Datasheet

UDG-11113

FB2

EN2/SS2/GSNS

ILIM2/VSNS

DIFFO

BP6

PARASITIC

VSNS

GSNS

Power Stage

PARASITIC

FB1

COMP1

VREF

COMP2

OUT

AGND PGNDx

TPS40322

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SLUSAF8D –JUNE 2011–REVISED JANUARY 2014

Two-Phase Mode, Remote Sense Amplifier, and Current Sharing Loop

The TPS40322 can be configured to operate in single-output, two-phase mode for high-current applications. With

proper selection of the external MOSFETs, this device can support up to 50-A of load current in a two-phase

configuration. As shown in Figure 18, to configure the TPS40322 for two-phase mode, FB2 is tied to BP6. In this

mode, COMP1 must be connected to COMP2 to ensure current sharing between the two phases. For high-

current applications, the remote sense amplifier is used to compensate for the parasitic offset to provide an

accurate output voltage. The EN2/SS2 and ILIM2 pins are designed for multiple functions. They are used as

VSNS and GSNS for remote sensing in two-phase mode. DIFFO, which is the output of the remote sensing

amplifier, is connected to the resistor divider of the feedback network.

Note that BP6 powers the remote sense amplifier. The DIFFO voltage must be 0.2-V lower than the BP6 voltage

under all conditions. If BP6 is lower than DIFFO voltage, the converter loses regulation. To ensure no regulation

loss, use a remote sense amplifier when the application output voltage is lower than 2.2 V. For an application in

which the output voltage is higher than 2.2 V, the remote sense amplifier can be bypassed and the voltage

output can be connected to the feedback resistor divider directly.

Figure 18. Two-Phase Mode Voltage Loop Configuration

When the device operates in two-phase mode, a current sharing loop as shown in Figure 19 is designed to

maintain the current balance between phases. Both phases share the same comparator voltage (COMP1). The

sensed current from each phase is compared first in a current share block, then each signal is summed with

COMP. The resulted error voltage is compared with the voltage ramp to generate the PWM pulse for each

channel.