PeakSwitch low AC line voltage sense
Posted by: rich_rizzo
on
The app. note EP-93 shows a 4.6Mohm resistor connected to the AC neutral to sense the 25uA upon power on. This looks like the half wave retified AC voltage across the resistor ? What AC voltage range is this set for ?
What resistor value would I use to connect to the DC bus side when the AC input is 208Vac ?
Is it 208Vdc * 2^ / 25uA = 11.76 Mohm ?
I plan on inserting 295Vdc directly into the DC bus cap. C4 150uF. Is there any other things I should be aware of ?
You can use the PIXls sheet for PeakSwitch to calculate the desired UV threshold (see AN-41 figure 9) and I attached the spreadsheet page from EP-93 that shows the UV threshold at ~90 VDC.
A value of 12 MOhm sounds about right (308 VDC = 308/srt 2 = 217 VAC).
Due to high voltage I'd recommend two 1/4w resistor in series which also allows flexibility is selecting value to get close to the desired 12 M or a single 12 M 0.5 W resistor.
Cheers
PI-Chekov