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DRV8873: Motor drivers forum (TEC)

Jerome Blanc-Gonnet
Prodigy 30 points
Part Number: DRV8873
Other Parts Discussed in Thread: DRV8962, DRV8262

Tool/software:

Bien sûr ! Voici la traduction en anglais de votre texte :

Subject: Technical inquiry about using the DRV8873 to control a Peltier module and a heating resistor

Dear Sir/Madam,

My client wishes to control the temperature of a plate used to heat a sample. Depending on the application, the temperature will be regulated either by a Peltier module or a heating resistor. Here are the specifications of the components involved:

  • Peltier module: CP10,31,08,L1,W.4.5 by LAIRD
  • Heating resistor: maximum power 80 W

The goal is to use a single controller to operate either the Peltier module or the heating resistor.

I have several technical questions on this matter:

  1. I am considering using the DRV8873 for this functionality. Do you think this component is suitable for the application?
  2. For the Peltier module, the DRV8873 would be configured in PWM mode, and for the heating resistor in PH/EN mode. Does this configuration seem appropriate to you?
  3. Do you have a reference schematic for controlling a Peltier module with the DRV8873?
  4. Is there a calculation method for determining the parameters of an appropriate LC filter?
  5. From my research, the cutoff frequency of the LC filter should be at least 10 times lower than the PWM frequency. Can you confirm this guideline?

Thank you in advance for your assistance, and please don’t hesitate to contact me for further information.

Best regards,
Jérôme Blanc-Gonnet

  • 0
    TI__Mastermind 48505 points

    Hi Jerome,

    Thank you for posting your question in this forum.

    Jerome Blanc-Gonnet said:
    I am considering using the DRV8873 for this functionality. Do you think this component is suitable for the application?

    Based on the TEC datasheet the Imax specification is 2.5 A is well within the DRV8873 drive capabilities. As long as the power dissipation is within the capability of the device under this operating condition the DRV8873 can support. The power dissipation and estimation of the die temperature can be calculated using formulae is section 8.2.1.2 Drive Current and Power Dissipation of the datasheet, page-41.

    The heating resistor is described as 80 W max. power. What would be the operating voltage? Based on this the current would vary for 80 W operation. The power dissipation must be calculated to see if the DRV8873 would be a good fit.

    Jerome Blanc-Gonnet said:
    For the Peltier module, the DRV8873 would be configured in PWM mode, and for the heating resistor in PH/EN mode. Does this configuration seem appropriate to you?

    The output drive from the H-bridge would be same for either of those drive modes. The heating resistor load would not support current regulation. The DRV8873 provides current regulation using internal tON and tOFF voltage chopping. To leverage this internal current regulation the load must have inductance to slow down the current rise and fall times. A suitable series inductor could solve the issue. Alternatively, internal current regulation can be disabled and the drive PWM duty cycle can be used to set the effective average voltage across the resistor load. Keep in mind during the PWM on the V/R continuous current must be within the DRV8873 drive capabilities.

    The TEC drive typically would use higher frequency PWM such as 100 kHz (the maximum supported by this device) along with LC filters which would mitigate the current rise and fall times. 

    Jerome Blanc-Gonnet said:
    • Do you have a reference schematic for controlling a Peltier module with the DRV8873?
    • Is there a calculation method for determining the parameters of an appropriate LC filter?
    • From my research, the cutoff frequency of the LC filter should be at least 10 times lower than the PWM frequency. Can you confirm this guideline?

    We have this information for a different product. This is generic enough to apply to any half-bridge or full-bridge drivers. The DRV8962, https://www.ti.com/lit/ds/symlink/drv8962.pdf section  8.1.4 Driving Thermoelectric Coolers (TEC) page-34 and the DRV8262, https://www.ti.com/lit/ds/symlink/drv8262.pdf section 7.1.3 Driving Thermoelectric Coolers (TEC) page-38.    

    In addition to these you can search for keywords "DRV8962 TEC" and "DRV8262 TEC" in the TI E2ETm design support forums https://e2e.ti.com/.  

    Regards, Murugavel