TPS7B6701-Q1: about capacitor at Figure 21

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Hi Yamamoto san,

Q1. Yes, electrolytic capacitor is also OK. Just make sure the capacitance and its ESR are located in the stable region. Figure 8 or figure 9 in the datasheet page 8.

Q2. That's typical value for the output voltage larger than 2.5V.
In datasheet page 1, you could find the information: Low-ESR (0.001 to 20 Ω) Ceramic Output-Stability Capacitor (10 to 500 µF When VO ≥ 2.5 V, 22 to 500 µF when VO = 1.5 to 2.5 V).

Best regards,
Jason Liu

Dear Jason,

Thank you for your reply.

Additionally, I would like to know about Q1.

Your answer mentioned about Output Capacitor.

How about Input capacitor?

Can we use electrolytic capacitor for Input Capacitor?

If it is OK, what is the range of ESR and capacitor?

Best regards,

Hi Yamamoto-san,

Yes!
If the input supply is located more than a few inches from the TPS7B67xx-Q1 device, an electrolytic capacitor with a value of 47 µF and a ceramic bypass capacitor are recommended to add at the input.
Otherwise, one capacitor larger than 10uF and one ceramic bypass capacitor are OK.
There is no special ESR requirement for the input capacitor.

Best regards,
Jason Liu

Dear Jason,

Thank you for your answer.

I would like to know more clearly.

Question 1,

You said that output capacitor range is 10 u ~500 uF When VO ≥ 2.5 V.

This range is considered error of capacitor value?

For example, if I use 10 uF(+/- 1uF) capacitor, is this out of use?

Question 2,

I would like to know about line transient response to select bypass capacitor.

How voltage should we suppress to stability output?

Best regards,

Hi Yamamoto-san,

Q1:What output capacitor does customer use? And what is the working temperature range?
Please keep the effective value of output capacitor within the range 10u~500 uF.

Q2: Do you mean the input bypass capacitor?
Capacitance is about 0.1uF with voltage higher than 50V.

Best regards,
Jason Liu

Dear Jason,

Customer will use electrolytic capacitor for input capacitor. They assume Ta = -40~105℃.

Yes, I mean the input bypass capacitor.
I understand about 0.1uF with voltage higher than 50V.

Could you give me line transient data?
I would like to know how large this device can handle line transient.

Best regards,

Hi Yamamoto-san,

The device TPS7B6701-Q1 has passed the line transient test with the condition: output voltage range from 1.5V to 18V, load range up to 450mA, input voltage range from Vout+0.5V to 40V with the fastest slew rate is 10V/us.

Best regards,
Jason Liu

Dear Jason,

Did you mean that this device output same voltage when line transient 10V/us input?
Is this correct?
My customer concern about output behavior when 3V ripple voltage input.

If you have line transient picture, could you give me?

Best regards,

Hi Yamamoto-san,

Input voltage ripple and the line transient, they are different in definition.

For the line transient, it refers to the input voltage change from one stable DC voltage to another stable DC voltage in one certain voltage slew rate.
As for this device, it has passed the line transient test with the condition: output voltage range from 1.5V to 18V, load range up to 450mA, input voltage range from Vout+0.5V to 40V with the fastest slew rate is 10V/us.

But for input voltage ripple, 3V is too large, we cannot make any promise for the output voltage.

Do you know why the input voltage condition is so bad?

Best regards,
Jason Liu