u blox LEONG100N User Manual

29.5 x 18.9 x 3.0 mm

Abstract

This document describes the features and integration of the LEON-G100 quad-band GSM/GPRS data and voice module. The LEON-G100 is a complete and cost efficient solution, bringing full feature quad-band GSM/GPRS data and voice transmission technology in a compact form factor.

www.u-blox.com

UBX-13004888 - R01

LEON-G1 series

quad-band GSM/GPRS data & voice modules

System Integration Manual

Document Information

Title

LEON-G1 series

Subtitle

quad-band GSM/GPRS data & voice modules

Document type

System Integration Manual

Document number

UBX-13004888

Revision, date

R01

25-Nov-2013

Document status

Advance Information

Document status explanation

Objective Specification

Document contains target values. Revised and supplementary data will be published later.

Advance Information

Document contains data based on early testing. Revised and supplementary data will be published later.

Early Production Information

Document contains data from product verification. Revised and supplementary data may be published later.

Production Information

Document contains the final product specification.

Name

Type number

Firmware version

PCN / IN MODEL

LEON-G100

LEON-G100-06S-02

07.60.16

UBX-13004655 LEON-G100N

LEON-G100-09S-00

07.91

UBX-13004655 LEON-G100N

This document and the use of any information contained therein, is subject to the acceptance of the u-blox terms and conditions. They can be downloaded from www.u-blox.com. u-blox makes no warranties based on the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice. u-blox reserves all rights to this document and the information contained herein. Reproduction, use or disclosure to third parties without express permission is strictly prohibited. Copyright © 2013, u-blox AG.

u-blox® is a registered trademark of u-blox Holding AG in the EU and other countries.

Trademark Notice

Microsoft and Windows are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries. All other registered trademarks or trademarks mentioned in this document are property of their respective owners.

This document applies to the following products:

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Preface

u-blox Technical Documentation

As part of our commitment to customer support, u-blox maintains an extensive volume of technical documentation for our products. In addition to our product-specific technical data sheets, the following manuals are available to assist u-blox customers in product design and development.

AT Commands Manual: This document provides the description of the supported AT commands by the LEON

GSM/GPRS Voice and Data Modules to verify all implemented functionalities.

System Integration Manual: This Manual provides hardware design instructions and information on how to

set up production and final product tests.

Application Note: document provides general design instructions and information that applies to all u-blox

Wireless modules. See Section Related documents for a list of Application Notes related to your Wireless Module.

How to use this Manual

The LEON-G1 series System Integration Manual provides the necessary information to successfully design in and configure these u-blox wireless modules.

This manual has a modular structure. It is not necessary to read it from the beginning to the end. The following symbols are used to highlight important information within the manual:

An index finger points out key information pertaining to module integration and performance.

A warning symbol indicates actions that could negatively impact or damage the module.

Questions

If you have any questions about u-blox Wireless Integration, please:

 Read this manual carefully.  Contact our information service on the homepage http://www.u-blox.com  Read the questions and answers on our FAQ database on the homepage http://www.u-blox.com

Technical Support

Worldwide Web

Our website (www.u-blox.com) is a rich pool of information. Product information, technical documents and helpful FAQ can be accessed 24h a day.

By E-mail

Contact the nearest of the Technical Support offices by email. Use our service pool email addresses rather than any personal email address of our staff. This makes sure that your request is processed as soon as possible. You will find the contact details at the end of the document.

Helpful Information when Contacting Technical Support

When contacting Technical Support, have the following information ready:

 Module type (e.g. LEON-G100) and firmware version  Module configuration  Clear description of your question or the problem  A short description of the application  Your complete contact details

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Contents

Preface ................................................................................................................................ 3

Contents .............................................................................................................................. 4

1 System description ....................................................................................................... 7

1.1 Overview .............................................................................................................................................. 7

1.2 Architecture .......................................................................................................................................... 9

1.2.1 Functional blocks ......................................................................................................................... 10

1.3 Pin-out ............................................................................................................................................... 11

1.4 Operating modes ................................................................................................................................ 13

1.5 Power management ........................................................................................................................... 15

1.5.1 Power supply circuit overview ...................................................................................................... 15

1.5.2 Module supply (VCC) .................................................................................................................. 16

1.5.3 Current consumption profiles ...................................................................................................... 23

1.5.4 RTC Supply (V_BCKP) .................................................................................................................. 27

1.6 System functions ................................................................................................................................ 28

1.6.1 Module power on ....................................................................................................................... 28

1.6.2 Module power off ....................................................................................................................... 32

1.6.3 Module reset ............................................................................................................................... 33

1.6.4 Note: tri-stated external signal ..................................................................................................... 36

1.7 RF connection ..................................................................................................................................... 36

1.8 SIM interface ...................................................................................................................................... 37

1.8.1 SIM functionality ......................................................................................................................... 38

1.9 Serial Communication......................................................................................................................... 39

1.9.1 Asynchronous serial interface (UART)........................................................................................... 39

1.9.2 DDC (I2C) interface ...................................................................................................................... 51

1.10 Audio .............................................................................................................................................. 55

1.10.1 Analog audio interface ................................................................................................................ 55

1.10.2 Digital audio interface ................................................................................................................. 61

1.10.3 Voice-band processing system ..................................................................................................... 64

1.11 ADC input ....................................................................................................................................... 65

1.11.1 ADC calibration ........................................................................................................................... 67

1.12 General Purpose Input/Output (GPIO) ............................................................................................. 68

1.13 Schematic for module integration ................................................................................................... 72

1.14 Approvals ........................................................................................................................................ 73

1.14.1 Product certification approval overview ....................................................................................... 73

1.14.2 Federal Communications Commission and Industry Canada notice .............................................. 74

1.14.3 R&TTED and European Conformance CE mark ............................................................................ 76

1.14.4 ANATEL certification .................................................................................................................... 76

2 Design-in ..................................................................................................................... 77

2.1 Design-in checklist .............................................................................................................................. 77

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2.1.1 Schematic checklist ..................................................................................................................... 77

2.1.2 Layout checklist ........................................................................................................................... 77

2.1.3 Antenna checklist ........................................................................................................................ 78

2.2 Design guidelines for layout ................................................................................................................ 78

2.2.1 Layout guidelines per pin function ............................................................................................... 78

2.2.2 Footprint and paste mask ............................................................................................................ 84

2.2.3 Placement ................................................................................................................................... 86

2.3 Module thermal resistance .................................................................................................................. 86

2.4 Antenna guidelines ............................................................................................................................. 87

2.4.1 Antenna termination ................................................................................................................... 88

2.4.2 Antenna radiation ....................................................................................................................... 89

2.4.3 Antenna detection functionality .................................................................................................. 91

2.5 ESD immunity test precautions ........................................................................................................... 93

2.5.1 ESD immunity test overview ........................................................................................................ 93

2.5.2 ESD immunity test of u-blox LEON-G1 series reference design ..................................................... 93

2.5.3 ESD application circuits ................................................................................................................ 94

3 Feature description .................................................................................................... 97

3.1 Network indication ............................................................................................................................. 97

3.2 Antenna detection .............................................................................................................................. 97

3.3 Jamming detection ............................................................................................................................. 97

3.4 Firewall ............................................................................................................................................... 97

3.5 TCP/IP ................................................................................................................................................. 98

3.5.1 Multiple IP addresses and sockets ................................................................................................ 98

3.6 FTP ..................................................................................................................................................... 98

3.7 HTTP ................................................................................................................................................... 98

3.8 SMTP .................................................................................................................................................. 98

3.9 AssistNow clients and GNSS integration.............................................................................................. 98

3.10 Hybrid positioning and CellLocateTM ................................................................................................ 99

3.10.1 Positioning through cellular information: CellLocateTM ................................................................. 99

3.10.2 Hybrid positioning ..................................................................................................................... 100

3.11 Firmware (upgrade) Over AT (FOAT) .............................................................................................. 101

3.11.1 Overview ................................................................................................................................... 101

3.11.2 FOAT procedure ........................................................................................................................ 101

3.12 Smart temperature management .................................................................................................. 102

3.12.1 Smart Temperature Supervisor (STS) .......................................................................................... 102

3.12.2 Threshold definitions ................................................................................................................. 104

3.13 In-Band modem (eCall / ERA-GLONASS) ........................................................................................ 104

3.14 Power saving................................................................................................................................. 105

4 Handling and soldering ........................................................................................... 106

4.1 Packaging, shipping, storage and moisture preconditioning ............................................................. 106

4.2 Soldering .......................................................................................................................................... 106

4.2.1 Soldering paste.......................................................................................................................... 106

4.2.2 Reflow soldering ....................................................................................................................... 106

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4.2.3 Optical inspection ...................................................................................................................... 108

4.2.4 Cleaning .................................................................................................................................... 108

4.2.5 Repeated reflow soldering ......................................................................................................... 108

4.2.6 Wave soldering.......................................................................................................................... 108

4.2.7 Hand soldering .......................................................................................................................... 108

4.2.8 Rework ...................................................................................................................................... 108

4.2.9 Conformal coating .................................................................................................................... 108

4.2.10 Casting ...................................................................................................................................... 109

4.2.11 Grounding metal covers ............................................................................................................ 109

4.2.12 Use of ultrasonic processes ........................................................................................................ 109

5 Product testing ......................................................................................................... 110

5.1 u-blox in-series production test ......................................................................................................... 110

5.2 Test parameters for OEM manufacturer ............................................................................................ 110

5.2.1 ‘Go/No go’ tests for integrated devices ...................................................................................... 111

5.2.2 Functional tests providing RF operation ..................................................................................... 111

A Glossary .................................................................................................................... 114

Related documents......................................................................................................... 116

Revision history .............................................................................................................. 117

Contact ............................................................................................................................ 118

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LEON-G1 series - System Integration Manual

Module

Data Rate

Bands

Interfaces

Audio

Functions

GPRS multi-slot class 10

GSM/GPRS quad-band

UART

SPI

USB

DDC for u-blox GNSS receivers

GPIO

Analog Audio

Digital Audio

Network indication

Antenna detection

Jamming detection

Embedded TCP/UDP

FTP, HTTP, SMTP

SSL

GNSS via Modem

AssistNow software

FW update over AT (FOAT)

FW update over the air (FOTA)

eCall / ERA Glonass

DTMF decoder

CellLocate

Low power idle-mode

Battery charging

LEON-G100-06S

• • 1 1 5 2 1 • • • • • • • • • • LEON-G100-09S

• • 1 1 5 2 1 • • • • • • • • • • • •

1 System description

1.1 Overview

LEON-G1 series modules are versatile 2.5G GSM/GPRS wireless modules in a miniature LCC (Leadless Chip Carrier) form factor.

LEON-G100 is a full feature quad-band GSM/GPRS wireless module with a comprehensive feature set including an extensive set of internet protocols. It also provides fully integrated access to u-blox GNSS positioning chips and modules, with embedded A-GNSS (AssistNow Online and AssistNow Offline) functionality.

LEON-G1 series wireless modules are certified and approved by the main regulatory bodies and operators, and RIL software for Android and Embedded Windows are available free of charge. LEON-G100 modules are manufactured in ISO/TS 16949 certified sites. Each module is tested and inspected during production. The modules are qualified according to ISO 16750 – Environmental conditions and electrical testing for electrical and electronic equipment for road vehicles.

Table 1 describes a summary of interfaces and features provided by LEON-G100 modules.

Table 1: LEON-G1 series features summary

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Item

LEON-G100

GSM/GPRS Protocol Stack

3GPP Release 99

Mobile Station Class

Class B1

GSM/GPRS Bands

GSM 850 MHz E-GSM 900 MHz DCS 1800 MHz PCS 1900 MHz

GSM/GPRS Power Class

Class 4 (33 dBm) for 850/900 Class 1 (30 dBm) for 1800/1900

Packet Switched Data Rate

GPRS multi-slot class 102 Coding scheme CS1-CS4 Up to 85.6 kb/s DL3 Up to 42.8 kb/s UL3

Circuit Switched Data Rate

Up to 9.6 kb/s DL/UL3 Transparent mode Non transparent mode

Network Operation Modes

I to III

Table 2 shows a summary of GSM/GPRS characteristics of LEON-G1 series modules.

Table 2: LEON-G1 series GSM/GPRS characteristics summary

Encryption algorithms A5/1 for GSM and GPRS as well as the bearer service fax Group 3 Class 2.0 are supported. GPRS multi-slot class determines the maximum number of timeslots available for upload and download and thus

the speed at which data can be transmitted and received: higher classes typically allow faster data transfer rates. The network automatically configures the number of timeslots used for reception or transmission (voice calls take precedence over GPRS traffic). The network also automatically configures channel encoding (CS1 to CS4).

The maximum GPRS bit rate of the mobile station depends on the coding scheme and number of time slots.

Device can be attached to both GPRS and GSM services (i.e. Packet Switch and Circuit Switch mode) using one service at a time GPRS multi-slot class 10 implies a maximum of 4 slots in DL (reception) and 2 slots in UL (transmission) with 5 slots in total The maximum bit rate of the module depends on the current network settings

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1.2 Architecture

Memory

UART

2 Analog Audio

DDC (for GNSS)

GPIO

ADC

SIM Card

Vcc

V_BCKP

Power-On

Reset

26 MHz

32.768 kHz

Headset Detection

Transceiver

Power

Management

Baseband

ANT

SAW Filter

Switch

Digital Audio

LEON-G1 series - System Integration Manual

Figure 1: LEON-G100 block diagram

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1.2.1 Functional blocks

LEON-G1 series modules consist of the following functional blocks:

 RF  Baseband  Power Management

1.2.1.1 RF

The RF block is composed of the following main elements:

 RF transceiver (integrated in the GSM/GPRS single chip) performing modulation, up-conversion of the

baseband I/Q signals, down-conversion and demodulation of the RF received signals. The RF transceiver includes:

Constant gain direct conversion receiver with integrated LNAs; Highly linear RF quadrature demodulator; Digital Sigma-Delta transmitter modulator; Fractional-N Sigma-Delta RF synthesizer;

3.8 GHz VCO; Digital controlled crystal oscillator.

 Transmit module, which amplifies the signals modulated by the RF transceiver and connects the single

antenna input/output pin of the module to the suitable RX/TX path, via its integrated parts:

Power amplifier; Antenna switch;

 RX diplexer SAW (band pass) filters  26 MHz crystal, connected to the digital controlled crystal oscillator to perform the clock reference in active

or connected mode

1.2.1.2 Baseband

The Baseband block is composed of the following main elements:

 Baseband integrated in the GSM/GPRS single chip, including:

Microprocessor; DSP (for GSM/GPRS Layer 1 and audio processing); Peripheral blocks (for parallel control of the digital interfaces); Audio analog front-end;

 Memory system in a multi-chip package integrating two devices:

NOR flash non-volatile memory; PSRAM volatile memory;

 32.768 kHz crystal, connected to the oscillator of the RTC to perform the clock reference in idle or power-

off mode

1.2.1.3 Power management

The Power Management block is composed of the following main elements:

 Voltage regulators integrated in the GSM/GPRS single chip for direct connection to battery

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Function

I/O

Description

Remarks

Power

VCC

50 I Module Supply

Clean and stable supply is required: low ripple and low voltage drop must be guaranteed. Voltage provided has to be always above the minimum limit of the operating range. Consider that there are large current spike in connected mode, when a GSM call is enabled. See section 1.5.2

GND

1, 3, 6, 7, 8, 17, 25, 36, 45, 46, 48, 49

N/A

Ground

GND pins are internally connected but good (low impedance) external ground can improve RF performances: all GND pins must be externally connected to ground

V_BCKP

I/O

Real Time Clock supply

V_BCKP = 2.0 V (typical) generated by the module to supply Real Time Clock when VCC supply voltage is within valid operating range.

See section 1.5.4

VSIM

35 O SIM supply

SIM supply automatically generated by the module. See section 1.8

ANT

I/O

RF antenna

50  nominal impedance. See section 1.7, 2.2.1.1 and 2.4

Audio

HS_DET

I/O

GPIO

Internal active pull-up to 2.85 V enabled when the “headset detection” function is enabled (default). See section 1.12 and section 1.10.1.3

I2S_WA

26 O I2S word alignment

Check device specifications to ensure compatibility of supported modes to LEON-G1 series module. Add a test point to provide access to the pin for debugging. See section 1.10.2.

I2S_TXD

27 O I2S transmit data

Check device specifications to ensure compatibility of supported modes to LEON-G1 series module. Add a test point to provide access to the pin for debugging. See section 1.10.2.

I2S_CLK

28 O I2S clock

Check device specifications to ensure compatibility of supported modes to LEON-G1 series module. Add a test point to provide access to the pin for debugging. See section 1.10.2.

I2S_RXD

29 I I2S receive data

Internal active pull-up to 2.85 V enabled. Check device specifications to ensure compatibility of supported modes to LEON-G1 series module. Add a test point to provide access to the pin for debugging.

See section 1.10.2.

HS_P

37 O First speaker output with low power singleended analog audio

This audio output is used when audio downlink path is “Normal earpiece“ or “Mono headset“. See section 1.10.1

SPK_P

38 O Second speaker output with high power differential analog audio

This audio output is used when audio downlink path is “Loudspeaker“. See section 1.10.1

SPK_N

39 O Second speaker output with power differential analog audio output

This audio output is used when audio downlink path is “Loudspeaker“. See section 1.10.1

1.3 Pin-out

Table 3 describes the pin-out of LEON-G1 series modules, with pins grouped by function.

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Function

I/O

Description

Remarks

MIC_BIAS2

41 I Second microphone analog signal input and bias output

This audio input is used when audio uplink path is set as “Headset Microphone“.

See section 1.10.1

MIC_GND2

42 I Second microphone analog reference

Local ground of second microphone. See section 1.10.1

MIC_GND1

43 I First microphone analog reference

Local ground of the first microphone. See section 1.10.1

MIC_BIAS1

44 I First microphone analog signal input and bias output

This audio input is used when audio uplink path is set as “Handset Microphone“. See section 1.10.1

SIM

SIM_CLK

32 O SIM clock

Must meet SIM specifications See section 1.8.

SIM_IO

I/O

SIM data

Internal 4.7k pull-up to VSIM. Must meet SIM specifications See section 1.8.

SIM_RST

34 O SIM reset

Must meet SIM specifications See section 1.8.

UART

DSR 9 O

UART data set ready

Circuit 107 (DSR) in V.24. See section 1.9.1.

10 O UART ring indicator

Circuit 125 (RI) in V.24. See section 1.9.1.

DCD

11 O UART data carrier detect

Circuit 109 (DCD) in V.24. See section 1.9.1.

DTR

12 I UART data terminal ready

Internal active pull-up to 2.85 V enabled. Circuit 108/2 (DTR) in V.24. See section 1.9.1.

RTS

13 I UART ready to send

Internal active pull-up to 2.85 V enabled. Circuit 105 (RTS) in V.24. See section 1.9.1.

CTS

14 O UART clear to send

Circuit 106 (CTS) in V.24. See section 1.9.1.

TxD

15 I UART transmitted data

Internal active pull-up to 2.85 V enabled. Circuit 103 (TxD) in V.24. See section 1.9.1.

RxD

16 O UART received data

Circuit 104 (RxD) in V.24. See section 1.9.1.

DDC

SCL

30 O I2C bus clock line

Fixed open drain. External pull-up required.

See section 1.9.2

SDA

I/O

I2C bus data line

Fixed open drain. External pull-up required.

See section 1.9.2

ADC

ADC1

5 I ADC input

Resolution: 12 bits. Consider that the impedance of this input changes depending on the operative mode See section 1.11

GPIO GPIO1

I/O

GPIO

Add a test point to provide access for debugging. See section 1.12

GPIO2

I/O

GPIO

See section 1.12 and section 1.9.2

GPIO3

I/O

GPIO

See section 1.12 and section 1.9.2

GPIO4

I/O

GPIO

See section 1.12 and section 1.9.2

System PWR_ON

19 I Power-on input

PWR_ON pin has high input impedance. Do not keep floating in noisy environment: external pull-up required.

See section 1.6.1

RESET_N

I/O

Reset signal

See section 1.6.3

Reserved Reserved

Do not connect

Reserved

Do not connect

Table 3: LEON-G1 series pin-out

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Operating Mode

Description

Features / Remarks

Transition condition

General Status: Power-down

Not-Powered

Mode

VCC supply not present or

below normal operating range. Microprocessor switched off (not operating). RTC only operates if supplied through V_BCKP pin.

Module is switched off. Application interfaces are not accessible. Internal RTC timer operates only if a valid voltage is applied to V_BCKP pin. Any external signal connected to the

UART I/F, I2S I/F, HS_DET, GPIOs must be tristated to avoid an increase of module power-off consumption.

Module cannot be switched on by a falling edge provided on the PWR_ON input, neither by a preset RTC alarm.

Power-Off Mode

VCC supply within normal

operating range. Microprocessor not operating. Only RTC runs.

Module is switched off: normal shutdown after sending the AT+CPWROFF command (refer to u-blox AT Commands Manual [2]).

Application interfaces are not accessible. Only internal RTC timer in operation. Any external signal connected to the UART I/F, I2S I/F, HS_DET, GPIOs must be

tristated to avoid an increase of the module power-off consumption.

Module can be switched on by a falling edge provided on the PWR_ON input, by a preset RTC alarm.

General Status: Normal Operation

Idle-Mode

Microprocessor runs with 32 kHz as reference oscillator. Module does not accept data signals from an external device.

If power saving is enabled, the module automatically enters idle mode whenever possible. If hardware flow control is enabled, the CTS line indicates that the module is in active-mode and the UART interface is enabled: the line is driven in the OFF state when the module is not prepared to accept data by the UART interface. If hardware flow control is disabled, the CTS line is fixed to ON state. Module by default is not set to automatically enter idle mode whenever possible, unless power saving configuration is enabled by appropriate AT command (refer to u-blox AT Commands Manual [2], AT+UPSV).

If the module is registered with the network and power saving is enabled, it automatically enters idle mode and periodically wakes up to active mode to monitor the paging channel for the paging block reception according to network indication. If module is not registered with the network and power saving is enabled, it automatically enters idle mode and periodically wakes up to monitor external activity. Module wakes up from idle-mode to active-mode for an incoming voice or data call.

Module wakes up from idle mode to active mode if an RTC alarm occurs. Module wakes up from idle mode to active mode when data is received on UART interface (see section 1.9.1). Module wakes up from idle mode to active mode when the RTS input line is set to the ON state by the DTE if the AT+UPSV=2 command is sent to the module (see section 1.9.1).

Active-Mode

Microprocessor runs with 26 MHz as reference oscillator. The module is ready to accept data signals from an external device.

Module is switched on and is fully active: power saving is not enabled. The application interfaces are enabled.

If power saving is enabled, the module automatically enters idle mode whenever possible.

1.4 Operating modes

LEON-G1 series modules include several operating modes, each have different features and interfaces. Table 4 summarizes the various operating modes and provides general guidelines for operation.

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Operating Mode

Description

Features / Remarks

Transition condition

Connected-Mode

Voice or data call enabled. Microprocessor runs with 26 MHz as reference oscillator. The module is ready to accept data signals from an external device.

The module is switched on and a voice call or a data call (GSM/GPRS) is in progress.

Module is fully active. Application interfaces are enabled.

When call terminates, module returns to the last operating state (Idle or Active).

Table 4: Module operating modes summary

LEON-G1 series - System Integration Manual

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1.5 Power management

V_BCKP

GSM/GPRS Chipset

PSRAM

NOR Flash

MCP Memory

4-Bands GSM FEM

Antenna

Switch

LDOs BB

LDOs RF

RTC

LDO

LDO EBU

Charging Control

1 µF

LDO

VSIM

VCC

LEON-G100

2 x 22 µF

1.5.1 Power supply circuit overview

LEON-G1 series - System Integration Manual

Figure 2: Power supply concept

Power supply is via VCC pin. This is the only main power supply pin. VCC pin connects the RF power amplifier and the integrated power management unit within the module: all

supply voltages needed by the module are generated from the VCC supply by integrated voltage regulators. V_BCKP is the Real Time Clock (RTC) supply. When the VCC voltage is within the specified extended operating

range, the module supplies the RTC: 2.0 V typical are generated by the module on the V_BCKP pin. If the VCC voltage is under the minimum specified extended limit, the RTC can be externally supplied via V_BCKP pin.

When a 1.8 V or a 3 V SIM card type is connected, LEON-G100 automatically supplies the SIM card via VSIM pin. Activation and deactivation of the SIM interface with automatic voltage switch from 1.8 to 3 V is implemented, in accordance to the ISO-IEC 78-16-e specifications.

The integrated power management unit also provides the control state machine for system start up and system reset control.

LEON-G1 series modules feature a power management concept optimized for most efficient use of battery power. This is achieved by hardware design utilizing power efficient circuit topology, and by power management software controlling the power saving configuration of the module.

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Name

Description

Remarks

VCC

Module Supply

GND

Ground

GND pins are internally connected but good (low impedance) external ground can improve RF performances: all GND pins must be externally connected to ground.

1.5.2 Module supply (VCC)

LEON-G1 series modules must be supplied through VCC pin by a DC power supply. Voltages must be stable, due to the surging consumption profile of the GSM system (described in the section 1.5.3).

Table 5: Module supply pins

VCC pin ESD sensitivity rating is 1 kV (HBM JESD22-A114F). A higher protection level could be required if

the line is externally accessible on the application board. A higher protection level can be achieved mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) on the line connected to this pin if it is externally accessible on the application board.

The voltage provided to VCC pin must be within the normal operating range limits specified in the LEON-G1 series Data Sheet [1]. Complete functionality of the module is only guaranteed within the specified operational normal voltage range.

The module cannot be switched on if the VCC voltage value is below the specified normal operating

range minimum limit: ensure that the input voltage at VCC pin is above the minimum limit of the normal operating range for more than 1 second after the start of the switch-on of the module.

When LEON-G1 series modules are in operation, the voltage provided to VCC pin can exceed the normal operating range limits but must be within the extended operating range limits specified in LEON-G1 series Data Sheet [1]. Module reliability is only guaranteed within the specified operational extended voltage range.

The module switches off when VCC voltage value drops below the specified extended operating range

minimum limit: ensure that the input voltage at VCC pin never drops below the minimum limit of the extended operating range when the module is switched on, not even during a GSM transmit burst, where the current consumption can rise up to maximum peaks of 2.5 A in case of a mismatched antenna load.

Operation above the extended operating range maximum limit is not recommended and

extended exposure beyond it may affect device reliability.

Stress beyond the VCC absolute maximum ratings may cause permanent damage to the module:

if necessary, voltage spikes beyond VCC absolute maximum ratings must be limited to values within the specified boundaries by using appropriate protection.

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Time

undershoot

overshoot

ripple

drop

Voltage

3.8 V (typ)

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

GSM frame

4.615 ms

(1 frame = 8 slots)

GSM frame

4.615 ms

(1 frame = 8 slots)

Time

undershoot

overshoot

ripple

drop

Voltage

3.8 V (typ)

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

GSM frame

4.615 ms

(1 frame = 8 slots)

GSM frame

4.615 ms

(1 frame = 8 slots)

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

GSM frame

4.615 ms

(1 frame = 8 slots)

GSM frame

4.615 ms

(1 frame = 8 slots)

When designing the power supply for the application, pay specific attention to power losses and

transients. The DC power supply has to be able to provide a voltage profile to the VCC pin with the following characteristics:

o Voltage drop during transmit slots has to be lower than 400 mV o Undershoot and overshoot at the start and at the end of transmit slots have to be not present o Voltage ripple during transmit slots has to be:

 lower than 100 mVpp if f  lower than 10 mVpp if 200 kHz < f  lower than 2 mVpp if f

≤ 200 kHz

ripple

> 400 kHz

ripple

≤ 400 kHz

ripple

Figure 3: Description of the VCC voltage profile versus time during a GSM call

Any degradation in power supply performance (due to losses, noise or transients) will directly affect the RF

performance of the module since the single external DC power source indirectly supplies all the digital and analog interfaces, and also directly supplies the RF power amplifier (PA).

1.5.2.1 VCC application circuits

The LEON-G100 module must be supplied through the VCC pin by a proper DC power supply, which most common ones are the following:

 Switching regulator  Low Drop-Out (LDO) linear regulator  Rechargeable Li-Ion battery  Primary (disposable) battery

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Main Supply

Available?

Battery

Li-Ion 3.7 V

Linear LDO

Regulator

Main Supply

Voltage >5 V?

Switching

Step-Down

Regulator

No, portable device

No, less than 5 V

Yes, greater than 5 V

Yes, always available

Figure 4: VCC supply concept selection

The switching step-down regulator is the typical choice when the available primary supply source has a nominal voltage much higher (e.g. greater than 5 V) than the LEON-G1 series operating supply voltage. The use of switching step-down provides the best power efficiency for the overall application and minimizes current drawn from main supply source.

The use of an LDO linear regulator becomes convenient for primary supplies with relatively low voltage (e.g. less than 5 V). In this case a switching regulator with a typical efficiency of 90% reduces the benefit of voltage step-down for input current savings. Linear regulators are not recommended for high voltage step-down as they will dissipate a considerable amount of power in thermal energy.

If the LEON-G100 is deployed in a mobile unit with no permanent primary supply source available, then a battery is required to provide VCC. A standard 3-cell Lithium-Ion battery pack directly connected to VCC is the typical choice for battery-powered devices. Batteries with Ni-MH chemistry should be avoided, since they typically reach a maximum voltage during charging that is above the maximum rating for VCC.

The use of primary (disposable) batteries is uncommon, since the typical cells available are seldom capable of delivering the burst peak current for a GSM call due to high internal resistance.

The following sections highlight some design aspects for each of these supplies.

Switching regulator The characteristics of the switching regulator connected to the VCC pin should meet the following requirements:

 Power capabilities: the switching regulator with its output circuit must be capable of providing a proper

voltage value to the VCC pin and delivering 2.5 A current pulses with a 1/8 duty cycle to the VCC pin

 Low output ripple: the switching regulator and output circuit must be capable of providing a clean (low

noise) VCC voltage profile

 High switching frequency: for best performance and for smaller applications select a switching frequency

≥ 600 kHz (since an L-C output filter is typically smaller for high switching frequency). Using a switching regulator with a variable switching frequency or with a switching frequency lower than 600 kHz must be carefully evaluated since this can produce noise in the VCC voltage profile and therefore impact and worsen GSM modulation spectrum performance. An additional L-C low-pass filter between the switching regulator output and the VCC supply pin can mitigate the ripple on VCC, but adds extra voltage drop due to resistive losses in series inductors

 PWM mode operation: select preferably regulators with Pulse Width Modulation (PWM) mode. Pulse

Frequency Modulation (PFM) mode and PFM/PWM mode transitions while in active mode must be avoided to reduce the noise on the VCC voltage profile. Switching regulators able to switch between low ripple

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LEON-G100

12V

C3C2

VIN

RUN

SYNC

BOOST

GND

C8 C9

VCC

GND

Reference

Description

Part Number - Manufacturer

47 µF Capacitor Aluminum 0810 50 V

MAL215371479E3 - Vishay

10 µF Capacitor Ceramic X7R 5750 15% 50 V

C5750X7R1H106MB - TDK

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

680 pF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71H681KA01 - Murata

22 pF Capacitor Ceramic COG 0402 5% 25 V

GRM1555C1H220JZ01 - Murata

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

470 nF Capacitor Ceramic X7R 0603 10% 25 V

GRM188R71E474KA12 - Murata

22 µF Capacitor Ceramic X5R 1210 10% 25 V

GRM32ER61E226KE15 - Murata

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 mΩ

T520D337M006ATE045 - KEMET

Schottky Diode 40 V 3 A

MBRA340T3G - ON Semiconductor

10 µH Inductor 744066100 30% 3.6 A

744066100 - Wurth Electronics

1 µH Inductor 7445601 20% 8.6 A

7445601 - Wurth Electronics

470 kΩ Resistor 0402 5% 0.1 W

2322-705-87474-L - Yageo

15 kΩ Resistor 0402 5% 0.1 W

2322-705-87153-L - Yageo

33 kΩ Resistor 0402 5% 0.1 W

2322-705-87333-L - Yageo

390 kΩ Resistor 0402 1% 0.063 W

RC0402FR-07390KL - Yageo

100 kΩ Resistor 0402 5% 0.1 W

2322-705-70104-L - Yageo

Step Down Regulator MSOP10 3.5 A 2.4 MHz

LT3972IMSE#PBF - Linear Technology

PWM mode and high efficiency burst or PFM mode can be used, provided the mode transition occurs when the GSM module changes status from idle mode (current consumption approximately 1 mA) to active mode (current consumption approximately 100 mA): it is permissible to use a regulator that switches from the PWM mode to the burst or PFM mode at an appropriate current threshold (e.g. 60 mA)

Figure 5 and the components listed in Table 6 show an example of a high reliability power supply circuit, where the VCC module supply is provided by a step-down switching regulator capable to deliver 2.5 A current pulses, with low output ripple, with 1 MHz fixed switching frequency in PWM mode operation. The use of a switching regulator is suggested when the difference from the available supply rail and the VCC value is high: switching regulators provide good efficiency transforming a 12 V supply to the 3.8 V typical value of the VCC supply. The following power supply circuit example is implemented on the LEON Evaluation Board.

Figure 5: Suggested schematic design for the VCC voltage supply application circuit using a step-down regulator

Table 6: Suggested components for VCC voltage supply application circuit using a high reliability step-down regulator

Figure 6 and the components listed in Table 7 show an example of a low cost power supply circuit, where the VCC module supply is provided by a step-down switching regulator capable of delivering 2.5 A current pulses, transforming a 12 V supply input.

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LEON-G100

12V

C6C1

VCC

INH

FSW

SYNC

OUT

GND

VCC

GND

COMP

Reference

Description

Part Number - Manufacturer

22 µF Capacitor Ceramic X5R 1210 10% 25 V

GRM32ER61E226KE15 – Murata

100 µF Capacitor Tantalum B_SIZE 20% 6.3V 15mΩ

T520B107M006ATE015 – Kemet

5.6 nF Capacitor Ceramic X7R 0402 10% 50 V

GRM155R71H562KA88 – Murata

6.8 nF Capacitor Ceramic X7R 0402 10% 50 V

GRM155R71H682KA88 – Murata

56 pF Capacitor Ceramic C0G 0402 5% 50 V

GRM1555C1H560JA01 – Murata

220 nF Capacitor Ceramic X7R 0603 10% 25 V

GRM188R71E224KA88 – Murata

Schottky Diode 25V 2 A

STPS2L25 – STMicroelectronics

5.2 µH Inductor 30% 5.28A 22 mΩ

MSS1038-522NL – Coilcraft

4.7 kΩ Resistor 0402 1% 0.063 W

RC0402FR-074K7L – Yageo

910 Ω Resistor 0402 1% 0.063 W

RC0402FR-07910RL – Yageo

82 Ω Resistor 0402 5% 0.063 W

RC0402JR-0782RL – Yageo

8.2 kΩ Resistor 0402 5% 0.063 W

RC0402JR-078K2L – Yageo

39 kΩ Resistor 0402 5% 0.063 W

RC0402JR-0739KL – Yageo

Step Down Regulator 8-VFQFPN 3 A 1 MHz

L5987TR – ST Microelectronics

Figure 6: Suggested schematic design for the VCC voltage supply application circuit using a low cost step-down regulator

Table 7: Suggested components for VCC voltage supply application circuit using a low cost step-down regulator

Low Drop-Out (LDO) linear regulator The characteristics of the LDO linear regulator connected to VCC pin should meet the following requirements:

 Power capabilities: the LDO linear regulator with its output circuit has to be capable to provide a proper

voltage value to VCC pin and has to be capable to deliver 2.5 A current pulses with 1/8 duty cycle to VCC pin

 Power dissipation: the power handling capability of the LDO linear regulator has to be checked to limit its

junction temperature to the maximum rated operating range (i.e. check the voltage drop from the max input voltage to the min output voltage to evaluate the power dissipation of the regulator)

Figure 7 and the components listed in Table 8 show an example of a power supply circuit, where the VCC module supply is provided by an LDO linear regulator capable to deliver 2.5 A current pulses, with proper power handling capability. The use of a linear regulator is suggested when the difference from the available supply rail and the VCC value is low: linear regulators provide good efficiency transforming a 5 V supply to the 3.8 V typical value of the VCC supply.

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5 V

C1 R1

IN OUT

ADJ

GND

C2R2

SHDN

LEON-G100

VCC

GND

Reference

Description

Part Number - Manufacturer

10 µF Capacitor Ceramic X5R 0603 20% 6.3 V

GRM188R60J106ME47 - Murata

10 µF Capacitor Ceramic X5R 0603 20% 6.3 V

GRM188R60J106ME47 - Murata

47 kΩ Resistor 0402 5% 0.1 W

RC0402JR-0747KL - Yageo Phycomp

4.7 kΩ Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

2.2 kΩ Resistor 0402 5% 0.1 W

RC0402JR-072K2L - Yageo Phycomp

LDO Linear Regulator ADJ 3.0 A

LT1764AEQ#PBF - Linear Technology

Figure 7: Suggested schematic design for the VCC voltage supply application circuit using an LDO linear regulator

Table 8: Suggested components for VCC voltage supply application circuit using an LDO linear regulator

Rechargeable Li-Ion battery

The characteristics of the rechargeable Li-Ion battery connected to VCC pin should meet the following requirements:

 Maximum pulse and DC discharge current: the rechargeable Li-Ion battery with its output circuit has to

be capable to deliver 2.5 A current pulses with 1/8 duty cycle to VCC pin and has to be capable to deliver a DC current greater than the module maximum average current consumption to VCC pin. The maximum pulse discharge current and the maximum DC discharge current are not always reported in batteries data sheet, but the maximum DC discharge current is typically almost equal to the battery capacity in Amperehours divided by 1 hour

 DC series resistance: the rechargeable Li-Ion battery with its output circuit has to be capable to avoid a

VCC voltage drop greater than 400 mV during transmit bursts

 Maximum DC charging current: the rechargeable Li-Ion battery has to be capable to be charged by the

charging current provided by the selected external charger. The maximum DC charging current is not always reported in batteries data sheet, but the maximum DC charging current is typically almost equal to the battery capacity in Ampere-hours divided by 1 hour

Primary (disposable) battery

The characteristics of the primary (non-rechargeable) battery connected to VCC pin should meet the following requirements:

 Maximum pulse and DC discharge current: the no-rechargeable battery with its output circuit has to be

capable to deliver 2.5 A current pulses with 1/8 duty cycle to VCC pin and has to be capable to deliver a DC current greater than the module maximum average current consumption to VCC pin. The maximum pulse and the maximum DC discharge current is not always reported in batteries data sheet, but the maximum DC discharge current is typically almost equal to the battery capacity in Ampere-hours divided by 1 hour

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Reference

Description

Part Number - Manufacturer

330 µF Capacitor Tantalum D_SIZE 6.3 V 45 mΩ

T520D337M006ATE045 - KEMET

100 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R61A104KA01 - Murata

10 nF Capacitor Ceramic X7R 0402 10% 16 V

GRM155R71C103KA01 - Murata

39 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E390JA01 - Murata

10 pF Capacitor Ceramic C0G 0402 5% 25 V

GRM1555C1E100JA01 - Murata

VBAT

C1 C4

LEON-G100

VCC

GND

C3C2

 DC series resistance: the no-rechargeable battery with its output circuit has to be capable to avoid a VCC

voltage drop greater than 400 mV during transmit bursts

Additional hints for the VCC supply application circuits

To reduce voltage drops, use a low impedance power source. The resistance of the power supply lines (connected to VCC and GND pins of the module) on the application board and battery pack should also be considered and minimized: cabling and routing must be as short as possible in order to minimize power losses.

To avoid undershoot and overshoot on voltage drops at the start and at the end of a transmit burst during a GSM call (when current consumption on the VCC supply can rise up to 2.5 A in the worst case), place a 330 µF low ESR capacitor (e.g. KEMET T520D337M006ATE045) located near VCC pin of LEON-G100.

To reduce voltage ripple and noise, place near VCC pin of the LEON-G100 the following components:

 100 nF capacitor (e.g Murata GRM155R61A104K) to filter digital logic noises from clocks and data sources  10 nF capacitor (e.g. Murata GRM155R71C103K) to filter digital logic noises from clocks and data sources  10 pF capacitor (e.g. Murata GRM1555C1E100J) to filter transmission EMI in the DCS/PCS bands  39 pF capacitor (e.g. Murata GRM1555C1E390J) to filter transmission EMI in the GSM/EGSM bands

Figure 8 shows the complete configuration but the mounting of the each single component depends on

application design.

Figure 8: Suggested schematics design to reduce voltage ripple, noise and avoid undershoot and overshoot on voltage drops

Table 9: Suggested components to reduce voltage ripple and noise and avoid undershoot and overshoot on voltage drops

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Time [ms]

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

GSM frame

4.615 ms

(1 frame = 8 slots)

Current [A]

200 mA

~170 mA

2500 mA

Peak current

depends on

TX power

GSM frame

4.615 ms

(1 frame = 8 slots)

1.5

1.0

0.5

0.0

2.5

2.0

~170 mA

~40 mA

1.5.3 Current consumption profiles

During operation, the current consumed by LEON-G100 through VCC pin can vary by several orders of magnitude. This is applied to ranges from the high peak of current consumption during the GSM transmitting bursts at maximum power level in connected mode, to the low current consumption in idle mode when power saving configuration is enabled.

1.5.3.1 Current consumption profiles – Connected mode

When a GSM call is established, the VCC consumption is determined by the current consumption profile typical of the GSM transmitting and receiving bursts.

The current consumption peak during a transmission slot is strictly dependent on the transmitted power, which is regulated by the network. If the module transmits in GSM talk mode in the GSM 850 or in the EGSM 900 band at the maximum power control level (32.2 dBm typical transmitted power in the transmit slot/burst), the current consumption can reach up to 2500 mA (with highly unmatched antenna) for 576.9 µs (width of the transmit slot/burst) with a periodicity of 4.615 ms (width of 1 frame = 8 slots/bursts), so with a 1/8 duty cycle, according to GSM TDMA.

During a GSM call, current consumption is in the order of 100-200 mA in receiving or in monitor bursts and is about 30-50 mA in the inactive unused bursts (low current period). The more relevant contribution to determine the average current consumption is set by the transmitted power in the transmit slot.

Figure 9 shows an example of current consumption profile of the data module in GSM talk mode.

Figure 9: Description of the VCC current consumption profile versus time during a GSM call (1 TX slot)

When a GPRS connection is established there is a different VCC current consumption profile also determined by the transmitting and receiving bursts. In contrast to a GSM call, during a GPRS connection more than one slot can be used to transmit and/or more than one slot can be used to receive. The transmitted power depends on network conditions and sets the peak of current consumption, but following the GPRS specifications the maximum transmitted power can be reduced if more than one slot is used to transmit, so the maximum peak of current consumption is not as high as can be the case in a GSM call.

If the module transmits in GPRS class 10 connected mode in the GSM 850 or in the EGSM 900 band at the maximum power control level (30.5 dBm typical transmitted power in the transmit slot/burst), the current consumption can reach up to 1800 mA (with highly unmatched antenna) for 1.154 ms (width of the 2 transmit

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Time [ms]

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

unused

slot

unused

slot

unused

slot

MON

slot

unused

slot

GSM frame

4.615 ms

(1 frame = 8 slots)

Current [A]

200mA

~170 mA

1800 mA

Peak current

depends on

TX power

~170 mA

GSM frame

4.615 ms

(1 frame = 8 slots)

1.5

1.0

0.5

0.0

2.5

2.0

~40 mA

slots/bursts) with a periodicity of 4.615 ms (width of 1 frame = 8 slots/bursts), so with a 1/4 duty cycle, according to GSM TDMA.

Figure 10 reports the current consumption profiles with 2 slots used to transmit.

Figure 10: Description of the VCC current consumption profile versus time during a GPRS connection (2 TX slots)

1.5.3.2 Current consumption profiles – Cyclic idle/active mode (power saving enabled)

The power saving configuration is by default disabled, but it can be enabled using the appropriate AT command (refer to u-blox AT Commands Manual [2], AT+UPSV command). When the power saving is enabled, the module automatically enters idle-mode whenever possible.

When power saving is enabled, the module is registered or attached to a network and a voice or data call is not enabled, the module automatically enters idle-mode whenever possible, but it must periodically monitor the paging channel of the current base station (paging block reception), in accordance to GSM system requirements. When the module monitors the paging channel, it wakes up to active mode, to enable the reception of paging block. In between, the module switches to idle-mode. This is known as GSM discontinuous reception (DRX).

The module processor core is activated during the paging block reception, and automatically switches its reference clock frequency from the 32 kHz used in idle-mode to the 26 MHz used in active-mode.

The time period between two paging block receptions is defined by the network. It can vary from 470.76 ms (width of 2 GSM multiframes = 2 x 51 GSM frames = 2 x 51 x 4.615 ms) up to 2118.42 ms (width of 9 GSM multiframes = 9 x 51 frames = 9 x 51 x 4.615 ms): this is the paging period parameter, fixed by the base station through broadcast channel sent to all users on the same serving cell.

An example of the current consumption profile of the data module when power saving is enabled is shown in Figure 11: the module is registered with the network, automatically goes into idle mode and periodically wakes up to active mode to monitor the paging channel for paging block reception (cyclic idle/active mode).

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~30 ms

IDLE MODE ACTIVE MODE IDLE MODE

500-700 µA

8-10 mA

20-22 mA

~150 mA

Active Mode

Enabled

Idle Mode

Enabled

PLL

Enabled

500-700 µA

~150 mA

0.44-2.09 s

IDLE MODE

~30 ms

ACTIVE MODE

Time [s]

Current [mA]

150

100

Time [ms]

Current [mA]

150

100

38-40 mA

DSP

Enabled

Figure 11: Description of the VCC current consumption profile versus time when power saving is enabled: the module is in idle mode and periodically wakes up to active mode to monitor the paging channel for paging block reception

1.5.3.3 Current consumption profiles – Fixed active mode (power saving disabled)

Power saving configuration is by default disabled, or it can be disabled using the appropriate AT command (refer to u-blox AT Commands Manual [2], AT+UPSV command). When power saving is disabled, the module does not automatically enter idle-mode whenever possible: the module remains in active mode.

The module processor core is activated during active-mode, and the 26 MHz reference clock frequency is used. An example of the current consumption profile of the data module when power saving is disabled is shown in

Figure 12: the module is registered with the network, active-mode is maintained, and the receiver and the DSP are periodically activated to monitor the paging channel for paging block reception.

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ACTIVE MODE

20-22 mA 20-22 mA

20-22 mA

~150 mA

0.47-2.12 s

Paging period

Time [s]

Current [mA]

150

100

Time [ms]

Current [mA]

150

100

Enabled

DSP

Enabled

~150 mA

38-40 mA

Figure 12: Description of the VCC current consumption profile versus time when power saving is disabled: active-mode is always held, and the receiver and the DSP are periodically activated to monitor the paging channel for paging block reception

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Name

Description

Remarks

V_BCKP

Real Time Clock supply

V_BCKP = 2.0 V (typical) generated by the module to supply Real Time Clock when VCC supply voltage is within valid operating range.

1.5.4 RTC supply (V_BCKP)

V_BCKP connects the Real Time Clock (RTC) supply, generated internally by a linear regulator integrated in the

module chipset. The output of this linear regulator is enabled when the main voltage supply providing the module through VCC is within the valid operating range, or if the module is switched-off.

Table 10: Real Time Clock supply pin

V_BCKP pin ESD sensitivity rating is 1 kV (HBM JESD22-A114F). A higher protection level could be

required if the line is externally accessible on the application board. A higher protection level can be achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) on the line connected to this pin if it is externally accessible on the application board.

The RTC provides the time reference (date and time) of the module, also in power-off mode, since the RTC runs when the V_BCKP voltage is within its valid range (specified in the LEON-G1 series Data Sheet [1]). The RTC block is able to provide programmable alarm functions by means of the internal 32.768 kHz clock.

The RTC block has very low, but highly temperature dependent power consumption. For example at 25°C and a V_BCKP voltage of 2.0 V the power consumption is approximately 2 µA, whereas at 85°C and an equal voltage it increases to 5 µA.

The RTC can be supplied from an external back-up battery through V_BCKP, when the main voltage supply is not provided to the module through VCC. This enables the time reference (date and time) to run even when the main supply is not provided to the module. The module cannot switch on if a valid voltage is not present on VCC, even when RTC is supplied through V_BCKP (meaning that VCC is mandatory to switch-on the module).

If V_BCKP is left unconnected and the main voltage supply of the module is removed from VCC, the RTC is supplied from the 1 µF buffer capacitor mounted inside the module. However, this capacitor is not able to provide a long buffering time: within 0.5 seconds the voltage on V_BCKP will fall below the valid range (1 V min).

If RTC is not required when VCC supply is removed, V_BCKP can be left floating on the application board.

If RTC has to run for a time interval of T [seconds] at 25°C and VCC supply is removed, place a capacitor of nominal capacitance of C [µF] at the V_BCKP pin. Choose the capacitor using the following formula:

C [µF] = (Current_Consumption [µA] x T [seconds]) / Voltage_Drop [V] = 2 x T [seconds]

The current consumption of the RTC is around 2 µA at 25°C, and the voltage drop is equal to 1 V (from the V_BCKP typical value of 2.0 V to the valid range minimum limit of 1.0 V).

For example, a 100 µF capacitor (such as the Murata GRM43SR60J107M) can be placed at V_BCKP to provide a long buffering time. This capacitor will hold V_BCKP voltage within its valid range for around 50 seconds at 25°C, after the VCC supply is removed. If a very long buffering time is required, a 70 mF super-capacitor (e.g. Seiko Instruments XH414H-IV01E) can be placed at V_BCKP, with a 4.7 k series resistor to hold the V_BCKP voltage within its valid range for around 10 hours at 25°C, after the VCC supply is removed. The purpose of the series resistor is to limit the capacitor charging current due to the big capacitor specifications, and also to let a fast rise time of the voltage value at the V_BCKP pin after VCC supply has been provided. These capacitors will allow the time reference to run during a disconnection of the VCC supply.

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LEON-G100

(a)

V_BCKP

C2 (superCap)

(b)

V_BCKP

(c)

V_BCKP

LEON-G100 LEON-G100

Reference

Description

Part Number - Manufacturer

100 µF Tantalum Capacitor

GRM43SR60J107M - Murata

4.7 kΩ Resistor 0402 5% 0.1 W

RC0402JR-074K7L - Yageo Phycomp

70 mF Capacitor

XH414H-IV01E - Seiko Instruments

Name

Description

Remarks

PWR_ON

Power-on input

PWR_ON pin has high input impedance. Do not keep floating in noisy environment: external pull-up required.

Figure 13: Real time clock supply (V_BCKP) application circuits: (a) using a 100 µF capacitor to let the RTC run for 50 s at 25°C; (b) using a 70 mF capacitor to let the RTC run for ~10 hours at 25°C when the VCC supply is removed; (c) using a not rechargeable battery

Table 11: Example of components for V_BCKP buffering

If longer buffering time is required to allow the time reference to run during a disconnection of the VCC supply, a rechargeable battery, which has to be able to provide a 2.0 V nominal voltage and must not exceed the maximum operating voltage value of 2.25 V, can be connected to the V_BCKP pin with a proper series resistor. Otherwise a not rechargeable battery, which has to be able to provide a 2.0 V nominal voltage and must not exceed the maximum operating voltage value of 2.25 V, can be connected to the V_BCKP pin with a proper series resistor and a proper series diode. The purpose of the series resistor is to limit the battery charging current due to the battery specifications, and also to let a fast rise time of the voltage value at the V_BCKP pin after VCC supply has been provided. The purpose of the series diode is to avoid a current flow from the V_BCKP pin of the module to the not rechargeable battery.

1.6 System functions

1.6.1 Module power on

The power-on sequence of the module is initiated in one of the following ways:

 Rising edge on the VCC pin to a valid voltage as module supply  Low level on the PWR_ON signal  RTC alarm

Table 12: Power-on pin

PWR_ON pin ESD sensitivity rating is 1 kV (HBM JESD22-A114F). A higher protection level could be

required if the line is externally accessible on the application board. A higher protection level can be achieved mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) on the line connected to this pin if it is externally accessible on the application board.

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1.6.1.1 Rising edge on VCC

When a supply is connected to VCC pin, the module supply supervision circuit controls the subsequent activation of the power up state machines: the module is switched-on when the voltage rises up to the VCC normal operating range minimum limit (3.35 V) starting from a voltage value lower than 2.25 V.

1.6.1.2 Low level on the PWR_ON

Power-on sequence of the module starts when a low level is forced on the PWR_ON signal for at least 5 ms. The electrical characteristics of the PWR_ON input pin are different from the other digital I/O interfaces: the high

and the low logic levels have different operating ranges and the pin is tolerant against voltages up to the battery voltage. The detailed electrical characteristics are described in the LEON-G1 series Data Sheet [1].

PWR_ON pin has high input impedance and is weakly pulled to the high level on the module. Avoid keep

it floating in noisy environment. To hold the high logic level stable, the PWR_ON pin must be connected to a pull-up resistor (e.g. 100 kΩ) biased by the V_BCKP supply pin of the module.

If PWR_ON input is connected to a push button that shorts the PWR_ON pin to ground, the V_BCKP supply pin of the module can be used to bias the pull-up resistor.

If PWR_ON input is connected to an external device (e.g. application processor), it is suggested to use an open drain output of the external device with an external pull-up. Connect the pull-up the V_BCKP supply pin of the module.

If PWR_ON pin is connected to a push-pull output pin of an application processor, the pull-up can be provided to pull high the PWR_ON level when the application processor is switched off. If the high-level voltage of the push-pull output pin of the application processor is greater than 2.0 V, the V_BCKP supply cannot be used to bias the pull-up resistor: the supply rail of the application processor, or the VCC supply could be used but this will increase the V_BCKP (RTC supply) current consumption when the module is in not-powered mode (i.e. VCC supply not present). Using a push-pull output of the external device, take care to fix the proper level in all the possible scenarios to avoid an inappropriate switch-on of the module.

The module can be switched-on by forcing a low level for at least 5 ms on the PWR_ON pin: the module

is not switched-on by a falling edge provided on the PWR_ON pin. The suggested PWR_ON pull-up resistor value is 100 kΩ: lower resistance value will increase the module power-off consumption. The suggested supply to bias the pull-up resistor is the V_BCKP supply pin of the module.

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Power-on

push button

LEON-G100

PWR_ON

LEON-G100

PWR_ON

Application Processor

100 k

V_BCKP

ESD

100 k

V_BCKP

Figure 14: Power on (PWR_ON) application circuits using a push button or using an application processor

1.6.1.3 RTC alarm

The module can be switched-on by the RTC alarm if a valid voltage is applied to VCC pin, when Real Time Clock system reaches a pre-defined scheduled time. The RTC system will then initiate the boot sequence by indicating to the power management unit to turn on power. Also included in this setup is an interrupt signal from the RTC block to indicate to the baseband processor, that a RTC event has occurred.

1.6.1.4 Additional considerations

The module is switched on when the voltage rises up to the VCC normal operating range: the first time that the module is used, it is switched on in this way. Then, the proper way to switch-off the module is by means of the AT+CPWROFF command. When the module is in power-off mode, i.e. the AT+CPWROFF command has been sent and a voltage value within the normal operating range limits is still provided to the VCC pin, the digital input-output pads of the baseband chipset (i.e. all the digital pins of the module) are locked in tri-state (i.e. floating). The power down tri-state function isolates the pins of the module from its environment, when no proper operation of the outputs can be guaranteed. To avoid an increase of the module current consumption in power down mode, any external signal of the digital interfaces connected to the module must be set low or tristated when the module is in not-powered mode or in the power-off mode.

The module can be switched on from power-off mode by forcing a proper start-up event (i.e. a low level on the PWR_ON pin, or an RTC alarm). After the detection of a start-up event, all the digital pins of the module are held in tri-state until all the internal LDO voltage regulators are turned on in a defined power-on sequence. Then, as described in Figure 15, the baseband core continues to be held in reset state for a time interval: the module still pulls the RESET_N pin low and any signal from the module digital interfaces is held in reset state. The reset state of all the digital pins is reported in the pin description table of the LEON-G1 series Data Sheet [1]. When the module releases the RESET_N pin, the level at this pin will be pulled high by the action of the internal pullup and the configuration of the module interfaces will start: during this phase any digital pin is set in a proper sequence from reset state to the default operational configuration. The module is fully ready to operate when all the interfaces are configured.

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