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LR8 High Input Voltage Adjustable 3-Terminal Linear Regulator
Features
13.2V to 450V input voltage range Adjustable 1.20V to 440V output regulation 5% output voltage tolerance Output current limiting 10A typical ADJ current Internal junction temperature limiting
General Description
The Supertex LR8 is a high voltage, low output current, adjustable linear regulator. It has a wide operating input voltage range of 13.2V to 450V. The output voltage can be adjusted from 1.20V to 440V 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 R1 and R2 as shown in the typical application circuits. The LR8 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 R1 and R2. An internal constant bias current of typically 10A is connected to the ADJ pin. This increases VOUT by a constant voltage of 10A times R2. The LR8 has current limiting and temperature limiting. The output current limit is typically 20mA and the minimum temperature limit is 125C. An output short circuit current will therefore be limited to 20mA. 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 LR8 turns off when an external voltage greater than the output voltage of the LR8 is applied to VOUT of the LR8. To maintain stability, a bypass capacitor of 1.0F or larger and a minimum DC output current of 500A are required. The device is available in TO-243AA (SOT-89), TO-252 (DPAK), and TO-92 packages.
Applications
Off-line SMPS startup circuits Adjustable high voltage constant current source Industrial controls Motor controls Battery chargers Power supplies
Typical Application Circuit
*
VOUT VIN VIN VOUT ADJ R1 C2 R2 RLOAD
LR8
C1
*Required for conditions where VIN is less than VOUT.
LR8 Ordering Information
DEVICE LR8 Package Option TO-243AA LR8N8-G TO-252 LR8K4-G TO-92 LR8N3-G
-G indicates package is RoHS compliant (`Green')
Absolute Maximum Ratings
Parameter VIN input voltage (voltages ref to ADJ) Output voltage range Operating ambient temperature range Operating junction temperature range Storage temperature range Value -0.5V to +480V -0.5V to +470V -40C to +85C -40C to +125C -65C to +150C
Pin Configurations
VOUT VOUT
VIN
VOUT
ADJ
VIN
ADJ
VIN
VOUT
ADJ
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
TO-243AA (SOT-89) TO-252 (D-PAK)
(top view) (top view)
TO-92
(front view)
Product Marking
Product marking for TO-243AA: LR8 where = 2-week alpha date code
Electrical Characteristics (Test conditions unless otherwise specified:
Symbol VIN - VOUT VOUT VOUT VOUT VOUT VOUT IOUT IOUT IOUT IADJ C2 DVOUT/DVIN TLIMIT Parameter Input to output voltage difference Overall output voltage regulation Overall output voltage regulation Line regulation Load regulation Temperature regulation Output current limit Output current limit Minimum output current Adjust output current Minimum output load capacitance Ripple rejection ratio Junction temperature limit Min 12 1.14 375 -1 10 5 1 50 125 Typ 1.20 400 0.003 1.4 0.3 10 60 -
-40C < TA < 85C.)
Max 450 1.26 425 0.01 3.0 +1 30 0.5 0.5 15 -
Units Conditions V V V %/V % % mA mA mA A F dB C --13.2V < VIN< 400V, R1 = 2.4K, R2 = 0 R1 = 2.4K, R2 = 782K 17V < VIN< 400V, VOUT = 5V, IOUT = 0.5mA VIN = 17V, VOUT = 5V, 0.5mA 125C, VIN - VOUT = 450V Includes R1 and load current ----120Hz, VOUT = 5V ---
2
LR8 Thermal Characteristics
Package TO-92 TO-243AA TO-252 Power Dissipation @ TA = 25C 0.74W 1.6W 2.5W JC C/W 125 15 6.25 JA C/W 170 78 50
Mounted on FR4 board, 25mm x 25mm x 1.57mm. Significant PD increase possible on ceramic substrate.
Functional Block Diagram
VIN
Pass Element
LR8
VOUT
Overtemp & Overcurrent
1.2V
10A
ADJ
Typical Application Circuits
Figure 1: High Input Voltage, 5.0V Output Linear Regulator *
VOUT = 5.0V VIN = 17V to 450V VIN VOUT ADJ
LR8
C1 R2 18.2K 1%
R1 6.04K 1% C2 1.0F RLOAD 16.5K
* Required for conditions where VIN is less than VOUT
R2 VOUT = 1.20V 1+ R1
+ IADJ R2
3
LR8 Typical Application Circuits
Figure 2: SMPS Start-Up Circuit
VIN = (VOUT + 12V) to 450V + VAUXILIARY VOUT1 VIN VOUT ADJ + VOUT2 VCC FB -
LR8
PWM IC
Figure 3: High Voltage Adjustable Constant Current Source
IOUT = R + VIN VOUT ADJ VIN = (VOUT + 12V) to 450V 1.20V R
LR8
1.0F
LOAD
-
4
LR8 Typical Performance Curves
Temperature Variation
1.30
VIN
VOUT = 1.2V
VOUT (V)
1.25
LR8
ADJ 12V
2.4K 1.0F
1.20
1.15
1.10
1.05 1.00 -50
-25
0
25
50
75
100
125
T(junction) ( OC)
Adjustment Current
12
11
VIN
VOUT = 1.2V
IADJ (A)
LR8
12V, 200V, 400V ADJ 2.4K I
ADJ
10 VIN = 400V 9 VIN = 12V
1.0F
8 VIN = 200V 7
6 -50
-25
0
25
50
75
100
125
T(junction) (OC)
Load Regulation
5.2
V
IN
V
OUT
= 5.0V
IOUT
5.1
LR8
ADJ 25V 18.2K 1%
VOUT (V)
RLOAD
6.04K 1% 1.0F
5.0
4.9
4.8 0 2 4 6 8 10
IOUT (mA)
5
LR8 Typical Performance Curves (cont.)
VOUT vs. VIN
6
VIN
VOUT = 5.0V
5
LR8
ADJ 0V to 50V 18.2K 1% 6.04K 1% 1.0F 1K
VOUT (V)
4
3
2
1
0 0 10 20 30 40 50
VIN (V)
Ripple Rejection
-65
VIN
LR8
ADJ
VOUT = 5.0V
IOUT
Ripple Rejection Ratio (dB)
-64
20VP-P @ 60Hz 65V
6.04K 1% 1.0F RLOAD 18.2K 1%
-63
-62
-61
-60 0 2 4 6 8 10
I OUT (mA)
30 25 l c l (m A ) 20 15 10 -40
-20
0
20
40
60
80
100
Temperature (C)
6
LR8 Typical Performance Curves (cont.)
LR8

Load Transient Response
LR8

Line Transient Response
Line Power Up Transient
Line Power Down Transient
7
LR8 3-Lead TO-243AA (SOT-89) Package Outline (N8)
4.50 0.10 1.72 0.10 0.40 0.05
Exclusion Zone
1.50 0.10
4.10 0.15 2.45 0.15 2.21 0.08
No Vias/Traces in this area. Shape of pad may vary.
1.05 0.15 0.42 0.06 1.50 BSC 3.00 BSC 0.5 0.06
Top View
Side View
Bottom View
Notes: All dimensions are in millimeters; all angles in degrees.
3-Lead TO-252 (D-PAK) Package Outline (K4)
0.250 - 0.265 0.195 -0.215 0.035 - 0.050 0.018 - 0.035 0.086 - 0.094
4
0O - 15O 0.370 - 0.410
0.240 0.005
0.040 MAX
0.005 MAX
1
2
3
0.047 - 0.070 0.108 REF 0O - 10O 0.018 - 0.024 0.20 BSC
0.030 - 0.045 0.025 - 0.035 0.170 MIN 0.090 BSC
4
Cutouts may not be present
0.205 MIN
Notes: All dimensions in inches; angles in degrees
3
2
1
8
LR8 3-Lead TO-92 Package Outline (N3)
0.135 MIN 0.125 - 0.165 0.080 - 0.105 1 2 3
Top View
0.175 - 0.205 0.170 - 0.210 123
Seating Plane
0.500 MIN 0.014 - 0.022 0.014 - 0.022 0.045 - 0.055 0.095 - 0.105
Front View
Side View
Notes: All dimensions are in millimeters; all angles in degrees.
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to http://www.supertex.com/packaging.html.)
Doc.# DSFP-LR8 A121806
9

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