WEBENCH® Tools/LM5175QUICKSTART-CALC: 12V Project: I/P Voltage 9-16V, O/P Voltage 8.5V, O/P Current 1.2A - 1.8A & 24V Project: I/P Voltage 18-32V, O/P Voltage 18V, O/P Current 1.2A - 2A

Arpit Gandhi

Prodigy 60 points

Part Number: LM5175QUICKSTART-CALC

Tool/software: WEBENCH® Design Tools

Hi,

one of our customer has considered LM5175QPWPTQ1 for below DC-DC LED drivers:

1. 12V Project: I/P Voltage 9-16V, O/P Voltage 8.5V, O/P Current 1.2A - 1.8A

2. 24V Project: I/P Voltage 18-32V, O/P Voltage 18V, O/P Current 1.2A - 2A,

now they are facing problem with circuit that o/p voltage regulation is poor & Noise in circuit board ( Q1 Gate waveform distortion observed as I/p voltage changes). they have referred WEBENCH online tool of TI & component values selected are as per tool only. Still facing Regulation & Noise issues in both board ( 12V & 24V) So please Suggest if any components need to change to overcome these issues or any change is required in schematic or PCB Layout.

please verify attached schematic & PCB Layout and suggest the corrections. Gerber Converter 22.01.2019.zip DC-DC Converter board.xls 3660.schematic.pdf

over 5 years ago

0 Garrett Roecker over 5 years ago

TI__Mastermind 21720 points

Hi Arpit,

Can you please post the waveforms of the Q1 gate?

Thanks,

Garrett

0 Youhao Xi over 5 years ago in reply to Garrett Roecker

TI__Guru 68395 points

Hi Arpit,

Can we assume this is resolved? Lets close this thread but you can always reopen it by following a new post.

Thanks,
Youhao Xi, Applications Engineering

0 Arpit Gandhi over 5 years ago

Prodigy 60 points

Please find above attached waveform for 12V and 24 V system.

0 Youhao Xi over 5 years ago in reply to Arpit Gandhi

TI__Guru 68395 points

Hi Arpit,

Can you specify what are the scope traces?

I also noticed your schematic does not show a clear connection between the having the ground connection between the input capacitor ground and the output capacitor ground. Could you double check that?

Thanks,
Youhao

0 Youhao Xi over 5 years ago in reply to Youhao Xi

TI__Guru 68395 points

Hi Arpit,

Any update? Can I assume the issue is resolved? We are required to close the thread if no activity for a few days. You can always reopen it by a new post.

Thanks,
Youhao

0 Arpit Gandhi over 5 years ago in reply to Youhao Xi

Prodigy 60 points

Please provide confirmation about inductor value & MOSFET Q1 specifications:

Input Voltage: 18V – 32V ( Automotive standard requirement for 24V battery type vehicle system)

Output Voltage: 18V

Output Current: 1.5 Ampere – 2 Ampere.

Frequency of our current PCB board ( measured on scope) : 178 KHz

Customer facing below Problems :

Output load ( LED Lamps) flickers below input voltage 20V & above input voltage 28V.
There is Noise from circuit
Inductor overheats after few Minutes ( We are using 8.2 microHenry inductor. Specifications mentioned above in this mail).

For reference schematic attached above.

LM5175Q1 circuit diagram 08.04.2019.pdf

Please reply on urgent basis as we are going to start production this week.

0 EricLee over 5 years ago in reply to Arpit Gandhi

TI__Mastermind 46011 points

Hi
The responsible engineer is out of office now. He will reply by 4/23.
Regards
EL

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WEBENCH® Tools/LM5175QUICKSTART-CALC: 12V Project: I/P Voltage 9-16V, O/P Voltage 8.5V, O/P Current 1.2A - 1.8A & 24V Project: I/P Voltage 18-32V, O/P Voltage 18V, O/P Current 1.2A - 2A