User Guide

After Sales
Technical Documentation
System Module
THX–4
Amendment 10/97 Page 4–11
Pin Name Description
72 ACLK Clock for NANTIC
73 XBUSY Busy signal for LCD driver
74 XLCDEN LCD driver IC select
75 C_XD LCD driver and EEPROM multiplex control
76 CSCK NANTIC and SIS serial interface clock
77 SYNCLK Synthesiser serial data clock
78 NMI Modem interrupt
79 SDA Serial data to EEPROM and LCD–driver
80 XAS Address bit for Modem
Modem
The NAT (N403) is a single VLSI chip modem for the AMPS/TACS mobile
telephone. It implements a Manchester data receiver–transmitter, and
provides supervisory audio tone (SAT) and signalling tone (ST) functions.
Received messages are corrected and checked by 3/5 voting and BTH
decoding blocks.
Modem (N403) Signals
Name Description
INT interrupt output to controller
XCLR reset input
XCS chip select from controller
D0–7 data bus to controller
A0–1 address lines for register selection
XRD, XWR read/write control from controller
DI data input from RF unit
DO data output to ANTIC
C1–2 clock generator
CLOCKOUT system clock output to controller and SIS
DAC 0 dac o/p to VALC
Regulators
Regulator PSL (N407) is the power supply circuit for battery operated
applications requiring separate voltage supplies (for the microcontroller,
logic and analogue functions). It has three voltage regulators (VL1, VL2
and VA), a reference voltage output (VREF), power on/off and reset logic,
and a watchdog, in addition to circuitry for supply voltage and battery
charger monitoring functions.