In two-phase operation, the current sharing between the two phases depends on the mismatch between the current sense circuitry of the two channels. The TPS92682-Q1 incorporates a feature and a register setting to improve the current sharing in two-phase operation. Table 7-40 includes three bits of calibration settings, CHxCAL2:0, which introduce an offset of 0 to 17.5 mV (with a resolution of 2.5 mV) to the channel switch current sense voltage. The calibration offset can be used to compensate for the mismatch offset between the two channels.
The following procedure is recommended for offset calibration between the two phases in a CV two-phase design:
- In two-phase CV, Comp1 and Comp2 pins are connected together.
- Configure the registers for the application and turn on the two-phase converter.
- Set the load at the output of the two-phase converter to half of the maximum load in the application.
- Set CH2GOFF = 1 and CH1GOFF = 0 in Table 7-40. This setting turns off channel-2. Measure the COMP voltage as shown in Figure 7-13 and record the measurement as VCOMP1.
- Set the CH1GOFF = 1 and CH2GOFF = 0 in Table 7-40. This setting turns off channel-1. Measure the COMP voltage and record the measurement as VCOMP2.
- The difference between the two measurements, ΔVOFST = VCOMP1 – VCOMP2, is the offset mismatch between the two phases.
- By setting a similar offset voltage through CHxCAL bits, the mismatch can be corrected (offset must be set in CH2CAL if VCOMP1 > VCOMP2, and in CH1CAL if VCOMP1 < VCOMP2).
- At the end of the procedure, set both CH1GOFF and CH2GOFF bits to zero.