Timeline for Li battery charger reference voltage problem
Current License: CC BY-SA 4.0
24 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 2, 2020 at 8:12 | vote | accept | JAGADISH K | ||
| Mar 2, 2020 at 8:12 | answer | added | JAGADISH K | timeline score: 0 | |
| Sep 20, 2019 at 7:16 | comment | added | diegogmx | @JAGADISHK Yay! :) | |
| Sep 13, 2019 at 5:43 | comment | added | JAGADISH K | @diegogmx, your hunch was right. The fault and charging pins cannot be directly connected to VIN, but a current limiting resistor must be used to connect them. I was in touch with Analog devices Engineering support, and they cleared my doubt. Thank's for your help. | |
| Jun 18, 2019 at 13:37 | comment | added | diegogmx | i was saying the fault or charging, the shutdown needs to be connected | |
| Jun 18, 2019 at 13:14 | comment | added | JAGADISH K | I look into your other hypothesis and i'll let you know the result. | |
| Jun 18, 2019 at 13:12 | comment | added | JAGADISH K | if the shutdown or fault is not desired it can be connected to Vin. | |
| Jun 18, 2019 at 13:10 | comment | added | JAGADISH K | @diegogmx im quoting this from datasheet for pin 3 which also applies to pin 5 "SHDN (Pin 3): Precision Threshold Shutdown Pin. The enable threshold is 1.2V (rising), with 120mV of input hysteresis. When in shutdown mode, all charging functions are disabled. The precision threshold allows use of the SHDN pin to incorporate UVLO functions. If the SHDN pin is pulled below 0.4V, the IC enters a low current shutdown mode where VIN current is reduced to 15µA. Typical SHDN pin input bias current is 10nA. If the shutdown function is not desired, connect the pin to VIN.". | |
| Jun 18, 2019 at 10:33 | comment | added | diegogmx | regarding the dfn package thing, you have to look at the datasheet, specifically where the function of the ntc pin is described, you can leave it disconnected if you don't want to use it, however the pin is considered open if and only if the path to ground is greater than 250k, this is just an hypothesis but maybe pin 7 and 8 being vfb and ntc got shorted by a whisker of tin or have some flux in between creating a resistive path of less than 250k, if that is the case then the ic will see that the thermistor is really hot (shorted) or really cold (high resistance path) either way it shuts down | |
| Jun 18, 2019 at 10:29 | comment | added | diegogmx | actually just caught a possibly big error in your design, pins 4 and 5 are open collector, and they are connected directly to the power supply, the can only sink 10ma, however i couldn't find anything saying its internally limited, meaning that when the circuit starts charging you could well burn it, if you dont intend to use those pins leave them disconnected or grounded, but not at vin | |
| Jun 18, 2019 at 9:57 | comment | added | JAGADISH K | @diegogmx i have used DFN package, i have not connected NTC pin to anywhere else,can you be more clear .please explain with regards to schematic. | |
| Jun 18, 2019 at 9:38 | comment | added | diegogmx | are you using the dfn package? the ntc pin gets disabled when there is more than 250k to ground, if it turns out to be shorted to the fb pin or maybe some flux decreases the resistance too much it can end up disabling the charging, its a long shot but its worth looking at | |
| Jun 18, 2019 at 8:59 | comment | added | JAGADISH K | @diegogmx the pins 3,5 report 24v. | |
| Jun 18, 2019 at 8:33 | comment | added | diegogmx | it may be interesting to see what pin 4 and 5 report | |
| Jun 18, 2019 at 8:26 | comment | added | JAGADISH K | @Bimpelrekkie my bad beginner here, i have edited the question. Any help now would be appreciated. | |
| Jun 18, 2019 at 8:24 | history | edited | JAGADISH K | CC BY-SA 4.0 |
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| Jun 18, 2019 at 7:40 | history | edited | Bimpelrekkie | CC BY-SA 4.0 |
copy-paste how hard is that?
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| Jun 18, 2019 at 7:38 | comment | added | Bimpelrekkie | Instead of adding information through comments, use Edit to add that to your question. | |
| Jun 18, 2019 at 7:35 | comment | added | JAGADISH K | when i measured across R16 the voltage was 3.22 with battery voltage being 12.6 and it kept increasing towards 3.3 the battery float voltage approaching 12.8, but when i remove the multimeters probe from R16 it stops charging. | |
| Jun 18, 2019 at 7:31 | history | edited | JAGADISH K | CC BY-SA 4.0 |
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| Jun 18, 2019 at 7:31 | comment | added | JAGADISH K | sorry, i haven't updated schematic .Actual resistor i have used achieves 12.8 float voltage. R15 is 976K, R16 is 340K. | |
| Jun 18, 2019 at 7:27 | comment | added | D.A.S. | You did not report Vfb measured, but it should be 3.3V, which it cannot be with the far too low value of R16. Since R17 is high impedance , your DMM is injecting noise current perhaps. Looks like R16 should move the decimal point over to the right. | |
| Jun 18, 2019 at 7:04 | history | edited | JAGADISH K | CC BY-SA 4.0 |
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| Jun 18, 2019 at 6:51 | history | asked | JAGADISH K | CC BY-SA 4.0 |