STM Part Selection for 1x USB-C PD and 1x USB-C DP Alt-Mode

[Antonio_Duneo]

Dear STM Community and Experts,

we are trying to implement a dual-port USB-C design using STM parts with the following requirements:

• Port 1: USB-C Power Delivery (PD) Sink, 100W, no data
• Port 2: USB-C non-PD Source 5V 2A max., USB 3.1 Gen 1 Data, Display Port (DP) Alt-Mode

There's plenty of documentation by STM on USB-C, but unfortunately we still have some uncertainties mainly about the companion circuitry and tying it all together.

We selected STM32G0B1 as the Platform Policy Device (PPD) and are planning to implement both UCPD interfaces on it, one for each USB-C port, using STM's UCPD firmware. The selection of the companion-chips for these port requirements is less clear to us:

For Port 1 (100W PD Sink) we decided to use TCPP01-M12 as the companion chip and STL40DN3LLH5 as the VBUS load switch.

For Port 2 (DP Alt-Mode, USB 3.1) we are using a USB 3.1 / Display Port MUX by TI (TUSB546), but we are unsure of which companion chip to use here. Should we use TCPP02-M18 or STUSB1700? This port also has way lower power requirements: Which load switch should we use here if at all?

We are also looking for STM part recommendations for ESD protection on these ports as well. I should note that this is a high-density design.

One final remark: In STM's documentation, the USB 2.0 D+/D- lines are always shown being connected to the PPD, but why? We want to connect these to our host Linux SoC so that we can use combined USB 2.0 and DisplayPort devices such as touch screens.

Thank you for your time and all the best from Munich,

Antonio Steiger
Mangement @ Duneo
Part of Technical University Munich Ecosystem

[FBL]

Hi @Antonio_Duneo 

Here are key points for implementing ESD and EOS protection, based on AN5225, along with inrush current management for your USB Type C

1. To identify suitable ESD for high power applications 100W : ESDA25P35-1U1M for 20V
2. To decide between TCPP02-M18 and STUSB1700 for port protection I suggest you taking a look to this thread.
3. About Load Switch selection for 5V, 2A power path. several design considerations and specifications are crucial to ensure optimal performance and compatibility:

• On-Resistance preferably less than 50 mΩ to reduce voltage drop.
• Low quiescent current essential for power efficiency, especially in battery-powered systems.
• Proper input and output capacitors are crucial to manage inrush currents and prevent reverse current flow.
• Overcurrent, thermal shutdown, reverse current blocking...

You can refer to MB1352 as an example.

Our experts @PPAIL.1 @MROUV.1 may help to assist you further.

[MROUV.1]

Dear Antonio,

For Port 2, I recommend TCPP02-M18 because STM32G0B1 can manage 2 ports.

Key parameters of load switch selection are :

• N-MOSFET
• Voltage : at least 30V max (to secure if a plug on defective source provides 20V instead of 5V)
• Rds-on : according to voltage drop and thermal losses at max current : 2A à 32mΩ x 2A = 0.064V acceptable and (32mΩ x 4A²) x 52°C/W = 6.7°C acceptable
• Single MOSFET if SOURCE only / dual MOSFET if DRP not VBUS powered

Find below a list of possible ST N-MOSFET :

On STM32 example, D+ and D- lines are connected to STM32 data lines for illustration.

If you want to use another SoC, these lines need to be connected only to the SoC.

About SS lines, you can have a look on AN4871 where HSP051-4M10 (ESD only) and ECMF4-40A100N10 (ESD + CMF) are presented.

Best regards,

Mathieu