Document
FA3641P(N), FA3647P(N) FA3641P(N), FA3647P(N)
s Description
The FA3641P(N) and FA3647P(N) are the PWM type switching power supply control ICs that can directly drive power MOSFET. These ICs use a CMOS device with high dielectric strength (30V) to implement low power consumption. They feature a number of functions that are equivalent to those of the FA531X series consisting of bipolar devices. In addition, they have a function that reduces the oscillation frequency to suppress loss of the power supply in light load mode and support an overvoltage protection detecting Vcc voltage. These ICs are most suitable for high-performance, energy-saving power supplies that require low input power in standby or no-load mode.
PWM control IC with light load power saving function For Switching Power Supply Control
s Dimensions, mm SOP-8
8 5
1 4.9
4
+0.1 –0.05
6.0±0.2
3.9
s Features
• Uses a newly developed CMOS process with high dielectric strength (30V) for implementing low power consumption • Standby current of 2µA or less (at Vcc=14V), and operating current of 1.9mA (typ.) • Automatically reduces the oscillation frequency to suppress loss of the power supply in light load mode • Overvoltage protection function detecting Vcc voltage • A drive circuit for connecting a power MOSFET directly • Output peak current: Source current –500mA Sink current +1A • Pulse-by-pulse overcurrent limiting function • Overload cutoff function (latch or non-latch mode selectable) • Output ON/OFF control function by external signal • Latch mode overvoltage shutdown function • Undervoltage lockout function (16.5V ON / 9V OFF) • Reference voltage output (5V) • 8-pin package (DIP/SOP)
0.4±0.1 1.27±0.2
DIP-8
8 5
1
9.3 1.5
4
6.4
3.0min 4.5max
3.3
0~8°
0.25 –
7.62
0~15 ˚
5˚ 0~1
2.54±0.25
0.46±0.1
58
1.7max
+0.1 5 0.0
0.20
FA3641P(N), FA3647P(N)
s Block diagram FA3641 FA3647
Pin No. Symbol Function 1 2 3 4 5 6 7 8 RT FB IS (+)/ IS (–) GND OUT VCC REF CS Oscillator timing resistor Feedback Overcurrent detection Ground Output Power supply
Description Setting oscillation frequency Input to PWM comparator Input to overcurrent limiting function Ground Output for direct driving a power MOSFET Power supply for IC (5V)
Reference voltage Reference voltage output Soft-start and ON/OFF control Soft-start, ON/OFF and latchmode shutdown operations
s Absolute maximum ratings (Ta=25˚C)
Item
Supply voltage Output peak current FB pin input voltage REF pin output current IS pin input voltage CS pin input current Total power dissipation Operating temperature Junction temperature Storage temperature
Note:
Symbol VCC1 VCC2 IOL IOH VFB IREF VIS ICS Pd Topr Tj Tstg
Test condition Low impedance source (Icc >15mA) Internal ZD clamp (Icc < 15mA) Sink current Source current
at Ta =25˚C
DIP SOP
Rating 30 Self limiting +1.0 –0.5 –0.3 to 5.0 –10 –0.3 to 5.0 2.0 800 *1 400 *2 –30 to +85 125 –40 to +150
Unit V V A A V mA V mA mW ˚C ˚C ˚C
*1 Derating factor Ta > 25˚C: 8.0mW/˚C *2 Derating factor Ta > 25˚C: 4.0mW/˚C
Maximum power dissipation curve
400mW (SOP) 800mW (DIP)
Max power disspation
0 –30
25
85
125
Ambient temperature Ta [˚C]
59
FA3641P(N), FA3647P(N)
s Recommended operating condition
Item Supply voltage REF pin bypass capacitor Soft-start capacitor Oscillation frequency (FB >1.2V) Min.oscillation frequency at light load mode (FB <1.2V) Symbol VCC Cref CS fOSC fOSCL Min. 10 0.1 0.01 30 10 0.47 1 500 Typ. Max. 28 Unit V µF µF kHz kHz
s Electrical characteristics (Vcc=18V, RT=47kΩ, Ta=25˚C) Reference voltage section
Item Reference voltage Voltage variation 1 (Line regulation) Voltage variation 2 (Load regulation)) Voltage variation 3 (Temperature stability) Symbol VREF VdV VdV VdT Test condition Tj=25˚C VCC=10 to 28V IL=0 to 10mA, Vcc=18V Ta= –30 to +85°C Min. 4.75 Typ. 5.00 ±6 ±6 ± 0.5 Max. 5.25 ±20 ±20 Unit V mV mV mV/°C
Oscillator section
Item Oscillation frequency Frequency variation 1 (Voltage stability) Frequency variation 2 (Temperature stability) Symbol Test condition RT=47kΩ, Tj=25˚C VCC=10 to 28V Ta= –30 to +85°C Min. 92.6 Typ. 100 ± 1.6 ± 0.02 Max. 107.4 Unit kHz % % / °C
fOSC fdV fdT
Pulse width modulation circuit section
Item FB pin source current Input threshold voltage (FB pin) Maximum duty cycle Symbol IFB VTH FBO VTH FBM DMAX Test condition VFB=0V Duty cycle =0% Duty cycle =DMAX VFB=2.5V 66 Min. –985 0.95 Typ. –750 1.03 2.40 70 74 Max. –615 Unit µA V V %
Reducing oscillation frequency section
Item FB pin threshold voltage Frequency reduction Minimum oscillation frequency Symbol VTH FBS kfS1 foscS2 VFB=1.10 to 1.15V Test condition Min. Typ. 1.18 16.7 46 Max. Unit V kHZ kHZ
Overcurrent limiting circuit section
Item Input threshold voltage (IS pin) Input terminal source current (IS pin) Delay time Symbol VTH IS I IS TPD IS VIS =0V 150 Test condition FA3641P/N Min. 215 Typ. 235 255 –5 FA3647P/N Max. Min. Typ. –20 150 Max. µA ns Unit
–188 –168 –148 mV
Soft-start circuit section
Item Charge current (CS pin) Input thres.