Trying to understand "over voltage shutoff" on VNH2SP30

Support Motor controllers/drivers and motors
1

The Pololu web page for the VNH2SP30 explains that while the battery volts can go up to 41V the over voltage shutoff kicks in at about 16 volts. OK, that is sort of clear. But 16 volts across which pins? Is this 16V across the motor or battery to ground? It makes a big difference because in the first case I can use a 17 volt battery and then run PWM at some low duty cycle to keep the motor volts well below 16 volts.

My goal is to use Lithum batteries such that when discharged to the low safe limit the battery still has more voltage than the motors are rated for (12V) So it looks like I want a four cell or “4S” LiPo battery but these will be just over 16V when fully charged. If the over voltage shutdown looks at input voltage then I will need to use a lower voltage battery that may go below 12V as it discharges.

In short, does the “over voltage shutdown” apply to the chip’s input or output voltage?

2

Hello.

The overvoltage protection is on the supply to the chip, as these things almost always are (by the way, any higher voltage you apply to the motor side would appear, minus a diode drop, on the supply side anyway because of the parasitic diodes in the H bridge). The VNH2SP30 is therefore not appropriate for use with a 4S LiPo pack; you should consider the similar VNH5019, for which the corresponding overvoltage trip point is 24V.

-Nathan

3

Thanks. It seemed odd that the chip is rated to 41V but cuts off at 16V. So I had to ask. I guess what this means is the chips works with <16V supplies but physically withstands destruction up to 41V. Seems reasonable for automotive use where battery volts don’t go over 14V.

So it looks to me like either the VNH5019 or I use a buck/boost SMPS regulator.

Thanks again.