CR6842 Ver la hoja de datos (PDF) - Unspecified

Número de pieza

componentes Descripción

Fabricante

CR6842

Green-Power PWM Controller with Freq. Jittering

Unspecified 

CR6842

will be charged up to the turn-on threshold voltage of 16.5V through the start-up resistor until PWM output

is restarted. This protection feature will continue to be activated as long as the over-loading condition

persists. This will prevent the power supply from overheating due to over loading conditions.

Thermal Protection

An external NTC thermistor can be connected from the RT pin to ground. A fixed current IRT is sourced

from the RT pin. Because the impedance of the NTC will decrease at high temperatures, when the voltage

of the RT pin drops below 1.065V, PWM output will be disabled. The RT pin output current is related to the

PWM frequency programming resistor RI

Noise Immunity

Noise from the current sense or the control signal may cause significant pulse width jitter, particularly

in continuous-conduction mode. Slope compensation helps alleviate this problem. Good placement and

layout practices should be followed. The designer should avoiding long PCB traces and component leads.

Compensation and filter components should be located near the CR6842. Finally, increasing the

power-MOS gate resistance is advised.

Dec.2006 V 1.3

7

Chengdu Chip-Rail Tech.Co.,Ltd

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