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Smart Power Switches Forum Discussions

Not applicable
Hello,

I have visited and posted to these forums many times with great success for help with the XMC4500 so I figured I would try to get some help here for some hardware.

I have the BTS432E2 "ProFET" and I am hoping to drive both(not at the same time) 12V and 24V proportional valves for a body controller I am developing. Using the XMC4500(Relax Lite Kit) I have a microcontroller outputting PWM voltage signals, and I want to connect these to the ProFET in order to drive my proportional valves (0 to 1.2A).

My problem is when I try to apply voltage to the ProFET I receive no output. Following the datasheet my connections are as follows:

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Pin 1: GND (Connected to XMC4500 Breakout so GND is common)
Pin 2: PWM Output from XMC4500
Pin 3: +12V (Bench Power supply rated up to 3A)
Pin 4: Voltage Meter to troubleshoot for now (Plan to connect to XMC4500 for feedback)
Pin 5: Proportional valve terminal

The other proportional valve terminal is connected to ground.

I have used these valves numerous times and they work flawlessly when adjusting current on bench supply, but they draw no current in my current configuration with the ProFET. Is the signal from the XMC to low, requiring a gate driver?

Any help would be greatly appreciated

Thank you,

Adam
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11 Replies
forix
Employee
25 replies posted 10 replies posted 5 replies posted
Employee
Hello,

The connections should be fine.

582.attach

The VoutHi of XMC4500 with VDDPmin=3.13V is 3.13-0.4V=2.73 (VoutHimin=2.4V, IOH ≥ -2 mA) seems to be sufficient. What about PWM freqeuncy, too high?

You may set output characteristic of the output pin to "strong", please check.
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Bernd,

First off thank for your response. I have my output characteristic set to strong by default, however I will experiment with the frequency. I noticed in the data sheet there was no mention of frequency, unless i misread it. Attached are my PWM settings. Am I better suited to include a gate driver? Or perhaps purchase a FET with a lower input turn on Voltage?

Thanks again,

Adam

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forix
Employee
25 replies posted 10 replies posted 5 replies posted
Employee
Hello,

The frequency of 1500Hz should be no problem for the ProFET.

Do you have an oscillosope available? You may test with a resistor as load at output pin of ProFET and check the input signal vs.output..

What about to program controller's output to open drain and use a pullup resistor to 5V supply? 5V is available at pin headers.
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Bernd,

I have tested my circuit with an oscilloscope and discovered some interesting findings (images are attached for reference). When I measure voltage at the ProFET output (pin 5 to power supply GND), I read roughly 6V regardless of PWM input at pin 2. When I attach a load that voltage at pin 5 drops to zero. (I tried with a valve, a valve with a diode in parallel, and also with just a resistor). This voltage remains zero regardless of my PWM setting. Any ideas what I have possibly done wrong?

Thanks,

Adam
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Bernd,

I also made the output an open drain but obtained similar results. In fact my voltage was lower. I was also wondering, the datasheet lacks a graph showing the current applied versus current out, any idea how I can obtain this data?

Regards,

Adam
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forix
Employee
25 replies posted 10 replies posted 5 replies posted
Employee
Adam,

PWM input signal looks good, it should switch the ProFETs output. Please addionally check the GND net.

The high power GND of the ProFET and GND of the load should be connected to GND of power supply directly.

The oscilloscope shows that the output MOSFET does not switch the load to Vbb, bad news. I guess the inductive switch-off energy dissipation of the valve has damaged the body diode in a way that you now have ~0V at the output.

Please refer to the datasheet page 4 and review the data of the valve.

Bernd
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Bern,

That may be possible, I did neglect to place a diode in parallel with the load, however, I have about 10 more, and this time instead of a valve, I used an LED for the load and found the following:

At 0% Duty Cycle I see roughly 1.5V at the output and, with small voltage spikes (picture attached), and the LED was dimly lit.

At 10-90% Duty Cycle I saw 1.5V with small square waves of 12 V (picture attached), and the LED was well lit but its brightness did not change.

At 100% Duty Cycle I saw 1.5V with no spikes (picture attached), and the LED was completely off.

I did also verify that my FET's Input GND and VBB were connected directly to power supply, and placed a diode in parallel with the Load.

Does the fact that I am using a breadboard matter? It seems like I am somehow connecting the FET wrong.

Thanks,

Adam

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forix
Employee
25 replies posted 10 replies posted 5 replies posted
Employee
Adam,

Using a breadboard does not matter except as you say ´there is a Chance that the device is not contacted or wired correctly. Can you post picture(s) of the breadboard showing all your wiring?

Bernd
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Here is a picture of the breadboard connections.


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With these connections I get no output. I also noticed that my scope reads 10V at pin 4 the status pin. That seems a bit high doesn't it?

Thanks,

Adam
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forix
Employee
25 replies posted 10 replies posted 5 replies posted
Employee
Adam,

Please shorten logic GND (XMC4500) and GND of power supply together.

Bernd
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Bernd,

Thanks for your suggestion, it works perfectly now! Thank you very much for the continued support.

-Adam
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