LR645
High-Input Voltage SMPS, Start-up/Linear Regulator
Features
Description
• Accepts inputs from 15 to 450V
• Output currents: up to 3.0mA continuous, 30mA
peak
• Supply current typically 50µA
• Line regulation typically 0.1mV/V
• Output can be trimmed from 8.0 to 12V
• Output current can be increased to 150mA with
external FET
LR645 is a high-input voltage, low-output current, linear
regulator that is available in two versions. A 3-terminal,
fixed-output voltage version is available in TO-92, TO220 and SOT-89 packages, as well as an adjustable
voltage version available in an 8-lead SOIC package.
Applications
• Off-line SMPS startup circuits (pulse loads)
• Low power off-line regulators
• Regulators for noisy inputs
The 3-terminal version of LR645 functions like any
other low-voltage, 3-terminal regulator except it allows
the use of much higher-input voltages. When used in a
Switched-mode Power Supply (SMPS), start-up circuit,
LR645 eliminates the need for large power resistors. In
this application, current is drawn from the high voltage
line only during start-up. Only leakage current flows
after start-up, thereby reducing the continuous power
dissipation to a few milliwatts.
The adjustable-voltage version allows trimming of the
output voltage from 8.0 to 12V. This version can also be
connected to an external depletion mode metal–oxide–
semiconductor field-effect transistor (MOSFET) for
increased output current. When used in conjunction
with depletion mode MOSFET DN2540N5, an output
current of up to 150mA is achieved.
WARNING
The LR645 does NOT provide galvanic isolation. When operated from an AC line, potentially lethal voltages can be
present on the IC. Adequate means of protecting the end user from such voltages must be provided by the circuit
developer.
2015 Microchip Technology Inc.
DS20005384A-page 1
LR645
Package Type
TRIM
NC
GATE
NC
VOUT
VIN
VOUT
GND
NC
+VIN
GND
TO-92
8-Lead SOIC
GND
GND
VOUT
GND
VIN
TO-243AA (SOT-89)
VOUT
+VIN
GND
TO-220
See Table 2-1 for pin information
DS20005384A-page 2
2015 Microchip Technology Inc.
LR645
1.0
ELECTRICAL CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
Input Voltage .................................................................................................................................................................................. 450V
Output voltage............................................................................................................................................................................... 15.5V
Operating and storage temperature ............................................................................................................................. -55°C to +150°C
Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at those or any other conditions, above those indicated in the operational listings of
this specification, is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
1.1
ELECTRICAL SPECIFICATIONS
TABLE 1-1:
Symbol
VOUT
∆VOUT
ELECTRICAL CHARACTERISTICS 1
Parameter
Min
Typ
Max
Output voltage
9.3
10
10.7
V
No load
Output voltage over temperature2
9.0
10
11.5
V
TJ = - 40 to +125°C, No load
-
40
200
mV
VIN = 15 to 400V, No load
VIN = 50V, IOUT = 0 to 3.0mA
Line regulation
Load regulation
Units Conditions
-
150
400
mV
15
-
450
V
Input quiescent current
-
50
150
µA
No Load
IOFF
VIN off-state leakage current
-
0.1
10
µA
VAUX ≥ VOUT +1V applied to VOUT pin
IAUX
Input current to VOUT
VIN
Operating input voltage range
IINQ
-
-
200
µA
VAUX ≥ VOUT +1V applied to VOUT pin
50
60
-
dB
120 Hz, No Load
voltage2
-
25
-
µV
0.01 to 100 KHz
IPEAK
Output peak current3
-
30
-
mA
COUT = 10 µF, VIN = 400V
VAUX
External voltage applied to VOUT
-
-
13.2
V
∆VOUT/∆VIN Ripple rejection ratio2
en
Noise
8-lead, adjustable voltage version only
VOUT
∆VOUT
1
2
3
8
-
12
V
Load regulation at 8V trim2
-
200
400
mV
VIN = 15V, IOUT = 0 to 1.0 mA
Load regulation at 12V trim2
-
100
400
mV
VIN = 50V, IOUT = 0 to 3.0 mA
No load
Test Conditions unless otherwise specified: TA = 25°C, VIN = 15V-450V, COUT = 0.01 µF
Guaranteed by design
Pulse test duration
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