AN2640 datasheet(17/36 Pages) STMICROELECTRONICS

Part #	AN2640

Description	Intelligent multipower digital ballast for fluorescent lamps

PDF	36 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

Logo

17 / 36 page

AN2640

ST7LIT19BF1 - 8-bit MCU

17/36

The zero-current detection circuit switches the external MOSFET ON as soon as the voltage

across the boost inductor reverses or the current through the boost inductor goes to zero.

This feature allows the transition mode operation. The signal for ZCD is obtained with an

auxiliary winding on the boost inductor. The secondary winding is connected to the LTIC pin

by means of a resistor. The MCU detecting negative dv/dt gives the turn-on signal to the

driver for the Power MOSFET commutation.

●

Pin 19: PC1 (not used). This pin is connected to micro VCC voltage by means of a 10

Ω resistor because an unused pin must be kept at a fixed voltage. It can be left

unconnected if it is configured as output (0 or 1) by the software.

●

Pin 20: Lamp Type Detection Circuit Enable. This pin is used to enable the "Lamp Type

Detection Circuit".

AN2640 Datasheet(PDF) 17 Page - STMicroelectronics