TPS65261-1 Automatic Power Sequencing

tateo yamashiro

Other Parts Discussed in Thread: TPS65261-1

Hi,

My customer has question about TPS65261-1.
Could you tell me about questoin?

[Question]
My customer considers to design Automatic Power Sequencing under the following condition.
(Buck2 -> Buck1 -> Buck3)

- Case 1 -
Vin=5V
Mode: High (pull up to Vin)
EN1: Low
EN2: High (pull up to Vin)
EN3: Open (pull up to internal current source)

- Case 2 -
Vin=5V
Mode: High (pull up to V7V)
EN1: Low
EN2: High (pull up to V7V)
EN3: Open (pull up to internal current source)

In datasheet figure 29 shows sequence requirement between MODE and ENx.
(EN1 and EN2 -> MODE -> EN3)
Can the device use with Case 1 and Case 2?
And which is better, Case 1 and Case 2?

Best Regards,
tateo

over 9 years ago

0 Jason Wang (BSR-MV) over 9 years ago

TI__Genius 9550 points

Tateo,

MODE, EN1, EN2 and EN3 have internal pull up circuit, so the pins do not need pull up to Vin, floating means HIGH.

Suggest:

Vin=5V
Mode: High (floating)
EN1: Low
EN2: High (floating)
EN3: Open (pull up to internal current source)

("floating" and "open" are same in upon content)

Jason Wang

0 tateo yamashiro over 9 years ago in reply to Jason Wang (BSR-MV)

Guru 10890 points

Thank you for your reply.
My customer has other question about RESET function.

My customer wants to monitor input voltage(5V) by VDIV. If input voltage is lower than threshold voltage, my customer wants the IC will be shutdown.
So my customer considers to use RESET pin pull up to EN3.
And bypass capacitor(0.47uF) is added to EN3 pin.
Can the device use with this usage?

Best Regards,
tateo

0 Jason Wang (BSR-MV) over 9 years ago in reply to tateo yamashiro

TI__Genius 9550 points

Tateo,

The device can support this application!

Jason Wang

Power management

Power management forum

TPS65261-1 Automatic Power Sequencing