8.2.2.2 Detailed Design Procedure

The recommended L1 = 22 µH with ISAT ≥ I-CHG(CBC_LIM)_MAX, L2 = 10 µH with ISAT ≥ I-BUCK(CBC_LIM)_MAX, CBYP = 0.01 µF and low leakage CREF = 10 nF are selected. In order to ensure the fastest recovery of the harvester output voltage to the MPPT level following power extraction, the minimum recommended CIN = 4.7 µF is selected. Because no large system load transients are expected and to ensure fast charge time during cold start, the minimum recommended CSTOR = 4.7 µF.

No MPPT resistors are required because VOC_SAMP can be tied to GND to give 50% MPPT.

Referring back to the procedure in Detailed Design Procedure or using the spreadsheet calculator at SLUC484 gives the following values:

• R_OV1 = 4.75 MΩ, R_OV2 = 8.25 MΩ resulting in VBAT_OV = 4.97 V due to rounding to the nearest 1% resistor.
• R_OK1 = 4.22 MΩ, R_OK2 = 8.06 MΩ, R_OK3 = 0.698 MΩ resulting in VBAT_OK = 3.5 V and VBAT_OK_HYST = 3.7 V after rounding.
• R_OUT1 = 8.66 MΩ and R_OUT2 = 4.22 MΩ resulting in VOUT = 1.8V.