LM5140-Q1 is a controller, not an integrated converter: it supplies the loop control, gate drive and protection for two synchronous buck power stages while the power MOSFETs and inductors sit outside the package. That split is what lets one small VQFN regulate rails that draw far more current than any integrated-FET device could, because the designer picks the external FETs to match the load. Each of the two channels is a complete current-mode buck controller with its own soft-start, feedback, compensation, current sense, enable and power-good, so the part behaves like two independent regulators that happen to share one bias supply and one oscillator.

The wide 3.8 V to 65 V input is the reason the device is aimed at automotive: it rides through cold-crank dips toward 3.8 V and load-dump transients toward the 70 V absolute maximum without the pre-regulator a narrower-input controller would need. The two channels are clocked 180 degrees out of phase, so their input current pulses interleave and the RMS ripple the input capacitors must absorb drops sharply, shrinking the input filter. Each output is accurate to within 1% and can be set by pin-strap to common fixed rails or divided down with a resistor pair anywhere from 1.5 V to 15 V, and the switching frequency is a simple choice between 2.2 MHz for the smallest magnetics and 440 kHz for the highest efficiency, with an OSC pin and SYNC input for anything in between.

Where LM5140-Q1 earns its place is drive flexibility and protection. The high-side and low-side gate drivers each break out separate turn-on and turn-off pins (HO/HOL and LO/LOL), so a designer tunes the rise and fall edges and the dead time independently to trade switching loss against shoot-through margin. Current limit is programmed by a single resistor and uses low-side MOSFET sensing, an emulated peak-current scheme keeps it stable at high duty cycles, and a sustained overload folds the part into hiccup mode rather than letting the FETs cook. A SYNC output lets a second LM5140-Q1 or downstream converter lock to the same clock for a clean multi-rail board.

Note: Values are taken from the Texas Instruments LM5140-Q1 datasheet (SNVSA02A). Output voltages, switching frequency and current limit are set by external components; confirm every parameter against the latest official documentation before committing a design.

LM5140-Q1 is supplied in a 40-pin VQFN (RWG) measuring 6 mm x 6 mm with a 0.9 mm maximum height and a 0.5 mm pin pitch. The package has wettable flanks, which let an automated optical inspection station verify each solder fillet, a requirement on many automotive assembly lines. A large center exposed pad must be soldered to the board ground plane for both the thermal path and the analog/power ground reference. The orderable LM5140QRWGRQ1 ships in tape and reel. Package dimensions and the pin-1 orientation are shown below.

📄 Download the official TI LM5140-Q1 Datasheet (PDF)

The 40 pins are organized as two mirrored channels (suffix 1 and 2) plus a shared bias and timing group. The key functional signals are:

• VIN: Power input, 3.8 V to 65 V, feeding the internal bias regulators and the high-side bootstrap path.
• EN1 / EN2: Independent per-channel enable inputs, allowing one rail to sequence or shut down without the other.
• FB1 / FB2: Feedback sense inputs; a resistor divider sets an adjustable output, or the pin is strapped for a fixed output.
• COMP1 / COMP2: Transconductance error-amplifier outputs for external loop compensation.
• CS1 / CS2: Current-sense inputs for the per-channel current limit and emulated peak-current control.
• HO1/HO2, HOL1/HOL2: High-side gate-driver turn-on and turn-off outputs; the split lets dead time and the rising edge be shaped independently.
• LO1/LO2, LOL1/LOL2: Low-side gate-driver turn-on and turn-off outputs.
• SW1 / SW2: Switch-node returns for the high-side drivers and bootstrap references.
• HB1 / HB2: High-side bootstrap bias supplies for the floating high-side drivers.
• VCC / VDD / VCCX / VDDA: Internal LDO output, driver bias, optional external bias bypass, and the quiet analog supply.
• PG1 / PG2: Open-drain power-good flags, one per channel.
• OSC, SYNIN, SYNOUT: Frequency-setting pin, external clock sync input, and clock output for cascading.
• ILSET, DEMB, RES, SS1/SS2: Current-limit set, diode-emulation select, restart/hiccup timing, and per-channel soft-start.
• AGND / PGND1 / PGND2: Analog ground reference and the two power-ground returns; the exposed pad bonds to both AGND and PGND on the PCB.

The parts below are references within TI's wide-input controller family and the surrounding system. They are not drop-in replacements; verify channel count, input range, frequency and package before substituting.

Selection Tips: Choose LM5140-Q1 when a wide-input automotive board needs two independent, accurate rails with external FETs sized to the load and tunable gate drive for EMI. Step to LM5141-Q1 for a single channel, to LM5145 for a higher-voltage single industrial rail, or to an integrated-FET regulator such as LM5160-Q1 when the per-rail current is low enough that on-chip switches simplify the design.

Texas Instruments Incorporated, headquartered in Dallas, Texas, USA, is one of the world's largest analog and embedded-processing semiconductor companies. The LM5140-Q1 belongs to TI's wide-VIN buck-controller portfolio, a line built around the SIMPLE SWITCHER and wide-input controller families that emphasize wide operating range, automotive qualification and robust protection.

For automotive power, TI pairs controllers like LM5140-Q1 with a deep catalog of compatible power MOSFETs, gate-drive support and reference designs, plus the AEC-Q100 qualification, functional-safety documentation and long-term supply that vehicle programs require. That ecosystem lets a designer move from a single-rail to a dual-rail wide-input supply, or scale current by choosing different external FETs, while staying inside one well-supported vendor family.