Fairchild SG6846A Data Handbook

6846A ig ly In teg rated reen -M e P tro ller

March 2012

SG6846A Highly Integrated Green-Mode PWM Controller

Features Description

 Low Startup Current: 8µA The SG6846A is especially designed for SMPS with surge-current output, incorporated with a two-level OCP

 Low Operating Current: 3.7m A

function. Besides the cycle-by-cycle current limiting, if  Peak-Current Mode of Operation with Cycle-by- the switching current is higher than two thirds the peak- current threshold for 1700ms, over-current protection is

Cycle Current Limiting

activated such that the SG6846A is latched off.

 PWM Frequency Continuously Decreasing with

Burst Mode at Light Loads If the switching current is higher than two thirds of the peak-current threshold for 100ms, and the voltage on

 VDD Over-Voltage Protection (OVP)

the VDD is still higher than VDD-OFF + 1V, the PWM pulses  AC Input Brownout Protection with Hysteresis are latched off immediately once the VDD voltage is lower than VDD-OFF + 1V. This is useful when an output

 Constant Output Power Limit (Full AC Input Range)

short circuit occurs.

 Internal Latch Circuit for OVP, OTP, and OCP

SG6846A also integrates a frequency-hopping function  Two-level OCP Delay: 1600ms internally to reduce EMI emission of a power supply with minimum line filters. Its built-in synchronized slope

 Output Short-Circuited Delay Time: 100ms

compensation provides proprietary internal  Programmable PWM Frequency with compensation for constant output power limit over universal AC input range. Also, the gate output is

Frequency Hopping

clamped at 18V to protect the external MOSFET from

 OCP Threshold is Half Peak Current Limit over-voltage damage. Internal soft-start is built-in to

soften the stress on the MOSFET and startup current

 Feedback Open-loop Protection with 1700ms Delay

during power on period.

 Built-in Soft-Start

Other protection functions include AC input brownout protection with hysteresis, VDD over-voltage protection, Applications and over-temperature protection. For over-temperature protection, an external NTC thermistor can be applied to

General-purpose switch-mode power supplies and

sense the ambient temperature. When OCP, VDD OVP,

flyback power converters, including:

or OTP is activated, an internal latch circuit latches off the controller. The PWM pulses stay latched off until the

 Power Adapters

power supply is disconnected from the mains outlet.

 Open-frame SMPS

SG6846A controller is available in 8-pin SOP package.

 SMPS with Surge-current Output, such as for Printers, Scanners, Motor Drivers

Ordering Information

Operating OCP Packing

Part Number Package

Temperature Range Latch Method

SG6846ALSY -40 to +105°C Yes 8-Pin Small Outline Package (SOP) Tape & Reel SG6846ALSZ -40 to +105°C Yes 8-Pin Small Outline Package (SOP) Tape & Reel SG6846ACSY -40 to +105°C No 8-Pin Small Outline Package (SOP) Tape & Reel

© 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com SG6846A • Rev. 1.1.5