LM74670-Q1: Bridged circuit for AC24Vin

ACGUY

Part Number: LM74670-Q1

Hello E2E,

Our customer are considering using the LM74670 for AC24Vin block on during to developing equipment. I obtained the capture of schematic from them. Could TI engineers check this schematic?

Best regards,
ACGUY

over 5 years ago

0 Karikalan Selvaraj over 5 years ago

TI__Genius 16305 points

Thank you for posting question on AC full bridge rectification.

Let me review the schematic and get back to you.

Is the maximum current limited to 8A from the DC load side?

Regards,

Kari.

0 ACGUY over 5 years ago in reply to Karikalan Selvaraj

Guru 11170 points

Hi,

Thank you for your comment,

Output current is limited by DC/DC in the latter stage. And, customer will add the inrush current limiting circuit.

Best regards,

ACGUY

0 Karikalan Selvaraj over 5 years ago in reply to ACGUY

TI__Genius 16305 points

Can you share the customer schematic?

I could not find it here.

Is this question related to the question at "https://e2e.ti.com/support/power-management/f/196/p/896786/3320859#3320859"?

Regards,

Kari.

0 ACGUY over 5 years ago in reply to Karikalan Selvaraj

Guru 11170 points

Hello,

>> Can you share the customer schematic?
Pasted schematic was deleted because by point out from customer. If you need the schematic that please apply to me friendship. I will send the schematic on private message.

>> Is this question related to the question at "E2E_URL"?
Yes.

Regards,
ACGUY

0 Karikalan Selvaraj over 5 years ago in reply to ACGUY

TI__Genius 16305 points

Hi,

I have sent the friendship request, please send the schematic for me.

Regards,

Kari.

0 Karikalan Selvaraj over 5 years ago in reply to Karikalan Selvaraj

TI__Genius 16305 points

I have received the schematic and will review it and get back with comments tomorrow.

Regards,

Kari.

0 Karikalan Selvaraj over 5 years ago in reply to Karikalan Selvaraj

TI__Genius 16305 points

We recommend to have sufficient capacitance for hold up after bridge rectifier (LM74670-Q1) so that the rectified output does not swing along with the AC input.

There is sufficient hold up capacitance (5x 4.7mF) placed after the inductor and another rectifier.

Concern is that if bridge rectifier output is not held up strongly, there may not be sufficient reverse current for LM74670-Q1 to turn off.

If it doesn't turn off, MOSFETs can heat due to AC RMS ripple current flowing.

Could you run simulation using spice model provided and let us know if you need some more help on this one.

Regards,
Kari.

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LM74670-Q1: Bridged circuit for AC24Vin