SLUSCC7C July 2016 – June 2018 TPS546C23
For two devices to operate in a 2-phase application, the SYNC, VSHARE, and ISHARE pins of both devices should be connected respectively, as shown in Figure 30. The loop master device shares the same VSHARE voltage. Essentially the internal COMP voltage is shared with the loop slave by connecting the VSHARE pin of each device together. The sensed current in each phase is compared first by connecting the ISHARE pin of each device, then the error current is added into the internal COMP. The resulting voltage is compared with the PWM ramp to generate the PWM pulse. This current sharing loop maintains the current balance between devices.
An additional resistor connected between the ISHARE pins of both devices can be used to lower the current-sharing loop gain for better stability margin. Use to calculate the current sharing gain (GISHARE).
In addition to sharing the same internal COMP voltage, the VSHARE pin is also used for fault communication between the loop master and slave devices. The VSHARE pin voltage is pulled low if any device encounters any fault conditions so that the other device sharing VSHARE pin is alerted and stops switching accordingly.
An optional high-frequency capacitor can be added between the VSHARE pin and ground in noisy systems, but the capacitance should not exceed 10 pF.