Motorola GP340 ATEX Service Information - Page 7

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Controller Circuits

Conventional MDC

Conventional 5 Tone

Privacy Plus

SmartZone

MPT

3.3

Real Time Clock

( Refer to Figure 1-3 and the Microprocessor schematic diagram )

Radios with displays support a Real Time Clock (RTC) module for purposes of message time

stamping and time keeping. The RTC module resides in the microcontroller.The clock uses a back-

up Lithium Ion battery for operating power when the primary battery is removed.

3.3.1

Circuit Description

The RTC module circuit, shown in Figure 1-3, is powered by the ModB/Vstby pin and PI6/PI7 from

the crystal oscillator circuit. A clock frequency of 38.4kHz from a crystal oscillator provides the

reference signal which is divided down to 1 Hz in the processor.

HC11FL0

MODA

MODB

PI6

PI7

As the RTC module is powered separately from the processor Vdd, the RTC is kept active through

the ModB / Vstby pin which provides the Lithium battery back-up power when the radio is switched

off.

Table 1-1 Radio Memory Requirements

RADIO

GP140

GP320, GP340

GP360, GP380

GP240, GP280

GP540, GP580

GP640, GP680

GP1280

FL401

C436

OUT

R420

38.4kHz

GND

R426

C437

Figure 1-3 RTC Circuit

ROM (KB)

128K

512K

Vddd

R461

C435

CR411

Q416

R462

R463

CR413

300

Q417

UNSWB+

SWB+

EXT RAM

EEPROM

(KB)

16K

UNSWB+

U410

3.3V

VIN VOUT

C434

R460

R419

LI_ION

BOOT_CTRL

TP405

TEST_POINT

1-3