Publishing Venue
Motorola
Related People
Authors:
Henry A. Bogut
•
Joseph Patino
•
Jose M. Fernandez
Abstract
Many users of portable radios equipped with an external speaker/microphone utilize their radios as mobile or fixed stations by placing them in a vehicular charger or desk top charger with a remote antenna attached to the radio. A problem arises with this conliguration, where the battery capacity is depleted faster than it is supplied from the charger when the radio is operated with a high tmnsmit duty cycle. A means of offsetting the transmit current is needed to insure that the radio battery capacity is topped off. This is especially required when the radio is removed from the charger and is used as a portable.
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MOTOROLA INC. Technical Developments Volume 14 December 1991
RF Dl3ECTOR CIRCUIT FOR CHARGER CURRENT COMPENSATION
by Henry A. Bogut, Joseph Patino and Jose WI. Fernandez
Many users of portable radios equipped with an external speaker/microphone utilize their radios as mobile or fixed stations by placing them in a vehicular charger or desk top charger with a remote antenna attached to the radio. A problem arises with this conliguration, where the battery capacity is depleted faster than it is supplied from the charger when the radio is operated with a high tmnsmit duty cycle. A means of offsetting the transmit current is needed to insure that the radio battery capacity is topped off. This is especially required when the radio is removed from the charger and is used as a portable.
Presently, chargers that have the capability of com- pensating for transmit current, do so by interconnecting to the radio back/side connector. This is accomplished by monitoring a radio state line or a serial bus to deter- mine when the radio is in transmit. A specific example of this is a vehicular convertacom, also known as a vehic- ular adapter. Desk top chargers and vehicular chargers have not offered this capability because they are not capa- ble of interfacing to the radio back/side connector.
The following circuit allows the battery charger to sense that the radio is in transmit without having to con- nect to the radio back/side connector. This allows the charger to compensate cha...
