RIM 902M, Integrator Manual

Page: 42 / 64

34 Power requirements: Plug-in supplies
Integrator’s Guide – RIM 902M OEM Radio Modem
“alkaline” on the label, or to use well-known brands such as Duracell or
Energizer. This should be communicated to the user of your product.
Plug-in supplies
A plug-in supply converts normal AC power (usually 110 volts or 220 volts)
into a steady DC source that can be used instead of batteries. The plug-in
supply must be designed to ensure voltage spikes, lightning, and other power
fluctuations cannot damage the radio modem. Transient voltage protection
zener diodes, or other spike arrestor circuits, may be added to keep the inputs
within the limits given in the RIM 902M load specifications. These should have
a value of 20 volts and be placed on the supply side of the regulator circuit.
RIM recommends a supply capable of providing 4.5 V and rated for 2.5 A peak
current.
Automotive supplies
If you plan to power the RIM 902M from an automotive supply, extra
protection must be included to protect the radio modem from the intense power
fluctuations experienced when the automobile is started. A circuit comprising
inductors, transorbs and voltage regulators should be used to ensure the radio
modem is protected from these power fluctuations.
Commonly, in automotive applications, voltages may be as high as 70 V on the
battery, especially during starting. Commercial automotive adapters are
available that will safely convert the 12 volt automotive supply to a regulated
supply suitable for operating the RIM 902M radio modem.