I tried to use the IR2153 to run a half bridge using two n-channel mosfets as in the circuit diagram on the first page of the data sheet, and it didn't work. I discovered that HO only sinks, it does not source. LO works; it sources and sinks, and the cap for Vb does take a charge. I found this out by slowing the timing down to about one hertz and using grain-of-wheat lamps to see what the outuputs were doing. Same thing happened with both chips that I tried. Has anyone used the IR2153, and what do you have to do to get the high side drive to work?
It works fine at 1Hz, or at DC, if a separate floating power supply is created for the HI-side driver section. A few years ago I posted the schematic of a high-speed 250V 50-ohm pulse generator using this approach with an IR2113, a chip with similar MOSFET drivers.
Kell, A couple of things to check: ~ Are you matching the recommended values of Rt, Ct to your switching frequency? Also the Voltage on the cap for Vb must be higher than Vs, by an amount equal to or greater than gate threshold voltage of the FET you are using. Regards, Jon
Thanks for the replies. I'll go into a little more detail. At first I tried to run it with a .01 uF cap and a 10 k resistor for the timing, to drive a ferrite transformer, using rectified mains for power. I used a MUR160 for the bootstrap diode. I had a 10 uF cap for the Vb/Vs cap. I used IRF740 mosfets. I don't have a scope so when the circuit wouldn't work I decided to check it out by bringing the timing down to something I could check by eye with test lamps. I disconnected from the high voltage and used a 12 volt battery for the test. I connected little lamps from pin 6 to Vcc and ground and set the timing to about 1 hz with an electrolytic cap and a 10 k resistor. The lower mosfet worked, but not the upper. So I tested pin 7, which drives the upper mosfet. It was sinking but not sourcing. It is my understanding that the chip is supposed to provide its own power for the high side because the Vb cap charges up every time the lower mosfet turns on, and this provides power for the upper driver. My test illustrated that this was happening. During the test I used a
680 uF cap. The cap took on a 12 volt charge. I don't see why I should need a separate floating supply to make this thing work. The cap is right there providing a floating power supply for driving the upper mosfet. Something else is going on here. I'm going to take another gander at the datasheet now.
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