DRV2604L does not work with LiPo Battery, only on USB. Being used with TPS6720 for charging.

Sangeet Dandona

Other Parts Discussed in Thread: DRV2604L, TPS65720

Hi,

We are currently using the drv2604L for driving an LRA motor and it seems to work when our boards are working off of USB power. When we either have our LiPo battery connected to the board or when we are just working off of the battery, the haptics stop working. We have checked the power at the VDD and the VREG pin and they seem to be stable so it seems like the driver is getting power. We have also confirmed that the EN pin toggles high when we use the drv as well. The only thing that may happen is that the supply voltage when working from USB power is 4.4V and when working purely off of battery goes down to 4V. We are currently using the TPS6720 to provide the regulated voltages for the rest of the board and as the battery charger.

We've checked the I2C communication on a logic analyzer and the device appears to provide a NACK when we send the slave address for the drv. According to the datasheet we waited more then 500us to make sure the device was in standby mode and then we turned off standby mode and tried to write and read data and nothing happened.

I can't tell if there is any real hardware issue. Is there some kind of system issue?

Thanks,

Sangeet

over 9 years ago

0 Kelly Griffin over 9 years ago

TI__Genius 10522 points

Hi Sangeet,

This forum question may help you out: e2e.ti.com/.../1336979
The DRV2604L needs to maintain a 3.6kV/s ramp on VDD. Please check the ramp rate of VDD going to the DRV2604L.
I tried looking up the TPS6720 but that doesn't seem to exist; maybe a typo?
Let me know the results and if you need further assistance.

Regards,
Kelly Griffin
Application Engineer
Low Power Audio and Actuators

0 Sangeet Dandona over 9 years ago in reply to Kelly Griffin

Prodigy 110 points

Hi Kelly,

Thanks for getting back to me. You were right, it was a typo, the part is the TPS65720 low power PMU:

www.ti.com/.../TPS65720

We are currently using this to power the DRV2604L and during startup, the device is not accessible from I2C. Currently we are powering the device from the sys pin which is an unregulated voltage which either is at 4.4V when connected to USB power or tracks the battery if there is no USB.

Thanks,

Sangeet

0 Kelly Griffin over 9 years ago in reply to Sangeet Dandona

TI__Genius 10522 points

Sangeet,

Cheak the ramp rate on VDD please. If it is slower than 3.6kV/s, this part can fall into an unknown state and not responsd to I2C.

Thanks,
Kelly Griffin

0 Sangeet Dandona over 9 years ago in reply to Kelly Griffin

Prodigy 110 points

Hi Kelly,

How would we measure ramp change? On an oscilloscope?

Thanks,

Sangeet

0 Kelly Griffin over 9 years ago in reply to Sangeet Dandona

TI__Genius 10522 points

Sangeet,

Yes. Connect a probe to the VDD line. Power the part off, and then power the part on and trigger your oscilloscope on the positive edge of the VDD probe. Measure the change in voltage and divide by the change in time from VDD = 0V to VDD = 4V.

Regards,
Kelly Griffin

0 Sangeet Dandona over 9 years ago in reply to Kelly Griffin

Prodigy 110 points

Hi Kelly,

If the slew rate on the VDD line is less then 3.6kV/s, how can we fix this problem? Right now we are driving supply voltage of the from the sys pin of the tps65720.

Thanks,

Sangeet

0 Omid (TI) over 9 years ago in reply to Sangeet Dandona

TI__Intellectual 1470 points

Hello Team,Can you please review and follow-up with our customer.
Very Respectfully,Omid D.

0 Kelly Griffin over 9 years ago in reply to Omid (TI)

TI__Genius 10522 points

Hi Omid,

I'm waiting to hear a response to our question about the power supply ramp rate. If the slew rate is less than 3.6kV/s, then our part will not operate correctly.

Regards
Kelly Griffin

0 Kelly Griffin over 9 years ago in reply to Kelly Griffin

TI__Genius 10522 points

Sangeet,

I have clarified with you via email about this issue. For anyone else looking at this post, I just want to clarify on here as well.
The DRV2604L part has brown-out protection as seen in figure 15 of the datasheet. If the part is slowly powered down and the VREG drops below VBOT (0.84V), then it can be booted back up with no problem. Keeping in mind the slew rate must be >3.6kV/s.
However, if the part is initially powered to a voltage between ~0.9V-1.85V, then VREG won't be below VBOT. Furthermore, if the part is powered up to 2V-5.2V, the part will power up in an unknown state and I2C will not ACK until the part is power cycled.

Regards,
Kelly Griffin
Haptics Application Engineer

0 Sangeet Dandona over 9 years ago in reply to Kelly Griffin

Prodigy 110 points

Hi Kelly,

Thanks for your reply. We really appreciate it.

So, what would be the best solution with our current design? Would switching to the 2605 avoid this issue? Or would we have to change the design so that the 2604L/2605 is driven from a buck converter to provide a stable reference at startup?

Thanks,

Sangeet

Motor drivers

Motor drivers forum

DRV2604L does not work with LiPo Battery, only on USB. Being used with TPS6720 for charging.