TPS63000 - Specifications @ –40°C to 85°C temperature range?

Hi Jeferson,

1. Vfb is spec'd over the recommended free-air temperature range and over recommended input voltage range. So, over those temp ranges Vfb should lie between 495mV and 505mV. At 25C one can expect 500mV for Vfb.
2. Isw switch limit is spec'd for Vin = 3.6V and Ta = 25C. When designing a robust system over your intended temperature range please design with margin in order to accommodate this.
3. As for your design schematic, it is recommended that you either increase your ceramic output capacitance or decrease your inductance. Try 40uF ceramic output capacitance, 2 more 10uF caps. Another thing to keep in mind is the derated capacitance value of your ceramic caps. It is always good to design with at least 2x the voltage rating on any ceramic capacitors so, be sure to use 10V caps on your output.

Hi.

1. Ok. I will consider that for an ambient temperature range of -40°C to 85°C , the feedback voltage can range from 495mV (MIN) to 505mV (MAX), thats right?

2. Ok. There is a good margin already.

3. The 10uF / 0805 capacitors shown in the schematic are ceramic SMDs and rated for 16VDC.

I will do the following changes:

- Add one more ceramic capacitor (10uF / 16V / SMD 0805) at the input.

- Increase electrolytic capacitor of the output to 470uF x 10V, Aluminium SMD, Low ESR, from FK Series from Panasonic. I have this capacitor model in my stock, that I 'm using for another products

OBS: In my design, the VIN range of TPS63000 will be 2,3V and 4,3V in the worst caseS (BUCK-BOOST-VIN at the schematic). Any problem with that?

Here is the datasheets of 4.7uH inductor and electrolytic capacitors. Both 100uF 16V and 470uF 10V are from FK Series (Panasonic)

http://www.yuden.co.jp/ut/product/category/inductor/NR3015T4R7M.pdf

http://industrial.panasonic.com/www-cgi/jvcr13pz.cgi?E+PZ+3+ABA0120+EEEFK1C101P+7+WW

Thanks

Thanks.

Jeferson,

1. Yes, the Vfb can vary over that voltage range. If you are operating at any temperature between -40C and 85C your Vfb is specified to maintain between the 495mV minimum and 505mV maximum.
2.  
3. For an inductor of that size, 4.7uF, TI would recommend you design with 4 10uF ceramic capacitors. 16V rated cap will work great, no problem there. The other thing you can do is reduce your inductor to maybe 2.7uF Then you can keep your capacitors to 2x10uF ceramics.

To comment on your application I will need to know your output current and what kind of load are you powering? What kind of transients are to be expected on your output?

Hi.

About your third question:

- Estimated mean consumption at the 3.9V output: 280mA

- Estimated peak at the 3.9V output: 1.4A during 500us, each 10 seconds interval. There is a peak current consumption, but with a very low "duty cycle"

About the ceramic caps: are you talking about the output ceramics, right?

Jeferson,

You might have an issue when Vin is 2.3V. At the low end of your Vin range, 1.4A is definitely out of the spec'd maximum output current capable of the part. (see figure 1 in the DS) But, since  you are pulsing the high current I think you will have to get an EVM and test it with your load and circuit changes. If you can increase your minimum Vin that would help. Take a look at TPS63020, it might help you out.

Hi.

Ok. I will get some samples of TPS63020 at Digikey. 

Can I use the EVM bellow????

http://www.digikey.com/product-search/en/programmers-development-systems/eval-boards-dc-dc-ac-dc-off-line-smps/2622539?k=TPS63020

I am waiting to receive these inductors to test with the TPS63000.

http://www.digikey.com/product-detail/en/NR3015T4R7M/587-1649-1-ND/1008264

http://www.digikey.com/product-detail/en/NR3015T3R3M/587-2619-1-ND/2349990

http://www.digikey.com/product-detail/en/NR3015T2R2M/587-1648-1-ND/1008263

http://www.digikey.com/product-detail/en/NR3015T1R0N/587-1647-1-ND/1008262

I am going to USA next weeks so I can get some of these EVMs at Digikey.

OBS: The minimum VIN of TPS63000 (2,3V), actually, is the cut-off voltage of the Li-ion batteries we will use (Li-Ion with 18650 case). The batteries we will use have an internal UVLO protection (at around 2,3~2,5V)

QUESTION: TPS63000 have internal over-current protection for its switches, right?

Thanks.

Jeferson,

Answer: Yes, 1.8A switch current limit for all switches.

You can order the EVM and samples from our website. TPS63020EVM-487, TPS63020, TPS63000EVM-148 and TPS63000

It is recommended to use the inductors listed in the datasheet or the on the EVM.