Special Logic Circuits - Motorola StarTAC 3000 Service Manual

Special Logic Circuits

A brief description of special logic circuits
used in the StarTAC:
• PAC IC —A triple 8 bit DAC that controls
the PA bias and internal charger
• Internal Charger —The microprocessor is
capable of reading a Motorola Li Ion
battery with internal ROM to determine
optimum charging conditions. If no ROM
is detected, then the battery is charged as if
it were a NiCd or NiMH battery. The
internal charger is disabled during a call.
• Vibrator Option —Used as a silent alert
option for incoming calls. This option is
controlled by the SNAP IC and a external
driver circuit.
• RF Switch Circuit —An RF switch driver
and RF switch FET normally select the
internal antenna.
connection is selected if an antenna is
detected on the option connector.
6/29/98
The external RF
5
Theory of Operation