Hello,
I am using the BQ25504 boost converter with a piezoelectric source. My configuration implements a full wave bridge rectifier to get a DC voltage that can be used by the chip to charge a supercapacitor, battery, or otherwise. I am interested in making use of the chip's ability to modulate its impedance.
The datasheet states the following:
Internally, the boost converter modulates the effective impedance of the energy transfer circuitry to regulate the input voltage (VIN_DC) to the sampled reference voltage (VREF_SAMP). The reference voltage is set by the following expression:
Vref_samp = Vin_dc_OpenCircuit * ( Roc1 / (Roc1 + Roc2))
With a piezoelectric source, it makes the most sense to have a matched load condition. My impedance is variable however, so I would still like to use the chips MPPT functionality.
What I can't quite figure out is whether Vref_samp should be set equal to Vin_dc or to 0.50*Vin_dc for the chip to always seek a matched load??
Best regards,
Hugo