ISSI's single-stage high-power factor AC/DC LED Controller targets retrofit LED bulbs



IS31LT3932 universal AC-input LED Controller

Integrated Silicon Solution, a leader in advanced memory and analog IC
solutions, announced the IS31LT3932, a high performance universal-AC-input
LED Controller for the solid-state lighting (SSL) market
place. With a universal input voltage range from 85 to 265VAC, a Power
Factor Correction greater than 0.97 and a typical output current
accuracy of +/-3%, the IS31LT3932 is ideally suited for a wide range of
offline LED retrofit lamp solutions including E26, GU10, PAR and T8.
This true constant current LED controller can support LED lighting
solutions of up to 30W with a minimal number of external components.

The IS31LT3932 utilizes a patent pending average current mode control
scheme to maintain inductor current regulation regardless of variation
of input and output voltage. The device implements a Pulse Frequency
Modulation (PFM) technology without an optocoupler and secondary side
control or loop compensation circuitry dramatically reducing the bill
of material (BOM) and overall cost. The controller can be configured to
operate in a Non-Isolated Buck or Buck Boost mode or Isolated Flyback
mode. The device's unique architecture continuously monitors the output
voltage and adjusts the operating frequency to maintain high LED
current accuracy.

The IS31LT3932 has special input power line sensing and output voltage
sensing circuits operating in primary feedback mode to deliver highly
accurate current regulation to the LED load. The IS31LT3932
incorporates many features found in more complex controllers such as
soft-start, Vcc under-voltage lockout with hysteresis, and protections
against output over-voltage, output open and short circuit, primary
side over-current and thermal shutdown with hysteresis. In addition,
the versatile high voltage gate drive of the IS31LT3932 will support a
wide range of low-cost power MOSFET devices.

"The IS31LT3932 expands our LED controller offering for the retrofit
lamp market," remarked Ven Shan, ISSI VP of Analog products. "Lighting
manufacturers will benefit from the versatility offered by a high
power-factor, universal AC input and constant current output because
one design will support multiple LED array load configurations. With
design re-use, our customers can truly maximize their design efforts."

Price and Availability
The IS31LT3932 is available in a space saving, RoHS compliant SOP-8
package and is priced at $0.69 in 1,000 piece quantities.