LXM1641-02(1999) View Datasheet(PDF) - Microsemi Corporation
Part Name
Description
Manufacturer
LXM1641-02 Datasheet PDF : 11 Pages
| |||
PRODUCT DATABOOK 1996/1997
LXM1641-01/-02/-03
DIGITAL DIMMING QUAD LAMP CCFL INVERTER MODULE
PRELIMINARY DATA SHEET
RangeMAXTM
H O W R A N G E M A X W O R K S (continued)
HIGHLIGHTS
s On-board brightness control circuit includes a DC voltage
to pulse width converter that minimizes system design work
and system noise susceptibility. This provides a familiar
and convenient interface while reducing the potential for
externally induced noise which can cause lamp flicker.
s An on-board oscillator operates the inverter BURST rate
above 95Hz, well beyond standard 50/60Hz video refresh
rates where the eye can perceive pulsing light.
s RangeMAX inverter modules are designed to operate with
the burst frequency synchronized to the video frame rate.
This provides operation with no visible display disturbances
caused by beat frequencies between the lamps and video
frame rates.
s In applications with no access to a vertical sync, the in-
verter burst frequency can be allowed to "free run" at 95Hz.
In this non-synchronous mode, minor display disturbances
may be found under certain video conditions. This per-
formance is acceptable for many applications, but synchro-
nization must be used when no disturbance can be toler-
ated.
s Separate feedback loops for lamp current and open circuit volt-
age regulation insure reliable strike under all operating conditions,
automatic over-voltage prevention with broken or failed lamps,
and accurate lamp current regulation.
TYPICAL 100:1 DIMMING APPLICATION
2.5VDC
£ 10k
9VDC- 16VDC
VIN
VHI4
VHI3
BRITE
VHI2
VHI1
LXM1641-xx
5V
0V
SLEEP
VSYNC
GND VLO
VSYNC
FIGURE 10 — Potentiometer Brightness Control
PWM Signal
from System
P.W.
£ 100µs
4.99k
4.99k*
4.7µF
BRITE
LXM1641-xx
s The brightness control may be a simple 10k
potentiometer or a voltage output DAC. A PWM
signal from a micro-controller may also be used
with a suitable filter such as shown in Figure 11.
s If synchronization to the video framerate is
desired, connect the vertical sync pulse from the
system video controller to the appropriate V input.
SYNC
If no video synchronization is desired, connect V
SYNC
to ground.
s If you need to turn the inverter ON/OFF remotely,
connect a 3V or 5V logic signal to the SLEEP input.
If remote ON/OFF is not needed, connect the
SLEEP input to VIN or any other voltage greater than
2.2V .
DC
s Connect VHI to high voltage wire from the lamp.
Connect VLO to the low voltage wire (wire with
thinner insulation). If both lamp wires have
heavy high voltage insulation, connect the
longest wire to VLO. VLO is connected directly to
ground (GND pin) on the inverter PCB. Always
insure a good lamp return by using a wire. Do
not rely on a chassis ground connection.
0 £ P.W. £ 100% of period
* use 4.99k for 5V PWM amplitude, 15k for 3.3V PWM
amplitude, and omit for 2.5V PWM amplitude.
FIGURE 11 — PWM Brightness Control
10
Copyright © 1999
Rev. 0.7 12/99
Share Link: 