Can the DW01A cutoff voltages be changed/fine-tuned?  - Page 1
Forum section: electronics / beginners

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: August 07, 2023, 10:59:09 pm
content: Datasheet:http://www.tp4056.com/d/dw01a-fs.pdfI understand that the DW01A has built-in overcharge/overdischarge pre-programmed into the I.C, but is there any way to externally control the trigger points? I'd love to change the trigger voltage from 4.25v to 4.0v. Thanks.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 08, 2023, 08:46:23 am
content: Its Vcc that monitors Vbat. So, essentially no. There may be a way of doing it, but the complexity would be irrational.Better to use a different charger ic with a dedicated voltage sense pin. Plenty out there.My bad (The OC pin detects the battery voltage. You can alter the voltage seen at this pin using a non inverting amplifier.The battery voltage of 4V appears to OC as 4.5V.The opamp is powered from Vcc.Just about any single supply opamp will do as long as it can tolerate >Vcc.You can tweak the resistor ratio to get the OC values you want.) Nah.... wont work.

author: Peabody
author_rank: Super Contributor
timestamp: August 08, 2023, 02:10:43 pm
content: I think OC and OD are the outputs that control the external charge and discharge mosfet gates, and they don't detect anything. The CS pin is used to sense the current flow, but not the battery voltage. It basically measures the voltage drop across the mosfets between the circuit/charger ground and the battery's negative terminal. I don't know of any way to modify any of the voltage-based protection parameters, but I think it would have to modify what's seen at the Vcc pin. But I think the discharge current limit could be increased by using mosfets with lower RDSon.I'm not sure which trigger point you're referring to, but if it's the overcharge voltage limit (VOCP) then perhaps it would make more sense to modify the charger if that's possible.

author: magic
author_rank: Super Contributor
timestamp: August 08, 2023, 04:07:13 pm
content: Doubt it.Per point 11, charge control MOSFET is only turned off when overcharge is detected.Overcharge is detected only when supply voltage to the chip exceeds 4.3V.You can't make this happen if running from a single cell charged at 4V, not without overkill measures like a voltage doubler.What you may do is to disconnect the charge control MOSFET from DW01 and build your own overcharge detection.There seems to be no documented way of altering the internal VOCP threshold and there is likely no known undocumented way either.

author: amyk
author_rank: Super Contributor
timestamp: August 09, 2023, 12:23:12 am
content: They make different variants with different voltage ranges, but the lowest they go is 4.25:https://www.ic-fortune.com/eng/new_product1_1.asp

author: Peabody
author_rank: Super Contributor
timestamp: August 09, 2023, 02:20:59 pm
content: I don't understand what you're trying to accomplish, but it seems to me that in general you don't want protection to ever kick in. It's there just in case, but if you only want the battery charged to 4V, that should be done in the charger circuit, not the protection circuit. But I think the charger chips also have fixed charging voltages, so I don't know how this would all work.