Figure 3-20. Power-Up Timing Regulators - Motorola APX 3000 Detailed Service Manual

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3.2.2.1.4 Power-up Timing

The powering up of the radio starts with the MAKO. Once the radio switch is pushed to 'ON' and

battery voltage is supplied, a pass FET is activated to deliver battery voltage to MAKO and external

regulators. The external 3.6 V is first turned on then MAKO activates its 24.576 MHz clock, and the

remaining regulators begin to turn on. Once all the regulators have turned on, MAKO releases its

reset. The CPLD is then powered on from the 1.875 V external regulator and takes MAKO 24.576

MHz clock and divides it to 32.768 kHz in order to provide for OMAP. OMAP starts to power up upon

receiving voltages 1.4 V, 1.85 V, and the 32.768 kHz clock. OMAP then activates its 12 MHz clock

and releases its reset. It then starts to run the boot loader stored in flash. A more detailed timing view

of the regulators is shown in

sw1_boost_slimit

sw2_softstart[0]

sw2_softstart[1]

sw2_softstart[2]

41.6us(1024clk24)

Figure 3-20. Power-up Timing Regulators

Theory of Operation

: Controller