BQ24075: BQ24075

Hi Dan,

The BQ24075 is designed to regulate at 5.5V if the VIN is above about 5.5V by the Q1 FET dropoff amount. Anything below this, such as 5V for VIN, will cause the device to act as a pass-through with a small voltage drop due to the Q1 FET. 

If you're looking for a voltage output below 5V, you'll need to consider your input voltage as the main factor if you wish to continue using the BQ24075. 

Another possibility is to use the BQ24073 or BQ24074 for 4.4V output but with a TD pin or a ITERM pin in place of SYSOFF. These are pin to pin compatible devices that are the same aside from the removal of the SYSOFF pin in place of the previous pins mentioned.

Best Regards,

Anthony Pham

HI Anthony,

We understand the BQ24075 is a pass through at <5.5Vin. That is not the problem.

The issue is that normally we see OUT = 4.6V-4.7V during production, and now we are suddenly seeing OUT=4.8V-5V in around 10% of production units.

We always expected the ~4.6V based on this Power Path statement on P.10 in the datasheet, and it seem to have been true for last few years.

So we are trying to evaluate if the units with OUT= 4.9-5V are actually faulty or there is some tolerance or other mechanism that can result in OUT=5V.

What is of interest is if you have any additional information about the Power Path and its voltage drop (IN-OUT) based on Iin <1A, as the datasheet state the test condition is with Iin=1A.

For instance, we know if BAT is not connected, then we get OUT=5V because the BQ24075 is doing battery detect function.

So we think maybe Iin<1A could be a tolerance we are now seeing in the chips. But without more detail about the Power Path we can't conclude this as the reason.

Thanks

Dan

Hi Dan,

The dropout will depend on the output current that is being pulled on the device. Do you have any information as to the output current when you are seeing the 5V output?

Best Regards,

Anthony Pham