SENSITRON

SEMICONDUCTOR

TECHNICAL DATA

©2007 Sensitron Semiconductor

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SPDPXXD375 SERIES

Status Outputs

condition and whether or not the line voltage is present. When an unsafe temperature condition is present, the

“S2” status goes to a logic high state and the output of the SPDPXXD375 is turned off. When the temperature

drops about 15

is turned back on. Both “S1” and “S2” status outputs go to a high level when the line voltage drops below 5

volts.

Table 5 shows the states of the “S1” and “S2” status outputs.

Table 5 – Control and Status

.

High Voltage Considerations

The SPDPxxD375 series is designed for 375VDC systems. The SPDPxxD375 contains an Output Leakage

Sink to ensure that the output is at a safe voltage when the SPDPxxD375 is off (whether the SPDPxxD375 is

turned off or is off due to loss of 5V BIAS Power). This circuitry absorbs the leakage current from the main

switch and keeps the output voltage less than 1.5VDC over the temperature range. Figure 3 shows the Output

Leakage Sink as a simple switch. However, the Output Leakage Sink is a transistor operating as a current

source with a value of 83 mA. When the current into the output leakage sink is less than 83 mA, the transistor

saturates and the output leakage sink looks like a resistor of about 36 Ohms. 83 mA can be used to determine

how long it takes to discharge a particular load capacitance if the load is a pure capacitance. If the load is a

combination of resistance and capacitance, it’s likely that the RC time constant will discharge the capacitance

faster than the output leakage sink

.

Sufficient spacing should be allowed for on the user’s PCB between the 375VDC line supply and the 375VDC

power return and between the CONTROL and 5VDC Bias circuits and the 375VDC circuit to prevent arcing.

Due to the small size of the SPDPXXD375 series, the spacing between pins is small so conformal coating

should be used to prevent arcing, especially if transient voltages above 375VDC are possible.

Wire Size

MIL-W-5088L has a chart the shows wire size as a function of wire temperature and current. This chart is for a

single copper wire in free air. For an ambient temperature of 70

10 Amps continuously at a wire temperature of 200

temperature limited to 150

requires a 20-gauge wire.