SPV1050 current limiting relationship to Veoc

[BLamb]

I have an SPV1050 configured as follows:

R4 = 6.2M

R5 = 1M

R6 = 3.9M

Veoc = 3.5V

Vuvp = 2.78V

The device is configured for boost mode with MPPT set to 75% and Vin = 2V. The device works as expected, except that it will only draw the full specified 70mA current when Vbatt is about 3.1V. As the battery approaches 3.3V, Vin drops to about 20mA and trails off to nearly nothing as Vbatt increases. I have verified that it is a function of Veoc - if I raise Veoc, the input current will rise to its maximum specification. Vbatt is connected to a 1100mAh LiFePo4 cell, and is fully capable of absorbing the current.

Is this current limiting behavior by design? Or might there be a problem with the inductance or layout of my circuit?

Thanks!

[Jostikas]

SPV1050 has a pass transistor with an annoyingly high series resistance (7 Ohm typ, if memory serves) between STORE and BATT. And it takes it's feedback voltage from STORE. This kills the charger efficiency in floating applications, as at that point it's an RC network with the associated 50% losses...

Abandoned it for an LT chip because of that. It's a massive flaw in an otherwise very useful design.