SMAR HI302, Руководство пользователя

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Basic Functioning Theory
6.2
Hardware
This chapter presents a summarized description of the main functional blocks that make
up the HI302 module, as a support for electricians and/or maintenance technicians. See
below the GLL1193 main board pictures.
Power Supply, Operation Voltage and Protection
HOT SWAP
The HI302 is equipped with a U22 HOT SWAP controller that allows the insertion or
removal of the module with the power input to be switched on. This is important when the
HI302 is being fed by a shared source, e.g., a rack with other HI302 or DF51 modules. In
addition to a 5V source, the HI302 should receive a failure signal from the source
(/PFAILR), working at a low level. That signal indicates to the HI302 that the feeding has
been stopped and the starts a safety procedure for failing feed. The Smar PS-AC and
DF50 sources also have this signal. The HOT SWAP controller also monitors the power
consumption and, if a problem arises, the feeding is switched off to avoid further damages
to the HI302 and the power supply.
ATTENTION
If the HI302 is fed by a source without the failure signal, the pin should be left open.
Regulators
The HOT SWAP controller re5VN voltage from the rack (or outside source) and,
through the MOS channel-N transistor, de5VD to all digital circuits. A 3V3 (U11)
regulator feeds the EPLD (U10). And there is yet a precision 2V5 (U9) power source of
reference for the virtual ground cable of the operational amplifiers in the Fieldbus and
HART communication circuits.
In the HI302-I and HI302-O modules there are also a DC-DC (U1) converter and the
optical couplers that completely isolate the ground cables of the analog and digital circuits.
The DC-DC converter generates, from the +5VD, a non-regulated voltage VA
(+9V) that is used by the analog inputs operational (HI302-I), and through a linear
regulator generates a +5VA voltage for the other circuits (ADC and DAC). As a voltage
reference for converters there is another 4V096 (U8) precision reference.