BD9207FPS 查看數據表（PDF） - ROHM Semiconductor
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BD9207FPS Datasheet PDF : 12 Pages
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BD9207FPS
Technical Note
●Functional explanation of block
・ VREF
The constant voltage to be temperature-compensated is created from the voltage inputted from VCC terminal.
・ OSC
Triangular wave with an oscillating frequency of 900 KHz is created, as an input of PWM comparator, by built-in resistor
and capacitor.
・ Error AMP
It detects, at INC terminal, the voltage of sense resistance terminal created by LEC current, and compares it to the
reference voltage, and amplifies and outputs the differential voltage.
(The reference voltage is 0.2V±3%)
・ PWM COMP
PWM COMP converts the output voltage of error amplifier into the pulse-width modulation waveform and outputs it to
DRIVER.
・ DRIVER
Push-pull FET driver takes in the PWM waveform and directly drives the Pch MOS FET that is built-in in the IC.
・ STBY
The ON/OFF control of output is performed by STBY terminal. The output becomes ON if STBY voltage is High level.
・ Thermal shutdown circuit (TSD)
TSD circuit protects the IC from runaway thermal operation or heat damage.
TSD circuit detects the temperature of chip, and the circuit becomes off if the temperature reaches 175℃. For TSD
detection and release, the hysteresis of 15℃ is set, so the malfunction caused by temperature variation is prevented.
・ Over Current Protection（OCP）
Out is turned off if the voltage difference between VCC – OUT, caused by the current flowing in the Pch MOS EFT built-in
in OCP circuit, is detected and reaches the reference value of OCP. The OCP is not of latch type but of self-return type.
・ Soft start circuit (SS)
Soft start time is set by the built-in capacitor connected to SS circuit. The capacitor is charged when STBY terminal
becomes High level and the IC is started. The soft start time is set at 4ms or so.
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4/11
2009.07 - Rev.A
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