SG6846ACSZ FAIRCHILD [Fairchild Semiconductor], SG6846ACSZ Datasheet - Page 10

• Manufacturer Part Number: SG6846ACSZ
• Description: Highly Integrated Green-Mode PWM Controller
• Manufacturer: FAIRCHILD [Fairchild Semiconductor]

Highly Integrated Green-Mode PWM Controller
Brownout Protection
Since the VIN pin is connected through a resistive
V
V
Over-Temperature Protection
An external NTC thermistor can be connected from the
© System General Corp.
Version 1.1.1 (IAO33.0059.B1)
divider to the rectified AC input line voltage, it can also
be used for brownout protection. If the V
less than 0.7V, the PWM output shuts off. If the V
voltage is over 0.9V, the PWM output turns on again.
The hysteresis window for ON/OFF is around 0.2V.
controller from over-voltage destruction. When V
voltage is over 23.6V, the SG6846A is latched off.
RT pin to GND. The impedance of the NTC decreases
at high temperatures. When the voltage of the RT pin
drops below 1.065V, the SG6846A is turned off. For
the protection modes options, please see ORDER
INFORMATION.
DD
DD
Over-voltage Protection
over-voltage protection is built-in to prevent the
IN
voltage is
DD
IN
- 10 -
Noise Immunity
Noise from the current sense or the control signal may
cause
continuous-conduction mode. Slope compensation
helps alleviate this problem. Good placement and
layout practices should be followed. Avoid long PCB
traces and component leads. Compensation and filter
components should be located near the SG6846A.
Usually an RC network is put on between sensing
resistor and the CS pin to filter high-frequency
switching noise, as shown Figure 1.
FIG-1 Current Sense RC Filter
significant
www.sg.com.tw • www.fairchildsemi.com
pulse
Product Specification
jitter,
September 26, 2007
particularly
SG6846A
in