Hi all,

I am having some issues with a TPS61023 from Texas Instrument.

I am using WEBENCH Power Designer from TI to design my power supply. (Link https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=596F065B4F17B3A1 to "my" design).

In theory, I can work from ~1.5V to 3.6V to boost voltage up to 3.3V.

However, below 2.5V, the IC "shuts off"...

I checked the feedback pin, it ranged from 0.3V bellow 2.5V input to 0.4;0.6V with input voltage above 3V.

This "power supply" powered an ESP 12F. You can check my PCB design here: https://pro.easyeda.com/editor#id=a962e7a75ae043559788beba2e07cb2e

Is there an obvious problem?
Thanks !

 

How much current is the load?
---edited---
I see 500mA

I have Vin 2.0V and Vout 3.3V at 500mA.

 

ESP 12F ; Around 300mA

 

Hi all,

I am having some issues with a TPS61023 from Texas Instrument.

I am using WEBENCH Power Designer from TI to design my power supply. (Link https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=596F065B4F17B3A1 to "my" design).

In theory, I can work from ~1.5V to 3.6V to boost voltage up to 3.3V.

However, below 2.5V, the IC "shuts off"...

I checked the feedback pin, it ranged from 0.3V bellow 2.5V input to 0.4;0.6V with input voltage above 3V.

This "power supply" powered an ESP 12F. You can check my PCB design here: https://pro.easyeda.com/editor#id=a962e7a75ae043559788beba2e07cb2e

Is there an obvious problem?
Thanks !

Please post the datasheet. Could be there is a quiescent mode.

 

Link for datasheet
It seems to work for me. (using the TI SPICE)

 

Ok, so:
By using the refenrece in the drawing on easy EDA (see attached) with a led as load (~20mA) :
- Vin @3.1V ; - Vout = 3.07V - Vfeedback = ; i =26mA
- Vin @3.0V - Vout = 2.97V - Vfeedback = ; i = 16mA
- Vin @2.8V - Vout = 2.81V - Vfeedback = ; i = 4mA
- Vin @2.5V - Vout = 2.57V - Vfeedback = ; i =? (led is on-ish..)

AND, without a load, evrything fine..
- Vin @3.0V - Vout = 3.320V - Vfeedback = ;
- Vin @2.5V - Vout = 3.321V - Vfeedback = ;
- Vin @1.7V - Vout = 3.321V - Vfeedback = ;

Note : I kill it while probing Vfeedback, i'm soldering a new one.

 

Is the compound résistor the issue ? Like RFBT + Rload = Some wierd value ?

 

Ok, so:
By using the refenrece in the drawing on easy EDA (see attached) with a led as load (~20mA) :
- Vbat @3.1V - VCC = 3.07V - Vfb = 0.554 V ; i =26mA
- Vbat @3.0V - VCC = 2.97V - Vfb = 0.541 V ; i = 16mA
- Vbat @2.8V - VCC = 2.81V - Vfb = 0.510 V; i = 4mA
- Vbat @2.5V - VCC = 2.57V - Vfb = 0.464 V; i =? (led is on-ish..)
- Vbat @2.3V - VCC = 2.57V - Vfb = 0.465 V; i =? (led is on-ish..)
- Vbat @2.0V - VCC = 2.57V - Vfb = 0.467 V; i =? (led is on-ish..)

AND, without a load, evrything fine..
- Vbat @3.0V - VCC = 3.320V - Vfb = 0.805 V;
- Vbat @2.5V - VCC = 3.321V - Vfb = ;
- Vbat @1.7V - VCC = 3.321V - Vfb = ;

Magic Smoke ; I kill it while probing Vfeedback, i'm soldering a new one.

Is the compound resistor the issue ? Like RFBT + Rload = Some wierd value ?

 

What is the part number for L1? I often people using an inductor that is rated for small current.

You are driving a LED directly? with no current limit resistor?

 

What is the part number for L1? I often people using an inductor that is rated for small current.

You are driving a LED directly? with no current limit resistor?

Hi, sorry for late (very late) reply.

Below you will find the inductor. In therory, its rated for 7.5A (Power Pench said inductor rated for 12A, but meh..)

Yes i drive it directly, it was just to see the output current.

You think the inductor is the problem ?
FTC252012SR47MBCA cjiang (Changjiang Microelectronics Tech) Inductors, Coils, Chokes | 6.5A 470nH Winding Inductor ±20% 7.5A SMD,2x2.5mm Power Inductors | LCSC Electronics

 

I believe the error is in selecting passive parts that have DCR and ESR that exceed the design spec. Not just one part but a combination of all CLC parts. I(L)pk = 360% x I(load) @ 1MHz. Layout and FB probing errors (noise radiation) contribute to bad experience.

If you had put in the values chosen into custom parts in Webench, it would have warned you.


Recommended Limits: Your choice
L: 0.37 μH - 2.9 μH 0.47 uH
DCR:1 mΩ - 20 mΩ 15~22 mΩ
IDC: 2.98 A - 10 kA

 

What a quality reply, Thanks !!

I think this project/Topic is quit out of my skill but this is how your learn, right ?

I might be tempted to use the reference part form PowerBench but its a 1$/U !

So, if i read correct, can i use FTC252010SR47MBCD ? Btw, I(L)pk = 1.5 @1MHz