Sony Ericsson GR47 Integrator's Manual page 52

LZT 123 7589 R2B
SYSTEM CONNECTOR INTERFACE
• 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.
In back-up mode, the back-up source must provide enough
power for RTC operation. Refer to the table for the amount of
current required.
The following table shows voltage characteristics for both
modes.
Parameter
Supply Voltage RTC (normal mode -
charging the capacitor)
Supply Voltage RTC (back-up mode -
Capacitor provides the current)
Current drawn
If the voltage drops below 1.0 V in back-up mode, the RTC will
stop working. The following diagram shows the RTC
connections.
Figure 5.13 RTC connections
Min.
1.6
1.0
VRTC
ackup
supply
GR47
+
DGND
Typ. Max. Units
1.8 2.0 V
1.8 2.0 V
5.0 10.0 µA
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