LM5019MRX from Texas Instruments, in a SO-8-EP. 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	RTN	power_in	Ground return of the integrated circuit. Also the reference for all internal analog and power domains. The exposed pad must be tied to this pin.
2	VIN	power_in	Input supply pin. Operating input voltage range is 7.5 V to 100 V. Feeds the internal high-voltage startup regulator and the high-side power MOSFET.
3	UVLO	input	Input to the undervoltage lockout comparator. A resistor divider from VIN sets the UVLO threshold; an internal current source provides programmable hysteresis when UVLO > 1.225 V. Pulling UVLO below 0.66 V forces shutdown.
4	RON	input	On-time programming pin. A resistor from RON to VIN sets the high-side switch on-time as a function of VIN, giving nearly constant switching frequency. Minimum recommended on-time is 100 ns at maximum VIN.
5	FB	input	Feedback pin, connected to the inverting input of the internal regulation comparator. Internal reference is 1.225 V; set output voltage with an external divider from VOUT to FB to RTN.
6	VCC	power_out	Output of the internal high-voltage series pass regulator, regulated at 7.6 V. Provides bias for the gate drivers and internal circuitry. Bypass with a 1.0-uF ceramic capacitor to RTN.
7	BST	power_in	Bootstrap capacitor pin for the high-side gate driver. Connect a 0.01-uF ceramic capacitor between BST and SW. The BST capacitor is refreshed from VCC through an internal diode while SW is low.
8	SW	output	Switching node between the integrated high-side and low-side power MOSFETs. Connect to the output inductor and to the bottom plate of the bootstrap capacitor. Absolute max SW to RTN is -1.5 V (steady) / -5 V (100-ns transient).
EP	EP	power_in	Exposed thermal pad on the underside of the package. Must be electrically connected to the RTN pin and tied to the system ground plane for reduced thermal resistance.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	SO-8-EP
Category	PMIC
Pins	9

Ordering variants

Same part, different packaging or reel option.

LM5019MRX
LM5019MRXSD
LM5019MRXSDX

CAD (KiCad official)

Symbol: LM5019MRX
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SO-8-EP (KiCad packages3D, STEP)

Provenance

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

Datasheet: Texas Instruments datasheet (35 pp, sha256 994feed72dee9bcb, retrieved 2026-08-17, tier: lcsc)
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