Fairchild FSL126MRT Specifications Manual
Summary
The FSL126MRT Green-Mode Power Switch is an integrated, high-efficiency solution designed for offline Switching Mode Power Supplies (SMPS). It combines PWM control and a SenseFET within one module, simplifying design while offering advanced features like Soft Burst-Mode operation for minimal standby power and low EMI. This manual provides engineers with detailed application circuits, technical specifications, protective ratings (OVP/OLP), and system diagrams required to implement robust and cost-effective flyback converter power supplies for home appliances or combinations units.
Page 1 Text Content
126M reen -M e F airch ild er S itch (F
May 2012
FSL126MRT Green-Mode Fairchild Power Switch (FPS™) Features Description
Internal Avalanched Rugged 650V Sense FET The FSL126MRT is an integrated Pulse Width Modulation (PWM) controller and Sense FET specifically
Advanced Soft Burst-Mode Operation for Low
designed for offline Switch-Mode Power Supplies
Standby Power and Low Audible Noise
(SMPS) with minimal external components. The PWM Random Frequency Fluctuation for Low EMI controller includes an integrated fixed-frequency oscillator, Under-Voltage Lockout (UVLO), Leading-
Pulse-by-Pulse Current Limit Edge Blanking (LEB), optimized gate driver, internal
soft-start, temperature-compensated precise current
Various Protection Functions: Overload Protection
sources for loop compensation, and self-protection
(OLP), Over-Voltage Protection (OVP), Abnormal
circuitry. Compared with a discrete MOSFET and PWM
Over-Current Protection (AOCP), Internal Thermal
controller solution, the FSL126MRT can reduce total
Shutdown (TSD) with Hysteresis and Under-Voltage
cost, component count, size, and weight; while
Lockout (UVLO) with Hysteresis
simultaneously increasing efficiency, productivity, and
Low Operating Current(0.4m A) in Burst Mode system reliability. This device provides a basic platform
suited for cost-effective design of a flyback converter.
Internal Startup Circuit Built-in Soft-Start: 15ms Auto-Restart Mode
Applications Power Supply for STB Home Appliances, and DVD Combination
Ordering Information
Output Power Table(2)
Operating
Part Current RDS(ON) 230VAC ± 15%(3) 85~265VAC
Package Junction Replaces Device
Number Limit (Max.)
Temperature Open Open
Adapter(4) Adapter(4)
Frame(5) Frame(5)
TO-220F
FSL126MRT 6-Lead(1) 1.2A 6.2Ω 30W 40W 17W 25W KA5M0265RYDTU
W-Forming
Notes: 1. Pb-free package per JEDEC J-STD-020B. 2. The junction temperature can limit the maximum output power. 3. 230VAC or 100/115VAC with voltage doubler. 4. Typical continuous power in a non-ventilated enclosed adapter measured at 50°C ambient temperature. 5. Maximum practical continuous power in an open-frame design at 50°C ambient temperature.
© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com FSL126MRT • Rev. 1.0.0
Page Summary Contents For Fairchild FSL126MRT Specifications Manual
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 13 |
| File Size | 868.15 KB |
| Published | July 10, 2026 |
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Frequently Asked Questions
How does this power switch operate in standby mode?
It uses Advanced Soft Burst-Mode Operation, which enables low audible noise and maintains an operating current of 0.4 mA.
What external condition limits the maximum output power?
The junction temperature can limit the device's maximum attainable output power during operation.
How do I ensure stable operation for the feedback pin (FB)?
For stable operation, a capacitor should be placed between the feedback pin and ground.
What causes the overload protection to trigger?
Overload protection triggers if the voltage of the feedback pin reaches 7V, which results in shutting down the FPS.