Service manual

17 P1.0 Backlight on / off control
e) Panel Power Sequencing (PANEL_PW12,3) (Pin 16, 18): The MTV312 has two dedicated outputs
VDDCTRL1 and 2 ( Pin32 and Pin3) to control LCD power sequencing once data and control signals
are stable.
f) Panel interface (Pin73~94): The RTD2523 driver interface is highly programmable. It supports dual bus /
dual port for SXGA drivers.
6.1.2 Power Regulator AIC1563 (U2), AIC1117CY (U1,U3): 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, a comparator, and a controlled duty cycle oscillator with an active current
sense circuit. The desired output voltage is determined by the equation, Volt = 1.25 (1 + R11 / R12).
In this case, the output voltage is 5 Volts. The AIC1563 is a low dropout positive adjustable
regulator with minimum of 1A output current capability, so it is well suited to serve as a 3.3 V or
2.5 V regulator.
6.1.3 Power Regulator AIC1117CY (U1,U3): The AIC1117CY is a monolithic control IC containing the
primary functions required for DC to DC converters. The device consists of an internal temperature
compensated reference, a comparator, and a controlled duty cycle oscillator with an active current
sense circuit. The desired output voltage is determined by the equation, Volt = 1.25 (1 + R17 / R15).
In this case, the output voltage is 2.5 Volts for panel power.
d) MTV312 Micro Controller: The MTV312 micro controller (MCU) serves as the system micro controller.
It programs the RTD2523 and manages other devices in the system such as the keypad, the backlight, the
LED, the audio system and the non-volatile RAM using general purpose input/output (GPIO) pins.
Pin number Pin Name Pin Usage
1 P5.2 Key / Power on, off
13 P3.4 NV_RAM (U4) SDA
14 P3.5 NV_RAM (U4) SCL
41 P5.4 Key_down
40 P5.5 Key_right
42 P5.3 Key_up
34 P5.6 Key_left
9 P6.3 Key_mute
2 P5.1 Key_select
27 P6.0 LED_red
26 P6.1 LED_green
16 P6.2 LCD panel power1 on / off control
26
ViewSonic Corporation Confidential
-
Do Not Copy
VX922-1