DRV8873-Q1: For TEC application, may we know how to set up HW&SW?

Bogey,

The EVM user's guide can be downloaded from www.ti.com/.../slvub68
The GUI user's guide can be downloaded from www.ti.com/.../slvubb3
Those documents give the setup from EVM HW/SW. Do you have the detail about TEC application? What is the detail request?

Hi Li

My customer just need quickly TEC cooling and qiuckly heating. no need accurate TEC temperature control.

Customer ever test TPS63070 in TEC application. it can work. but we now change to use DRV8873 because TPS63070 have no Q rating device.

e2e.ti.com/.../2791181

For TPS63070, TI have reference design in TEC, so we know how to use it, and control way we just adj Vout voltage then we can control cooling and heating.

But For DRV8873, we have no idea how to set up it in TEC applcation. or you need us provide what kind data? pls advice.

                                                                                                                             Bogey

1. TPS63070 is a 2~16V buck boost converter with 3.6A switching current.

2. According to your description: the only requirement is: adjust output voltage.

DRV8873H can support output voltage adjustment by setting different duty cycle. The output voltage equals duty cycle * Vin.

a. From the equation, the output voltage is always lower than input voltage.

b. DRV8873H input voltage range is from 4.5-V to 38-V which is different than TPS63070.

c. You have to know what the output current do you want? 

Hi Wang

thanks for your reply,

Is it mean DRV8873 can control TEC cooling only(or heating only)?

Because we use D2D to control TEC cooling (when Vout > Vin) and TEC heating (when Vout < Vin).

                                                             Bogey

Bogey,

DRV8873 wasn't integrated a buck boost converter inside. In general, the VM voltage is higher than OUTx voltage.

Typically, a H-bridge can handle a TEC application. For example: a typical application circuit in DRV8412 datasheet: 8.2.4 TEC Driver.

a. Heating: OUTA/B voltage is higher than OUTC/D voltage.

b. Cooling: OUTC/D voltage is higher than OUTA/B voltage.

DRV8412 and DRV8873 can both support H-Bridge operation. DRV8412 can support operate at up to 500-kHz switching frequency. DRV8873 can only support 100kHz.

If you need both VOUTx>VM and VOUTx<VM with a single motor drive device, we don't have a buck-boost motor drive device so far.

Hi Li

Many thanks for your reply,
Some circuit set up, may we check with you,
1) OUT1/OUT2 also need add L(4.7uH)/C(47uF) in both TEC 2 sides, and TEC need parallel 47uF capacitor?
2) how to connect nITRIP/nOL/SR /nSCS/nSLEEP pins?
3)For GUI, what Rsense 1/Resese 2 /R amp rate value we need to key in ?
Bogey

Bogey,

1. I would think TEC likes a DC voltage at its input terminal. So, the filter is needed. DRV8412 has a higher PWM frequency. So, the size of filter could be smaller than DRV8873's.

2. If you want to use DRV8873H, it doesn't have nSCS pin it is for SPI communication. When you want to enable IC, set nSLEEP pin high.

You can use a 0ohm series resistor to connect nITRIP to DVDD pin. If you leave the 0ohm open, you can get the ITRIP feature. Same as: open load detection pin.

3. Please check the EVM design file to find out the Rsense1/2 and Ramp rate setting.

Hi Li
there have another question that when we set Vout1 6.4V, Vout2 6.94V, so TEC power consumption is 500mW.
VM 7V@0.56A 3.9W(we read from power supply meter). it is mean our DRV8873 power consumption is 3.4W?
May my understand is correct? or some thing i need to check?(we use L(4.7uH)/C(47uF) in output side )
Bogey

Bogey,

How hot is the DRV8873 IC? Can you set VOUT1 near 0V; VOUT2 near 0.54V?