Motorola APX 7000 Detailed Service Manual page 62

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3-38
3.2.2.1.4 Power-up Timing
The powering up of the radio starts with the MAKO. Once the radio knob is turned to the 'ON' position
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 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 MHz
clock and divides it to 32 kHz in order to provide for OMAP. OMAP starts to power up upon receiving
voltages 1.4 V, 1.875 V, and the 32 kHz clock. OMAP than activates it 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
Figure
3-28.
fet_en
20ms
rcosc_en
rcosc
1ms
sw1_enldo
210us
sw1_en
sw1_on
24mhz_clk
600us
extldo_2.23V
v9_on
v4_on
v3_on
extsw_1.4
v8_on
v2_on
extsw_1.875
v6_on
v7_on
v10_on
sys_rstx
Figure 3-28. Power-up Timing Regulators
1ms
4ms
4ms
1ms
1ms
1ms
2ms
1ms
1ms
1ms
1ms
Theory of Operation
1ms
14ms
: Controller

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