Figure 3-19. Power-Up Timing Regulators - Motorola APX 5000 Service Manual

3-32
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 24.576 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 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
fet_en
rcosc_en
rcosc
sw1_enldo
sw1_en
sw1_on
24mhz_clk
extldo_2.23V
v9_on
v4_on
v3_on
extsw_1.4
v8_on
v2_on
extldo_1.85
v6_on
v7_on
v10_on
sys_rstx
20ms
1ms
210us
1ms
600us

Figure 3-19. Power-up Timing Regulators

Figure 3-19.
4ms
4ms
1ms
1ms
1ms
2ms
1ms
1ms
1ms
Theory of Operation
1ms
1ms
14ms
: Controller