Specifications
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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ELS81-US Hardware Interface Description
3.2 Power Up/Power Down Scenarios
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els81-us_hid_v01.004 2017-09-27
Confidential / Preliminary
Page 57 of 107
3.2.1.2 Switch on ELS81-US Using ON Signal
After the operating voltage BATT+ is applied, ELS81-US can be switched on by means of the
ON signal.
The ON signal is an edge triggered signal and allows the input voltage level up to 5V. The mod-
ule starts into normal mode on detecting the rising edge of the ON signal. The rising edge of
ON signal must be applied at least 100 milliseconds later than BATT+. See Figure 31.
The following Figure 30 shows recommendations for possible switch-on circuits.
Figure 30: ON circuit options
It is recommended to set a serial 1kOhm resistor between the ON circuit and the external ca-
pacitor or battery at the VDDLP power supply (i.e., RTC backup circuit). This serial resistor pro-
tection is necessary in case the capacitor or battery has low power (is empty).With Option 2 the
typical resistor values are: R1 = 150k and R2 = 3k. But the resistor values depend on the cur-
rent gain from the employed PNP resistor.
Please note that the ON signal is an edge triggered signal. This implies that a micro-second
high pulse on the signal line suffices to almost immediately switch on the module, as shown in
Figure 31. After module startup the ON signal should always be set to low to prevent possible
back powering at this pad.
1
1. Please take due discretion when designing the filtering circuit, especially ESD, which may cause unin-
tended switch on.
VDDLP
ON
1k
+
R1
R2
Option 1 Option 2
RTC backup