PMP10110: cc cv Set from MCU

Hi Venkatesh,

Both CV and CC loops of the PMP10110 are taking their references from U5. R29 and R34 are setting the cathode of U5 to get 5 V reference. Then two PWM inputs (pins 1 and 3 of J5) are defining the references for CC and CV loops (pins 3 and 5 of both error amplifiers U3A and U3B) in the following way: if, for example, pin 1 of J5 is 3.3 V or 5 V, then Q4 is acting as a short to ground; in this case we have zero volt on the center point of R31 and R32 (let's call it PWM_V). Now R31, C21, R30, C20 and R33 are defining a double low pass filter and the voltage on R33 is therefore the average of a PWM_V signal, which is zero; that means V(pin 3 of U3A) = 0. At this voltage, as already described in the schematic, the converter will supply zero volt. 

On other hand, if pin 1 of J5 is connected to ground, Q4 is off and the voltage on pin 3 of U3A will be simply the reference U5 (5V) reduced by the resistor divider R32 + R32 + R30 together with R33, which yields pin 3 to reach 2 V. Then, as described in the schematic, at 2V reference for U3A the converter will supply the maximum output voltage: 30 V.

Now, by providing pin 1 of J5 with a 3.3 V or 5 V PWM signal, with duty cycle variable from 0 to 100%, we will get respectively Vout = 30 V to 0 V.

Let's recap it:

PWM(pin 1 of J5)  duty cycle = 0%  --> Vout = 30 V

PWM(pin 1 of J5)  duty cycle = 100% --> Vout = 0 V

Similarly (the two circuits for CV and CC are working the same way) we can say:

PWM(pin 3 of J5)  duty cycle = 0% --> Iout = 6 A

PWM(pin 3 of J5)  duty cycle = 100% --> Iout = 0 A

Please let me know if you want to know more about this circuit.

Regards,

Roberto