Texas Instruments LM5166DRCT

Overview

LM5166DRCT from Texas Instruments is a 3-V to 65-V input, 500-mA synchronous buck converter with ultra-low 9.7-µA no-load quiescent current, integrated 1-Ω P-channel high-side and 0.5-Ω N-channel low-side MOSFETs, and fixed 5-V output (LM5166X variant). It operates in COT or PFM mode, supports 100% duty cycle for low-dropout operation, and delivers precision regulation in factory automation power rails and automotive battery-supplied systems.

For engineers reviewing the LM5166DRCT datasheet, LM5166DRCT pinout, LM5166DRCT application, or LM5166DRCT equivalent, key selection criteria include its wide VIN range (3–65 V), ultra-low IQ, programmable current limit (200/300/500 mA), open-drain PGOOD flag, and thermal shutdown with hysteresis - all in a compact 10-pin VSON (3 mm × 3 mm) package.

Technical Context

The LM5166DRCT implements a constant-on-time (COT) or pulse-frequency-modulation (PFM) control architecture with no loop compensation required. Its integrated high-side P-channel MOSFET enables 100% duty-cycle operation, eliminating bootstrap capacitor needs and supporting ultra-low dropout under high-VIN/low-VOUT conditions.

Internal voltage reference accuracy is ±1.2% (1.223 V), FB comparator hysteresis is 4 mV in COT mode, and PGOOD activation threshold tracks FB regulation with 94% rising / 87% falling thresholds. Current limiting is set via external resistor on ILIM pin, enabling discrete selection among 200 mA, 300 mA, or 500 mA peak limits.

Key Specifications

Pinout & Package

LM5166DRCT is housed in a thermally enhanced 10-pin VSON package (3 mm × 3 mm, 0.5-mm pitch) with exposed thermal pad connected to GND. The package supports high-power-density layouts and efficient heat transfer to PCB copper.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck converter applications.

Compared with LM5165DRCT and TPS54202DRCT, the LM5166DRCT uniquely combines ultra-low IQ (9.7 µA), 65-V max input, and integrated dual-FET topology in a 3-mm × 3-mm package - making it the only option for space-constrained, wide-input, battery-sensitive applications requiring both high efficiency and long-term reliability.

Availability

LM5166DRCT is available at Aetrix Electronics and suitable for factory automation power supplies, automotive body control modules, and high-voltage LDO replacement designs requiring stable component supply, long-lifecycle assurance, and automotive-grade thermal performance.

Supply support for LM5166DRCT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability power conversion ICs.

The LM5166 product line targets wide-input industrial and automotive DC-DC conversion, emphasizing ultra-low quiescent current, integrated FETs, and simplified design for harsh-environment applications.

FAQ

What is the maximum input voltage rating for the LM5166DRCT?

The LM5166DRCT has an absolute maximum input voltage rating of 68 V and a recommended operating maximum of 65 V. This allows direct connection to 48-V industrial buses and automotive systems experiencing load dump transients, provided proper input filtering and clamping are implemented per TI's layout guidelines.

Does the LM5166DRCT require external compensation components?

No, the LM5166DRCT does not require external loop compensation components. Its constant-on-time (COT) and pulse-frequency-modulation (PFM) control architectures are inherently stable across all operating conditions, eliminating the need for compensation networks and reducing bill-of-materials count and design iteration time.

How is the output current limit configured on the LM5166DRCT?

The LM5166DRCT output current limit is configured using an external resistor connected from the ILIM pin to GND. Three discrete settings are supported: 200 mA (100 kΩ), 300 mA (33.2 kΩ), or 500 mA (0 Ω short). This allows optimization of inductor selection and fault protection level for each specific application load profile.

What is the purpose of the HYS pin on the LM5166DRCT?

The HYS pin on the LM5166DRCT provides access to the internal NFET used for input UVLO hysteresis. By adding two external resistors between HYS, EN, and GND, designers can program custom turn-on/turn-off thresholds and hysteresis width - enabling tailored brown-out protection for variable-input systems such as solar or battery-backed supplies.

Can the LM5166DRCT operate with 100% duty cycle, and why is this important?

Yes, the LM5166DRCT supports true 100% duty cycle operation due to its integrated P-channel high-side MOSFET. This is critical for applications where input voltage approaches or falls below the desired output (e.g., 5.5-V input → 5-V output), enabling uninterrupted regulation without dropout - a capability not possible with N-channel high-side topologies requiring bootstrap circuitry.