Hi, I'm facing an issue with the TPS61040.I would like to create an output voltage up to 14V from a 3v3 input voltage. For the drawing I used the typical one described in the chip datasheet. The list of my components: Cin = 4,7µF (X5R)Co = 1µF L1 = 10µH (LQH32CN100K33L from Murata) D1 = MBR0530T1G (from ON Semiconductor) R1 = 1M (+/- 1%) R2 = 100K (+/- 1%) Cff = 33pF
When I change the voltage level on the En PIN I can see the Feedback voltage changing from 0.29V to 1.37V
But the output voltage stays at (3V3 - 0.25V)
I join a picture of my PCB,
Is anyone could help?
The values of the components seen reasonable although the inductor current rating is a bit low, which will limit the maximum output current, and its DCR is really high, which will reduce efficiency and also limit maximum output current capability. If the output voltage does not change when EN goes high but the FB voltage does change, then something is wrong with the FB resistors because the FB pin should follow Vo through those resistors. On the PCB, is R2 connected to GND?
Thanks for your reply,
In the datasheet there is no indication about the DCR value for the inductor :(
I have checked that R2 is grounded, and it is OK.
I have found this part from Murata for the inductor LQH32CN4R7M33L, that offers lower DCR and higher rated current in the same package.
Do you think that could help?
I am not convinced that the inductor DCR is the problem but you could change it. Also make sure that the inductor was installed properly and not shorted.
I don't understand how the output voltage remains constant while the FB pin voltage changes. The FB pin is a high impedance input pin and so it should follow the output voltage, scaled by the FB resistors.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.