1
LT1120
Micropower Regulator with
Comparator and Shutdown
The LT
1120 is a combination micropower positive regu-
lator and free collector comparator on a single monolithic
chip. With only 40
A supply current, the LT1120 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. 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.
The 2.5V reference will source or sink current. This allows
it to be used as a supply splitter or auxiliary output.
s
40
A Supply Current
s
125mA Output Current
s
2.5V Reference Voltage
s
Reference Output Sources 2mA and Sinks 2mA
s
Open Collector
s
Comparator Sinks 10mA
s
Logic Shutdown
s
0.2V Dropout Voltage
s
Thermal Limiting
s
Available in 8-Lead DIP, SO and Metal Can Packages
s
Battery Systems
s
Battery-Backup System
s
Portable Terminals
s
Portable Instruments
s
Memory Keep-Alive
, LTC and LT are registered trademarks of Linear Technology Corporation.
5V Regulator
Dropout Voltage and Supply Current
OUTPUT CURRENT (mA)
0.1
1
0.01
DROPOUT VOLTAGE (V)
SUPPLY CURRENT (mA)
0.10
1.00
0.1
1
10
10
100
1000
1120 TA02
+
+
V
IN
V
OUT
FB
GND
SHDN
SHUTDOWN
LT1120
4
0.001
F
1M
1M
25
F
5V
V
IN
> 5.2V
I
Q
= 40
A
1120 TA01
10
F
2
1
3
5
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LT1120
Input Voltage ........................................................... 36V
NPN Collector Voltage ............................................. 36V
Output Short-Circuit Duration .......................... Indefinite
Power Dissipation ............................... Internally Limited
ABSOLUTE AXI U
RATI GS
W
W
W
U
Operating Temperature Range
LT1120C ................................................ 0
C to 100
C
LT1120I ................................................ 40 to 100
C
Storage Temperature Range ................. 65
C to 150
C
ELECTRICAL CHARACTERISTICS
PACKAGE/ORDER I FOR ATIO
U
U
W
T
JMAX
= 150
C,
JA
= 100
C/W (J)
T
JMAX
= 110
C,
JA
= 130
C/W (N)
T
JMAX
= 110
C,
JA
= 150
C/W (S)
Consult factory for Military grade parts.
TOP VIEW
COMPOUT
INPUT
GND
FB
REF
V
IN
SHDN
V
OUT
8
7
6
5
3
2
1
4
H PACKAGE
8-LEAD TO-5 METAL CAN
ORDER PART
NUMBER
LT1120CH
ORDER PART
NUMBER
LT1120CJ8
LT1120CN8
LT1120CS8
LT1120IN8
LT1120IS8
1
2
3
4
8
7
6
5
TOP VIEW
GND
FB
SHDN
V
OUT
INPUT
COMPOUT
REF
V
IN
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
J8 PACKAGE
8-LEAD CERDIP
S8 PART MARKING
T
JMAX
= 150
C,
JA
= 150
C/W,
JC
= 45
C/W
The
q
denotes the specifications which apply over the full
1120
1120I
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Reference
Reference Voltage
4.5V
V
IN
36V
2.46
2.50
2.54
V
Line Regulation
4.5V
V
IN
36V
0.01
0.015
%/V
Load Regulation
2mA
I
REF
2mA, V
IN
= 12V
0.3
0.6
%
Output Source Current
V
IN
= 5V
2
4
mA
Output Sink Current
V
IN
= 5V
2
4
mA
Temperature Stability
1
%
Regulator
Supply Current
V
IN
= 6V, I
OUT
100
A
45
80
A
V
IN
= 36V, I
OUT
100
A
75
100
A
V
IN
= 12V, I
OUT
= 125mA
11
20
mA
Output Current
(V
IN
V
OUT
)
1V, V
IN
6V
125
mA
Load Regulation
(V
IN
V
OUT
)
1V, V
IN
6V
0.2
0.5
%
Line Regulation
6V
V
IN
36V
0.01
0.015
%/V
Dropout Voltage
I
OUT
= 100
A
0.02
0.05
V
I
OUT
= 125mA
0.4
0.65
V
Feedback Sense Voltage
V
IN
= 12V
2.44
2.5
2.56
V
Shutdown Pin Voltage
Normal
0.4
V
V
OUT
0.5V
Shutdown
2.2
1.4
V
(Note 1)
operating temperature range, otherwise specifications are at T
A
= 25
C. T
j
= 25
C
3
LT1120
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Reference
Reference Voltage
4.5V
V
IN
36V
q
2.40
2.50
2.55
V
Line Regulation
4.5V
V
IN
36V
q
0.01
0.02
%/V
Load Regulation
2mA
I
REF
2mA, V
IN
= 12V
q
0.4
0.8
%
Output Source Current
V
IN
= 5V
q
2
mA
Output Sink Current
V
IN
= 5V
q
2
mA
Regulator
Supply Current
V
IN
= 6V, I
OUT
100
A
q
65
95
A
V
IN
= 36V, I
OUT
100
A
q
85
100
A
V
IN
= 12V, I
OUT
= 125mA
q
11
20
mA
Output Current
(V
IN
V
OUT
)
1V, V
IN
6V
q
125
mA
Load Regulation
(V
IN
V
OUT
)
1V, V
IN
6V
q
1
%
Line Regulation
6V
V
IN
36V
q
0.02
%/V
Dropout Voltage
I
OUT
= 100
A
q
0.06
V
I
OUT
= 125mA
q
0.85
V
Feedback Sense Voltage
V
IN
= 12V
q
2.38
2.5
2.57
V
Feedback Bias Current
q
50
nA
Minimum Load Current
V
IN
= 36V
q
50
A
Short-Circuit Current
V
IN
= 36V
q
300
400
mA
Shutdown Pin Current
V
IN
= 1.4V
25
A
Feedback Bias Current
15
40
nA
Minimum Load Current
V
IN
= 36V
1
5
A
Short-Circuit Current
V
IN
= 36V
300
400
mA
Comparator
Offset Voltage
V
IN
= 36V
3
7
mV
Bias Current
V
IN
= 36V (Note 2)
15
40
nA
Gain
V
OUT
= 29V, R
L
= 20k
2000
10000
V/V
Power Supply Rejection
4.5V
V
S
36V
80
96
dB
Output Sink Current
V
IN
= 4.5V
10
18
mA
Saturation Voltage
I
OUT
= 1mA
0.4
0.6
V
Input Voltage Range
0
V
IN
1
V
Response Time
5
s
Leakage Current
2
A
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25
C. T
j
= 25
C
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25
C.
4
LT1120
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
a device may be impaired.
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
REGULATOR OUTPUT CURRENT (mA)
0.1
1
0.01
SUPPLY CURRENT (mA)
1
100
10
100
1000
1120 G02
0.1
10
T
J
= 55
C TO 125
C
TEMPERATURE (
C)
50
10
30
70
110
150
SHORT-CIRCUIT CURRENT (mA)
1120 G03
350
300
250
200
150
100
50
0
CURRENT LIMIT TIED TO GROUND
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE CHANGE (%)
0.3
0.2
0.1
0
0.1
0.2
0.3
0.1
10
100
1000
1120 G01
1
PRELOAD = 100
A
T
J
= 125
C
T
J
= 25
C
T
J
= 55
C
Regulator Load Regulation
Supply Current
Regulator Short-Circuit Current
Dropout Voltage
TEMPERATURE (
C)
70
80
90
100 110 120 130 140 150
MINIMUM LOAD CURRENT (
A)
100
10
1
1120 G05
RIPPLE FREQUENCY (Hz)
RIPPLE REJECTION (dB)
70
65
60
55
50
45
40
35
30
10
1k
10k
100k
1120 G06
100
I
OUT
= 100mA
I
OUT
= 1mA
V
IN
= 10VDC, 1V
PP
V
OUT
= 5V
C
OUT
= 10
F
I
OUT
= 10mA
Regulator Minimum Load Current
Regulator Ripple Rejection
REGULATOR OUTPUT CURRENT (mA)
0.1
1
0.01
REGULATOR INPUT-OUTPUT DIFFERENTIAL (V)
0.1
1
10
100
1000
1120 G04
V
OUT
= 100mV
Comparator
Offset Voltage
q
10
mV
Bias Current
V
IN
= 36V (Note 2)
q
15
60
nA
Gain
V
OUT
= 29V, R
L
= 20k
q
1000
V/V
Output Sink Current
V
IN
= 4.5V (Note 3)
q
5
10
mA
Leakage Current
V
IN
= 36V
q
8
A
The
q
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25
C.
Note 2: TA > 85
C, I bias maximum is 100nA.
Note 3: For T
A
40
C output current sink drops to 2.5mA.
5
LT1120
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
REGULATOR INPUT-OUTPUT DIFFERENTIAL (V)
1
5
10
15
20
25
SUPPLY CURRENT (mA)
10
1
0.1
0.01
1120 G07
I
OUT
= 100mA
I
OUT
= 1mA
V
OUT
= 5V
T
J
= 55
C TO 125
C
I
OUT
= 10mA
REGULATOR INPUT-OUTPUT DIFFERENTIAL (V)
1
0.1
0.2
0.3
0.4
0.5
0.6
SUPPLY CURRENT (mA)
10
1
0.1
0.01
1120 G08
I
OUT
= 100mA
I
OUT
= 1mA
T
J
= 55
C TO 125
C
I
OUT
= 10mA
REFERENCE OUTPUT CURRENT (mA)
1.5
1.0
0.5
0
0.5
1.0
1.5
REFERENCE VOLTAGE CHANGE (mV)
1120 G09
4
3
2
1
0
1
2
3
4
TIME (ms)
0
20 40 60 80 100 120 140 160 180
OUTPUT
CURRENT (mA)
OUTPUT VOLTAGE
CHANGE (%)
1120 G12
0.1
0
0.1
0
50
V
IN
= 15V
V
OUT
= 5V
REGULATOR OUTPUT CURRENT (mA)
FEEDBACK CURRENT (nA)
40
35
30
25
20
15
10
5
0
0.1
10
100
1000
1120 G11
1
T
J
= 125
C
T
J
= 25
C
T
J
= 55
C
Supply Current
Supply Current at Dropout
Reference Regulation
Feedback Pin Current
Regulator Thermal Regulation
LT1120 Turn-On Characteristic
INPUT VOLTAGE (V)
0
1
2
3
4
5
6
7
8
OUTPUT VOLTAGE (V)
1120 G13
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
0
V
OUT
= 5V
R
L
= 50
R
L
= 500
NO LOAD
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