User's Manual

MC55/56 Hardware Interface Description
Confidential / Preliminary
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MC55/56_hd_v03.00 Page 62 of 104 16.08.2005
3.12.2 Outputs
3.12.2.1 Synchronization signal
The synchronization signal serves to indicate growing power consumption during the transmit
burst. The signal is generated by the SYNC pin. Please note that this pin can adopt two
different operating modes which you can select by using the AT^SSYNC command (mode 0
and 1). For details refer to the following chapter and to [1].
To generate the synchronization signal the pin needs to be configured to mode 0 (= default).
This setting is recommended if you want your application to use the synchronization signal
for better power supply control. Your platform design must be such that the incoming signal
accommodates sufficient power supply to the MC55/56 module if required. This can be
achieved by lowering the current drawn from other components installed in your application.
The timing of the synchronization signal is shown below. High level of the SYNC pin
indicates increased power consumption during transmission.
Figure 22: SYNC signal during transmit burst
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The duration of the SYNC signal is always equal, no matter whether the traffic or the
access burst are active.
Transmit burst
1 Tx 577 µs every 4.616 ms
2 Tx 1154 µs every 4.616 ms
300 µs
SYNC signal
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