TPS552892: TPS552892

Nasrin Enayatzadeh

Part Number: TPS552892
Other Parts Discussed in Thread: TPS552882

Hi Support team,

I want to use TPS552892 in my design, the System requirements are:

Vin range = 3-20V, Max Iout = 3A and need to have both Vout = 5V and Vout = 12

I have concern at low input voltage, Vin= 3V, Dose the part can provide 3A output current for Vout = 5V and 1.5A for Vout = 12 ?

Also I don't have external 5V available, Do I just connect Vcc to EXTVCC? Is this case still work for low input voltage Vin= 3

If I need to useTI Pspice model do I need to purchase the software?

over 1 year ago

0 Bryce Xun over 1 year ago

TI__Mastermind 27830 points

Hi Nasrin,

Thanks for reaching out. Please expect a late reply due to public holiday. We will be back on May 6th.

BRs,

Bryce

0 Bryce Xun over 1 year ago

TI__Mastermind 27830 points

Hi Nasrin,

Thanks for your patience.

The LDO of TPS552892 selects the power supply by below strategy, so even Vin is 3V, the VCC will still be about 5V since Vout is 5V. And it can cover 3Vin-18W application.

No need to purchase the software, you can download the software and PSpice simulation file from the product page directly.

BRs,

Bryce

0 Nasrin Enayatzadeh over 1 year ago in reply to Bryce Xun

Prodigy 40 points

Hi Bryce,

Thanks for your response. Completed my design, could you please review my design and let me know if needed to change any values of the inductor and loop stability and Do I have enough Cin and Cout for my requirements. So appreciate you help

requirements:

Vin= 3-20V

Vout= 5V and 12V

Iout Max =3A

Current limit not required

Please see the attached, Thanks!

0 Bryce Xun over 1 year ago in reply to Nasrin Enayatzadeh

TI__Mastermind 27830 points

Hi Nasrin,

Please see my comments about the schematic:

1. PG and CC pins are both open-drain connections, it needs to connect to VCC through 100k pull-up resistors.

2. What is the ESR and part number of the output capacitors (C35, C36, C37), then we can check the COMP parameters.

3. Recommend to select the inductor with saturation current>8A.

4. Follow the attached layout guideline.

8880.TPS55289 Layout Guide line.pdf

BRs,

Bryce

0 Nasrin Enayatzadeh over 1 year ago in reply to Bryce Xun

Prodigy 40 points

Hi Bryce,

output cap:

C37, PN: EEH-ZK1V101XP, (ESR: 35 mOhm)

C35, C36, PN: GRM21BZ71E106KE15L

C33,C34, PN: CC0603KRX7R7BB104

Inductor value: PN: XAL7070-472MEC. 4.7uH. Current rate:13.6A, saturation current:15.2A (I have output voltages of 12V and 5V, with Iout max = 3A)

Thanks for your help

0 Bryce Xun over 1 year ago in reply to Nasrin Enayatzadeh

TI__Mastermind 27830 points

Hi Nasrin,

Thanks for feedback, I will look into this and reply to you tomorrow.

BRs,

Bryce

0 Bryce Xun over 1 year ago in reply to Bryce Xun

TI__Mastermind 27830 points

Hi Nasrin,

Sorry for late, due to bandwidth limit, please expect our reply next Monday.

BRs,

Bryce

0 Mulin Yuan over 1 year ago in reply to Bryce Xun

TI__Genius 15160 points

Hi Nasrin,

Thank you for your patient waiting. Recommended compensation: R31=10kohm, C31=15nF, C32=100pF.

By the way, I have concern that in Vin=3V, output 12V/1.5A situation, saying 85% efficiency worst, input current would exceed 7A. which exceed minimum current limit. There is risk that output voltage can be out of regulation. If you change to TPS552882, there will not be such concern.

Regards,

Mulin

0 Nasrin Enayatzadeh over 1 year ago in reply to Mulin Yuan

Prodigy 40 points

Hi Mulin,

there is no requirement for output current limit ( tied Isp and ISN to Vout )

If I change the part to TPS552882:

1) would I still be okay with Cin/ Cout and inductor value I have already ?

2)Does components values you suggested for compensation will stay the same ?

0 Mulin Yuan over 1 year ago in reply to Nasrin Enayatzadeh

TI__Genius 15160 points

Hi Nasrin,

1. I mean average inductor current limit.

Nasrin Enayatzadeh said:
1) would I still be okay with Cin/ Cout and inductor value I have already ?

It is ok

Nasrin Enayatzadeh said:
2)Does components values you suggested for compensation will stay the same ?

Basically compensation is ok, but you can send schematic to us to review again if you change to TPS552882 and we can check it again,

Regards,

Mulin

0 Nasrin Enayatzadeh over 1 year ago in reply to Mulin Yuan

Prodigy 40 points

Hi Mulin,

Please see the attached for updated schematic with TPS552882, let me know I need to change any components. Cin/Cout and inductor PN stayed the same as I mentioned above. Please let me know if you need more information. Thank.

Also could you please explain briefly what you mean by average inductor current limit.