AME9002 Datasheet, PDF (17/37 Pages) Asahi Kasei Microsystems – CCFL Backlight Controller

AME, Inc.
AME9002
Preliminary
CCFL Backlight Controller
Figure 11. Start Up and Steady State Waveform
3V
BRIGHT *
CT1
CSDET
1.25V
} VBATTOK
VDDOK ^VALID
<3V
SSC
**
5V
BLANK
BLANK
OVPH>3.3V
F = f_MIN
F_COMP
OVPL<2.5V
OVPH<3.3V
OVPL>2.5V OVPL OVPL>2.5V
OVPH < 3.3V <2.5V OVPH < 3.3V
<1 Sec
OVPL<2.5V
OVPH<3.3V
F = f_MIN
~ 6mS
SSV
< Initial Start Up Period>
<Two full scale brightness cycles after strike> <Steady state op. with duty cycle dimming>
IF:
OVPL<2.5V
OVPH<3.3V
OVPL>2.5V
OVPH < 3.3V
OVPH>3.3V
CSDET > 1.25V
THEN:
F_COMP ramps up
Frequency decreases
F_{COMP constant}
Frequency constant
F_COMP = V
Frequency = F_MAX
SSV=0V COMP=0V
Tube has struck and initial
start period has ended.
IF:
OVPH > 3.3V
<After CCFL strikes>
THEN:
Immediate shutdown
OVPL > 2.5V
CSDET < 1.25V for
4 consecutive clock cycles
during blanking period: nothing
after blanking period: shutdown
during blanking period: nothing
after blanking period: shutdown
* BRPOL is Low
** Time axis is not to scale
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