User guide
CM52 Integrators’ Manual
CM52 Integrators’ Manual
WI_DEV_CM52_UGD_001-001
Page 26 of 53
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
Parameter Minimum Typical Maximum Units
Supply Voltage Reference 2.45 2.9 3.1 V
Output Current 1000 uA
Application Load 10 100 KΩ
Rise Time 3300 us
Fall Time 0.8 ms
Table 14: VREF Supply Details
2.5 Real Time Clock (RTC) Circuit
The real time clock is a feature provided by the CM52 that allows the Wireless CPU
®
to sleep and
wakeup for a definable number of cycles, as configured by the host application. This feature is an
optional hardware feature. Please refer to the CM52 Software User’s Guide and AT Command
Manual for more details about usage scenarios and programming this feature.
The following table defines the Frequency Characteristics of the RTC:
Item Symbol Condition Rating Unit
Frequency
precision
Δf / f Ta = +25 °C,
VDD = 3.0 V
5 ± 23 (*1) X 10-6
Frequency /
voltage
characteristics
f / V Ta = +25 °C,
VDD = 2.0 V to 5.0 V
± 2 Max. X 10 -6 / V
Frequency /
temperature
characteristics
Top Ta = -20 °C to +70 °C,
VDD = 3.0 V;
+25 °C reference
+10 / -120 X 10 -6
Aging fa Ta = +25 °C,
VDD = 3.0V,
first year
± 5 Max. X 10 -6 / year
Table 15: Frequency characteristics of the RTC
(*1) precision gap per month: 1 minutes (excluding offset value)
2.5.1 RTC Initialization
When power is first applied to the RTC via the VRTC pin of the system connector it is necessary to
allow the CM52 to initialize the RTC. In order to initialize the RTC the CM52 must be powered up
while power is applied to the RTC. Once the Restart message is received the CM52 can be
shutdown via the normal procedures. If the supply to the VRTC input is interrupted then the CM52
must be allowed to power up to initialize the RTC again.
2.5.2 RTC Functional Block Diagram
The purpose of this section is to provide an overview of the Real Time Clock feature functional
block and interconnects that are shared with the application.