SENSITRON

SEMICONDUCTOR

TECHNICAL DATA

DATASHEET 5023, Rev D.1

©2007 Sensitron Semiconductor

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• www.sensitron.com • sales@sensitron.com • Page 7

SPDPXXD28 SERIES

Figure 5 - Electrical Block Diagram

Description

I/O. This TTL compatible device has a Schmitt-Trigger input to minimize the effects of noise on the input. Its

outputs can each drive more than 10 standard TTL loads. It’s also compatible with CMOS inputs and outputs.

The SN74LVC3G14 is isolated from the remainder of the module circuitry by three optocouplers.

The block labeled “Control & Protection Circuitry” gets power from the DC-DC converter and is referenced to the

resistor. It also contains a microcontroller with on-board timers, A/D converter, clock generator and independent

watchdog timer. The microcontroller implements a precision I

function to protect the wiring and to protect itself. It performs all of the functions of multiple analog comparators

and discrete logic in one high-reliability component.

The “Control & Protection Circuitry” block also has the ability to adjust the current rating of each model of the

SPDPXXD28 Series over a 5:1 range. If the “Gain” terminal is left open, the SSPC will be set for maximum

rating. If the “Gain” terminal is connected directly to the “Gain Return” terminal, the SSPC will be set for 1/5 of

the maximum rating. Furthermore, a resistor connected between the “Gain” terminal and the “Gain Return”

terminal will set a rating between maximum and 1/5 of maximum. See Figure 10 for the relationship between

rating and resistor value.

GAIN

GAIN RTN