RIM 1802G, Руководство интегратора

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Power requirements
Integrator Guide 47
Power requirements
The RIM 1902G or RIM 1802G requires a clean power source that is capable of delivering bursts of
high current. You can provide this power source through the following sources:
• a rechargeable battery pack or single-use batteries
• a plug-in power supply unit
• an automotive supply
These sources are discussed below.
Batteries
If the RIM 1902G or RIM 1802G is integrated into a handheld device, it can be powered by batteries.
This technology is easily available, and it eliminates the need for power supply components, such as
voltage regulators.
Rechargeable batteries
Nickel cadmium
For battery-operated applications that require a wide operating temperature range, RIM
recommends using rechargeable nickel cadmium (NiCad) batteries to power the radio modem. You
can also successfully use nickel metal hydride (NiMH) and lithium ion (Li+) cells. However, many of
these cells work poorly at temperatures below freezing. Battery specifications should be obtained
from the manufacturer.
The cells that you use must meet the radio modem load specifications (refer to page 46); for
transmission, they must provide 1.2 A (RIM 1902G) or 2.0 A (for the RIM 1802G) at 4.2V.
Rechargeable cells vary considerably; even if two cells have the same published capacity, one might
be less efficient than another when the radio transmitter is turned on. This is because some batteries
have a higher equivalent series resistance (ESR) at high current drain. The ESR should be low
enough that the battery can supply the transmission current required without a large voltage drop.