ViewSonic VX924 Service Manual page 28

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
1
13
14
41
40
42
34
9
2
27
26
16
17
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.
ViewSonic Corporation
Pin Name Pin Usage
P5.2 Key / Power on, off
P3.4 NV_RAM (U4) SDA
P3.5 NV_RAM (U4) SCL
P5.4 Key_down
P5.5 Key_right
P5.3 Key_up
P5.6 Key_left
P6.3 Key_mute
P5.1 Key_select
P6.0 LED_red
P6.1 LED_green
P6.2 LCD panel power1 on / off control
P1.0 Backlight on / off control
25
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VX924