Specifications
WM_PRJ_Q2501_PTS_001 – 003
March 2004
© 2003 All rights reserved
Page: 32 / 93
This document is the sole and exclusive property of WAVECOM. Not to be distributed or divulged without prior written
agreement.
Ce document est la propriété exclusive de WAVECOM. Il ne peut être communiqué ou divulgué à des tiers sans son
autorisation préalable.
Because VBATT supplies directly the GSM RF power amplifier component, it is
essential to keep a minimum voltage ripple at this connection in order to avoid
any phase error or spectrum modulation degradation. See paragraph 2.9
Electrical characteristics for detailed information.
Refer to document [2] for further information about power supply design.
VBATT
IBATT
Uripp Uripp
T = 4.615ms
T=577µs
Vmax
Vmin
In GSM or GPRS class 2 modes
In GPRS class 10 mode
Legend:
Figure 8: Typical power supply voltage in GSM/GPRS mode
2.5.1.2 RTC back-up power supply
If using the WISMO Quik Q2501 internal Real Time Clock (RTC), it is necessary
to provide a back-up power supply because:
• When the WISMO Quik Q2501 module is powered on, the RTC power
supply is provided by the module.
When the WISMO Quik Q2501 module is powered off, a back-up power supply
is needed to save RTC date and time information for GSM part and to save
Backup RAM with RTC data, valid almanac and ephemeredes to perform a Hot
start or a War mstart for GPS part (The GPS will perform a FIX faster).
Nevertheless, since it is possible to retrieve GPS time and date information, it is
not necessary to use this backup power supply interface.
If the RTC is not used, this pin can be left open.
Note
: Only after GPS have been supplied, the RTC section and the back-up
battery switch will be initialized properly. If only VCC_RTC is applied first, the
current consumption of the RTC and back up SRAM is undetermined.