BD9763FVM Datasheet, PDF (4/12 Pages) Rohm – Single-output Step-up,High-efficiency Switching Regulator (Controller Type)

BD9763FVM
●Pin configuration
Technical Note
●Pin number , Pin name
Pin No.
1
2
3
4
5
6
7
8
VCC
1pin
RT
8pin
2pin
OUT
CTL/SS
7pin
3pin
GND
FB
6pin
4pin
VREF
INV
5pin
Fig.6
Pin name
VCC
OUT
GND
VREF
INV
FB
CTL/SS
RT
Function
Power supply
FET driver output
Ground
Reference voltage (2.5V±1%) output
Inverting input of error amplifier
Output of error amplifier
Stand-by switch/Soft start capacitor connecting pin
Timing resistor connecting pin
●Block description
・VOLTAGE REFERENCE(VREF) BLOCK
This voltage reference block generates 2.5V internal reference voltage.
・OSCILLATOR BLOCK
Oscillator block sets the oscillating frequency adjusted by an external resistance in RT pin. The oscillating
frequency can be set within a range of 100~1200kHz.. (See the description of how to set the frequency on page6.)
・PWM COMP
The PWM comparator transforms the voltage outputted from error amp to PWM waveform and outputs to FET driver.
The maximum duty cycle is limited up to 90%.
・ERROR AMP BLOCK
The error amp block detects the output voltage from the INV pin, amplifies the difference between the detected voltage
and the reference voltage, and outputs it to FB pin. The reference voltage is 1V±2%.
・PROTECTION CIRCUIT BLOCK
The under voltage lock out circuit is activated to shut down the whole circuit when the VCC voltage is up to 3.8V.
When the thermal shutdown circuit detects abnormal heating of the chip (150℃), the output becomes off.
And the output turns back on when the chip temperature goes down to a specific level.
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2009.05 - Rev.A