Part Number: TPS61094
Hi everyone,
I’m using a TPS61094 as a supercap backup supply. Goal: charge a supercap from 5 V VIN, and when VIN is removed the supercap should take over and supply my load. I’m currently focusing on the boost switchover logic.
After VIN is disconnected one can clearly see in the attached image of an oszilloscope trace that the dropping supply is discharging the capacitors of the circutry slowly (load is not very high right now). At some point (3.3V setted treshhold exceeded) the boost function jumps in to maintain the system, so far so good. The voltage applied to vout is exactly the voltage of the supercap.
But eventually the voltage drops entirely at VOUT. The voltage which can be measured at the supercap is still over 4V. So the chip decided to disconnect the supercap.
I build my schematic based on the datasheet figure 8-14.
What I thought was maybe if VIN drops under a certain level then connecting VIN with mode and enable is not the best idea, because maybe the chip is using a dynamic config not boot config? So i put both on a fixed level, but still the same result!
What is going on here?
In the attached OSZI screen capture you see blue = Vout, yellow = vin
Greetings
Nick
