Regarding GND connections in TPS61032

Thank you for the reply...
Actually i need fixed +5V o/p, so i m not using resistors R3 and R4 on FB pin. So should i use a single ground for all ??
Also, i m having confusion in equation no.3 on page.13 of the datasheet that requires VBAT value in equation. What should be the value of VBAT here if i m using a battery at input ?? Is it minimum VBAT voltage...? if yes than it should be 1.8V as the min. input voltage to regulator is 1.8V. Right ??

you can connect the GND directly to thermal PAD. and if LBI function accuracy is important to your application, make sure not power current flowing through the GND track of the divide resistor for the LBI pin.

what is the input voltage range in your application? the VBAT in the equation should be higher than 1.8V.

thanks
Jasper Li

Input is the battery of 3.7V 1000mAh Li-Ion/Li-Pol

in the li-ion input voltage application, i would suggest TPS61230 instead of TPS61030. I guess the input current will not higher than 1A, so you can have a look at TPS61253 series or TPS61252.

thanks
Jasper Li

ok but the min. input is that case will be 2.3V. since the input is battery, the min. input voltage should be as low as possible for longer battery back-up

Regards
Kamesh Lakhwani

it is impossible that a li-ion battery can go to 2.3V. the lifetime of the battery will be hurt . and the battery can't output energy at this voltage.

thanks
Jasper Li

Ok thanks. what will be the minimum o/p voltage of Li-Ion battery when/while it gets discharge ?

Here, i chose TPS61032 thinking that while discharging the battery voltage will be getting reduced. Since the minimum i/p of TPS61032 is 1.8V, for the battery output less than 1.8V the regulator will not function. Also, the output from regulator that i required is minimum 5V 1A.

I was also looking for a regulator which has minimum i/p voltage less than 1.8V so that the regulator will give me fixed +5V 1A o/p for a longer period of time.

Thanks
Kamesh

the minimum voltage of li-ion is between 3V~3.3V (relate to the material of the battery) . please refer to the datasheet of the battery planning to use.

may i know the end-product of your project and what does the boost converter power?

thanks
Jasper Li

It will power microcontroller and other low power peripherals

Thanks

Kamesh

hi Kamesh
i'm wandering why a microcontroller and low power peripherals need this large current 1A ?

thanks
Jasper Li

Hi Jasper Li,

I m using 3.7V Li-Ion/Li-Pol battery. what would be VBAT in the equation no. (3) on page.13 ? it would be equal to my battery voltage 3.7V only or min. battery voltage when it is discharging ?

Thanks
Kamesh

Hi Jasper Li,

Any updates ??

Regards

Kamesh

hi Kamesh
the minimum battery voltage, so the VBAT in the equation could be 3V. the LBO will indicate low when the VBAT voltage is lower than 3V. but the device does not shutdown automatically .

may i know how are you going to use this function?

thanks
Jasper Li

Hi Jasper Li,

Thanks for the reply...
Actually, we are connecting +3.7 V Battery at the i/p. Now, as the battery goes on discharging the voltage also goes on decreasing....We want to utilize the full i/p range i.e; 1.8-3.7 V (in this case) of the regulator so that it gives us continuos +5V at the o/p till the battery voltage at i/p is greater than or equal to +1.8 V. So, i think the VBAT should be greater than or equal to +1.8 V... Applying this thought and substituting value of R2=390K ohms, value of R1=1.014M ohms... right??? Correct me if i m wrong...

Also, i m using a common GND for all the connections in the regulator. please give your feedback on this asap...

Regards
Kamesh

hi Kamesh
the LBI/LBO is just for indicate battery voltage information. it does not shutdown the device. in your application, you can set VBAT to 1.8V or just connect the LBI to GND.
The device only shutdown when the VIN is lower than approx. 1.7V.

yes, you can using common GND and please share the PCB when it ready.

thanks
Jasper Li

Hi Jasper Li,

We want to indicate battery information only...since it is rechargeable battery, we want the indication of Low battery and so we need the LBO output. This LBO o/p, we will give to our microcontroller. So i m asking you the VBAT voltage at which we should consider it as Low battery.

Also, my question here again is what would be VBAT in the equation if i m considering this scenario ? Will the value of VBAT in the equation depend upon the min. battery voltage or min. input voltage of the regulator(i.e; 1.8V)..??

Regards
Kamesh

hi Kamesh

"Will the value of VBAT in the equation depend upon the min. battery voltage or min. input voltage of the regulator"
no sure if i understand your question correctly, could you draw a figure to show your idea? the LBI/LBO is just a comparator. you can define how to use it depend on your application. i think it could be any value no lower than 1.8V.

Thanks
Jasper Li

Hi jasper li,

I got the idea of using the comparator. R2=390K ohms, R1=1.44M ohms, VBAT=2.3 V, so VLBI=0.49 V. i m using 2.3 V battery voltage as reference. as the battery voltage becomes 2.3 V, the LBO pin will go low since the threshold voltage of LBI is 0.5 V. LBO is connected with the microcontroller which indicates my low battery...

Regards
Kamesh

LBI/LBO is good for this application.

Thanks
Jasper Li

Hi Jasper Li,

So am i sounding correct this time ? I need LBO o/p for my controller to indicate low battery by keeping the VLBI-threshold=0.49 V. At VBAT= 2.3 V my LBO will be low else it will be high. correct?

Regards
Kamesh

yes. correct

but this comparator is disable when EN is disable.

thanks
Jasper Li

thank you very much for the support...

Regards
Kamesh

Hi Jasper li,

Can you please send the layout guidelines for TPS61032  TSSOP-16 package..? the one is datasheet id for QFN package.

Also, a layout guideline is available from the EVM at:   But  that too is not understandable. The schematics and layout seems to be out of sync with each other here.

Regards

Kamesh Lakhwani

"The schematics and layout seems to be out of sync with each other here."
no sure about the meaning. could you point out which component didn't match in PCB and schematic?

i think EVM is a good example to follow

thanks
Jasper Li

Hi Jasper Li

The placement of components in figure.1 on Page.4 seems to differ from the layout shown in Figure.2 & 3.

Placement of comps. like inductor L1, C1, etc. could not be determined from fig.2. Can you please help out ?

Regards
Kamesh Lakhwani

please refer following figure. you can find other components by comparing the figure 1 and figure 2.

Hi jasper Li,

Got it !! Thanks a lot...

Regards

Kamesh

Hi Jasper Li,

I have used R1 = 1M ohm, R2 = 270K ohm. So according to equation (3) in the datasheet, if my input voltage/VBAT is 2.35V then the LBO should go low... But this does not happen and the LBO pin remains active high all the time. Please suggest what to do asap...

Regards
Kamesh Lakhwani

did you set the EN pin to high logic? because this circuit only works when EN is high

yes i have connected it to high logic...i.e; it is connected to VBAT

could you share the schematic and layout?
please measure the LBI and LBO voltage at the pin of the device, make sure the LBI voltage at the IC's PIN is really lower than 0.49V, (the minimum voltage of this reference voltage)

Hi jasper Li,

The problem is solved..sorry for late reply.

Regards

Kamesh Lakhwani