XL6009

Far less than 4 A. The 4 A rating is the internal switch current, and a boost converter's switch carries the input current: IOUT ≈ ISW x (VIN/VOUT) x efficiency. From 12 V to 24 V at 90% efficiency that is about 1.6 A; from 12 V to 35 V it is under 1 A; from 5 V to 12 V it is roughly 1.5 A. The published module curves showing 4 A are input-side or short-duration figures, so always design against the switch current, not the module's optimistic label.

The XL6009 is the big one: 4 A switch, 32 V input, up to about 35 V output, 400 kHz, in TO-263-5 with an exposed tab, suited to 1 A to 2 A outputs from a 12 V rail. The MT3608 is a SOT-23-6 part with a 1.2 MHz oscillator and roughly 2 A switch current for outputs up to 28 V at a few hundred milliamps, and the SX1308 sits below it again at 1 A switch current. Choose by output current and thermal budget: above about 500 mA of boosted current, the XL6009's tab and 110 mΩ switch make it the only one of the three that stays cool.

Three usual causes. First, excessive duty: pushing 5 V to 24 V needs a duty cycle near 80%, above the 90% limit when losses are included, so the converter cannot regulate — keep the boost ratio below about 4:1. Second, an undersized inductor saturating above 4 A peak, which collapses inductance and forces the switch current limit; use a 33 µH to 47 µH part rated for 4 A saturation, not just 4 A thermal. Third, a slow or marginal catch diode and thin PCB copper — fit an SS36/MBR360 Schottky rated above the output voltage and keep the switch loop short.

Yes. The datasheet explicitly supports inverting and buck-boost configurations using the single feedback pin: the output divider is returned to the positive rail instead of ground, and the load sits between the negative output and ground. This is the classic way to build a -12 V or -5 V rail for op-amps and RS-232 from a single supply. Watch the switch voltage rating — the switch sees VIN plus the magnitude of the negative output — and keep that total inside the 36 V absolute maximum.

92% typical is specified at 12 V in, 18.5 V out and 2 A, with up to 94% at lighter loads. Losses come from the 110 mΩ switch, the 2.5 mA quiescent current (about 30 mW from a 12 V rail, which alone caps light-load efficiency), inductor DCR and core loss, and the catch diode forward drop. At 100 mA output from 12 V you will see well under 80%. For light-load-sensitive products use a synchronous boost such as the TPS61088 or MT3608-class part, or enable the EN pin to drop to 70 µA between bursts.

Measure three things. Oscillator frequency on the switch node should be 320 kHz to 480 kHz; clones often sit near 200 kHz or drift with temperature. Switch current limit: ramp a variable load with the feedback pin forced low and confirm the part holds about 4 A before folding back — remarked die typically limit near 2.5 A. Hot resistance: at 4 A the switch drop should be about 0.44 V (110 mΩ); a clone with a smaller die reads much higher and the tab overheats. Physically, genuine XLSEMI TO263-5 parts are laser-marked XL6009E1 with matte tin leads and a solid bonded tab.

MOQ is 100 pcs loose for samples or 800 pcs on tape-and-reel (XL6009TRE1). Shenzhen stock ships in one to two business days; authorised XLSEMI factory lead time is six to ten weeks. Assembled XL6009 boost modules are available in packs of 10 with screw terminals already fitted.