MC13109
20
MOTOROLA ANALOG IC DEVICE DATA
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Inactive Mode Operation and Hardware Interrupt
In some handset applications it may be desirable to power
down all circuitry including the microprocessor (MPU). First
put the MC13109 into the Inactive mode, which turns off the
MPU Clock Output (see Figure 22), and then disable the
microprocessor. In order to give the MPU adequate time to
power down, the MPU Clock output remains active for a
minimum of one reference counter cycle (about 200
μ
s) after
the command is given to switch into the “Inactive” mode. An
external timing circuit should be used to initiate the turn–on
sequence. The “CD Out” pin has a dual function. In the Active
and Rx modes it performs the carrier detect function. In the
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2nd LO Oscillator
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MPU Clock Output
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Data Amp
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NOTE:
1.In Standby and Inactive Modes, “PLL Vref” remains powered but is not regulated. It will fluctuate with VCC.
Standby and Inactive modes the carrier detect circuit is
disabled and the “CD Out” pin is in a “High” state due to the
external pull–up resistor. In the Inactive mode the “CD Out”
pin is the input for the hardware interrupt function. When the
“CD Out” pin is pulled “l(fā)ow” by the external timing circuit, the
MC13109 swtiches from the Inactive to the Interrupt mode
thereby turning on the MPU Clock Output. The MPU can then
resume control of the combo IC. The “CD Out” pin must
remain low until the MPU changes the operating mode from
Interrupt to Standby, Active or Rx modes.
Figure 22. Hardware Interrupt Operation
Mode
EN
CD Out/Hardware Interrupt
MPU Clock Out
CD Out Low
Delay after MPU selects Inactive Mode to when CD turns off.
CD Turns Off
External Timer
Pulls Pin Low
MPU Initiates
Mode Change
Timer Output
Disabled
MPU Initiates
Inactive Mode
“MPU Clock Out” remains active for a minimum of one count of reference
counter after “CD Out/Hardware Interrupt” pin goes high
Active/Rx
Inactive
Interrupt
Standby/Rx/Active