Motorola APX 7000 - Page 62

3-38 Theory of Operation: Controller
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.
Figure 3-28. Power-up Timing Regulators
fet_en
rcosc_en
rcosc
sw1_enldo
sw1_en
20ms
1ms
210us
sw1_on
1ms
4ms
24mhz_clk
600us
extldo_2.23V
4ms
v9_on
v4_on
1ms
1ms
v3_on
extsw_1.4
2ms
v8_on
1ms
1ms
v2_on
extsw_1.875
1ms
v6_on
1ms
1ms
v7_on
v10_on
sys_rstx
14ms
1ms