VBUS_C_CTRL0 and VBUS_C_CTRL1 voltage

[TeIk_3653391]

Hi,

These pins drive the consumer path FET's. I measured gate voltage 10.5V with 5V VBUS supply. This seems to be good marginal to get low Rds for the FET's. However when PD negotiates 20V/3A VBUS (measured 19.7V) the gate voltage is mere 20.5V.  The FET heats up on higher currents so I assume reason is the low gate voltage and thus too high Rds.

What kind of  driver voltage I should expect to see on 20V VBUS, I assume it should be around 25V?
We're using CYPD3120.

[Giraffe1492]

When using the CYPD3120 with a 20V VBUS, you should expect a higher gate voltage to ensure low Rds for the FETs and prevent them from heating up at higher currents. Ideally, the gate voltage should be around 25V for optimal performance.

It's important to ensure that the gate driver you're using is capable of providing the required gate voltage. One option to consider is the 2ED21824S06J, a 650V, 2.5A high current half-bridge gate driver IC with an integrated bootstrap diode. This gate driver can provide the necessary gate voltage for your application and offers excellent ruggedness and noise immunity.

Additionally, make sure that the MOSFET you're using is suitable for your application. The IPD90P03P4-04 is a -30V, P-Channel, 4.5 mΩ max Automotive MOSFET with excellent performance and reliability. It is designed for high-side drive applications without the need for a charge pump, making it a suitable choice for motor bridges (half-bridges, H-bridges, 3-phase-motors).

If you're still experiencing issues with gate voltage and FET heating, consider reviewing your circuit design and layout to ensure proper operation and performance.

https://www.infineon.com/cms/en/product/power/mosfet/automotive-mosfet/ipd90p03p4-04/?redirId=114410...
https://www.infineon.com/cms/en/product/power/gate-driver-ics/2ed21824s06j/

[Pranava_YN]

Hi @Giraffe1492 ,

Thank you for participating in the community discussion. In the CYPD3120 part, the gate driver is inbuilt and there is no requirement of adding an external gate driver.

@TeIk_3653391 ,

The gate driver is designed to drive the gate voltage to VBUS + 2 * (VDDD). However from your observation it looks like it is not doing this. How about other PDOs such as 15V or 9V?  Is the gate drive voltage proper there?  Is it possible to share the schematic of the FET part? Also, which SDK project are you using to design this?

[TeIk_3653391]

Hi @Pranava_YN . 

I measured following values with various PDO's. We've shorted together VDDIO and VDDD and are using VDDIO for various 10k pull-ups so it's impedance to ground is only few kilo-ohms and is pulling some current. Could this have something to do with the problem?

PDO	VBUS	VBUS_C_CTRL0
5V	5V	10.5V
9V	9V	13.9V
15V	14.7V	16.9V
20V	19.7V	20.5V

Dev environment

Environment:
PSoC Creator 3.3 DP1 (3.3.0.9604)
Culture: English (United States)
OS Version: Microsoft Windows NT 6.2.9200.0
CLR Version: 4.0.30319.42000

Installed CyInstaller Products:
Cypress Document Manager 1.0 SP1
EZ-PD CCGx SDK 3.0.1
EZ-PD Configuration Utility 1.0
PSoC Programmer 3.29.5
PSoC Creator 3.3 DP1

Attached schematic of the FET part. 

[Pranava_YN · Accepted solution]

Hi,

Looks like some external component is causing this issue. I tested similar reading from my side (Used CYPD3125 instead of CYPD3120) and for 20V VBUS I am seeing around 27V in the gate drive.
3 - 4 10kOhm pullups should not affect this so much. But if you have more please check.
Also, can you please check the VDDD VDDIO and VCCD whether have healthy readings in this condition.

[TeIk_3653391]

Hi, 

Thank you for confirming the correct voltage. We found a error in our board, the FET pull-downs (should be 10Meg) were assembled with a wrong resistor size (1Meg) . After removing those we see now 27V voltage. We'll have to try with 10Meg pull-downs still but looks like we found the main issue.