LR12
High Input Voltage, Adjustable
3-Terminal Linear Regulator
Features
►
13.2 to 100V input voltage range
►
Stable with 100nF output capacitor
►
Adjustable 1.20 to 88V output regulation
►
5% reference voltage tolerance
►
Output current limiting, 50mA min.
►
10µA typical ADJ current
►
Over temperature protection
►
Available in 3 different packages
General Description
The Supertex LR12 is a high voltage, low output current,
adjustable linear regulator. It has a wide operating input
voltage range of 13.2 - 100V. The output voltage can be
adjusted from 1.20 - 88V, provided that the input voltage
is at least 12V greater than the output voltage. The output
voltage can be adjusted by means of two external resistors
R
1
and R
2
as shown in the typical application circuits. The
LR12 regulates the voltage difference between VOUT
and ADJ pins to a nominal value of 1.20V. The 1.20V is
amplified by the external resistor ratio R
1
and R
2
. An internal
constant bias current of typically 10µA is connected to
the ADJ pin. This increases V
OUT
by a constant voltage of
10µA times R
2
.
The LR12 has current limiting and temperature limiting. The
output current limit is 100mA maximum and the minimum
temperature limit is 125°C. An output short circuit current
will therefore be limited to 100mA maximum. When the
junction temperature reaches its temperature limit, the
output current and/or output voltage will decrease to keep
the junction temperature from exceeding its temperature
limit. For SMPS start-up circuit applications, the LR12
turns off when an external voltage greater than the output
voltage of the LR12 is applied to VOUT of the LR12. To
maintain stability, a bypass capacitor of 100nF or larger
and a minimum DC output current of 500µA are required.
Applications
►
DC/DC SMPS startup circuits
►
Adjustable high voltage constant current sources
►
Industrial controls
►
Motor controls
►
Battery powered systems
►
Power supplies
►
Telecom applications
►
LED drivers
►
Automotive applications
LR12 Typical Application
*
V
OUT
1.2V to 88V
V
IN
VIN
VOUT
ADJ
R1
C2
R2
R
LOAD
13.2V to
100V
C1
LR12
*Required for conditions where V
IN
is less than V
OUT
.
LR12
Ordering Information
Package Options
Device
LR12
8-Lead SOIC
LR12LG-G
TO-252
(D-PAK)
LR12K4-G
TO-92
LR12N3-G
VIN
ADJ
Pin Configurations
VOUT
-G indicates package is RoHS compliant (‘Green’)
TO-252 (K4)
ADJ
NC
NC
VIN
VOUT
VOUT
VOUT
VOUT
ADJ
VIN
VOUT
Absolute Maximum Ratings
Parameter
V
IN-ADJ
V
OUT-ADJ
V
IN
- V
OUT
Operating ambient temperature
Operating junction temperature
Storage temperature
Value
-0.5V to +120V
-10V to +10V
-0.5V to +120V
-40°C to +85°C
-40°C to +125°C
-65°C to +150°C
8-Lead SOIC (LG)
TO-92 (N3)
Product Marking
Si YYWW
LR12K4
LLLLLLL
YY = Year Sealed
WW = Week Sealed
L = Lot Number
= “Green” Packaging
Package may or may not include the following marks: Si or
TO-252 (K4)
YYWW
LLLL
Absolute maximum ratings are those values beyond which damage to the device may oc-
cur. Functional operation under these conditions is not implied. Continuous operation of the
device at the absolute rating level may affect device reliability. All voltages are referenced
to device ground.
LR12
YY = Year Sealed
WW = Week Sealed
L = Lot Number
= “Green” Packaging
8-Lead SOIC (LG)
Thermal Characteristics
Package
TO-252
8-Lead SOIC
TO-92
Power Dissipation
@ T
A
= 25 C
O
O
Package may or may not include the following marks: Si or
( C/W)
θ
jc
( C/W)
O
θ
ja
2.0W
1.8W
0.6W
6.25
-
125
50
55
*
170
SiLR
1 2
YWLL
Y = Last Digit of Year Sealed
W = Code for Week Sealed
L = Lot Number
= “Green” Packaging
TO-92 (N3)
Package may or may not include the following marks: Si or
Notes:
* Mounted on FR4 board, 25mm x 25mm x 1.57mm
Electrical Characteristics
(Test conditions unless otherwise specified: -40 C < T
O
A
< +85
O
C)
Sym
Parameter
Min
Typ
Max
Units
Conditions
V
IN
- V
OUT
V
OUT
Input to output voltage difference
Overall output voltage regulation
Line regulation
12
1.14
-
-
-1.0
-
1.20
0.003
1.4
-
98.8
1.26
0.03
3.0
+1.0
V
V
%/V
%
%
---
13.2V < V
IN
<100V, R
1
= 2.4KΩ, R
2
= 0
15V < V
IN
<100V, V
OUT
= 5.0V, I
OUT
= 0.5A
V
IN
= 15V, V
OUT
= 5.0V,
0.5mA< I
OUT
<50mA
V
IN
= 15V, V
OUT
= 5.0V, I
OUT
= 10mA,
-40
O
C < T
A
< 85
O
C
ΔV
OUT
Load regulation
Temperature regulation
2
LR12
Electrical Characteristics
(cont.)
Sym
I
OUT
I
ADJ
C2
DV
OUT
/D
VIN
T
LIMIT
Parameter
Output current limit
Minimum output current
Adjust output current
Minimum output load
capacitance
Ripple rejection ratio
Junction temperature limit
Min
50
-
0.5
5.0
100
50
125
Typ
-
-
-
10
-
60
-
Max
100
-0.5
-
15
-
-
-
Units
ma
mA
µA
nF
dB
O
Conditions
T
J
< 85
O
C, V
IN
- V
OUT
< 12V
T
J
< 125
O
C, V
IN
- V
OUT
< 100V
Includes R
1
and load current
---
---
120Hz, V
OUT
= 5.0V
---
C
Functional Block Diagram
Pass
Element
LR12
VOUT
VIN
Overtemp &
Overcurrent
1.2V
6.5V
1.0KΩ
10μA
ADJ
Current Limit
100
90
80
70
60
50
I
C
(mA)
-40
-20
0
20
40
60
80
100
Temperature (
o
C)
3
LR12
Typical Application Circuits
Figure 1: High Input Voltage, 5.0V Output Linear Regulator
* Required for conditions where V
IN
is less than V
OUT
.
*
V
IN
=17V to 100V
VIN
VOUT
ADJ
R1
6.04KΩ
±1%
R2
18.2KΩ
±1%
V
OUT
= 5.0V
LR12
C1
C2
100nF
R
LOAD
≤ 16.5KΩ
V
OUT
= 1.20V 1+ R2
R1
+ I
ADJ
R2
Figure 2: SMPS Start-Up Circuit
V
IN
=15V to 100V
V
AUX
+
V
OUT
1
-
VIN
VOUT
ADJ
V
CC
FB
+
V
OUT
2
LR12
PWM IC
-
Figure 3: High Voltage Adjustable Constant Current Source
I
OUT
=
+
V
IN
= 15V to 100V
-
VIN
VOUT
ADJ
1.20V
R
R
LR12
100nF
4
LR12
Typical Performance Curves
VIN
VOUT
ADJ
13.2V
V
OUT
= 1.2V
1.30
Temperature Variation
LR12
2.4KΩ
100nF
1.25
V
OUT
(V)
1.20
1.15
1.10
1.05
1.00
-50
-25
0
25
50
75
100
125
T(junction) (
o
C)
VIN
VOUT
ADJ
V
OUT
= 5.0V
I
OUT
Load Regulation
5.30
5.25
LR12
25V
18.2KΩ
±1%
6.04KΩ
±1%
100nF
R
LOAD
V
OUT
(V)
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
4.80
0
5
10
15
20
25
30
35
40
45
50
I
OUT
(mA)
5
