4-22 Theory of Operation
4.2.12 Front Panel LEDs
For details on this section, refer to Table 1-5 on page 1-11.
4.2.13 Supply Voltage Circuitry
The SCM contains on-board regulator and filtering circuitry to generate the various operating
voltages required by the SCM circuitry. The SCM routes +10 V and +8 V from two regulators on the
backplane to the Receiver and Exciter modules. +14.2 V and +5.1 V from the power supply (via the
backplane) are used as sources for the following supply voltage circuits:
• +14.2V Regulator Circuitry – input to generate 9.3 V for MAKO, 5 V analog for audio circuit.
This regulator also routes 14 VDC to the Receiver and Exciter modules.
• +5.1V Regulator Circuitry – input to generate the following voltage: 3.3 V, 3.3 V analog,
2.775 V analog, 1.875 V, 1.4 V Core for Tx and Rx OMAP1710, 1.2 V Core for FPGA.
The SCM requires a specific power-up and reset sequence. At initial power-up, the power supply of
the base station/repeater provides 14 V and 5 V directly to the SCM. The SCM also provides 10 V
and 8 V through the base station/repeater backplane directly to Exciter and Receiver without any
additional delay. 14 V is used only to derive a 9.3 V supply voltage for the Mako IC and a 5 V supply
voltage for the audio section. The 14 V is also used to derive a 12 V supply voltage for the OCXO.
The majority of supply voltages on the SCM are derived from the 5 V using linear regulators. Each
regulator outputs are enabled in the sequence shown in Figure 4-9 to meet all the device power-up
sequences. 1 indicates the first power-rail that reaches steady state, and 7 is the last voltage rail
that reaches the steady state.
During the power-up sequence, the SCM is held in a reset state. Once the power-up sequence is
completed, the FPGA and the MAKO IC complete their internal initialization; then the main-reset is
released, and the SCM starts its normal operation. There are several sources, both hardware and
software, that can reset the SCM. From a hardware perspective, when the 5 V, Tx OMAP or Rx
OMAP core voltage dip below the minimum operation threshold, then the SCM enters and stays in
the reset state, until the voltage reaches its operation level again. From the software perspective,
both the Tx OMAP and Rx OMAP have the means to initiate SCM reset. This can be done from
either the CPS or RDAC application.
Refer to Figure 4-9 for the MTR3000 power up block diagram.
G3 GND GND GND Ground
G4 GND GND GND Ground
Table 4-15 SCM FP External Reference Connector Pin-out (Continued)
Pin Number Pin Name I/O
Voltage
Level
Pin Description
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