User's Manual
LE920 Hardware User Guide
1vv0301026 Rev.8 2015-01-03
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 6 of 88
4.2. Initialization and Activation state ...................... 29
4.3. Turning OFF the LE920 .................................... 30
4.3.1. Shutdown by Software Command ............................... 31
4.3.2. Hardware Shutdown .......................................... 32
4.3.3. Hardware Unconditional Restart (RESET) ..................... 33
4.3.4. Hardware Unconditional Shutdown ............................ 34
4.4. Summary of Turning ON and OFF the module ................. 35
5. Power Supply ................................................ 36
5.1. Power Supply Requirements ................................ 36
5.2. General Design Rules ..................................... 38
5.2.1. Electrical Design Guidelines ............................... 38
5.2.1.1. + 5V Input Source Power Supply Design Guidelines ........ 38
5.2.1.2. + 12V Input Source Power Supply Design Guidelines ....... 39
5.2.1.3. Battery Source Power Supply Design Guidelines ........... 41
5.2.2. Thermal Design Guidelines .................................. 42
5.2.3. Power Supply PCB Layout Guidelines ......................... 43
6. Antenna(s) .................................................. 45
6.1. GSM/WCDMA/LTE Antenna Requirements ....................... 45
6.2. GSM/WCDMA/LTE Antenna – PCB line Guidelines .............. 46
6.3. GSM/WCDMA/LTE Antenna – Installation Guidelines .......... 47
6.4. Antenna Diversity Requirements ........................... 47
6.5. GPS/GNSS Antenna Requirements ............................ 48
6.5.1. Combined GPS/GNSS Antenna .................................. 49
6.5.2. Linear and Patch GPS/GNSS Antenna .......................... 49
6.5.3. Front End Design Considerations ............................ 49
6.5.4. GPS/GNSS Antenna - PCB Line Guidelines ..................... 50
6.5.5. GPS/GNSS Antenna – Installation Guidelines ................. 50
7. Logic Level Specifications .................................. 51
8. USB Port .................................................... 52
9. Serial Ports ................................................ 53
9.1. Modem Serial Port 1 ...................................... 54
9.2. Modem Serial Port 2 ...................................... 55
9.3. RS232 Level Translation .................................. 55