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LT4041 Assistance

Question asked by demedeirosa on Aug 9, 2018
Latest reply on Aug 10, 2018 by demedeirosa

Hi all,


I am using the LTC4041 in a new application. For backup I am using a 3V, 5F capacitor. System voltage is 3.3V.


It appears that my actual charge current is not what is programmed by the PROG resistor. It is currently programmed to be 1A, I believe I am seeing under 1mA. In addition, the charge voltage is programmed to be 3V, the charge voltage is peaking at 2.631V. I modified the charge voltage to be 3.36V, and still the peak charge voltage is 2.631V.


Schematic below


Note that R12 was modified to 100K, and R16 was modified to 300K (for 3.36V charge voltage)


L1: Coilcraft XAL5030-222ME_

Supercaps: This one and this one.


Any thoughts as to what could be happening here?