User Manual

SDB670 – SERVICE MANUAL TNM-M-E-0032
May 13 Page 31 TECHNICAL DESCRIPTION
5.2.2 Circuit Description
A detailed block diagram of the Control Board is provided in Appendix A.
5.2.2.1 Power
The control board requires a 12 V nominal supply. A switch mode power supply IC is used to
generate the 5 V supply used by the Power Management Multi-Channel Integrated Circuit (PMIC)
to supply the power rails of the processor. Linear regulators are provided to reduce the 5 V rail
down to provide supply voltages to the Digital Signals Processor (DSP) Co-Processor, Ethernet
and USB devices.
5.2.2.2 Main Processor
The main processor is a Texas Instruments OMAP DM3725; this is a dual core device containing
an ARM Cortex A8 and a C64+ DSP. The Open Multimedia Applications Platform (OMAP) is a
package-on-package device where the device providing the flash and Synchronous Dynamic
Random Access Memory (SDRAM) is soldered directly to the top of the processor.
5.2.2.3 DSP Co-processor
The DSP Co-processor is a Texas Instruments TMS320C5509, which provides the additional DSP
processing power.
5.2.2.4 Ethernet Interface
A LAN9514 USB Ethernet Hub device provides an Ethernet interface to the OMAP processor. This
device is interfaced to an RJ45 socket with built in magnetics.
5.2.2.5 Radio Interface
The control card supports the connection of three SDM radio modules, one as a transmitter and
two as receivers. These are connected to the OMAP processor via a Low Voltage Differential
Signal (LVDS) interface presented on 10 Way RJ45 connectors.
5.2.2.6 USB A
A USB Ethernet Hub device provides four USB A connections two of which are presented
externally.
5.2.2.7 USB B
The PMIC device provides a USB B type interface for connection to a PC.
5.2.2.8 Digital I/O
Digital I/O is provided by the OMAP processor to provide digital I/O to the Facilities Connector as
well as internal control.
5.2.2.9 Fan Control
The OMAP processor performs fan control via a Maxim Fan Controller IC. The speed of the Fan is
dependent on the temperature reported by the Tx Radio engine. The fan generates a tachometer
output that allows the software to detect a fan failure or potential failure by monitoring fan speed.
5.2.2.10 Analogue Outputs
Two analogue outputs are provided by a dual-channel DAC (AD5322). One provides control of the
Voltage Controlled Temperature Compensated Crystal Oscillator (VCTCXO) and the other
provides an analogue output to the Facilities Connector, for example the Received Signal Strength
Indicator (RSSI) level.