The only difference between the TPS40210-Q1 and the TPS40211-Q1 devices is the reference voltage that the error amplifier uses to regulate the output voltage. The TPS40211-Q1 device uses a 260-mV reference and is intended for applications where the output is actually a current instead of a regulated voltage. A typical example of an application of this type is an LED driver. Figure 27 shows an example schematic.
An example of an LED driver design using the TPS40211-Q1 device with detailed analysis is available in the TPS40211 – SEPIC Design for MR-16 LED Application Report.
The current in the LED string is set by the choice of the resistor RISNS as shown in Equation 30.