Hello Tom,
We have both a Bridgeless PFC (PMP22220) and Totem Pole PFC (PMP20873) reference design with the UCD3138x digital controllers.
The question you are asking relates to why the UCD is different than other DSP-based MCUs, such as the C2x products. In a typical DSP-based MCU, everything must be coded, including your ADCs, control loop and DPWM modules. However, the UCD has the control loop already etched into the silicon. Thus, the UCD is an MCU that is specialized for any power supply.
In the below diagram from SLUAAS7, the entire control loop, from the Error ADC, PID and DPWM modules, are etched into the silicon. You can only change the parameters that modify the control loop, such as your Kp, Ki, Kd values.
The UCD also uses our powerful Fusion Digital Power Studio GUI (https://www.ti.com/tool/FUSION-DIGITAL-POWER-STUDIO). The Fusion GUI allows you to see the registers and values real-time while your power supply is running. Thus, you can modify values live and see how they affect your power supply's performance, such as your Kp values or fault thresholds,
I would view the below resources to learn more about the differences between the two products.
Regards,
Jonathan Wong
1. Does L102 (487uH) in PMP20873 connect to ISO-RET_H in the daughter board? LMG3410RWHT forms the fast tube of the totem pole, while STY105NM50N forms the slow tube of the totem pole, similar to this
2. Isn't there a rectifier bridge in PMP22220? Why is it also called bridgeless? Additionally, why is there no boost inductor in this bridgeless circuit?
3. Is there any source code for PMP20873? What ways can I obtain it?
Hello Tom,
1) Does L102 (487uH) in PMP20873 connect to ISO-RET_H in the daughter board? LMG3410RWHT forms the fast tube of the totem pole, while STY105NM50N forms the slow tube of the totem pole, similar to this
Yes, you are correct. The Q1+Q2 MOSFETs are the slow FETs that rectify the AC line. The fast PFC FETs are on the GaN Half-Bridge daughter card. The PMP20873 uses the LMG3410-HB-EVM (https://www.ti.com/tool/LMG3410-HB-EVM).
2) Isn't there a rectifier bridge in PMP22220? Why is it also called bridgeless? Additionally, why is there no boost inductor in this bridgeless circuit?
The PMP22220 is an AC Switch Bridgeless PFC. This is a unique configuration that is not the same as a typical totem-pole PFC. We have an explanation of the AC Switch Bridgeless PFC topology on our Bridgeless PFC video (https://www.ti.com/video/6123653129001). The below screenshot is halfway in the video.
I believe the design uses the inductance in the common mode chokes (CMCs) and EMI filter as the boost inductance.
I forgot to mention that the UCD3138PFCEVM-026 (https://www.ti.com/tool/UCD3138PFCEVM-026) also has a bridgeless PFC configuration. Please see the "Evaluating UCD3138 in Interleave PFC or Bridgeless PFC Configurations" (https://www.ti.com/lit/an/slua677/slua677.pdf) application note for instructions on how to configure the EVM in a bridgeless PFC configuration. The firmware for the UCD3138PFCEVM-026 is available online (https://www.ti.com/tool/UCD3138FW-PFC).
3) Is there any source code for PMP20873? What ways can I obtain it?
The source code is currently under NDA. Please reach out to your local Field Applications Engineer (FAE) to contact us for the PMP20873 source code.
Regards,
Jonathan Wong
Hello Tom,
The UCD3138 has an integrated PID controller. You can see the PID stage on page 37 of the UCD3138 datasheet.
All of the PID paths are etched into the chip itself. The only things you can change are parameters, such as your kp, ki or kd values.
However, the PFC control requires more customization that is programmed in C. While we do not have a diagram for the totem-pole PFC, the UCD3138PFCEVM-026 User's Guide shows the block diagram on page 33 for the bridgeless PFC, which is similar to the totem-pole PFC. All of the processing in the dark grey box are etched paths in the chip itself. The rest of the processing is programmed in C.
Regards,
Jonathan Wong
Hello Tom,
The design zip file on the UCD3138PFCEVM-026 page is of the PWR050 board, not the UCD3138PFCEVM-026. The PWR050 is the auxiliary power board that uses the UCC28600 flyback controller. The PWR050 is used to supply auxiliary power and monitoring signals of the input AC voltage. You can see where the PWR050 fits in the schematic on page 8 of the UC3138PFCEVM-026 User's Guide.
Regards,
Jonathan Wong
Is there a mistake in this diagram? The interleaved PFC only has one current input, while the bridged PFC has two current inputs?
（Semi-Bridgeless=interleaved Bridgeless）
Hello Tom,
I will be combining your questions into one post.
1) Is there a GUI software for UCD3138 similar TI-Fusion-Digital-Power-Designer which supports UCD9240?
The UCD92xx products do have a GUI that is different than the GUI that the UCD3138x products use.
Fusion Digital Power Studio: UCD3138x products
Fusion Digital Power Designer: UCD92xx and others
2) Can the UCD92 * * series support interleaving or totem poles? What are the advantages of UCD3138 compared to UCD92 * * series?
The UCD92xx are not flexible for a wide variety of topologies. I recommend using the UCD3138 since it is a newer product with better support.
3) What are the advantages and benefits of UCD3138 compared to UC3854, both of which have three inputs?
The UC3854 is a pure analog controller. You cannot program the UC3854.
4) Is there a mistake in this diagram? The interleaved PFC only has one current input, while the bridged PFC has two current inputs?
On the UCD PFC EVM, the Interleaved PFC measures the current using the ISENSE shunt while the Bridgeless PFC measures the current using two current sense transformers. This is not the only way to control an interleaved PFC. I think the design was chosen to maximize compatibility of having a Single-phase PFC, Interleaved PFC and Bridgeless PFC topology all on the same board. If you decide to control an Interleaved PFC with two current sense transformers, then you can modify the schematic and firmware to do so.
As Ning mentioned above, please share your project information with us to help better support your questions. Also, you can contact your local TI FAE for direct support.
Regards,
Jonathan Wong
