M51995

Manufacturer Part NumberM51995
DescriptionSWITCHING REGULATOR CONTROL
ManufacturerMitsubishi
M51995 datasheet
 
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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.
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
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
...........................10k to 75k
ON
•T-OFF pin resistance R
..........................2k to 30k
OFF
MITSUBISHI (Dig./Ana. INTERFACE)
SWITCHING REGULATOR CONTROL
PIN CONFIGURATION (TOP VIEW)
COLLECTOR
1
V
OUT
2
EMITTER
3
VF
4
ON/OFF
5
OVP
6
DET
7
F/B
8
Outline 16P4
COLLECTOR
1
V
2
OUT
3
EMITTER
4
VF
5
HEAT SINK PIN
6
7
ON/OFF
8
OVP
9
DET
F/B
10
Outline 20P2N-A
(
/ 27 )
1
M51995AP/FP
Vcc
16
CLM+
15
CLM-
14
GND
13
CT
12
11
T-OFF
CF
10
9
T-ON
Vcc
20
CLM+
19
CLM-
18
GND
17
16
HEAT SINK PIN
15
CT
14
13
T-OFF
12
CF
11
T-ON
Connect the heat sink pin to GND.

M51995 Summary of contents

  • Page 1

    ... 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 ...

  • Page 2

    ... COMPARATOR LATCH +CURRENT -CURRENT LIMIT LATCH LIMIT LATCH CLM- CLM+ +CURRENT LIMIT -CURRENT LIMIT Conditions Peak Continuous Ta=25˚C Ta>25˚ M51995AP/FP SWITCHING REGULATOR CONTROL F/B GND DET OP AMP 2.5V INTERMITTENT INTERMITTENT ACTION AND ACTION OSC CONTROL CT INTERMITTENT OPERATION DETERMINE CAPACITANCE Ratings 36 36 ±2 ± ...

  • Page 3

    ... THOVPL V =400mV OVP OVP terminal is open. (high impedance) Vcc=30V Vcc=18V C =4.7µ =3.3V,Ta=-5°C CT Ta=25°C Ta=85° 85°C V -=-0.1V CLM OUT -5 Ta 85°C V +=0V CLM OUT ( M51995AP/FP SWITCHING REGULATOR CONTROL Limits Min. Typ. Max. Vcc(STOP) 16.2 17.2 15.2 9.0 9.9 10.9 5.0 6 140 40 90 190 10 15 0.95 1. 140 0.95 1 ...

  • Page 4

    ... ON OFF V =2V C =220pF F F Min off duty/Max on duty V =0.2V F Source current Vcc=18V,Io=10mA Vcc=18V,Io=100mA Vcc=5V,Io=1mA Vcc=5V,Io=100mA Vcc=18V,Io=-10mA Vcc=18V,Io=-100mA No load No load ( M51995AP/FP SWITCHING REGULATOR CONTROL Limits Min. Typ. Max. 170 188 207 47.0 50.0 53.0 3.97 4.37 4.77 1.76 1.96 2.16 2.11 2.41 2.71 170 188 207 108 ...

  • Page 5

    ... CIRCUIT CURRENT VS.SUPPLY VOLTAGE 3.0 2.0 1.0 0 40.0 0 30.0 OVP TERMINAL THRESHOLD VOLTAGE 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 - M51995AP/FP SWITCHING REGULATOR CONTROL (NORMAL OPERATION) =18k ON =20k OFF f =500kHz OSC f =100kHz OSC Ta=-30°C Ta=25°C Ta=85° SUPPLY VOLTAGE Vcc(V) (OFF STATE) Ta=25°C Ta=85°C Ta=-30° SUPPLY VOLTAGE Vcc(V) VS ...

  • Page 6

    ... ON AND OFF DURATION OF TIMER 175 TIMER ON•••CIRCUIT OPERATION ON TIMER OFF••CIRCUIT OPERATION OFF 150 125 100 75 - 100 - M51995AP/FP SWITCHING REGULATOR CONTROL ON OFF OFF - AMBIENT TEMPERATURE Ta(°C) DISCHARGE CURRENT OF TIMER VS.AMBIENT TEMPERATURE 80 -20 ...

  • Page 7

    ... CLM+ TERMINAL VOLTAGE V 2.6 Vcc=18V 2.4 Ta=25°C 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 1m -0.8 -1.0 -(V) OUTPUT SOURCE CURRENT I CLM ( M51995AP/FP SWITCHING REGULATOR CONTROL VS. AMBIENT TEMPERATURE - AMBIENT TEMPERATURE Ta(°C) CLM+ TERMINAL CURRENT VS. CLM+ TERMINAL VOLTAGE Ta=-30°C Ta=25°C Ta=85°C +(V) CLM OUTPUT HIGH VOLTAGE VS. OUTPUT SOURCE CURRENT 100m 10m 1 (A) ...

  • Page 8

    ... VS. F/B TERMINAL INPUT CURRENT 50 =100kHz) =20k 2.0 2.5 0 F/B TERMINAL INPUT CURRENT I (mA) F M51995AP/FP SWITCHING REGULATOR CONTROL DETECTION VOLTAGE VS. AMBIENT TEMPERATURE - AMBIENT TEMPERATURE Ta(°C) VS. FREQUENCY 1k 10k 100k 1M FREQUENCY f(Hz) ON duty (f =200kHz) OSC R =18k ON R =20k OFF Ta=-30°C Ta=25° ...

  • Page 9

    ... R =24k ON R =20k OFF 600 C =330pF F 500 400 300 200 60 80 100 - M51995AP/FP SWITCHING REGULATOR CONTROL VS. AMBIENT TEMPERATURE R =18k ON R =20k OFF f =500kHz OSC f =200kHz OSC f =100kHz OSC f =100kHz OSC f =200kHz OSC f =500kHz OSC -40 -20 ...

  • Page 10

    ... OFF =24k OFF 100µ =22k OFF =20k OFF =12k OFF =6.2k OFF 10µ 1µ 0 OVP TERMINAL INPUT VOLTAGE M51995AP/FP SWITCHING REGULATOR CONTROL (f =200kHz) OSC - AMBIENT TEMPERATURE Ta(°C) EXPANSION RATE OF PERIOD (f =100kHz) OSC ...

  • Page 11

    ... CURRENT FROM OVP TERMINAL FOR OVP RESET VS. SUPPLY VOLTAGE 800 700 600 500 Ta=-30°C Ta=25°C 400 Ta=85°C 300 200 100 SUPPLY VOLTAGE Vcc( M51995AP/FP SWITCHING REGULATOR CONTROL ...

  • Page 12

    ... FUNCTION DESCRIPTION Type M51995AP and M51995AFP are especially designed for off-line primary PWM control IC of switching mode power supply (SMPS) to get DC voltage from AC power supply. Using this IC,smart SMPS can be realized with reasonable cost and compact size as the number of external electric ...

  • Page 13

    ... MITSUBISHI (Dig./Ana. INTERFACE) M51995AP/FP SWITCHING REGULATOR CONTROL current and one OFF current by the function of Q2,Q3 and 1/16 T-ON Q3 T-OFF FROM VF SIGNAL ~ Vz 4. M51995 control circuit for OSC.capacitor C operation of intermittent action and OSC.control circuit (V/s) .....................( OSCL F (s) ...

  • Page 14

    ... M51995AP/FP SWITCHING REGULATOR CONTROL OSCH 4.4V OSCL 2. and OSC.control circuit operation START FROM 0V OSCH OSCL GENERATE PULSE OPERATION START circuit operation at start up M51995 V OUT R VFFB VF C VFFB to VF terminal FIRST PULSE ...

  • Page 15

    ... POINT B TO LATCH OUTPUT POINT C FROM OSC OSC WAVEFORM OF CF TERMINAL WAVEFORM OF CLM- TERMINAL ( / M51995AP/FP SWITCHING REGULATOR CONTROL OSC WAVEFORM OF CF TERMINAL ~ V THCLM WAVEFORM OF CLM+ TERMINAL CURRENT LIMIT SIGNAL TO SET LATCH WAVEFORM OF V TERMINAL ...

  • Page 16

    ... Therefore the parts in power circuit including secondary rectifier diodes are protected from the overheat by the over current. Fig.14 Block diagram of intermittent action circuit ( M51995AP/FP SWITCHING REGULATOR CONTROL (b) Without current limit signal of about 3V,so the CT terminal voltage is THTIME THTIME is charged up by the current of ...

  • Page 17

    ... Q4 "off" As the constant current source connected to Q4 base terminal has such the hysteresis characteristics of 20µA at operation and 3µA at stopping.So the unstable operation is not appeared even if the ON/OFF terminal voltage signal varies slowly M51995AP/FP SWITCHING REGULATOR CONTROL 500 F/B DET 5 ...

  • Page 18

    ... Vcc lower than the OVP reset supply voltage. As the OVP reset voltage is settled on the rather high voltage of 9.0V,SMPS can be reset in rather short time from the switch-off of the AC power source if the smoothing capacitor is not so large value M51995AP/FP SWITCHING REGULATOR CONTROL charging BE of Q3. ...

  • Page 19

    ... I 1 For example,the through current may reach such the high current level of 1A,if type M51995A has the "conventional" totempole circuit.For the high frequency application such as higher than 100kHz,this through current is very important factor and will cause not only the large Icc current and the inevitable heat- but also the noise voltage ...

  • Page 20

    ... M51995A from the GND line of the IC (b)The locate the C and connect directly (c)To separate the collector line of type M51995A from the Vcc line of the IC (d)To connect the ground terminals of peripheral parts of ICs to GND of type M51995A as short as possible COLLECTOR ...

  • Page 21

    ... THIS PART SHOULD BE SHORT Fig.29 Example circuit diagram to make the OVP-reset-time fast Vcc 470 M51995A OVP CVcc GND third winding voltage on fly back system • (R1+R2) is long. Under such the circuit FIN VCC TO MAIN TRANSFORMER Vcc Cvcc M51995A GND MAIN TRANSFORMER THIRD WINDING forcedly and ...

  • Page 22

    ... CLM terminal and propagation delay time T terminal to output terminal of type M51995A.The typical T is 100ns. As the frequency becomes higher,the delay time must be shorter.And as the secondary output voltage becomes higher,the dynamic range of on-duty must be wider ...

  • Page 23

    ... Fig.36 How to control the knee point (b)In case of fly back system The DC output voltage of SMPS depends on the Vcc voltage of type M51995A when the polarity of the third winding is negative and the system is fly back.So the operation of type M51995A will stop when the Vcc becomes lower than "Operation-stop voltage" ...

  • Page 24

    ... To use the printed circuit board with the good thermal conductivity (3) To use the buffer circuit shown next section (3)Output buffer circuit It is recommended to use the output buffer circuit as shown in Fig.42,when type M51995A drives the large capacitive load or bipolar transistor. as the GS affect to the ...

  • Page 25

    ... DETECTING VOLTAGE R1 R3 How to synchronize with external circuit B Type M51995A has no function to synchronize with external circuit,however,there is some application circuit for R2 synchronization as shown in Fig.46.If this circuit is used,the synchronization may be out of order at the overload condition when the current limiting function starts to operate and VF terminal voltage becomes lower than 3V ...

  • Page 26

    ... In this case,over current can not be detected by detecting resistor in series to bipolar transistor, recommended to use the CT(current transformer). For the low current rating transistor,type M51995A can drive it directly as shown in Fig.48. Attention for heat generation The maximum ambient temperature of type M51995A is +85° ...

  • Page 27

    ... APPLICATION EXAMPLE Feed forward types SMPS with multi-output FIN V OUT VF SWITCHING REGULATOR CONTROL R1 COLLECTOR Vcc M51995AP ON/OFF OFF MITSUBISHI (Dig./Ana. INTERFACE) M51995AP/ Cvcc OVP F/B V OUT2 V OUT1 ON/OFF ...