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TPCMQ48 SERIES
INSTALLATION & OPERATING MANUAL
Manual No. tpcmq48-4
tpcmq48-man-rev4-0116.indd
Disconnect the input power source.
20.0 OPTIONAL I²C SERIAL BUS INTERFACE
The I²C interface that is incorporated into the TPCMQ48 Series includes facilities to monitor
various operating parameters within the unit and transmit these to a host computer on demand over
an industry standard I²C Serial bus.
Three forms of data are available. These allow the user to monitor the actual status of an individual
unit, manage system loading through measurement of the actual load on the output and also control
inventory through an inbuilt EEPROM containing specific data about each individual unit.
The implementation of I²C that has been utilized is a subset of more complete implementations such
as IPMI. The following provides information for the system designer to make decisions on how to
utilize the available information within his overall system philosophy.
20.1
I²C devices employed
PCF8574 - This device is an 8-bit digital register manufactured by Philips.
PCF8591 - This device is a Quad A/D converter manufactured by Philips.
24C02
- This device is a 256 byte EEPROM manufactured by ST
MAX6633 - This is a 12-bit temperature measurement device manufactured by Maxim.
For detailed information about the operation of these devices please consult the original
manufacturers’ data-sheets.
20.2
Electrical Interface
20.2.1
Addressing (GA0, GA1 and GA2)
Three external address lines are employed allowing up to eight TPCMQ48 modules to be
addressed on a single I²C bus.
Module addressing is achieved through hard-wiring the address lines to -Sense or the +5V
standby supply via a 100-ohm resistor on the system back-plane. In this way it is the location
or position of the module rather than any particular module that is identified by an individual
address.
20.2.2
Serial Clock (SCLK)
This line is clocked by the processor which controls the I²C serial bus. It should be tied to
+5V via a pull-up resistor in the range 3k to 10k.
20.2.3
Serial Data (SDA)
This line is a bidirectional data line. It should be tied to +5V via a pull-up resistor in the
range 3k to 10k.
