SPV1050 datasheet(21/36 Pages) STMICROELECTRONICS

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SPV1050

Functional description

In case of buck-boost configuration, once the harvested source is connected, the IN_HV

and STORE pins will be internally shorted until VSTORE < 2.6 V. Figure 13 shows the

behavior of the input voltage VIN_HV and VSTORE at the startup.

Figure 13. Buck-boost startup (IIN = 5 µA)

In the range 2.6 V

 VSTORE < VEOC the integrated DC-DC converter will start switching. In

this operating range the SPV1050 input impedance is set by the embedded MPPT algorithm

(the MPPT mode is active). The SPV1050 device will stop switching for 400ms (TSAMPLE)

every 16 seconds (TTRACKING). During the TSAMPLE, the input open circuit voltage VOC is

sampled by charging the capacitor on the MPP-REF pin. Once the TSAMPLE is elapsed, the

DC-DC converter will start switching back by setting its own impedance such that VIN stays

as close as possible to VMPP of the source. A resistor partitioning connected between the

source and the pins MPP and MPP-SET has to be properly selected in order to match the

VMPP given by the source manufacturer. Please refer to Section 6.4: MPPT setting for

further details.

The periodic sampling of VOC guarantees the best MPPT in case of source condition

variations (e.g. irradiation and/or temperature changes).

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