TPS562209: About current limit value in customer condition

Tsukui Yusuke

Guru 21930 points

Part Number: TPS562209

Hi,

Our customer would like to know about current limit value(min/typ/max) at the following conditions.

[conditions]
VOUT pattern1 =3.65V
VOUT pattern2 =1.8V
L=4.7uH

Please tell me the overcurrent value of this condition.
I have already confirmed the current limit in the datasheet but this test condition is different from the condition of our customer.

Could you give me your advice?

Best Regards,
Yusuke/Japan Disty

over 7 years ago

0 Yuchang Zhang over 7 years ago

TI__Mastermind 18510 points

Hi Yusuke-san,
The load current is higher than the over-current threshold by one half of the peak-to-peak inductor ripple current. So no matter with Vout voltage is 1.05V or 1.8V, 3.65V. please refer to below post for details.

e2e.ti.com/.../1968732

BR,
Yuchang

0 Tsukui Yusuke over 7 years ago in reply to Yuchang Zhang

Guru 21930 points

Yuchang-san,

Thank you for your information.
Customer's input voltage fluctuates.
In that case, is it correct with understanding that current limit value also changes?
And,Is it correct in thinking to add ripple current to 3.2A(typ)?

Best Regards,
Yusuke / Japan Disty

0 Yuchang Zhang over 7 years ago in reply to Tsukui Yusuke

TI__Mastermind 18510 points

Yusuke-san,

Vin change will cause inductor pk-pk change and then valley value changed as well.
and yes you need add 3.2typ to 1/2 p-p for DC current output.

BR,
Yuchang

0 Tsukui Yusuke over 7 years ago in reply to Yuchang Zhang

Guru 21930 points

Yuchang-san,

Thank you for your support.
Let me ask you one more thing.
I calculated the overcurrent value with the calculation method you taught.
However,It became an overcurrent value larger than a small inductor.
Is this correct in the calculation method?

Best Regards,
Yusuke / Japan Disty

0 Yuchang Zhang over 7 years ago in reply to Tsukui Yusuke

TI__Mastermind 18510 points

Yusuke-san,

Sorry for the typo mistake at last reply, maybe that confuse you, I corrected it right now.
The OCL spec. in DS should be the valley value, if use 1.5uH, the ripple current p-p should be larger than 4.7uh, and then the IDCocl should be bigger.

BR,
Yuchang

0 Tsukui Yusuke over 7 years ago in reply to Yuchang Zhang

Guru 21930 points

Yuchang-san,

Thank you for your information.
I am confused.
Could you tell me calculation example in The following condition?

・Vin=12V,Vout=1.05V,L1=4.7uH
・Vin=12V,Vout=1.05V,L1=1.0uH

I'm sorry to trouble you.

Best Regards,
Yusuke / Japan Disty

0 Yuchang Zhang over 7 years ago in reply to Tsukui Yusuke

TI__Mastermind 18510 points

Yusuke-san,
Take 4.7uH for example, Ip-p/2=0.157
So the Iout DC OCL should be 3.2+0.157 as you calculated.
anyway, valley is ocl spec, and IP-P is varied by VIN, VOUT, L

Regard,
Yuchang

0 Tsukui Yusuke over 7 years ago in reply to Yuchang Zhang

Guru 21930 points

Ychang-san,

Thank you for your time.
When L is changed under the same condition, there is a contradiction in relation to the inductance.
We would like to get your feedback.

	4.7uH	2.2uH	1.5uH
Iocl(typ)	3.357A	3.2A	4.2A

Best Regards,
Yusuke / Japan Disty

0 Yuchang Zhang over 7 years ago in reply to Tsukui Yusuke

TI__Mastermind 18510 points

Yusuke-san.

First, maybe the different indutor value make you confuse, the two typical ocl spec should be 3.2A@tps562209, and 4.2A@563209, no matter with indutcor value.

So as I said, the spec of 2.2uH in DS is Valley value, 3.357 is for DC value of output, valley value spec is still the 3.2A for TPS562209, so no contradiction.

Regards,

Yuchang

0 Tsukui Yusuke over 7 years ago in reply to Yuchang Zhang

Guru 21930 points

Yuchang-san,

I appreciate your kind response.
I understood everything you've said.

Best Regards,
Yusuke / Japan Disty

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TPS562209: About current limit value in customer condition