Forum: Analog Circuits Looking for recommendation for full-bridge IC

von Wolfgang (pollvx)

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Good morning folks,

my problem in short:
I'm looking for the right full-bridge IC (single or double). I would 
like to be able to both power it and control it with 24V and the output 
voltage should also be +-24V. The load is only around 40mA.
Does anyone have a good suggestion?

Detailed explanation:
At work I'm working on a self-made model of an electric motor. Right now 
it's built with a rotor with permanent magnets, which is turned by 6 
individual coils, which I removed from old relais. The coils are 
controlled with 24V by a PLC.

To improve the system I would like to be able to change the polarity of 
the coils while running the motor. With the normal digital outputs of 
the PLC I'm limited to only one polarity and analogue outputs provide 
only +-10V.
After a day of research and puzzling about MOSFETs and full-bridges I 
let go of the idea of building my own bridges, because I'm lacking the 
know-how at this point. That's why I'm looking for fitting full-bridge 
ICs to individually control the coils. The requirements would be that I 
can both power and control the chip with 24V via the PLC and that the 
output voltage is also 24V, which is the nominal value for the coils.



von Harald A. (embedded)

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Maybe the old fashioned L272 (max. 28V could be a bit tough) or a more 
modern DRV8816

Edit: Sorry, missed your bipolar supply requirements.

: Edited by User
von Wolfgang (pollvx)

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Thank you for the suggestions!
I looked into the L272 and it raised some questions for me:

In the datasheet, there's an example for how to drive a DC motor. What 
is the meaning of that new Value Vs1? Is that just supposed to set the 
voltage difference between the output pins? If so, should that be ground 
if I want to run the coils with 24V? And if so, could those inputs be 
shorted to ground if I dont wish to modulate the voltage? [page 5, 
Figure 9]

Another issue is power dissipation. With a supply voltage of 24V I get 
200mW of power from just the circuitry and having a 40mA load adds 
another 600mW. 800mW is within bounds, but should I perhaps take extra 
care to glue a piece of metal on top to better dissipate heat?

Last is concerning switching the direction. Could too sudden of a switch 
result in a potential of 48V for a moment because of the impedance of 
the coil?

>Edit: Sorry, missed your bipolar supply requirements.
I don't quite understand what you mean?

: Edited by User
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