A differential remote sense amplifier enables the controller to compensate for I×R drop due to PCB copper, in high current applications. Connect the AVSP/BVSP and AVSN/BVSN pins respectively to the output voltage at the load point, through the network described in Figure 7-2. A connection to the output voltage, local to the power stages, shown by R_{LCL_P} and R_{LCL_N}, maintains closed loop operation even if the load is uninstalled, or the remote sense connection is opened. Route the differential remote sense lines as a tightly-coupled differential pair, and maintain a wide clearance to any fast switching nets, such as power stage switch nodes or power input voltage. Optionally, use a small filtering capacitor, shown as C_FILT, at the controller side to improve noise immunity.

An internal precision reference DAC generates the output voltage set-point. The reference DAC is produces reference voltages up to 1.87 V. For output voltage set-points below 1.87 V, no scaling (internal or external) is required, and the sensed output voltage is compared directly to the reference voltage.

For output voltage set-points between 1.87 V and 3.74 V, the controller applies internal scaling of the remote sense amplifier, and no external sense divider is needed. Set the VOUT_MAX command greater than 1.87 V to enable this internal scaling. For output voltage set-points greater than 3.74 V, apply an external sense divider with R_{RMT_P} = R_DIV = 500 Ω, and set the VOUT_SCALE_LOOP command to 0.5 V/V. This enables output voltage set-points up to 5.5 V. The overvoltage/undervoltage thresholds are referenced to the VSP/VSN pins only and need to be scaled appropriately for applications with an external resistor divider. Refer to Table 7-1 for more information.

TPS53676 performs an open- and short-circuit detection on the AVSP/AVSN and BVSP/BVSN pins at initialization to determine if the voltage sense lines are open. The controller flags a fault condition and does not attempt to boot if an open sense line is detected. Ground the VSP/VSN lines for unused channels to prevent false-triggering, in applications which do not make use of both channels. As such, the local sense resistor connection may be omitted, but is still recommended for debug and system bode plot measurement.

Figure 7-2 Differential remote sensing