MITSUBISHI (Dig./Ana. INTERFACE)
M51995AP/FP
SWITCHING REGULATOR CONTROL
DESCRIPTION
M51995A is the primary switching regulator controller which is
especially designed to get the regulated DC voltage from AC power
supply.
This IC can directly drive the MOS-FET with fast rise and fast fall
output pulse.
Type M51995A has the functions of not only high frequency OSC
and fast output drive but also current limit with fast response and
high sensibility so the true "fast switching regulator" can be
realized.
It has another big feature of current protection to short and over
current,owing to the integrated timer-type protection circuit,if few
parts are added to the primary side.
The M51995A is equivalent to the M51977 with externally re-
settable OVP(over voltage protection)circuit.
COLLECTOR
V
OUT
EMITTER
VF
ON/OFF
OVP
DET
F/B
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
PIN CONFIGURATION (TOP VIEW)
Vcc
CLM+
CLM-
GND
CT
T-OFF
CF
T-ON
Outline 16P4
FEATURES
500kHz operation to MOS FET
•Output current...............................................................±2A
•Output rise time 60ns,fall time 40ns
•Modified totempole output method with small through current
Compact and light-weight power supply
•Small start-up current............................................90µA typ.
•Big difference between "start-up voltage" and "stop voltage"
makes the smoothing capacitor of the power input section small.
Start-up threshold 16V,stop voltage 10V
•Packages with high power dissipation are used to with-stand the
heat generated by the gate-drive current of MOS FET.
16-pin DIP,20-pin SOP 1.5W(at 25°C)
Simplified peripheral circuit with protection circuit and built-in
large-capacity totempole output
•High-speed current limiting circuit using pulse-by-pulse
method(Two system of CLM+pin,CLM-pin)
•Protection by intermittent operation of output over current......
..........................................................Timer protection circuit
•Over-voltage protection circuit with an externally re-settable
latch(OVP)
•Protection circuit for output miss action at low supply
voltage(UVLO)
High-performance and highly functional power supply
•Triangular wave oscillator for easy dead time setting
HEAT SINK PIN
6
15
14
13
12
11
COLLECTOR
V
OUT
EMITTER
VF
1
2
3
4
5
20
19
18
17
16
Vcc
CLM+
CLM-
GND
HEAT SINK PIN
ON/OFF
OVP
DET
F/B
7
8
9
10
CT
T-OFF
CF
T-ON
Outline 20P2N-A
Connect the heat sink pin to GND.
APPLICATION
Feed forward regulator,fly-back regulator
RECOMMENDED OPERATING CONDITIONS
Supply voltage range............................................12 to 36V
Operating frequency.................................less than 500kHz
Oscillator frequency setting resistance
•T-ON pin resistance R
ON
...........................10k to 75kΩ
•T-OFF pin resistance R
OFF
..........................2k to 30kΩ
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MITSUBISHI [ MITSUBISHI ELECTRIC SEMICONDUCTOR ]
