Integration Manual
Table Of Contents
- Preface
- Contents
- 1 System description
- 1.1 Overview
- 1.2 Architecture
- 1.3 Pin-out
- 1.4 Operating modes
- 1.5 Power management
- 1.6 System functions
- 1.7 RF connection
- 1.8 (U)SIM interface
- 1.9 Serial communication
- 1.10 DDC (I2C) interface
- 1.11 Audio Interface
- 1.12 General Purpose Input/Output (GPIO)
- 1.13 Reserved pins (RSVD)
- 1.14 Schematic for LISA-U series module integration
- 1.15 Approvals
- 2 Design-In
- 2.1 Design-in checklist
- 2.2 Design Guidelines for Layout
- 2.2.1 Layout guidelines per pin function
- 2.2.2 Footprint and paste mask
- 2.2.3 Placement
- 2.3 Thermal aspects
- 2.4 Antenna guidelines
- 2.5 ESD precautions
- 3 Features description
- 4 Handling and soldering
- 5 Product Testing
- Appendix
- A Migration to LISA-U2 series wireless modules
- B Glossary
- Related documents
- Revision history
- Contact
LISA-U series - System Integration Manual
3G.G2-HW-10002-A3 Preliminary System description
Page 37 of 160
LISA-U series
Rext
2
V_BCKP
19
PWR_ON
Power-on
push button
ESD
Open
Drain
Output
Application
Processor
LISA-U series
Rext
2
V_BCKP
19
PWR_ON
Figure 17: PWR_ON application circuits using a push button and an open drain output of an application processor
Reference
Description
Remarks
Rext
100 kΩ Resistor 0402 5% 0.1 W
External pull-up resistor
ESD
CT0402S14AHSG - EPCOS
Varistor array for ESD protection
Table 16: Example of pull-up resistor and ESD protection for the PWR_ON application circuits
1.6.1.3 Rising edge on RESET_N
LISA-U series modules can be switched on by means of the RESET_N input pin: the RESET_N signal must be
forced low for at least 50 ms and then released to generate a rising edge that starts the module power-on
sequence.
RESET_N input pin can also be used to perform an “external” or “hardware” reset of the module, as described
in the section 1.6.3.
Electrical characteristics of the LISA-U series RESET_N input are slightly different from the other digital I/O
interfaces: the pin provides different input voltage thresholds. Detailed electrical characteristics are described in
LISA-U1 series Data Sheet [1] and LISA-U2 series Data Sheet [2].
RESET_N is pulled high to V_BCKP by an integrated pull-up resistor also when the module is in power-off
mode. Therefore an external pull-up is not required on the application board.
The simplest way to switch on the module by means of the RESET_N input pin is to use a push button that
shorts the RESET_N pin to ground: the module will be switched on at the release of the push button, since the
RESET_N will be forced to the high level by the integrated pull-up resistor, generating a rising edge.
If RESET_N is connected to an external device (e.g. an application processor on an application board) an open
drain output can be directly connected without any external pull-up. A push-pull output can be used too: in this
case make sure that the high level voltage of the push-pull circuit is below the maximum voltage operating
range of the RESET_N pin (specified in the RESET_N pin characteristics table in LISA-U1 series Data Sheet [1]
and LISA-U2 series Data Sheet [2]). To avoid unwanted power-on or reset of the module make sure to fix the
proper level at the RESET_N input pin in all possible scenarios.
Some typical examples of application circuits using the RESET_N input pin are described in the section 1.6.3.