Product Overview
Micrel MIC4575BU - 200kHz 1A Adjustable Buck Regulator, 5-Lead TO-263
Condition
New old stock, unused. The photo shows a representative unit from our stock; the body reads mMIC / 4575BU / 9631 R4 9728 / THAILAND in light lettering on a black molded case, and the reverse shows the large exposed metal tab and five formed leads. Ten on the shelf, sold each. Same or next business day shipping from our Idaho warehouse. Honest pricing, no nonsense. Online since 1999. We are here for our customers, with a no-hassle satisfaction guarantee.
Product Overview
This is the switching regulator you solder down by its exposed tab and forget: a BiCMOS step-down converter with the power switch on the die, so an inductor, a catch diode and a couple of capacitors finish the supply. The MIC4575 is Micrel's 200 kHz drop-in for the 52 kHz National LM2575, duplicating that part's pinout and function per Microchip's published product data, which is why it turns up in repairs of boards that were never designed for it. The units here are Micrel-marked and Thailand-assembled, and the plain BU suffix with no voltage group in front of the B makes them the adjustable version rather than a fixed 3.3 V or 5 V part.
Key Features
- Step-down (buck) switch-mode regulator, switch integrated on chip - buck only, no boost mode
- Input 4 V to 24 V; output adjustable 1.23 V to 20 V, per the published MIC4575 data
- 1 A guaranteed switch current; fixed 200 kHz switching frequency
- Typically better than 75 percent efficiency; plus or minus 2 percent maximum feedback voltage on the adjustable version
- Thermal shutdown and current limit on board; junction temperature range -40 degC to +85 degC
- Five pins - VIN, SW, GND, FB, SHDN - in a 5-lead TO-263 (TO-263-5) surface mount package with an exposed thermal solder tab, not a 6-pin part
- Verify against Microchip's published MIC4575 data before designing in.
Applications
- Dropping a 12 V or 24 V rail to 5 V, 3.3 V or a trimmed intermediate voltage on a board
- Repairing or rebuilding older equipment that used an LM2575 in the same footprint family
- Bench supplies and instrument subassemblies needing a compact 1 A regulated rail
- Replacing a hot linear regulator where the input-to-output gap is wasting watts
Frequently Asked Questions
How many should I order? Order the count your build needs plus whatever you want on the shelf; ten are here and they are sold each, so there is no reel or minimum to work around. Shipping is $8 flat rate and free on orders over $28, so small parts like this ship smartest as part of a larger order.
Is this a fixed 3.3 V or 5 V part? No. Under Micrel's published ordering grammar a voltage group ahead of the B marks a fixed version - MIC4575-3.3BU, MIC4575-5.0BU - and this body reads 4575BU with no voltage group, which is the adjustable 1.23 V to 20 V part set by an external divider on FB. The U is the TO-263-5 package; a T in its place would be the same die in TO-220-5.
It drops into the footprint an LM2575 board already expects and runs at four times the switching frequency, which is the whole of its ambition.
