage
Shutdown Pin Voltage
1120afb
For more information
www.linear.com/LT1120A
3
LT1120A
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
J
= 25°C.
PARAMETER
Reference
Reference Voltage
Line Regulation
Load Regulation
Output Source Current
Output Sink Current
Regulator
Supply Current
V
IN
= 6V, I
OUT
≤ 100µA
V
IN
= 36V, I
OUT
≤ 100µA
V
IN
= 12V, I
OUT
= 125mA
(V
IN
– V
OUT
) ≥ 1V, V
IN
≥ 6V
(V
IN
– V
OUT
) ≥ 1V, V
IN
≥ 6V
6V ≤ V
IN
≤ 36V
I
OUT
= 100µA
I
OUT
= 125mA
V
IN
= 12V
V
IN
= 36V
V
IN
= 36V
V
IN
= 36V
V
IN
= 36V
∆V
OUT
= 29V, R
L
= 20k
V
IN
= 4.5V
V
IN
= 36V, V(Pin 7) = 36V
l
l
l
l
l
l
l
l
l
l
l
l
elecTrical characTerisTics
CONDITIONS
4.5V ≤ V
IN
≤ 36V
4.5V ≤ V
IN
≤ 36V
MIN
l
l
l
l
l
TYP
2.50
0.01
0.4
MAX
2.55
0.02
0.8
UNITS
V
%/V
%
mA
mA
2.40
–2.0mA ≤ I
REF
≤ 2mA, V
IN
= 12V
V
IN
= 5V
V
IN
= 5V
2
2
30
40
11
125
1
0.02
0.06
0.85
2.38
2.5
2.57
50
50
240
400
10
15
1000
5
10
8
60
40
50
20
µA
µA
mA
mA
%
%/V
V
V
V
nA
µA
mA
mV
nA
V/V
mA
µA
Output Current
Load Regulation
Line Regulation
Dropout Voltage
Feedback Sense Voltage
Feedback Bias Current
Minimum Load Current
Short-Circuit Current
Comparator
Offset Voltage
Bias Current
Gain
Output Sink Current (Note 2)
Leakage Current
l
l
l
l
l
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:
For T
A
≤ –40°C output sink current drops to 2.5mA.
1120afb
4
For more information
www.linear.com/LT1120A
LT1120A
Typical perForMance characTerisTics
Regulator Load Regulation
0.3
OUTPUT VOLTAGE CHANGE (%)
0.2
0.1
0
–0.1
–0.2
–0.3
0.1
0.01
0.1
T
J
= 125°C
PRE-LOAD = 100µA
100
T
J
= –55°C
SUPPLY CURRENT (mA)
10
SHORT-CIRCUIT CURRENT (mA)
Supply Current
350
300
250
200
150
100
50
Regulator Short-Circuit Current
T
J
= 25°C
1
0.1
1
10
100
OUTPUT CURRENT (mA)
1000
1120A G01
10
100
1
1000
REGULATOR OUTPUT CURRENT (mA)
1120A G02
0
–50
–10
30
70
110
TEMPERATURE (°C)
150
1120A G03
Dropout Voltage
REGULATOR INPUT-OUTPUT DIFFERENTIAL (V)
1
∆V
OUT
= 100mV
MINIMUM LOAD CURRENT (µA)
100
Regulator Minimum Load Current
70
65
RIPPLE REJECTION (dB)
60
55
50
45
40
35
1
70
80
90
100 110 120 130 140 150
TEMPERATURE (°C)
1120A G05
Regulator Ripple Rejection
I
OUT
= 100mA
0.1
10
I
OUT
= 10mA
I
OUT
= 1mA
V
IN
= 10VDC,
1V
P-P
V
OUT
= 5V
C
OUT
= 10µF
10
100
1k
10k
RIPPLE FREQUENCY (Hz)
100k
1120A G06
0.01
0.1
1
1000
10
100
REGULATOR OUTPUT CURRENT (mA)
1120A G04
30
Supply Current
10
I
OUT
= 100mA
SUPPLY CURRENT (mA)
1
SUPPLY CURRENT (mA)
1
10
Supply Current at Dropout
4
I
OUT
= 100mA
REFERENCE VOLTAGE CHANGE (mV)
3
2
1
0
–1
–2
–3
Reference Regulation
0.1
I
OUT
= 10mA
I
OUT
= 1mA
0.1
I
OUT
= 10mA
I
OUT
= 1mA
V
OUT
= 5V
0.01
0.01
5
1
10
25
15
20
REGULATOR INPUT-OUTPUT DIFFERENTIAL (V)
1120A G07
0.1
0
0.2
0.6
0.3
0.5
0.4
REGULATOR INPUT-OUTPUT DIFFERENTIAL (V)
1120A G08
–4
–1.5
–1.0 –0.5
0
0.5
1.0
REFERENCE OUTPUT CURRENT (mA)
1.5
1120A G09
1120afb
For more information
www.linear.com/LT1120A
5
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