TPS54020: questions about regulator operation

Hello,

thanks for your kind answer.

Here's some additional questions.

Why does the R bottom value range have to be between 1kohm and 3khom?

What is the problem with the R bottom value of 15Kohm?

The R top required to implement the AVS function required on the chip is more than 9kohm, and the R bottom value to match Voutput 1.0V is more than 15Kohm.

I wonder whether the following chip AVS HW setting can not be applied with TPS54020RUWR.

For reference, the load specification of the power supply is as follows.

Each output voltage / Max current: 1.0V / 7.476A

thanks,

TS

I would like to request a review of the below attached TI Power.

TI power review.pdf

1. load conditions: each input voltage: 12V / each output voltage: 1.0V / output current rms: 7.476A,

Output efficiency: 90% or more
Output voltage accuracy: +/- 2%

2. power sequence : ratio-metric and simultaneous startup sequence ; tracking 3.3V (net name : VCC_3_3)- see the figure below

We will ask you to:
1. Schematic review result
2. Output efficiency (1.0V) waveform
3. Output waveform (3.3V, 1.0V x8)

thanks,

TS

Hi,

The formula used depends on the type of sequence. Please confirm that the schematic I attached before is correct to be in the following sequence.

The methodology used when calculating component values is as below.

1. Refer to online simulate & Typical application.
  -> The input and output capacitor values are different from each other, I would like to ask what value would be better.

Enter a value as below.

Equations used when calculating component values.

TPS54020

Ratiometric and Simultaneous Startup Sequence equations

ΔV = 0 (because, The ΔV variable is zero volts for simultaneous sequencing. )

Vout1 = 3.3V (ß track target)

When, Rtop =10kohm, Rbot = 14.3kohm,

Vout2 = 1.0195V ß Equation 1

RS1 > 9.24Kohm ß equation 8

When, set RS1 = 12.7kohm,

RS2 = 18.1kohm ß equation 6

Set RS2 = 19.1kohm (only available resistor value)

Thus,

Rtop =10kohm

Rbot = 14.3kohm

RS1 = 12.7kohm

RS2 = 19.1kohm  

In addition, I have questions about artwork.

In the typical application, designed GND by PGND and AGND as below. At what point exactly does PGND and AGND short?

I would like to ask if it is better to keep VIN bypass and PVIN bypass apart as shown below.

The PGND area and the AGND area are divided into separate planes as described below, and only connected to the vias, is that right what I understand?

thanks,

TS

Hello, TI

We have set the values as shown below with reference to the comments you sent.

1. Can RS1, RS2, Rtop, Rbot be applied to the following values?

Hi I am Yoo Jae cheon. Dasan networks engineer.

I am asking you again because there are still something confusing me.

First, you mentioned a typo in EQ 5,

You have changed two things at once.

Vout2 à Vout1 ,

and

Vout1 * delta V à Vout1 + delta V.

But in my calculation below, changing Vout2 à Vout1 in EQ 5 doesn’t seem to correct.  

In my calculation, I guess Vout2 should be applied in EQ 5 in order to track 3.3V as you mentioned.

(See the figure 21 below where Vout1 and Vout2 refers to)

So I have applied Vout2 (1.0V) in EQ 5 instead of Vout1 (3.3V)

And then I could have calculated exact same result as you did.

Vss = 29mV, Iss =2.3uA, Vout2 = 1.0 V

According to modified EQ 5,

Register for Ratio-metric and Simultaneous Startup,

RS1 = 21.014kohm, (which you mentioned as the top resistor) à 21kohm (standard)

RS2 = 31.521kohm. , à 31.6kohm(standard)

According to EQ 1

Register for output voltage, Vout=1.0195V

R4(Rupper) =10kohm

R8(Rlower) = 14.3kohm

2. I do not think there is any review on the circuit diagram I have given you before.Is it possible to design with the following structure?

thanks,

TS