LX1692B

Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 4

Copyright

© 2005

Rev. 1.1, 12/20/2006

Full Bridge Resonant CCFL Controller

TM

®

FUNCTIONAL PIN DESCRI PTION (CONTINUED)

Name

Description

OC_SNS

Over current sense input. The OC_SNS input is compared to a 2V reference. The comparator output shuts off

the PWM outputs to prevent possible secondary failures. The input voltage at this pin is not rectified. Normal

operating voltage levels will be in the range of ±0.5V to VDDP. An abnormal voltage can operate continuously

permitted. An input voltage above 4 peak but less than ±11V peak may cause saturation but will not cause

malfunction, phase reversal, or reliability issues with the IC.

OV_SNS

Over Voltage Sense Input. This input pin monitors a voltage divider (approximately 1000:1) placed across the

lamp. The open lamp voltage regulator uses it to regulate open circuit voltage. During both run and strike

modes, fault detection comparators monitor voltage amplitude to determine if load opens occur. See functional

description section for details on internal circuit operation. Frequency range of the input signal is from DC to

An abnormal voltage can operate continuously as high as ±7V peak under load fault conditions. Transients

under load fault conditions up to ±11V peak are permitted. An input voltage above ±4Vpk may cause

saturation, but will not cause malfunction, phase reversal, or reliability issues with the IC

ISNS

Current Sense Input. The ISNS input is full wave rectified by an On-Chip circuit, then presented to the inverting

input of the current error amplifier. Frequency range of the input signal is DC to 200KHz. The ISNS pin also

monitors lamp current to determine if the lamp is ignited. If a single cycle at the ISNS pin is greater than 1V, the

strike / run flip flop is clocked to the RUN state and threshold of the strike comparator is lowered to 0.3V. During

RUN mode current levels are continuously monitored to detect less than 0.3V. A counter clocked by

RMPD_OUT is reset each time current is sensed at this input. If the counter overflows (256 counts) a fault latch

is set which shuts down the IC. This fault is expected to occur when the lamp is shorted to ground through an

impedance of less than 2K ohms or the ISNS resistor itself is shorted. The counter is inhibited during digital

dimming off time. Normal operating voltage levels will be in the range of ±0.5V to ±5.5V. An abnormal voltage

can operate continuously as high as ±7V peak under load fault conditions. Transients under fault conditions up

to ±11 VPK are permitted. Input voltages up 4V peak are linearly rectified. An input voltage above ±4V peak

but less than ±11V peak may cause saturation but will not cause malfunction, phase reversal, or reliability

issues with the IC.

DOUT

Ω

30

COUT

Ω

30

BOUT

Ω

30

AOUT

Ω

30

GND

Ground

VDDP

Input Supply Voltage, 4.5V to 5.5V input range. VDDP is switched (see ENABLE) to remove power from chip.

the VDDP input. The output capacitor should be a 1000nF or larger ceramic dielectric type.