It's my first question on this platform and I hope somebody can help me with my problem. I have connected the LTC3890 with the LTC4000 to charge 4 Li-ion batteries. Before connecting the ITH pin both boards worked good. The ITH on the LTC3890 is 0.535 V and the Vout is 16,8V. When i connected the pin ITH between the charger and the converter, the pin ITH dropped to 0.4V. As result the Vout of the converter dropped from 16.8V to 12.5V. I have checked all the Amplifiers which effect the pin ITH in the LTC4000 but non of it have reached its maximal value. I am using the evaluation kits of both of the components (DC1830A-B for the LTC4000 and DC2236A-B for the LTC3890). IN the datasheet of the LTC4000 page 23 i have read the next:
How can I make the pin ITH in the LTC4000 goes to 0.535 V to reach the needed Vout of the LTC3890?
Thank you in advance .
Hi, thank you for your reaction. Your right!! Ith was not functioning correctly by sinking the current. I have replaced the LTC4000 IC and finally its working completely.
There is an LTspice demo circuit combining these two parts available in ADI website that's worth checking.
What's connected to J13, J14 (BAT, GND) on DC1830A-B? Why do not use a formal stand-alone battery charger controller?
What is the relation between Vith of the LTC3890 en it's output voltage?
Hi, The measured values are the blue letter. I have discharged the battery so its lower than 15,1V (the maximal voltage of the converter that i measure) and then i see that the battery is charging to 15,1V. I am noticing that the value of the ITH is maximal 0.2V the whole test. All the pins seems working expect ITH pin.
I have to say i just measured a resistance of 1.7 kOhm between ITH pin and the ground (pin GND) in LTC4000. I thought that ITH is a high impedance pin. this pic is from the datasheet of the LTC4000
Hi it looks like the Ith pin is sinking current. Have you tried to check if any of the parameter mentioned above is hitting its limit? Also make sure the connection between ith pin as close as possible to avoid any interference with the compensation.
That's great to hear Ayham!