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9.POWER SUPPLY (SMPS)
The DC voltages required at various parts of the chassis are provided by an SMPS transformer
controlled by the IC MC44608, which is designed for driving, controlling and protecting switching
transistor of SMPS. The transformer generates 145V for FBT input, +/-14V for audio amplifier, 5V and
3.3V stand by voltage and 8V, 12V and 5V supplies for other different parts of the chassis.
An optocoupler is used to control the regulation of line voltage and stand-by power consumption. There
is a regulation circuit in secondary side. This circuit produces a control voltage according to the
changes in 145V DC voltage, via an optocoupler (TCET1102G) to pin3 of the IC.
During the switch on period of the transistor, energy is stored in the transformer. During the switch off
period energy is fed to the load via secondary winding. By varying switch-on time of the power
transistor, it controls each portion of energy transferred to the second side such that the output voltage
remains nearly independent of load variations.
10.MICROCONTROLLER SDA55XX
10.1.General Features
• Feature selection via special function register
• Simultaneous reception of TTX, VPS, PDC, and WSS (line 23)
• Supply Voltage 2.5 and 3.3 V
• ROM version package PSDIP52-2, PMQFP64-1
• Romless version package PMQFP100-2, PLCC84-2
10.2.External Crystal and Programmable Clock Speed
• Single external 6MHz crystal, all necessary clocks are generated internally
• CPU clock speed selectable via special function registers.
• Normal Mode 33.33 MHz CPU clock, Power Save mode 8.33 MHz
10.3.Microcontroller Features
• 8bit 8051 instruction set compatible CPU.
• 33.33-MHz internal clock (max.)
• 0.360 ms (min.) instruction cycle
• Two 16-bit timers
• Watchdog timer
• Capture compare timer for infrared remote control decoding
• Pulse width modulation unit (2 channels 14 bit, 6 channels 8 bit)
• ADC (4 channels, 8 bit)
• UART (rxd, txd)
10.4.Memory
• Non-multiplexed 8-bit data and 16 ... 20-bit address bus (ROMless Version)
• Memory banking up to 1Mbyte (Romless version)
• Up to 128 Kilobyte on Chip Program ROM
• Eight 16-bit data pointer registers (DPTR)
• 256-bytes on-chip Processor Internal RAM (IRAM)
• 128bytes extended stack memory.
• Display RAM and TXT/VPS/PDC/WSS-Acquisition-Buffer directly accessible via MOVX
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