Compal ACY25 series Service Manual page 76

PWM signal
11
*note 4
lamp current
12
over-shoot
Current
13
Waveform factor
Unbalance
14
Rate
15 Turn off voltage
Voltage Rise
16
time
17 Voltage fall time
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
142 150
3.0 3.3
INV_PWM
30 --
I
-- --
−
Zero PK
I
p
1.27
I
rms
−
I I
−
p p
-10%
I
rms
Voff -- --
Trise -- --
Tfall -- --
158 Hz
3.6 V
100 %
10 %
1.56 Multiple
2
0 +10% Multiple
100Vp-p V
300us us
300us us
PWM signal frequency
PWM signal amplitude
Ton
Duty =
Period
Line transient( 10.8V to
21V/100us) and turn on
transient
I
−
p
OR *10
I
rms
PWM=40%
PWM=40%
PWM=40%