CR6203 데이터 시트보기 (PDF) - Unspecified

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CR6203

Switching Power Supply Controller ICs

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CR6203

current source starts up; the oscillator output OSC1 decides the maximum duty cycle, output OSC2 tries to

touch off the power supply to enter open cycle to enter the open cycle, and shield flashing peak current of

the power transistor ; if FB is less than 1.8V (about between 1.2-1.8V), the cycle of the oscillator will

increase with it, the less FB is, the wider the cycle of the oscillator is, until the oscillation stops (This

characteristic reduces the standby power consumption of the switching power.) ; if the peripheral feedback

tries to make VCC more than 9.6V, the in-circuit is fed back to FB and makes VCC stabilize the voltage at

9.6V (According to this characteristic, we can may not adopt peripheral feedback circuit, and stabilize the

output voltage by in-circuit, but the precision of stabilizing voltage is low); During the open cycle, OB

supplies base current for the power transistor, OE pulls down the emitter of the power transistor to IS,

and OB adopts the driving parameter of ramp current ( it refers to that OB on-current is the parameter of

IS, when IS is 0V, OB on-current is about 40mA, then OB on-current increases linearly with IS, when IS

increases to 0.6V, OB on-current is about 120mA, this characteristic makes effective use of the output

current of OB, decreases the power consumption of CR6203), if IS detects that the specified current FB, it

will come into the close cycle; during the close cycle, OB pulls down, the power transistor will not shut

off immediately, but OE clamps 1.5V (after the power transistor is shut off, the base will be biased

reversely, which improves the voltage endurance); during open or close cycle, if the power transistor is

detected beyond the upper limit current, the trigger of the upper limit current will be placed preferentially

and forces FB to drop, the duty cycle will become less so as to protect the power transistor and

transformer; at the beginning of next close cycle or when FB is less than 1.8V, the trigger of the upper

limit current will reset. In addition, CR6203 is installed over heat protection internally, when the internal

temperature is higher than 140ć, it will broaden the cycle of the oscillator and makes the temperature of

CR6203 less than 150ć; The ramp compensation is also placed internally, when CR6203 is in a big duty

cycle or in the mode of constant current, it can stabilize the open/close cycle.

If VCC declines to 4.3V or so, the oscillator will shut off, OSC1 and OSC2 are in the low level, and the

power supply keeps at close cycle; when VCC goes on declining to 3.7V or so, CR6203 will come into the

start-up phase once again.

Definition of Electric Parameter

Start-up acceptance current: the current on OC when OB inputs 0.5mA during the start-up phase

Start-up Quiescent Current: the current of minimum current source that can make VCC oscillate (namely

finish the start-up of CR6203) when VCC meets filter capacitance and adjustable current source, CT meets

680PF, and other pins hang in the air.

Start-up Voltage: Maximum VCC value of above VCC oscillation.

Re-start Voltage: Minimum VCC value of above VCC oscillation.

Close Voltage of Oscillator: VCC value that makes RC oscillator stop oscillating when the above VCC

oscillates the falling edge.

Quiescent Current: VCC power current when FB is grounded with 1.0K of resistance at normal phase.

Aug.2008 V2.0

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