User Guide

After Sales
Technical Documentation
System Module
THX–4
Amendment 10/97 Page 4–9
Functional Description
Logic Circuit Description
General
The audio/logic unit consists of 5 IC’s: controller D404, modem N403,
audio NANTIC N408, EEPROM D406, regulator PSL N407.
Micro–controller
Micro–controller D404 has six 8–bit I/O ports (Ports 1, 3, 4, 5, 7 and 9),
one 5–bit port (Port 2), one 4–bit I/O port (Port 6) an 10–bit 8–channel A/D
converter (Port 8), three PWM timers, serial communication interface. All
memory (62 kB ROM, 2 kB RAM), except EEPROM, is located in the
micro–controller.
Micro–controller D404 Pinout
Pin Name Description
1 R_XW Address Bit for Modem
2 XCS Chip Select for Modem
3 XRD Read Control to Modem
4 XWR Write Control to Modem
5 VCC Logic Supply Voltage VL1
6–8 MD0–MD2 Mode Selection
9 XSTBY HW Standby Mode input from PSL
10 XRES Reset from PSL
11 NMI Modem Interrupt
12 VSS1 Ground
13–20 D0–D7 Data bus for modem
21 PDB2 bit 2 of the predriver bias adjustment
22 PDB1 bit 1 of the predriver bias adjustment
23 PDB0 bit 0 of the predriver bias adjustment
24 PAB2 bit 2 of the power amplifier bias adjust-
ment
25 PAB1 bit 1 of the power amplifier bias adjust-
ment
26 PAB0 bit 0 of the power amplifier bias adjust-
ment
27 XBIAS PA and predriver bias voltage switch
28 VDRIVER_EN RF power supply control switch
29 VSS2 Ground