simple hbridge question

irf530 h-bridge

hello
attached is a simple h-bridge circuit from "pic microcontroller project book"
can anyone describe whats the function of the 10k resistor to the 2 pair of transistors ?

also in the original circuit hes putting a protection diode accross each transistor. isnt the tip120 already gut those ?

thank you all

ir2101 application

Hi max_imum2000,

You are right the TIP120, 122 etc.. does have body diodes in them. But the recovery time for these diodes may be too slow for this type of application so you might want to put some faster diodes around them for protection against reverse voltage flyback. Now as for the resistor pair I started to think that they were using them to help prevent an overlap of conduction for q1 & q2 or q3 & q4 but this would also work against you on turn off as well as turn on so I am not sure. I have recently been doing some stepper motor drive using hbridges and have been controlling them with a basic stamp. I have been using the IR2101 high side and low side drivers with good success. I am also using simple IRF530 fets in place of the transistors ... also with success. No resistors on the gates just straight drive .. Works for me.....

Good luck


dfullmer

h bridge diode protection

thanks a lot for your reply
what diodes did u use with the fets ?
also i am having a strange problem with the above circuit
it seems that its taking it power from the signal lines and not the main lines
i have connected 30v to the main power (adaptor) and another adaptor 6v to the signal lines with 6v.
the motor turn according to the 6v and not the 30v
any ideas ?

ir2101 h bridge schematic

Hi,

I am using some MBR160 diodes but any fast diodes would probably work for you. I just happen to have these at hand. I bet the motor is being driven off the current through the transitor base drive. Some of the motors don't take much. If you use the fets this would probably stop.

Regards

dfullmer

how to use ir2101

dfullmer said:

Hi max_imum2000,

I have been using the IR2101 high side and low side drivers with good success. I am also using simple IRF530 fets in place of the transistors ... also with success. No resistors on the gates just straight drive .. Works for me.....

Good luck


dfullmer

Click to expand...

Hi, it is possible to use IR2101 in low voltage systems? I mean using 24VDC PMDC motors. I have seen on their data sheet that this IC is designed for high voltages, but I need a reliable half-bridge driver. Can I use this one for 24VDC?
Thanks!