I'm building an LED driver using the LM3410. The internal switch supports a current of about 2A which should be adequate for my needs, but if I need more, can I use an external MOSFET to act as a switch instead? I was thinking a pFET with the gate connected to the switching pin, since in a boost converter the inductor is connected to ground during the charging phase.
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- \$\begingroup\$ There are lots of SMPS ICs to choose from, many will support an optional external switching transistor. \$\endgroup\$KalleMP - CoDidact fan– KalleMP - CoDidact fan2015-07-12 22:46:19 +00:00Commented Jul 12, 2015 at 22:46
- \$\begingroup\$ That is true and I'm looking elsewhere, but I'm asking more in general. There are some non-controller ICs that have very desirable characteristics that I can't find elsewhere. \$\endgroup\$Alex Freeman– Alex Freeman2015-07-13 20:39:52 +00:00Commented Jul 13, 2015 at 20:39
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1 My impression by reading "Theory of operation" and the schematic in figure 13 of the datasheet is that you will break the control loop:
IL ismeasured by the current sense amplifier, which generates an output proportional to the switch current.
- \$\begingroup\$ Oh that's strange. My bad. I assumed from the example circuits that the current was measured with a sense resistor. \$\endgroup\$Alex Freeman– Alex Freeman2015-07-13 20:42:16 +00:00Commented Jul 13, 2015 at 20:42