ULC1001-DRV290XEVM: OUTPUT

WONBIN LEE

Intellectual 260 points

Part Number: ULC1001-DRV290XEVM
Other Parts Discussed in Thread: ULC1001, DRV2901

Tool/software:

Hello.

I have some questions.

Q1. I measured PWM A and PWM B of ULC1001 with an oscilloscope.

Is there a reason why PWM A and PWM B are about 180 degrees different?

Q2. Should I use a differential probe to measure the waveform in the picture below? Please tell me where you measure.

over 1 year ago

0 Sydney Northcutt over 1 year ago

TI__Mastermind 18290 points

Hello,

Q1: Yes. When PWM A and PWM B are connected to the respective piezo terminals, the piezo sees the differential voltage. With this configuration you get a larger peak to peak voltage. Measuring this differentially on the scope will make it more clear.

Q2: Yes. You can either use a differential probe or two single ended probes. If you use two single ended probes you can use the math function on your scope to show the differential signal (PWM A - PWM B).

Regards,
Sydney Northcutt

0 WONBIN LEE over 1 year ago in reply to Sydney Northcutt

Intellectual 260 points

Hello.

Is it correct that the output of DRV2901 is DIFFERENTIAL OUTPUT as shown in the photo below?

Do OUT+ and OUT- below mean PWM A and PWM B in DRV2901?

0 Sydney Northcutt over 1 year ago in reply to WONBIN LEE

TI__Mastermind 18290 points

Hello,

Yes, you are correct on both.

Regards,
Sydney Northcutt

0 WONBIN LEE over 1 year ago in reply to Sydney Northcutt

Intellectual 260 points

Hello.

Thank you.

Can you tell me the formula to calculate the impedance and resonant frequency using ISNS and VSNS from the DRV2901 output?

0 Sydney Northcutt over 1 year ago in reply to WONBIN LEE

TI__Mastermind 18290 points

Hi,

Isns and Vsns are used to calculate the current and voltage across the LCS, so impedance is calculated using ohms law (v=ir). The resonance frequency is essentially calculated by finding which frequency has the lowest impedance magnitude.

Regards,
Sydney Northcutt

0 WONBIN LEE over 1 year ago in reply to Sydney Northcutt

Intellectual 260 points

Hello,

I have some questions.
Q1. How do I calculate impedance using ohms law (V=IR)?
Is the R value impedance?

Q2. Are the registers below correct?
USER_Params_ohms_sf _Q22: Resistance (R),
USER_Params_watts_sf _Q18: Power (P)
USER_Params_Imag_max_sf_Q27: Current (I)

0 Kelly Griffin over 1 year ago in reply to WONBIN LEE

TI__Genius 10522 points

Hi Wonbin,

Q1: Yes, R is impedance.

Q2: Yes, there is also one additional scale factor USER_Params_sfaultParams_Imag_threshold_A_Q9

We will release an excel tool to help setup these registers and the IV sense resistor path. If you are not changing the IV sense resistors on the EVM, then the default values loaded by the GUI can be used.

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ULC1001-DRV290XEVM: OUTPUT