TPS92513 (LED Driver) - Question about varying the reference voltage
Create a resistive ladder with a zener shunt regulator. You can short selected resistors(BJT, MOSFET or analog switches) to change the effective voltage at the IADJ pin
If you have a DAC in the MCU you can use it to change the voltage at the IADJ pin
2nd PWM signal to create a filtered analog Voltage using RC circuit and or an opamp as a buffer.