User's Manual
Table Of Contents
- Contents
- Tables
- Figures
- 1 Introduction
- 2 Interface Characteristics
- 2.1 Application Interface
- 2.2 RF Antenna Interface
- 2.3 Sample Application
- 3 Operating Characteristics
- 3.1 Operating Modes
- 3.2 Power Up/Power Down Scenarios
- 3.3 Power Saving
- 3.4 Power Supply
- 3.5 Operating Temperatures
- 3.6 Electrostatic Discharge
- 3.7 Blocking against RF on Interface Lines
- 3.8 Reliability Characteristics
- 4 Mechanical Dimensions, Mounting and Packaging
- 5 Regulatory and Type Approval Information
- 6 Document Information
- 7 Appendix
Cinterion
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ELS61-AUS Hardware Interface Description
2.1 Application Interface
52
ELS61-AUS_HID_v00.031 2016-06-03
Confidential / Preliminary
Page 32 of 102
2.1.7 RTC Backup
The internal Real Time Clock of ELS61-AUS is supplied from a separate voltage regulator in
the power supply component which is also active when ELS61-AUS is in Power Down mode
and BATT+ is available. An alarm function is provided that allows to wake up ELS61-AUS with-
out logging on to the UMTS network.
In addition, you can use the VDDLP pad to backup the RTC from an external capacitor. The
capacitor is charged from the internal LDO of ELS61-AUS. If the voltage supply at BATT+ is
disconnected the RTC can be powered by the capacitor. The size of the capacitor determines
the duration of buffering when no voltage is applied to ELS61-AUS, i.e. the greater the capac-
itor the longer ELS61-AUS will save the date and time. The RTC can also be supplied from an
external battery (rechargeable or non-chargeable). In this case the electrical specification of
the VDDLP pad (see Section 2.1.2) has to be taken in to account.
Figure 12 shows an RTC backup configuration. A serial 1k
Ω resistor has to be placed on the
application next to VDDLP. It limits the input current of an empty capacitor or battery.
Figure 12: RTC supply variants
Capacitor
VDDLP
GSM processor and
power management
LRTC
RTC
Application interface
BATT+
Module
1k
GND