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AL7020S Designer’s Guide 

 

Doc. No. DG_7020B 

Altec Electronic AG  

Seite 23 / 32 

3.9  Reset Signal (ON/OFF Signal) 

 
 

After power is applied to the AL7020S module, the power-on process is initiated, 
which lasts about five seconds, after which the module is ready to communicate. After 
power-on, the on/off signal is pulled high to the VCC by a 200k

 resistor. The module 

remains active until power is turned off or the power-off process is initiated by 
activating the Reset (ON/OFF) signal. The AT interface answers "OK" to the 
application, when the reset is complete. 
 
 
After the AL7020S is turned on, the line should be pulled low for a minimum of 2 
seconds to turn it off. The unit can be turned off only if at least 10 seconds have 
elapsed since turning it on. To turn the AL7020S on again, the on/off signal should be 
pulled low for a minimum of 800 ms. 
 
Figure 3.8 shows the timing diagram for the on/off signal. 
 
Figure 3.8. On/Off Signal Timing Diagram 
 
 
 
 
 
 
 
 
 
 
 
In Figure 3.8, the following timing requirements apply: 
 
• T1 minimum = 800 ms. 
• T2 minimum = 10 seconds. 
• T3 minimum = 2 seconds. 
 

 
 

3.9.1   Software Reset  

 
It is possible to reset the module by software, which activates an internal reset 
generator (see AT Commands Reference Manual).  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

T1

T2

T3

Summary of Contents for AL7020S Series Designer's guide

Page 1: ...AL7020S Designer s Guide Doc No DG_7020C Altec Electronic AG Seite 1 32 GSM Socket Modem AL7020S AL7020S 3V Series Designer s Guide RELEASED 17 JANUARY 2005...

Page 2: ...Altec other than for circuitry embodied in Altec products Altec Electronic reserves the right to change circuitry at any time without notice This document is subject to change without notice Please re...

Page 3: ...ion 20 3 7 4 Layout Restrictions 20 3 8 Audio Interface 21 3 8 1 Speaker Circuit 21 3 8 2 Microphone circuit 22 3 8 3 Audio Circuit Design Considerations 22 3 9 Reset Signal ON OFF Signal 23 3 9 1 Sof...

Page 4: ...3 3 Signal Descriptions Cont d 12 Table 3 4 Analog Electrical Characteristics 12 Table 3 5 Digital Electrical Characteristics 13 Table 3 6 Absolute Maximum Ratings 14 Table 3 7 Antenna Performance Re...

Page 5: ...or portable applications such as pocket modems and for a wide variety of embedded control applications The pin compatibility between the full range of all ALXXXX Series Socket Modems and ISDN Socket T...

Page 6: ...ta Features GPRS Multi slot class 8 4 down 1 up Max BR 85 6 Kbps Class B GSM 07 10 multiplexing protocol Coding scheme CS1 CS4 CSD Max BR 14 4 Kbps SMS MO MT Text and PDU modes Cell broadcast FAX Clas...

Page 7: ...2 1 Interface Block Diagram The RS232 Interface is connected via eight pins to the module The SIM card is connected via 4 pins to the module The Microphone is connected via 2 pins to the module The S...

Page 8: ...e Socket Modem pin assignments with DTE serial TTL interface SIM Card and Analog Interface are shown in Figure 3 1 and are listed in Table 3 1 3 2 Signal Description The Socket Modem interface signals...

Page 9: ...pin 17 No pin 49 No pin 18 No pin 50 No pin 19 No pin 51 No pin 20 No pin 52 No pin 21 No pin 53 No pin 22 No pin 54 No pin 23 No pin 55 No pin 24 RESET Input 56 No pin 25 NC NC 57 No pin 26 DGND GND...

Page 10: ...N OFF To be pulled to ground by external transistor for reset on module pull up resistor of 200K The GSM Modem has already an internal power up reset circuit Needs special timing for RESET and ON OFF...

Page 11: ...state when no data is being transmitted or during intervals between characters CTSTTL OB Clear To Send TTL Active Low CTS is controlled by the modem to indicate whether or not the modem is ready to tr...

Page 12: ...ut MICV is a single ended microphone input from the analog switch circuit The maximum input to the MICV pin before there is signal distortion in the network is 12mVRMS SPKR O DF Speaker Output SPKR is...

Page 13: ...Output Low Voltage pins 34 36 37 38 VOL 0 0 0 1 0 33 Vdc ILOAD 20 uA ILOAD 4 8 mA Output Low Voltage VCC 4 5V pin 39 VOL 0 1 0 44 Vdc ILOAD 50 uA ILOAD 8 mA max Reset Low Input Voltage pin 24 VIL 0 8...

Page 14: ...V Version 3V Version VDD 4 75 3 20 5 25 3 45 Vdc Static Discharge Voltage 25 C VESD 2500 V Operating Temperature Range Operational Functional TA 20 20 60 70 C Storage Temperature Range TSTG 40 85 C Su...

Page 15: ...nce in the relevant frequencies The AL7020S can be connected to any antenna with 50 ohm impedance in the relevant frequency bands The AL7020S is designed to work on VSWR up to 3 1 The antenna should m...

Page 16: ...ess than 3 0 Watts ERP 4 9 Watts or 36 9 dBm EIRP This requires that the combination of antenna gain and feed line loss does not exceed 16 dBi 3 4 4 User Operation Do not operate your unit when a pers...

Page 17: ...the side of the connectors bottom side The SIM Interface controls a 3V SIM card This interface is fully compliant with GSM 11 11 recommendation concerning SIM functions 3 5 1 SIM Card reader pins sup...

Page 18: ...AL7020S Designer s Guide Doc No DG_7020B Altec Electronic AG Seite 18 32 3 6 SIM Card Mechanical Drawings...

Page 19: ...e less than 10pF have to be connected on SIMCLK and SIMDATA to avoid any disturbance of the rising and falling edge These types of diodes are mandatory for the Full Type Approval They shall be placed...

Page 20: ...icroelectronics for the ESD protection of SIMVCC On the board near SIM connector we also add on SIMVCC a 100nF capacitor in parallel as close as possible to the SIM connector to minimize noise Schemat...

Page 21: ...ly adjusted and can be tuned using an AT command The possible range of output levels is 4mV to 210mV rms max Levels Recommended characteristics for the speaker Type 10mW electro magnetic Impedance 32...

Page 22: ...B Frequency response compatible with the GSM specifications 3 8 3 Audio Circuit Design Considerations In order to design an audio circuit that produces clear audio without being affected by the GSM tr...

Page 23: ...to the application when the reset is complete After the AL7020S is turned on the line should be pulled low for a minimum of 2 seconds to turn it off The unit can be turned off only if at least 10 seco...

Page 24: ...crophone Possible references HOSIDEN KUF3323 HOSIDEN KUF4323 PANASONIC WM64 4 3 Speaker Possible references SANYO M15X0080 PHILIPS PRIMO 4 4 Antenna Cable The following cable reference has been qualif...

Page 25: ...ion value and tolerance interface connections and shielding are required for the board design to achieve desired modem performance and to attain EMI certification 5 1 Electromagnetic Interference EMI...

Page 26: ...your board The ground area should completely cover the area below and around the module and the regulator Make the connections as wide as possible For better RF perfomance connect the metal housing to...

Page 27: ...h 3 3V The 3 3V trace between regulator and module should be at least 2 5mm wide or better an entire layer Important The module draws up to 0 8A max for 577 s every 4 6ms at GSM transmit level PCL5 2W...

Page 28: ...of a GSM terminal The antenna cable and the antenna should be as far as possible away from other circuitry specially switching regulators analog and uC digital circuits It is recommended to place the...

Page 29: ...esigner s Guide Doc No DG_7020B Altec Electronic AG Seite 29 32 6 6 M MO OD DU UL LE E D DI IM ME EN NS SI IO ON NS S FIGURE 6 2 MECHANICAL DRAWINGS 7 0 mm Top View Pin 1 2 0 Top View Dimensions in Mi...

Page 30: ...fety precautions must be observed during all phases of the operation usage service or repair of any cellular terminal or mobile incorporating the AL7020S module Manufacturers of the cellular terminal...

Page 31: ...mitting devices IMPORTANT To comply with the FCC RF exposure limits and satisfy the categorical exclusion requirements for mobile transmitters the following requirements must be met 7 2 2 Antenna Inst...

Page 32: ...and GT 01 v4 2 1 GSM1800 ph2 Layer 3 ETSI GSM 04 08 and GT 01 v4 2 1 GSM900 GSM1800 Multiband ETSI GSM 02 07 03 22 04 08 04 13 05 05 05 08 and GT 01 v4 2 1 GSM ph2 SIM ETSI GSM 11 11 and GT 01 v4 2 1...

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