142 150 158 Hz PWM signal frequency
3.0 3.3 3.6 V PWM signal amplitude
11
PWM signal
*note 4
INV_PWM
30 -- 100 %
Period
Ton
Duty =
12
lamp current
over-shoot
PKZero
I
−
-- -- 10 %
Line transient( 10.8V to
21V/100us) and turn on
transient
13
Current
Waveform factor
rms
p
I
I
1.27
2
1.56 Multiple
OR
rms
p
I
I
−
*10
14
Unbalance
Rate
rms
pp
I
II
−
−
-10% 0 +10% Multiple
15 Turn off voltage Voff -- -- 100Vp-p V PWM=40%
16
Voltage Rise
time
Trise -- -- 300us us PWM=40%
17 Voltage fall time Tfall -- -- 300us us PWM=40%
Notes:
*1. Limited lamp maximum current by DAC_BRIG signal:
When DAC_BRIG voltage is 0V and INV_PWM enables (100%), lamp has max. limited
current.
When DAC_BRIG voltage is 3.3V and INV_PWM enables (100%), lamp has min. limited
current.
DAC_BRIG signal comes from system chipset with internal resistance of 3KΩ.
*2. Inverter operating frequency should be within specification (45~65kHz) at max. and min.
brightness load.
*3. INV_PWM enable implies INV_PWM signal is High level (On duty cycle is 100%). It is a
square wave of 150Hz to adjust backlight brightness that is a function of PWM duty cycle.
Backlight brightness is maximum value under INV_PWM at 100% and brightness is
minimum under INV_PWM at 40%.
*4. The system interface signals belong to 3.3V.
*5. Please make sure open lamp output voltage should be within starting voltage specification.
*6. Inverter should pass human body safety test.
*7. Inverter should no smoking by any component open/ short test
*8. Transformer voltage stress should not be over 85% under any condition
( turn on overshoot transient and line transient).
*9. Audio noise should be less than 36dB at 10 cm distance.
Chapter 4-8
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