Acer TravelMate 270 TravelMate 270 Service Guide - Page 37

When DAC_BRIG voltage is 0V and INV_PWM enables (100%), lamp has max. current. When DAC_BRIG voltage is 3.3V and INV_PWM enables (100%), lamp has min. current. DAC_BRIG signal comes from system chipset with internal resistance of 3K Ω *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 30%. *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 be 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 10cm distance. . Electrical specification No . Symbol Min. Typ. Max. Unit Comment 1 V oper* -- 700 Il 5.7 6.0 Il 2.7 3.0 F 45 55 η 80% -- -- Vrms Lamp operating voltage 6.3 mArms DAC_BRIG: 0V, PWM:100% 3.3 mArms DAC_BRIG: 0V, PWM:30% 65 kHz -- -- Thermal All components on inverter board should follow below rules: 1. Component using conditions (component stress) must be within component specification including voltage rating, current rating, temperature etc. 2. Component temperature shold follow below: K ∆T