Will there be any problem if the voltage difference between input and output of the boost circuit is too small?

小太阳yy

Will there be any problem if the voltage difference between input and output of the boost circuit is too small? [Copy link]

 

Is there any problem if the voltage difference between input and output of the boost circuit is too small? For example, if I boost from 19V to 20V, the voltage difference is very small, is there any problem?

maychang

[For example, if I increase the voltage from 19V to 20V, the voltage difference is very small. Will there be any problem? ]

If it's designed correctly, there's no problem.

小太阳yy

maychang posted on 2023-12-14 20:23 [For example, if I increase the voltage from 19V to 20V, the voltage difference is very small. Will there be any problem? ] If the design is correct, there will be no problem.

Won't this cause job instability or something like that?

maychang

Xiaoyangyy posted on 2023-12-14 20:39 Won’t it cause job instability or something like that?

In the boost circuit, the input voltage is only slightly lower than the output voltage, which means that the duty cycle of the PWM pulse is very small, that is, the pulse width is quite small. This requires the control circuit to be able to output narrow pulses. But this does not affect the stability of the circuit.

maychang

Xiaoyangyy posted on 2023-12-14 20:39 Won’t it cause job instability or something like that?

If you are worried that the small difference between input and output voltage will lead to unstable control, you can tap the inductor and output from the tap. This will make the duty cycle slightly larger.

wangerxian

I remember that some chips require a certain voltage difference between input and output, otherwise the output voltage may not be correct. However, if you can output 20V normally, there should be no problem.

qwqwqw2088

There should be no problem if the boost circuit has a small voltage difference, and the efficiency will definitely be high

However, the input of the boost circuit must be lower than the output, and different circuits should have a minimum difference requirement. Otherwise, when the input is greater than the output, the circuit will enter an unstable state.

maychang

qwqwqw2088 is right in the 7th floor. This operating point is at the edge of the working range of the boost circuit. If you want to allow the input voltage to have a larger range of variation, you can use a buck-boost circuit.

小太阳yy

maychang posted on 2023-12-15 10:46 qwqwqw2088 is right on the 7th floor. This operating point is at the edge of the boost circuit's operating range. If you want the input voltage to have a larger range of variation...

Because of some restrictions, I have to use boost, and I am also worried that there will be non-steady-state situations.

maychang

Xiaoyangyy posted on 2023-12-15 20:04 Because of some restrictions, all boosting must be used. I am also worried that there will be non-steady-state situations

[Because of some restrictions, all boost must be used]

So, you are using a boost chip?

If you are using a ready-made boost chip, you must read its instruction manual carefully to see if it can work stably.

小太阳yy

maychang posted on 2023-12-15 20:32 [Because of some restrictions, all boost must be used] So, are you using a boost chip? If you are using a ready-made boost chip, ...

Yes, the chip is used. OK, I am reading the datasheet.