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A couple of problems stick out; one glaring and one a little subtler. Read this in the data sheet: - You have the enable pin connected to your 25 volt output. I'm not saying this is definitely cau...
Answer
#4: Post edited
by
Andy aka
·
2020-06-29T10:43:36Z (over 4 years ago)
- A couple of problems stick out; one glaring and one a little subtler. Read this in the data sheet: -
- 
- You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: -
- 
Other than that your circuit values looks compatible with the data sheet but what is the loading you are using on the output? The inductor you have used isn't the LQH43CN100K03 recommended in the data sheet of the chip - is there a reason why you have chosen that part?I'm not convinced that the inductor you have chosen is suitable for such high frequency operation. In the data sheet they don't give much detail about self-resonant-frequency whereas the Murata part is quoted at 23 MHz.- The inductor you have chosen only says that the inductance was tested at 100 kHz and this, in my opinion, hints that it probably isn't suitable for a boost converter running at nominally 1.2 MHz.
- A couple of problems stick out; one glaring and one a little subtler. Read this in the data sheet: -
- 
- You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: -
- 
- Other than that your circuit values looks compatible with the data sheet but what is the output load you are using?
- The inductor you have used **isn't** the Murata LQH43CN100K03 part recommended in the data sheet of the chip - is there a reason why you have chosen that part? I'm not convinced that the inductor you have chosen is suitable for such high frequency operation. In the data sheet they don't give much detail about self-resonant-frequency whereas the Murata part is quoted at 23 MHz.
- The inductor you have chosen only says that the inductance was tested at 100 kHz and this, in my opinion, hints that it probably isn't suitable for a boost converter running at nominally 1.2 MHz.
#3: Post edited
by
Andy aka
·
2020-06-29T05:14:14Z (over 4 years ago)
Read this in the data sheet: -- 
- You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: -
- 
Other than that your circuit looks compatible with the data sheet but what is the loading you are using on the output? The inductor you have used isn't the LQH43CN100K03 recommended in the data sheet of the chip - is there a reason why you have chosen the part you did?- I'm not convinced that the inductor you have chosen is suitable for such high frequency operation. In the data sheet they don't give much detail about self-resonant-frequency whereas the Murata part is quoted at 23 MHz.
- The inductor you have chosen only says that the inductance was tested at 100 kHz and this, in my opinion, hints that it probably isn't suitable for a boost converter running at nominally 1.2 MHz.
- A couple of problems stick out; one glaring and one a little subtler. Read this in the data sheet: -
- 
- You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: -
- 
- Other than that your circuit values looks compatible with the data sheet but what is the loading you are using on the output? The inductor you have used isn't the LQH43CN100K03 recommended in the data sheet of the chip - is there a reason why you have chosen that part?
- I'm not convinced that the inductor you have chosen is suitable for such high frequency operation. In the data sheet they don't give much detail about self-resonant-frequency whereas the Murata part is quoted at 23 MHz.
- The inductor you have chosen only says that the inductance was tested at 100 kHz and this, in my opinion, hints that it probably isn't suitable for a boost converter running at nominally 1.2 MHz.
#2: Post edited
by
Andy aka
·
2020-06-29T05:12:16Z (over 4 years ago)
- Read this in the data sheet: -
- 
- You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: -
- Read this in the data sheet: -
- 
- You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: -
- 
- Other than that your circuit looks compatible with the data sheet but what is the loading you are using on the output? The inductor you have used isn't the LQH43CN100K03 recommended in the data sheet of the chip - is there a reason why you have chosen the part you did?
- I'm not convinced that the inductor you have chosen is suitable for such high frequency operation. In the data sheet they don't give much detail about self-resonant-frequency whereas the Murata part is quoted at 23 MHz.
- The inductor you have chosen only says that the inductance was tested at 100 kHz and this, in my opinion, hints that it probably isn't suitable for a boost converter running at nominally 1.2 MHz.
#1: Initial revision
by
Andy aka
·
2020-06-29T04:55:54Z (over 4 years ago)
Read this in the data sheet: -  You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives you the symptoms you are seeing: - 