Acer AL708 AL708 Monitor Service Guide - Page 12

4.1.3 Power Regulator AIC1563 (U12),LT1117 (U5, U6) The AIC1563 is a monolithic control IC containing the primary functions required for DC to DC converters. The device consists of an internal temperature compensated reference, conparator, controlled duty cycle oscillator with an active current sense circuit. Desired output voltage are determined by the equation Vout = 1.25 ( 1 + R104 / R103), In this case, the output voltage are 5 Volts. The AIC1117 is a low dropout positive adjustable regulator with minumum of 1A output current capability. So it is well suited for 3.3 V and 2.5 V Rregulator. U6 as a 2.5 V regulator , Desired output voltage are determined by the equation Vout=5 x ( R53 / R53+R56)= 2.5 U5 as a 3.3 V regulator , Desired output voltage are determined by the equation Vout=5 x ( R30 / R30+R36)= 3.3 4.2 Audio Board AN7522 (U1) The AN7522 is a 2 channel audio power amplifier capable of delivering 2W of continuous average power to an 8 ohms with less than 0.5% (THD) from a 12 V power supply. An7522 can directly drive 8 ohms speaker , does not require output coupling capacitor, bootstrap capacitor ,or snubber network. Audio line-in are feed into pin 6,8 of the AN7522. The output power is controlled by the DC voltage of pin 8 from gm2120 GPIO port. 4.3 Inverter Board This is a specific inverter for L7E monitor backlight which converters 12 Vdc to drive four cold cathod fluorescence tubes. Electrical specification describled as below. INPUT Rated Input Voltage Maximum Input Voltage Input Current Off state Input Power On / Off Voltage 12Vdc 11.4~12.6 Vdc < 2A < 0.1 W 2~3.3 for On, 0~1 for Off OUTPUT Rated Output Strike-on Voltage 1310 Vrms Rated Output Voltage Rated Output Frequency Rate Output Current per tube 710 Vrms at 6 mA 45~60KHz 6 mA L7EA (AL708) 4-3