lx1692 Microsemi Corporation, lx1692 Datasheet - Page 4

• Manufacturer Part Number: lx1692
• Description: Ccfl Backlight Controller Ic
• Manufacturer: Microsemi Corporation

Copyright © 2004
Rev. 1.2, 12/20/2006
OC_SNS
OV_SNS
DOUT
COUT
BOUT
AOUT
VDDP
Name
ISNS
GND
TM
A buffer P-FET driver output. Has a 20K pull up, R
A buffer P-FET driver output. Has a 20K pull up, R
A buffer N-FET driver output. Has a 20K pull down, R
A buffer N-FET driver output. Has a 20K pull down, R
Ground
Input Supply Voltage, 4.5V to 5.5V input range. VDDP is switched (see ENABLE) to remove power from chip.
An LDO regulator follows the switch and generates 4.0V
the VDDP input. The output capacitor should be a 1000nF or larger ceramic dielectric type.
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
as high as ±7V peak under load fault conditions. Transients under fault conditions up to ±11 V
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.
Over Voltage Sense Input. This input pin monitors a voltage divider (approximately 1000:1) placed across the
lamp. During strike mode the frequency tracking oscillator uses the voltage waveform from the divider to
determine and track load resonant frequency, and 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 or shorts occur. See functional description section for details on internal circuit
operation. Frequency range of the input signal is from 30KHz to 150KHz and must not be rectified. Normal
operating voltage levels will be in the range of ±0.5 to ±VDDP peak, centered about +0.2 V
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
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 0.7V,
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.
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
F U N C T I O N A L P I N D E S C R I P T I O N ( C O N T I N U E D )
Integrated Products Division
®
Microsemi
Description
DS
DS
Full Bridge Resonant CCFL Controller
ON nominal =
ON nominal =
DS
DS
DC
ON nominal =
ON nominal =
. The output driver stages are powered directly from
P
RODUCTION
30
30
30
30
Ω
Ω
Ω
Ω
D
ATA
S
HEET
DC
. An abnormal
PEAK
are
LX1692
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