Circuit Description; Cpu Pwb Circuit Operation - NEC NP-NC900C-A Service Manual

Dlp cinema projector

Table of Contents

The CPU PWB (PWC-4707) is in charge of maintaining the projector functions and the control of major boards.

1. CPU

The S3C2440A-400 (IC7000) is an ARM9 core CPU.

It controls the Reset / Power sequence toward each board, data setting for each device, and the respective

functions of the projector.

After the power is ON and the reset condition is canceled by BD4730G (IC7002), the CPU reads out BIOS

from the flash memory (IC7008) to start itself up.

After that, the CPU reads the F/W info from the flash memory (IC7009) and starts its behavior based on the

data in IC7008.

・ Power

　 The CPU operates on the two types of power supplies specified below.

　 I/O

: 3.3V

Core : 1.3V Stepped down from 3.3V (P3P3V) through the Series Regulator (PQ015YZ01 @IC7001).

・ Clock

The SG8002 (X7000) is a 12MHz OSC that is used as a bus clock for the main clock in the CPU and other

devices.

・ Reset

The BD4730G (IC7002) is used to supervise the main power 3.3V generated in IC7300.

When the 3.3V (P3P3V) line lowers to 3.0V or below, the "low" output is generated and sent to the CPU for

resetting.

LED (D7000) is synchronized with this reset status.

Off : CPU Reset

On : CPU Active

・ Memory

- Flash memory

MX29LV640EBTI-70G (IC7008): BIOS, data storage

M29W320EB70N6E (IC7009): Firmware storage

- SDRAM

IS42S16160C-7TL(IC7007) is a cash memory.

Synchronized with the bus clock @133MHz.

・ Control

External I/O

: RS232 (M7002), USB (M7000), Remote control (M7003),

GPIO (M7001), 3D control (M7004)

　　 Projector Ctl : Reset, POWER_GOOD, POWER_DOWN, Memory, I2C, UART, SPI

Lamp, LED(Light), MM, etc.

Functions of each I/F

- I2C: EEPROM IC7006 (BR24L32F)

Serial No., cumulative time of projector, lamp, etc., and other data are saved here.

Clock function

The 32.768KHz built-in real-time clock RTC-8564JE (IC7005) is in charge.

A back-up feature is given by the super-capacitor C7036.

- SPI: Light Sensor (via the A/D converter ADCS7476 of DIV)

"Confidential, Do Not Duplicate without written authorization from NEC."