ViewSonic VX2235wm-4, Service Manual

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ViewSonic Corporation
Confidential - Do Not Copy
VX2235wm-4
Crystal Frequency Output
RTD can output crystal frequency or 1/2 crystal frequency to external MCU to save a crystal device.
Once power state is on and reset is finished, we can set crystal frequency by firmware and output to pin
48 and pin 110 simultaneously, and then can turn off them in Pin Share Part. Pin 48 and PIN 110 is
configurable, detail setting is listed in Pin-Share part
RTD2120 8051 Embedded Micro-Controller for Monitor
Overview
This chip is the micro-processor of LCD monitor. It uses the design ware DW8051 of
Synopsys as the 8051 core of this chip and is compatible with other industry 8051 series. Also,
96Kbyte FLASH with 8 bit bus is embedded in this chip which is licensed from TSMC 0.18um
e-FLASH process. Here we use the package of PLCC44/LQFP48 if we would like to have a
discrete MCU controller or we make a multi-chip package with our LCD monitor controller to
form one chip package to save the cost of package and PCB material.
Features
Operating voltage range : 3.0V to 3.6V
8051 core, CPU operating frequency up to 50MHz
4 clocks per machine cycle
256-byte internal RAM
512-byte external data RAM, including 256-byte DDC RAM(128-byte x 2) and 256-byte
general purpose RAM
96K-byte flash memory, 64k for program and 32k for saving parameter
Two DDC ports compliant with VESA DDC1/2B/2Bi/CI
Three channels of PWM DAC with programable frequency from 100K to 100Hz
Watchdog timer with programmable interval
Three 16-bit counters/timers (T0, T1, and T2)
One PLL to provide programmable operating frequency and clock output, 2 clock output ports
One full-duplex serial port
Six interrupt sources with 2 external interrupts
z Four channels of 6-bit ADC
z Hardware In System Programming(ISP) capability, no boot code required
z Built-in Low voltage reset circuit
z Embedded 1.8V regulator
z Code protection
z Available in 44-pin PLCC or 48-pin LQFP package
AUDIO
STEREO CLASS-D AUDIO POWER AMPLIFIER
DESCRIPTION
The TPA2008D2 is a third generation 5-V class-D amplifier from Texas Instruments. Improvements to
previous generation devices include: dc volume con-trol, lower supply current, lower noise loor ,higher
efficiency, smaller packaging, and fewer external components. Most notably, a new filter-free class-D
modulation technique allows the TPA2008D2 to directly drive the speakers, without needing a low-pass
output filter consisting of two inductors and three capacitors per channel. Eliminating this output filter
saves approximately 30% in system cost and 75% in PCB area.
The improvements and functionality make this device ideal for LCD projectors, LCD on itors ,powered
speakers, and other applications that demand more battery life, reduced board space, and functionality
that surpasses currently available class-D devices.
A chip-level shutdown control limits total supply current to 1 µA, making the device ideal for bat-
Tery powered applications. Protection circuitry in-creases device reliability: thermal and short circuit.
Under voltage shutdown saves battery power for more essential devices when battery voltage drops to
low leve.