Green-Power PWM Controller with Freq. Jittering
Features
Low Cost, Green-Power Burst-Mode PWM
Very Low Start-up Current ( about 7.5μA)
Low Operating Current ( about 3.0mA)
Current Mode Operation
Under Voltage Lockout (UVLO)
VDD Over Voltage Protection(OVP)
programmable over-temperature protection
Internal Latch Circuit(OTP,OVP)
Built-in soft start with 1ms
Built-in Frequency jitter for better EMI Signature
Soft Clamped gate output voltage 16.5V
VDD over voltage protect 25.5V
Cycle-by-cycle current limiting
Sense Fault Protection
Output SCP (Short circuit Protection)
Built-in Synchronized Slope Compensation
Leading-edge blanking on Sense input
Programmable PWM Frequency
High-Voltage CMOS Process with ESD
DIP-8 & SOP-8 Pb-Free Package
Compatible with SG6842J&LD7552&OB2269
Applications
Power Adaptor
Battery Charger Adapter
Open Frame Switching Power Supply
LCD Monitor
General Description
The CR6842 is a low startup current , low cost, current
mode PWM controller with Green-Power & burst-mode
power-saving operation. The integrated functions such as
the leading-edge blanking of the current sensing, internal
slope compensation provide the users a high efficiency,
low external component counts, and low cost solution for
AC/DC power applications. The special Green-Power
function provides off-time modulation to linearly decrease
the switching frequency under light-load conditions. And
under zero-load conditions, the power supply enters
burst-mode to further reduce power consumption by
shutting off PWM output. When the output of power
supply is short or over loaded, the FB voltage will
increase ,and if the FB voltage is higher than 5.2V for
longer than 56msec the PWM output will be turned off. A
external NTC resistor connected from pin RT to ground
can be applied to over-temperature protection. Pulse by
pulse current limit ensures a constant output current even
under short circuit. PWM output will be disabled as long
as VDD exceeds a threshold. When internal latch circuit is
used to latch-off the controller, the latch will be reset when
the power supply VDD is disabled.
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