BQ769142: maximum current gate driver

Hello Jonathan,

It depends on what is the condition you are wondering on and which driver. Most commonly this is asked for the turn-off of the DSG FET, so I will answer assuming that.

This answer is complex since the driver is non-linear and can vary depending on a multitude of different factors. However, the maximum initial turn-off current for the DSG driver is ~70-mA or so.

For more details I'd recommend to read Section 9 DSG Driver Current Paths of the Multiple FETs with the BQ76952, BQ76942 Battery Monitors application note.

Now, I first I want to point out that the part's drivers were characterized with turn-on/off rise/fall times at specific loads (Found in the datasheet), so an exact timing is not really usually possible to calculate.

Hope that helps .

Best Regards,

Luis Hernandez Salomon

Hello Jonathan,

As I mentioned, this device was not characterized in driver strength, so a maximum turn-on/off was not characterized.

We know from internal discussions that the maximum turn-off current of the DSG driver is ~70-mA or so. But this is not a constant value at all times.

The strength of turn-on is not as high, this may be hundreds of uA or so.

Typically for load switching drivers like these, we find that this strength is more than fast enough for most cases so we do not excite the parasitic inductances of the battery/traces/load.  

If the turn-off speed is not sufficient, there are still other ways to enhance the turn-off of the FETs using an external BJT local turn-off circuit. This is explained in the same application note I shared above. This is often not necessary, but may be necessary once you have a large amount of FETs in parallel. Again, the application note shows examples of the fall times at different number of FETs. I would recommend to read this for information.

Best Regards,

Luis Hernandez Salomon