ISL62776IRTZ datasheet(21/50 Pages) RENESAS

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ISL62776

3. Theory of Operation

R16DS0044EU0200 Rev.2.00

Page 21 of 49

Oct.8.20

The ISL62776 makes VISEN1 = VISEN2 = VISEN3 as shown in Equation 12 and Equation 13:

Rewriting Equation 12 gives Equation 14:

Rewriting Equation 13 gives Equation 15:

Combining Equation 14 and 15 gives Equation 16:

Therefore:

Current balancing (IL1 =IL2 =IL3) is achieved when Rdcr1 =Rdcr2 =Rdcr3. Rpcb1, Rpcb2, and Rpcb3 have no effect.

Because the slave ripple capacitor voltages mimic the inductor currents, the R3 modulator can naturally achieve

excellent current balancing during steady state and dynamic operations. Figure 16 shows the current balancing

performance of the evaluation board with a load transient of 12A/51A at different repetition rates. The inductor

currents follow the load current dynamic change with the output capacitors supplying the difference. The inductor

currents can track the load current at a low repetition rate, but cannot keep up when the repetition rate is in the

hundred-kHz range, where it is outside of the control loop bandwidth. The controller achieves excellent current

balancing in all cases installed.

V1p V2n V3n

V1n V2p V3n

(EQ. 12)

V1n V2p V3n

V1n V2n V3p

(EQ. 13)

V1p V1n

–

V2p V2n

–

(EQ. 14)

V2p V2n

–

V3p V3n

–

(EQ. 15)

V1p V1n

–

V2p V2n

–

V3p V3n

–

(EQ. 16)

Rdcr1 IL1



Rdcr2 IL2



Rdcr3 IL3



(EQ. 17)

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