ML4836CS View Datasheet(PDF) - Micro Linear Corporation
Part Name
Description
Manufacturer
ML4836CS Datasheet PDF : 15 Pages
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FUNCTIONAL DESCRIPTION (Continued)
After cathode heating, the inverter frequency drops to
FSTART causing a high voltage to appear to ignite the lamp.
If lamp current is not detected when the lamp is supposed
to have ignited, the CX charging current is shut off and the
inverter is inhibited until CX is discharged by RX to the
1.25V threshold. Shutting off the inverter in this manner
prevents the inverter from generating excessive heat when
the lamp fails to strike or is out of socket. Typically this
time is set to be fairly long by choosing a large value of
RX.
LFB OUT is ignored by the oscillator until INTERRUPT is
above 1.20V The CX pin is clamped to about 7.5V.
Care should also be taken not to turn on the VCCZ clamp
ML4836
so as not to dissipate excessive power in the IC. This will
cause the temp sensor to become active at a lower
ambient temperature.
A summary of the operating frequencies in the various
operating modes is shown below.
OPERATING MODE
Preheat
After
Preheat
Dimming
Control
OPERATING FREQUENCY
[F(MAX) to F(MIN)]
2
F(START)
F(MIN) to F(MAX)
6.75
RX/CX 4.75
1.25
.7
0
HEAT
LEA_ENB OR
DIMMING LOCKOUT
INTERRUPT
INHIBIT
7.5
Figure10. Lamp Starting and Restart Timing
11
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