LM5009MMX from Texas Instruments, in a VSSOP-8-0.65mm. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	SW	output	Switching output. Power switching node of the integrated N-channel buck MOSFET. Connect to the buck inductor, recirculating (freewheeling) diode, and the bottom plate of the bootstrap capacitor. Absolute maximum steady-state SW voltage is -1 V referenced to RTN.
2	BST	power_in	Boost pin. External bootstrap capacitor (0.022 uF ceramic recommended) between BST and SW that provides gate drive for the internal high-side buck switch. An internal diode charges the bootstrap capacitor from VCC. BST-to-VCC absolute maximum is 100 V; BST-to-SW absolute maximum is 14 V.
3	RCL	input	Current limit off-time set pin. A resistor from RCL to RTN programs the off-time asserted when a current limit event is detected. Off-time defaults to 35 us when FB = 0 V (RCL = 100 kOhm).
4	RTN	power_in	Ground return pin. Ground reference for the entire circuit and current-return path for the internal buck switch and control logic.
5	FB	input	Feedback input from the regulated output. Connects to the inverting input of the internal regulation comparator with an internal 2.5-V reference (2% accurate over -40 C to +125 C). An overvoltage threshold at 2.875 V turns the switch off. FB bias current is 1 nA typical.
6	RON/SD	input	On-time set pin and remote shutdown. A resistor from RON/SD to VIN sets the switch on-time as a function of VIN (feed-forward). Minimum recommended on-time is 250 ns at maximum input voltage. Pulling this pin below ~0.7 V (typ) shuts the device down; IN shutdown current is 76 uA typical.
7	VCC	power_out	Output of the internal high-voltage startup regulator (7.0 V typical, 6.6 V to 7.4 V). Provides gate-drive power for the internal buck switch. If an auxiliary voltage above ~7 V is applied, the internal pass regulator shuts down to reduce dissipation; do not exceed 14 V. An internal diode connects VCC to BST. A 0.1-uF local decoupling capacitor is required.
8	VIN	power_in	Input voltage supply pin. Recommended operating range 9.5 V to 95 V; absolute maximum 100 V referenced to RTN. Supplies the internal startup regulator and the top of the buck switch through the internal MOSFET.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	VSSOP-8-0.65mm
Category	PMIC
Pins	8

Ordering variants

Same part, different packaging or reel option.

LM5009MMX
LM5009MMXDGK
LM5009MMXSD
LM5009MMXSDX
LM5009MMXNGU

CAD (KiCad official)

Symbol: LM5009MMX
Footprint: Package_SO:VSSOP-8_2.3x2mm_P0.5mm
3D model: VSSOP-8-0.65mm (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Texas Instruments datasheet (26 pp, sha256 21d1709ee8fe241d, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF