User's Manual

Interface Specification Document Rev. -
Cellular Radio Module CRM4250/4200
Company Confidential
Standard Communications Corp. -27- November 20, 2000
8.0 POWER MANAGEMENT
The CRM radio in AMPS mode draws approximately 30-50mA. This is in a state
where the CRM is listening to the control channel for pages (incoming calls). If your
application does not utilize incoming calls, then the CRM may be switched OFF (VCC
remove from pins 9 & 10 (CRM4200) or pins 13 & 14 (CRM4250) to conserve power
completely.
During a phone call / conversation, the CRM4250 can draw a nominal 1.0 Amps (3
watts), the CRM4200 can draw a nominal 700mA (600mW). Depending upon how
long the call lasts will determine the length of time that the power supply must
maintain at least 1.3 Amps for Class I operation (3 watts) or up to 740mA for Class III
operation (600Mw). The CRM may be asked by the cellular system to reduce the
output power due to the strong RSSI (received signal strength indication) by the cell
site during the call. This depends upon the physical location of the CRM to the cell
site. In mobile applications the CRM may change power levels several times during a
conversation.
Fixed applications usually have consistent power consumption based on the locked
location. You should consider worst case scenarios in the event that the CRM is placed
in a spot that is located far from the nearest cell or located near the cell site.
When planning a power consumption model the efficiency of the DC regulator needs to
be accounted for. For example if the power conversion of the regulator is 75% then the
total power draw from the CRM including regulation is used for you calculations.