SPDP50D375 Datasheet, PDF (8/10 Pages) Sensitron – DC Solid State Power Controller Module

SENSITRON
SEMICONDUCTOR
SPDP50D375
TECHNICAL DATA
DATASHEET 5115, REV -
Status Outputs
The “S1” and “S2” status outputs of the SPDP50D375 show whether or not there is an over-temperature
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 SPDP50D375 is turned off. When the temperature
drops about 15 ^oC to a safe condition, the “S2” status output goes back low and the output of the SPDP50D375
is turned back on. Both “S1” and “S2” status outputs go to a high level when line voltage drops below 5 volts.
Table 6 shows the states of the “S1” and “S2” status outputs.
Table 6 – Control and Status
High Voltage Considerations
The SPDP50D375 series is designed for 375VDC systems. The SPDP50D375 contains an Output Leakage
Sink to ensure that the output is at a safe voltage when the SPDP50D375 is off (whether the SPDP50D375 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 SPDP50D375 series, the spacing between pins is small so conformal coating
should be used to prevent arcing, especially if transient voltages above 375VDC are possible.
Conductor 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 ^oC, the chart allows a 24-gauge wire to handle
10 Amps continuously at a wire temperature of 200 ^oC – a wire temperature rise of 130 ^oC. For a wire
temperature limited to 150 ^oC, the chart requires a 22-gauge wire and for a wire temperature of 105 ^oC, the chart
requires a 20-gauge wire.
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