Sony Ericsson GR47/GR48 User Manual

5. SYSTEM CONNECTOR INTERFACE

49

LZT 123 7589 R1A

Burst transmission is the time when a GSM transceiver unit is transmitting 
RF signals. TX_ON indicates the radio device is going into transmission 
mode. 

The Real Time Clock (RTC) provides the main microprocessor with a 
time-of-day calendar and alarm, and a one-hundred-year calendar. Its 
accuracy is shown in the table below

The Real Time Clock operates in two modes when connected to a separate 
power supply:

• RTC normal mode: the radio device is in ON or OFF mode and it is 

supplied with power (VCC is applied).

• RTC back-up mode: VCC is disconnected and the RTC is maintained 

by a separate backup power supply connected to the VRTC input (see 
Figure 5.13 below).

Backup power is provided by a capacitor, golden-capacitor or battery in 
your application and must be connected to the VRTC pin. During RTC 
normal operation, the back up source will be charged.

Re

ce

iv

e

oper

at

ion

Frequency I 

2 

C CLK

400

kHz

High or low I 

2 

C CLK

1.2

µs

Delay time after falling edge of I 

2 

C 

CLK

100

ns

Hold time after falling edge of I 

2 

C 

CLK

0

ns

35

TX_ON

O

GSM radio device to transmit

25

VRTC

-

Voltage for the Real Time Clock

RTC accuracy

25°C

8 (21)

20 (52)

ppm (s/month)

RTC accuracy

extreme 

temperatures

89 (231)

101 (262)

ppm (s/month)