i have been working on making a boost converter circuit to incorporate into my PCB and have ordered these inductors. I believe i have tracked down the datasheet(difficult with these cheap chinese parts) and it looks like the max dc current is 1A which is fine for me. i just wanted to ask if i was correct in my judgement as i am not completely confident and dont want to use an inductor which cant handle the current. thanks!
\$\begingroup\$
\$\endgroup\$
3
-
\$\begingroup\$ It would be helpful to include the schematic of your PCB, and the requirements of your boost converter \$\endgroup\$– MIL-SPECCommented Jun 11, 2019 at 8:59
-
\$\begingroup\$ Never buy electronic components that don't have a linked data sheet or are not sold from someone who is reputable. Even if they have a DS and are from a good source, you read the DS first and raise questions before buying. \$\endgroup\$– Andy akaCommented Jun 11, 2019 at 9:08
-
\$\begingroup\$ At what temperature are the datasheet promises made? and are the promises WORST_CASE or nominal? at 25C only? \$\endgroup\$– analogsystemsrfCommented Jun 11, 2019 at 15:24
Add a comment
|
1 Answer
\$\begingroup\$
\$\endgroup\$
8
1A through such a small inductor might be just below its saturation point but that might not be enough.
I mean: even if these inductors can handle up to 1 A that will not be enough to use in a 1 A output current boost converter.
In all DCDC converters the inductor must be able to handle a higher current than the required output current. That is because the average current through the inductor is the same as the output current but the peak current can be much higher.
In a boost converter the peak current during the charging phase of the coil can be quite high, in some circumstances (low input voltage and high output voltage) much higher than the output current.
Note that when an inductor saturates it will behave like a very low value resistor. In some cases where there is no overcurrent protection, this can damage the switching transistor.
answered Jun 11, 2019 at 9:19
-
\$\begingroup\$ the saturation point according to the datasheet is 1.4A. I will be using the boost converter to power a small servo motor which according to my measurements doesnt get higher than 200mA but i am aware that the stall current may be higher...? \$\endgroup\$ Commented Jun 11, 2019 at 9:22
-
1\$\begingroup\$ @user2105725 I would imagine that you'd need to look at the datasheet of the converter IC, not the inductor. \$\endgroup\$– LundinCommented Jun 11, 2019 at 9:25
-
\$\begingroup\$ the converter ic is the mt3608 and can handle 2A so is fine. this is the only component i am unsure of because i am modifying a design to make it smaller. \$\endgroup\$ Commented Jun 11, 2019 at 9:27
-
\$\begingroup\$ the converter ic is the mt3608 and can handle 2A Then still the datasheet is leading, the current ripple (min and max current) through the inductor also depends on the switching frequency and the value of the inductor. So saying "the switch can handle 2A" means you do not fully comprehend DCDC converters. The MT3608 switches at 1.2 MHz, how do you know that this inductor is still OK at that frequency: you don't because you have no datasheet. \$\endgroup\$ Commented Jun 11, 2019 at 9:34
-
\$\begingroup\$ i certainly dont fully comprehend dcdc converters. i am a hobbyist. i just want to make sure i dont set anything on fire. \$\endgroup\$ Commented Jun 11, 2019 at 9:56