Neoway Technology 1232 GPRS Module User Manual

Shenzhen Neoway Technology Co., Ltd GPRS Module

User Manual

Neo_M680 Hardware User Guide Version 1.0 Let's enjoy the wireless life
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 2 of 31 Copyright Copyright © 2008 Neoway Technology All rights reserved. is a trade mark of Neoway Technology Co., Ltd. Notice This document is intended for the customer engineers. This document is subject to change without any notice. No responsibility is assumed by Neoway Technology for the use of this document. Neoway Technology always provides the best supports. For pricing, delivery, and ordering information please contact: Sales@neoway.com.cn For any technical support requests please contact: Support@neoway.com.cn For further information please visit: http://www.neoway.com.cn
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 3 of 31 Contents Copyright ............................................................................................................................................ 21. Introduction ................................................................................................................................ 62. General Description ................................................................................................................... 63. Simplified Block Diagram ......................................................................................................... 64. Key Features ............................................................................................................................... 75. Product Specifications ............................................................................................................... 85.1 Variants ................................................................................................................................. 85.2 Dimension & Package ........................................................................................................... 85.3 Pin Description ...................................................................................................................... 95.4 PCB foot print ..................................................................................................................... 126. Application Interface ............................................................................................................... 136.1 Power Supply Requirements ................................................................................................ 136.1.1 Power Supply Basic Design Rules ........................................................................ 136.1.2 Extended Design Rules for Power Supply: ........................................................... 156.2 ON/OFF Procedure ............................................................................................................. 176.2.1 Turning on the module: ......................................................................................... 186.2.2 Turning off the module: ........................................................................................ 186.2.3 RESET .................................................................................................................. 196.2.4 VMC ..................................................................................................................... 196.3 UART .................................................................................................................................. 206.3.1 Basic Descriptions of UART ................................................................................. 206.3.2 Level Translators for UART .................................................................................. 206.4 Sleep mode .......................................................................................................................... 226.4.1 DTR ....................................................................................................................... 226.4.2 RING ..................................................................................................................... 236.5 SIM interface ...................................................................................................................... 236.6 Running LED Indicator ....................................................................................................... 256.7 Audio Interface ................................................................................................................... 266.8 Antenna Interface ................................................................................................................ 287. Mounting the Module onto the Application Board ............................................................... 30
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 4 of 31 8. Package ..................................................................................................................................... 309. Terms and Abbreviations ......................................................................................................... 31
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 5 of 31 Document History Revision History Version Remarks Date Issue V1.0 Initial Version 2013-9
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 6 of 31 1. Introduction This document describes the hardware features of M680, and guides for the relevant application design. 2. General Description With the ultra-compact design, M680 is intended to be used in a wide range of applications, including industrial and consumer devices. M680 is a GSM/GPRS module with EDGE of downlink. It features with voice, SMS, and data services. 3. Simplified Block Diagram Figure 1 M680 Block Diagram Baseband Controller PA Power Manager Application Interface RF Section FLASH Audio Section SIM UART x 2 ADC/PWM I2C
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 7 of 31 4. Key Features Table 1 M680 Key Features Feature Implementation Frequency Bands 850/900/1800/1900 MHz quad-band Compliant with GSM/GPRS Phase2/2+ Sensitivity < -107dBm Transmit Power 850/900 Class4(2W) 1800/1900 Class1(1W) AT GSM07.07 Extended AT commands Audio CODEC FR、EFR、HR、AMR SMS TEXT/PDU Point-to-point / cell broadcast DATA GPRS: Class 12 Supplementary Service Call forwarding（CFB, CFNA, CFU） Call waiting & Call hold Multiparty call USSD CPU ARM7-EJ@260MHz, 32Mbits SRAM, 16~32Mbits Nor Flash Open Resources 16Mbits RAM, 0.3~16Mbits Flash Interfaces UART x 2, I2C, SPI, ADC, PWM, GPIO Operational Temperature -40℃～+85℃ Operating Voltage 3.5V～4.2V（typical 3.9V） Peak Current Max 1.8A Power Consumption < 2mA @DRX5 (Sleep mode)
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 8 of 31 5. Product Specifications 5.1 Variants Variants Frequencies Packages M680-QUAD-AA0/A00 850/900/1800/1900MHz Quad-band 71 Pin LCC 5.2 Dimension & Package Physical Characteristics Dimensions 15mm*18mm*2.1mm (Length*Width*Thickness) Weight 2 g Package 71 Pin LCC Figure 2 M680 Sketch
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 9 of 31 5.3 Pin Description Table2 M680 pin definition M680 Pin Signal I/O Function Note 1 ON/OFF DI Switch the module on/off Low level pulse triggered 2 SPKP AO Speaker output P Use AT command to open and 0.9W@8Ω 3 SPKN AO Speaker output N 4 MICP0 AI MIC+ Vi ≤ 200mVpp 5 MICN0 AI MIC- Vi ≤ 200mVpp 6 EAR-L AO Earpiece output L Signal Ended Output. Can drive a 16Ω/32Ω earpiece directly. 7 EAR-R AO Earpiece output R Signal Ended Output. Can drive a 16Ω/32Ω earpiece directly. 8 MICN1 AI MIC- Vi ≤ 200mVpp 9 MICP1 AI MIC+ Vi ≤ 200mVpp 10 RECN AO Receiver output N 32Ω receiver output 11 RECP AO Receiver output P 12 Reserved Reserved 13 Reserved Reserved 14 Reserved Reserved 15 Reserved Reserved 16 Reserved Reserved 17 Reserved Reserved 18 GND PWR GND 19 SIM_CLK DO SIM clock 20 SIM_DATA DIO SIM data 5KΩ internal pull-up 21 SIM_RST DO SIM reset Prompted by module 22 VSIM PWR SIM supply voltage 1.8/3.0V compatible. 23 DAISYNC DO Digital audio synchronization 24 DAIPCMIN DI Digital audio input 25 DAIPCMOUT DO Digital audio output 26 DAICLK DO Digital audio signal clock 27 Reserved Reserved 28 Reserved Reserved 29 GND PWR GND 30 BT_ANT I/O Antenna interface for BT Connect 50Ω antenna 31 GND PWR GND 32 Reserved Reserved
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 10 of 31 33 Reserved Reserved 34 Reserved Reserved 35 Reserved Reserved 36 VMC PWR Output 2.8V Can be used to power the level translators. Imax=50mA 37 URXD DI Serial data input of module 38 UTXD DO Serial data output of module 39 Reserved Reserved 40 Reserved Reserved 41 VRTC PWR RTC power 2.8V, Imax=2mA 42 DTR DI Data Terminal Ready Can be used to control sleep mode. 43 RING DO Output for RING indicator Can be used to indicate an incoming voice call or SMS. 44 LIGHT DO Status LED 2.8V/4mA output Can drive a LED directly 45 Reset DI Reset input Active low 46 GND PWR GND 47 GPRS_ANT I/O GPRS antenna interface Connect 50Ω antenna 48 GND PWR GND 49 Reserved Reserved 50 Reserved Reserved 51 Reserved Reserved 52 Reserved Reserved 53 Reserved Reserved 54 Reserved Reserved 55 Reserved Reserved 56 ADC AI ADC input 0V<Vin<2.8V 61 USB_DM I/O Software download interface 62 USB_DP I/O 57 VBAT PWR Main power supply 3.5V~4.3V (typical 3.9V) 58 59 68 VBAT PWR Main power supply 3.5V~4.3V (typical 3.9V) 60 GND PWR GND 63 64 65 66 67 69
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 11 of 31 70 71
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 12 of 31 5.4 PCB foot print Recommended foot print: Figure 3 Recommended foot print of M680 (all dimensions in millimeters) Note： There may be some masks on the bottom of the module PCB, created by hollowing the solder resist layer, causing reveal of copper. To avoid short circuits, it is recommended to cover the application PCB with a silkscreen block at the area under the module, but excluding soldering area.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 13 of 31 6. Application Interface 6.1 Power Supply Requirements Table3 Power Supply and ON/OFF Control Signal I/O Function Note VMC PWR 2.8V power output Can be used to power the level translators. Imax=5mA Reset DI Reset input Active low > 60mS. ON/OFF DI Switch the module on/off Low level pulse triggered. VBAT PWR Main Power Supply 3.5V~4.3V(typical 3.9V) 6.1.1 Power Supply Basic Design Rules VBAT is the main power supply for internal base band and radio PA of the module, in a range of 3.5V-4.3V. A 3.9V voltage is preferable. The performance of power supply issued, is a critical path to module’s performance and stability. The GSM bursts can cause current peaks up to 1.8A, therefore large bypass capacitors are expected to reduce voltage drops during the bursts. The biggest current occurs when the received signal is very low. It’s very important to ensure that the voltage of supply rail never drops below 3.5V while any burst occurs. Figure 4 shows how the GSM bursts and voltage drops. Figure 5 shows how the capacitor helps to improve peak current performance:
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 14 of 31 Figure 4 Burst Caused Current Peaks and Voltage Drops Figure 5 Test Circuit and Peak Current Results may vary depending on the ESR of capacitors, and the impedance of power source.  A low ESR 1000uF aluminum capacitor for C1 can be selected. As an alternative, a 470uF tantalum capacitor is also suited. In case of Li-Ion cell battery used, 220uF or even 100uF tantalum capacitor may be applicable because of the battery’s low internal impedance and the ability to provide high transient current.  Use a low impedance power source, and keep the resistance of the power supply lines as low as possible.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 15 of 31  The power source should be able to output an average current greater than 1A.  Some small capacitors, with values of 0.1uF, 100pF, 33pF, placed close to the module’s power pin, are very helpful to suppress high frequency disturbances.  The voltage range of power supply must never be exceeded. Over-voltage can even destroy the module permanently.  Ensure the trace for VBAT to be wide enough, in order to pass the current peaks without significant voltage drops. The width of 2mm is preferable. 6.1.2 Extended Design Rules for Power Supply: 6.1.2.1 Power Control A controlled power supply is preferable if used in harsh conditions. RESET pin may be not functioning under strong disturbance. The output enable pin of LDO or DC/DC chipset could be used for emergency power control of the module, as shown in Figure 6. Figure 6 Using LDO’s enable pin for emergency power control The alternative way is to use a P-MOSFET to control the module’s power, as shown in Figure 7. The GPRS_EN signal is routed to host GPIO, controlling the ON/OFF of the P-MOSFET. The host can cut off and then switch on the power supply in case of abnormal conditions, such as no response from the module or the disconnection of GPRS.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 16 of 31 Figure 7 Using PMOS for power control Q2 is for eliminating the need for a high enough voltage level of the host GPIO. In case that the GPIO can output a high voltage greater than VDD3V9 - |VGS(th)|, where VGS(th) is the Gate Threshold Voltage, Q2 is not needed. Reference components: Q1: IRML6401 Q2: MMBT3904 C4: 470uF tantalum capacitor rated at 6.3V; or 1000uF aluminum capacitor. It’s strongly recommended to place a TVS diode on VBAT to ground, in order to absorb the power surges subjected. The SMAJ5.0A from Vishay can be as a choice. 6.1.2.2 Power Separating As described in section 6.1.1, the GSM device works in burst mode generating voltage drops on power supply. And furthermore this results in a 217Hz TDD noise through power (One of the way generating noise. Another way is through RF radiation). Analog parts, especially the audio circuits, are subjected to this noise, known as a “buzz noise” in GSM systems. To prevent other parts from being affected, it’s better to use separated power supplies. The module shall be supplied by an
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 17 of 31 independent power, like a DC/DC or LDO. The inductor used in Reference Design (b), should be a power inductor and have a very low resistance. The value of 10uH, with average current ability>1.2A and low DC resistance, is recommended. Figure 8 Using separated power supply for module Never use a diode to make the drop voltage between a higher input and module power. It will obviously decrease the module performances, or result in unexpected restarts, due to the forward voltage of diode will vary greatly in different temperature and current. 6.1.2.3 EMC Considerations for Power Supply Place transient overvoltage protection components like TVS diode on power supply, to absorb the power surges. SMAJ5.0A could be a choice. 6.1.2.4 Power-on Sequence Prior to turning on the module, turn on the host MCU and finish the UART initialization. Otherwise conflictions may occur during initialization, due to unstable conditions. 6.2 ON/OFF Procedure ON/OFF is a low level pulse active input, used to turn on or off the module.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 18 of 31 Figure 9 Turning on /off the module using ON/OFF 6.2.1 Turning on the module: While the module is off, drive the ON/OFF pin to ground for at least 600mS (800mS is recommended) and then release, the module will start. An unsolicited message will be sent to host through AT port (“+EIND: 1”), indicating the powering up of the module and the AT commands can respond. It’s recommended to drive the ON/OFF to low before applying the VBAT to module. 300mS (400mS is recommended) later from the VBAT applied, release the ON/OFF. Therefore the module starts up. The simplest way to power on the module, is to directly tie the ON/OFF to ground, issuing to an auto-power-on feature. After the module is operating, keep ON/OFF being high level. 6.2.2 Turning off the module: While the module is on, drive the ON/OFF pin to ground for at least 500mS and then release, the module will try to detach to network and normally 1 second later it will shut down. Another approach to turn off the module is with AT command. Figure 10 shows a reference circuits for ON/OFF control with inverted control logic.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 19 of 31 Figure 10 Reference circuit for ON/OFF control Reference Components: Q1: MMBT3904, or to use digital transistor with bias resistors built in, like DTC123/114 The combination of R3 and R4, should limit the high voltage of ON/OFF less than 3.0V. Note:  If the host itself is not initialized before turning on the module, some abnormal conditions on IO or UART may affect the power on procedure.  The better way to rescue the module from abnormal condition, is to apply a power OFF-ON procedure, rather than using the ON/OFF control signal. In fact ON/OFF signal is software-dependent. 6.2.3 RESET Pull the Reset signal to low level for at least 60mS to reset the module. A pull-up resistor is internally included. Reset pin can be left open if not used. 6.2.4 VMC VMC is provided to power the level translators, with a 2.8V / 5mA output. VMC can also be used to monitor the on/off state of module. It outputs 2.8V high level while the module is on, and low level while the module is off.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 20 of 31 6.3 UART 6.3.1 Basic Descriptions of UART Table 4 UART Signal I/O Function Note URXD1 DI Serial input of module UTXD1 DO Serial output of module DTR DI Signal for controlling sleep mode RING DO Ringing output UART1 is for AT commands, data sending/receiving, firmware updating, etc. As a DCE device, the module is connected to DTE as shown in Figure 11. Supported baud rates are 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400bps, and the default is 115200. Figure 11 Connection between DCE (module) and DTE The UART of M680 works at 2.8V CMOS logic level. The voltages for input high level should not exceed 3.0V. 6.3.2 Level Translators for UART If the UART is interfacing with a MCU that has 3.3V logic levels, resistors should be connected in series with the signals.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 21 of 31 Figure 12 Interfacing with 3.3V logic levels of MCU If the UART is interfacing with a MCU that has 5V logic levels, general level translators are required, for both inputs and outputs. As shown in Figure 13. Figure 13 Interfacing with 5V logic levels of MCU Reference components: R2: 2K-10K. The higher rate the UART works at, the smaller value used R3: 4.7K-10K. The higher rate the UART works at, the smaller value used Q1: MMBT3904 or MMBT2222. High-speed transistors preferred. Used for 5V logic -> 2.8V logic: While this circuit used between MCU TXD and module URXD1, the INPUT signal is connected to MCU TXD, and OUTPUT connected to module URXD1. VCC_IN powered from 5V and VCC_OUT powered from 2.8V (module’s VMC can be used). This applies to DTR control as well. Used for 2.8V logic -> 5V logic: It can be used between module UTXD1 and MCU RXD as well, with INPUT connected to module UTXD1, and OUTPUT connected to MCU RXD. VCC_IN powered from 2.8V (module’s VMC) and VCC_OUT powered from 5V. This applies to RING signal as well.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 22 of 31 Note: Avoid sparks and glitches on UART signals while the module is in a turning on procedure. Avoid sending any data to UART during the beginning of 2 seconds after the module being turned on. 6.4 Sleep mode 6.4.1 DTR Generally DTR is used for sleep mode control. For details, see AT commands manual. Based on the setting of the selected mode, pulling DTR low will bring the module into relevant power saving mode. Working in this mode, the power consumption is around 2mA, depending on the DRX setting of network. In sleep mode, the module can also respond to the incoming call, SMS, and GPRS data. The host MCU can also control the module to exit sleep mode by controlling DTR. The controlling of sleep mode: 1) Keep DTR high in normal working mode. Activate the sleep mode by using the AT command AT+ENPWRSAVE=1. 2) Pull DTR low, the module will enter sleep mode, but only after process and pending data finished. 3) UART is not available in sleep mode. 4) In sleep mode, the module can be woken up by the events of incoming voice call, received data, or SMS. Meanwhile the module will send out the unsolicited messages by the interface of RING or UART. Upon receipt of the unsolicited messages, the host MCU should pull DTR high firstly, otherwise the module will resume sleep mode shortly. And then the host MCU can process the voice call, received data, or SMS. After processing is finished, pull DTR low again to put the module into
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 23 of 31 sleep mode. 5) Pull DTR high, the module will exit from sleep mode actively, and furthermore enable the UART. Thus the voice call, received data, or SMS can be processed through UART. After processing finished pull it low again, to take the module back to sleep mode. 6.4.2 RING 1) Once the incoming voice call, the module sends out “ring” message through UART and meanwhile outputs 250mS low pulses at 4S period on RING signal. See Figure 14. Figure 14 RING indicator for incoming call 2) Upon receipt of SMS, the module outputs one 600mS low pulse. See Figure 15. Figure 15 RING Indicator for SMS 6.5 SIM interface Table 5 SIM Interface Signal I/O Function Note VSIM PWR SIM supply voltage 1.8/3.0V SIM_CLK DO SIM clock SIM_RST DO SIM reset SIM_DATA DIO SIM data Internal pull up
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 24 of 31 Figure 16a Reference design of SIM interface Pin1=VCC, Pin2=RST, Pin3=CLK, Pin4=GND, Pin5=VPP, Pin6=DATA Figure 16b a sample of SIM card socket Figure 16c the recommended ESD diode array M680 SIM interface is 3V/1.8V compatible. VSIM is for SIM power and can supply a 30mA current. SIM_DATA is internally pulled up with a 5KΩ resistor. External pull-up resistor is not needed. SIM_CLK can work at several frequencies, but at 3.25MHz typically. ESD protectors, such as ESD diodes or ESD Varistors, are recommended on the SIM signals, especially in automotive electronics or other applications with badly ESD. The total equivalent capacitance on any SIM signal, include the junction capacitance of the ESD diode and the distributed capacitance of PCB trace, can’t be higher than 120pF. If the SIM card is installed in a closed case without human touch or ESD, 22~33pF MLCC capacitors can replace the ESD diodes for cost down. SIM card is sensitive to GSM TDD noise and RF interference. So, the rule is very important in the PCB design, listed as the following.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 25 of 31 ☆ The antenna should be installed a long distance away from the SIM card and SIM card traces, especially to the build-in antenna. ☆ The PCB traces of SIM should be as short as possible and shielded with GND copper. ☆ The ESD diodes or small capacitors should be closed to SIM card. Note: Small capacitors and the junction capacitance of the ESD diode are to avoid the interference from/to antenna, ensuring the correct SIM access and good RF performance. 6.6 Running LED Indicator Table 6 Running Indicator Signal I/O Function Note BACK_LIGHT DO Running Status Can drive a LED directly The various blink behaviors of LED indicate different of module status. It can output a 4mA current and 2.8V voltage, therefore a LED can be directly connected to this pin with a resistor in series. For better luminance, drive the LED with a transistor instead, see Figure 17. Figure 17 LED Indicator
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 26 of 31 6.7 Audio Interface Table 7 Audio Interface Signal I/O Function Note SPKP AO Speaker output P Use AT command to open and 0.9W@8Ω SPKN AO Speaker output N MICP0 AI MIC+ input Vpp≤ 200mV MICN0 AI MIC- input EAR-L AO Earpiece output L Can drive a 16Ω/32Ω earpiece directly EAR-R AO Earpiece output R Can drive a 16Ω/32Ω earpiece directly MICN1 AI MIC- Vpp≤ 200mVpp MICP1 AI MIC+ RECN AO Receiver output N 32Ω receiver output RECP AO Receiver output P 32Ω receiver output For reference audio interface see Figure 18. The peak-peak voltage routed to MIC+/MIC- should not exceed 200mV. AGC circuit is integrated inside the module. Electret microphone is suited. Figure 18 Reference design of microphone interface A bias voltage for microphone is provided through MICP and MICN, as shown in Figure 19. But if an amplifier is used between the microphone and module, capacitors like C1 and C2, should be placed between the outputs of amplifier and module, to block the bias voltage. For a peak-peak voltage greater than 200mV, an attenuation circuit comprised of R1-R4 should be used.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 27 of 31 Figure 19 Reference design for MIC interface Figure 20 Reference design for Ear interface Figure 20 shows a reference design for earpiece interface. A 16Ω/32Ω earpiece can be directly driven by the module. To pass the low frequency audio, use large capacitors for C1 and C2. If an external amplifier is used for driving the speakers, 1uF~4.7uF coupling capacitors should be used to block the DC voltage, as shown in Figure 21.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 28 of 31 Figure 21 Using capacitors to couple audio outputs As the description of TDD noise before, the GSM radio frequency is modulated at 217Hz. The 217Hz and its derivative frequency is well within audio band, therefore a TDD noise often affect the audio performance through power and air. Some small capacitors between 27pF-100pF and ferrite beads, placed on the audio path can attenuate TDD noise. For Suppressing the TDD noise, differential audio interface is preferable. The PCB trace of audio signal should be routed as differential line. In particular, the microphone interface is a pair of small signal, peak-peak voltage <200mV, must comply the rule of differential line. The microphone interface should be routed as short as possible. 6.8 Antenna Interface A 50Ω antenna is required. VSWR < 1.5. The antenna should be well matched to achieve best performance. It should be installed far away from high speed logic circuits, DC/DC power, or any other strong disturbing sources. ESD protection is built in module. For special ESD protection, a ESD diode can be placed close to the antenna. But ensure to use a low junction capacitance one. The junction capacitance should be less than 0.5pF, otherwise the RF signal will be attenuated. RCLAMP0521P from Semtech, or ESD5V3U1U from Infineon, can be used here. See Figure 22. The trace between the antenna pad of module and the antenna connector, should have a 50Ω characteristic impedance, and be as short as possible. The trace should be surrounded by ground copper. Place plenty of via holes to connect this ground copper to main ground plane, at the copper edge.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 29 of 31 If the trace between the module and connector has to be longer, or built-in antenna is used, a π-type matching circuit should be needed, as shown in Figure 22. The types and values of C1, L1, and L2 should be verified by testing using network analyzer instrument. If the characteristic impedance is well matched, and VSWR requirement is met, just use a 0Ω resistor for C1 and leave L1, L2 un-installed. Avoid any other traces crossing the antenna trace on neighboring layer. Figure 22 Reference design for antenna interface Figure 23 Reference parameters for 50Ω trace on a 1.6mm double layer PCB
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 30 of 31 Figure 24 Reference layout for antenna interface 7. Mounting the Module onto the Application Board M680 is compatible with industrial standard reflow profile for lead-free SMT process. The reflow profile is process dependent, so the following recommendation is just a start point guideline:  Only one flow is supported.  Quality of the solder joint depends on the solder volume. Minimum of 0.15mm stencil thickness is recommended.  Use bigger aperture size of the stencil than actual pad size.  Use a low-residue, no-clean type solder paste. 8. Package M680 modules are packaged in sealed bags on delivery to guarantee a long shelf life. Package the modules again in case of opening for any reasons. If exposed in air for more than 48 hours at conditions not worse than 30°C/60% RH, a baking procedure should be done before SMT. Or, if the indication card shows humidity greater than 20%, This GND Pad should be well routed to ground Antenna trace should be surrounded by ground which is connected to main ground plane with plenty of via holes. The trace width and the space to ground should be decided by calculating of 50Ω impedance match.
Neo_M680 Hardware User Guide V1.0 Copyright Neoway Techlology Co., Ltd. Page 31 of 31 the baking procedure is also required. The baking should last for at least 24 hours at 90℃. 9. Terms and Abbreviations ADC Analog-Digital Converter AGC Automatic Gain Control AMR Acknowledged multirate (speech coder) CSD Circuit Switched Data CPU Central Processing Unit DCE Data Communication Equipment DTE Data Terminal Equipment DTR Data Terminal Ready EFR Enhanced Full Rate EMC Electromagnetic Compatibility EMI Electro Magnetic Interference ESD Electronic Static Discharge FR Full Rate GPRS General Packet Radio Service GSM Global Standard for Mobile Communications HR Half Rate IC Integrated Circuit IMEI International Mobile Equipment Identity LED Light Emitting Diode PCB Printed Circuit Board RAM Random Access Memory RF Radio Frequency SIM Subscriber Identification Module SMS Short Message Service SMT Surface Mounted Technology SRAM Static Random Access Memory TDMA Time Division Multiple Access UART Universal asynchronous receiver-transmitter Varistor Voltage Dependent Resistor VSWR Voltage Standing Wave Ratio
ESDprotectionEADSrequiresthattheM680GPRSModule'sservicepointshavesufficientESDprotection(againststaticelectricity)whenservicingtheproduct.AnyproductwhichhasitscoversremovedmustbehandledwithESDprotection.Toreplacethecovers,ESDprotectionmustbeapplied.AllelectronicpartsoftheproductaresusceptibletoESD.AllESD‐sensitivepartsmustbepackedinmetallizedprotectivebagsduringshippingandhandlingoutsideanyESDProtectedArea(EPA).EveryrepairactioninvolvingopeningtheproductorhandlingtheproductcomponentsmustbedoneunderESDprotection.ESD‐protectedsparepartpackagesMUSTNOTbeopened/closedoutsideofanESDProtectedArea.EURegulatoryConformanceAscertifiedbythequalifiedlaboratory,theproductisincompliancewiththeessentialrequirementsandotherrelevantprovisionsoftheDirective1999/5/EC.PleasenotethattheaboveinformationisapplicabletoEUcountriesonly.AntennaInstallation:InstalltheGPRSmoduleantennaatleast20cmawayfromyourbody,inaccordancewiththerequirementsoftheantennamanufacturer/supplier.FCCStatmentThisdevicecomplieswithpart15oftheFCCRules.Operationissubjecttothefollowingtwoconditions:(1)Thisdevicemaynotcauseharmfulinterference,and(2)thisdevicemustacceptanyinterferencereceived,includinginterferencethatmaycauseundesiredoperation.AnyChangesormodificationsnotexpresslyapprovedbythepartyresponsibleforcompliancecouldvoidtheuser'sauthoritytooperatetheequipment.Note:ThisequipmenthasbeentestedandfoundtocomplywiththelimitsforaClassBdigitaldevice,pursuanttopart15oftheFCCRules.Theselimitsaredesignedtoprovidereasonableprotectionagainstharmfulinterferenceinaresidentialinstallation.Thisequipmentgenerates,usesandcanradiateradiofrequencyenergyand,ifnotinstalledandusedinaccordancewiththeinstructions,maycauseharmfulinterferencetoradiocommunications.However,thereisnoguaranteethatinterferencewillnotoccurinaparticularinstallation.Ifthisequipmentdoescauseharmfulinterferencetoradioortelevisionreception,equipmentgenerates,usesandcanradiateradiofrequencyenergyand,ifnotinstalledandusedinaccordancewiththeinstructions,maycauseharmfulinterferencetoequipmentdoescauseharmfulinterferencetoradioortelevisionreception,—Reorientorrelocatethereceivingantenna.—Increasetheseparationbetweentheequipmentandreceiver.—Connecttheequipmentintoanoutletonacircuitdifferentfromthattowhichthereceiverisconnected.
—Consultthedealeroranexperiencedradio/TVtechnicianforhelp.LabelofTheEndProductThefinalendproductmustbelabeledinavisiblearewiththefollowing“ContainsTXFCCID:PJ7‐1232”.TheFCCpart15.19statementbelowhastoalsobeavailableonthelabel:ThisdevicecomplieswithPart15ofFCCrules.Operationissubjecttothefollowingtwoconditions:(1)Thisdevicemaynotcauseharmfulinterference,and(2)thisdevicemustacceptanyinterferencereceived,includinginterferencethatmaycauseundesiredoperation.TocomplywithFCCregulationslimitingbothmaximumRFoutputpowerandhumanexposuretoRFradiation,themaximumantennagainincludingcablelossinamobile‐onlyexposureconditionmustnotexceed1dBiforbothGSM850andPCS1900.AusermanualwiththeendproductmustclearlyindicatetheoperatingrequirementsandconditionsthatmustbeobservedtoensurecompliancewithcurrentFCCRFexposureguidelines.TheendproductwithanembeddedM680GPRSModulemayalsoneedtopasstheFCCPart15unintentionalemissiontestingrequirementsandbeproperlyauthorizedperFCCPart15.Note:Ifthismoduleisintendedforuseinaportabledevice,youareresponsibleforseparateapprovaltosatifytheSARrequirementsofFCCPart2.1093.

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