TLV8544 PIR application problem

yang hu

Other Parts Discussed in Thread: TLV8544

I used your design parameter of TLV8544 for PIR application to simulate circuit as your reference design. however, the result of simulation is not good. the signal of pir cannot be amplified, the gain is just -300db. I used software is TINA and model of tlv8544 of component is from TI.

Would you please tell why?

over 7 years ago

0 Miriam Mesek over 7 years ago

TI__Intellectual 1095 points

Hi Yang,

we are sorry to hear that you are facing some issues.
Can you please share your TINA schematic? It helps us to understand your problem.

Thanks and best,
Miriam

0 Bahram Mirshab over 7 years ago

TI__Expert 3350 points

Hello Yang,

Please provide me your simulation file, I will check it for you. You may also want to use the attached TINA simulation file as a starting point and compare it with yours.

The circuit has been implemented and tested in a demonstration board available for purchase at the TI site; TLV8544 https://store.ti.com/BOOSTXL-TLV8544PIR-and-LaunchXL-CC2650-Bundle-P52062.aspx

A TI reference design, TIDA01398, using the same circuit is also available at TI website www.ti.com/.../TIDA-01398. The refence design is using the same ciruit.

Best regards,

TLV8544_PIR_CKT_051217.TSC

0 yang hu over 7 years ago in reply to Bahram Mirshab

Prodigy 50 points

Hello Bahram;

Thanks to reply me and share your simulation file to me. I checked your simulation, it works well. but my simulation cannot be work well. I don't know why.

Attached please find the simulation of TLV8544 for PIR application.

It will be appreciated if you can explain what the problem is!

Thanks!

BR!

op circuit base tlv8544.TSC

0 yang hu over 7 years ago in reply to Miriam Mesek

Prodigy 50 points

Thanks to reply me.

I share my schematic of simulation. As calculation, the gain should be >80db, but the simulation result is around -300db. I don't know why.

It will be appreciated if you can help me solve this problem.

BR!

4237.op circuit base tlv8544.TSC

0 Bahram Mirshab over 7 years ago in reply to yang hu

TI__Expert 3350 points

Hello Yang,

The problem in your circuit is that the first amp stage (U1) input does not have a bias voltage. I added a 1.5V DC level bias to the input signal source (VG1), the circuit works as expected. I am attaching your fixed simulation file with simulation waveform. To see the fix in the circuit, click on VG1voltage source and notice the added 1.5V DC bias. You could also use the bias voltage of the second stage generated by R2 and R4 divider.

Regards,

4237.op circuit base tlv8544-BM.TSC

0 yang hu over 7 years ago in reply to Bahram Mirshab

Prodigy 50 points

Thanks!

0 yang hu over 7 years ago in reply to Bahram Mirshab

Prodigy 50 points

Hi Bahram;

another question. Why don't TI use normal resistance (619k, 6.81k, 68.1k) for reference design? As my calculation, if I change resistance 6.81k to 6.8k, the cutoff freq. is just change a little.

BR!

0 Bahram Mirshab over 7 years ago in reply to yang hu

TI__Expert 3350 points

Hello Yang,

Should be no problem, you can use 6.8K instead of 6.81k.

Best regards,

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TLV8544 PIR application problem