| POWER FACTOR CORRECTED DIMMABLE LED DRIVER
DESCRIPTION
The UTC L8532 is a switch mode power supply controller
intended for low to medium power single stage power factor (PF)
corrected LED Drivers. The device is designed to operate in
critical conduction mode (CrM) and is suitable for flyback as well
as buck topologies. Constant on time CrM operation is particularly
suited for isolated flyback LED applications as the control scheme
is straightforward and very high efficiency can be achieved even
at low power levels. These are important in LED lighting to
comply with regulatory requirements and meet overall system
luminous efficacy requirements. In CrM, the switching frequency
will vary with line and load and switching losses are low as
recovery losses in the output rectifier are negligible since the
current goes to zero prior to reactivating the main MOSFET
switch.
The device features a programmable on time limiter, zero
current detect sense block, gate driver, trans-conductance error
amplifier as well as all PWM control circuitry and protection
functions required to implement a CrM switch mode power
supply. Moreover, for high efficiency, the device features low
startup current enabling fast, low loss charging of the VCC
capacitor. The current sense protection threshold has been set at
500 mV to minimize power dissipation in the external sense
resistor. To support the environmental operation range of Solid
State Lighting, the device is specified across a wide junction
temperature range of -40℃ ~125℃
FEATURES
* Very Low 24A Typical Startup Current
* Constant On Time PWM Control
* Cycle-by-Cycle Current Protection
* Low Current Sense Threshold of 500mV
* Low 2mA Typical Operating Current
* Source 500mA/Sink 800mA Totem Pole Gate Driver
* Reference Design for TRIAC and Trailing Edge Line Dimmers
* Wide Operating Temperature Range
* No Input Voltage Sensing Requirement
* Enable Function and Overvoltage Protection |
