User's Manual
Table Of Contents
- GC864 QUAD V2andGC864 DUAL V2Hardware User Guide
- APPLICABILITY TABLE
- 1 Introduction
- 2. Overview
- 3. GC864 Mechanical Dimensions
- 4. GC864-QUAD V2 / GC864-DUAL V2 Module Connections
- 5. Hardware Commands
- 6. Power Supply
- 7. Antenna
- 8. Logic Level Specifications
- 9. Serial Ports
- 10. Audio Section Overview
- 11. General Purpose I/O
- 11.1. GPIO Logic Levels
- 11.2. Using a GPIO Pad as INPUT
- 11.3. Using a GPIO Pad as OUTPUT
- 11.4. Using the RF Transmission Control GPIO4
- 11.5. Using the RFTXMON Output GPIO5
- 11.6. Using the Alarm Output GPIO6
- 11.7. Using the Buzzer Output GPIO7
- 11.8. Magnetic Buzzer Concepts
- 11.9. Using the Temperature Monitor Function
- 11.10. Indication of Network Service Availability
- 11.11. RTC Bypass Out
- 11.12. DAC Converter
- 11.13. ADC Converter
- 12. Assembly the GC864-QUAD V2 / GC864-DUAL V2 on the Board
- 13. Packing System
- 14. Conformity Assessment Issues
GC864 Hardware User Guide
1vv0300874 Rev.0 – 2010-01-25
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved. Page 28 of 64
NOTE:
The average consumption during transmissions depends on the power level at which
the device is requested to transmit by the network. The average current consumption
hence varies significantly.
Considering the very low current during idle, especially if Power Saving function is
enabled, it is possible to consider from the thermal point of view that the device
absorbs current significantly only during calls.
If we assume that the device stays into transmission for short periods of time (let us
say few minutes) and then remains for a quite long time in idle (let us say one hour),
then the power supply has always the time to cool down between the calls, and the
heat sink could be smaller than the calculated one for 500mA maximum RMS
current, or even could be the simple chip package (no heat sink).
Moreover, in the average network conditions, the device is requested to transmit at a
lower power level than the maximum, hence the current consumption will be less
than 500mA, usually around 150mA.
For these reasons the thermal design is rarely a concern and the simple ground
plane where the power supply chip is placed grants a good thermal condition to avoid
overheating as well.
As far as the heat generated by the GC864-QUAD V2 / GC864-DUAL V2, you can
consider it to be during transmissions of 1W max during CSD/VOICE calls and 2W
max during class10 GPRS upload.
This generated heat will be mostly conducted to the ground plane under the GC864-
QUAD V2 / GC864-DUAL V2; you must ensure that your application can dissipate it.
6.2.3. Power Supply PCB Layout Guidelines
As seen on the electrical design guidelines the power supply shall have a low ESR
capacitor on the output to cut the current peaks and a protection diode on the input
to protect the supply from spikes and polarity inversion. The placement of these
components is crucial for the correct working of the circuitry. A misplaced
component can be useless or can even decrease the power supply performances.
• The Bypass low ESR capacitor must be placed close to the Telit GC864-
QUAD V2 / GC864-DUAL V2 power input pads or in the case the power
supply is a switching type it can be placed close to the inductor to cut the
ripple provided the PCB trace from the capacitor to the GC864-QUAD V2 /
GC864-DUAL V2 is wide enough to ensure a dropless connection even
during the 2A current peaks.
• The protection diode must be placed close to the input connector where
the power source is drained.