EMB1499Q: EMB1428Q & EMB1499Q - charging only lasts for 2 seconds (instead of 8 seconds) before shutting down

Hello,

Thank you for bringing up the questions. I am going to get back to you when I have more information on this device.

Best,

Zachary

Hello,

Balancing current is set using VSET and the secondary sense resistor. Which value are you using for Rsense? We also recommend VSET to be set to 2v. When starting cell balancing, is voltage on VSET maintained? Is this an issue that you see on only 1 device or multiple devices?

Thanks,

Zachary

I initially set the VSET to 2V as recommended, but I encountered an issue where the charging only lasted for 2 seconds. To troubleshoot, I explored other VSET values. As I mentioned earlier, the problem occurs when the VSET exceeds 1V. The VSET value remains constant during runtime and consistently stays at 2V. I’m using a 10m Ohm Rsense. Currently, I’m testing this on one device; I haven’t checked the other one yet.

Feel free to refer to the schematic of my system below:

Thank you for your schematic.

Are you able to monitor the EN and DONE pins during an operating cycle? Is EN toggled LOW and DONE toggled HIGH after 2 seconds? Are any FAULT pins being asserted after the cycle? Furthermore, 8 seconds is the maximum operating cycle length before watchdog shuts off the forward converter. This doesn't necessary mean that a cycle needs to last 8 seconds. While VSET = 1V is technically within the operating conditions of the device, our testing was done with VSET = 1.2 - 2v. It seems at 1V, watchdog is manually shutting off the operating cycle.

Best,

Zachary

Yes, I successfully observed the EN and DONE pins behavior. The charge cycle completes successfully in 2 seconds, with EN going Low and DONE switching to High. Additionally, I checked the fault bits and consistently received 0xA0 for stop, 0xA2 for initiating a charge cycle on cell 2, and 0xAA for starting a discharge cycle on cell 2, without detecting any faults.

My goal is to maintain the charging process for 60 seconds, intending to alternate between stop and start commands every 5 seconds to sustain the charging activity. However, the attempt to keep the charging ongoing with a 5A current for 8 seconds, as specified in the datasheet, by setting VSET to 2V using a 10mOhm resistor to achieve approximately 4.6A, does not succeed. Do you have any suggestions?

I've continued testing cell balancing more in my setup and now I am noticing that incorrect data is being transmitted from the EMB1428 to the STM microcontroller for the STOP and START commands, resulting in the failure of charging and discharging operations. Now, the EMB1428Q chip doesn't perform cell balancing at all, instead it sends incorrect data to microcontroller. I'm unable to interpret the DATA sent by the EMB1428, as it is not specified in the datasheet. Could you please explain the meaning of the data on the MOSI line from the table below?

Hello,

Can you provide logic waveforms for the mosi miso lines. I am not quite sure what the table is showing. Can you also measure VDDio, VDD5v, and VDD12v?

Thank you for your reply. I'll record the waveforms and share them with you later.

I've updated the table to provide a clearer perspective on the situation. I believe this updated table will provide you with more comprehensive details and enhance your understanding of my setup. Please provide your feedback if this info is not sufficient:

I measured the VDDio, VDD5v and VDD12v and the voltages are as expected shown in the schematic below.

Updated table below:

Hello,

Since Zach is out-of-office, I was assigned to help you with this request. Allow me to catch up with what you were previously discussing and I will get back to you within the next days.

Thanks for understanding!