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billr
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We're using the PSFB_3300W (aka EAL_3K3W_BIDI_PSFB) eval board, running in reverse (boost) mode. We're currently setting output parameters via the SMPS GUI app, but would like to control it from another microcontroller in the end product application. The serial protocol is straight forward from the control board source code. What is not clear at all are the various conversion factors to go between ADC counts (which is what the serial protocol uses) to volts, amps and degrees. The controller.h file gives some scaling information, but it's not exact and is confusing.

So, my questions are:

1) is a portion of the SMPS source code available (the part that converts between SI units and counts)?

2) if that part of the GUI source is not available, is there a table that shows the conversions that can be shared?

    -Bill 

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Pranava_YN
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100 likes received 500 replies posted 250 solutions authored

Hi,

All the conversions are present in Converter.cs file attached. Please refer to it and let me know if you have any further questions.

Best regards,
Pranava

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Pranava_YN
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100 likes received 500 replies posted 250 solutions authored

Hi Bill,

Source code directly uses ADC counts rather than the SI units, as the conversion from ADC count to Voltage depends on the ADC VREF (Reference voltage) and external resistor divider ratio. Therefore it's not specified or documented in the source code.

voltage_adc = (Vref / (2 ^ resolution of ADC) - 1) * count_adc.

actual_voltage = voltage_adc * (R1 + R2) / R1    if R1 and R2 are resistor dividers.

Best regards,
Pranava
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billr
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Thanks, Pranava. I understand the generalized formula you provided above. My interest is specifically for the eval board, as that's what we will be using for a protoype build. The source code I was asking about was for the SMPS GUI program, which does the conversion. Since I don't see where Vref is sent in the communications interface between the controller and the GUI, the GUI must be making assumptions about the Vref value and R1/R2 values and shunt R for the current calculations. By looking at the GUI code, I was hoping to save some time from pouring over the PSFB schematics to find those values for Vin. Vout, Iin, Iout and the internal and external temperature sensors.

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billr
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I looked at the schematics (CD10000681 EVAL_3K3W_BIDI_DCDC_CTRL_PCB.pdf and M10000681 EVAL_3K3W_BIDI_DCDC_MAIN PCB.pdf) and the calculations are not quite as simple as it first might seem. The Vin measurement goes through a divider, into a 5v to 3.3v voltage translator, then through an OpAmp. Vout has a simple 2k/47.4k divider, so it's more straight forward. The current measurements are also buffered by an OpAmp. Vref is 2.5V; that is clear. Can you provide the actual conversion values for this eval kit for all four voltage/current measurements and the two temperature measurements? Otherwise, I'll have to get our analog engineer to go through all the calculations.

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billr
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Hi Pranava,

Is there any chance of getting the conversion factors for this Eval board? They should be well known to Infineon, as they are clearly baked into the SMPS GUI tool, provided as an executable as part of the  Exclusive Information package. It would save us a lot of work.

 

 

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Pranava_YN
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100 likes received 500 replies posted 250 solutions authored

Hi,

All the conversions are present in Converter.cs file attached. Please refer to it and let me know if you have any further questions.

Best regards,
Pranava

Thank you so much for the support!

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