Texas Instruments TPS621351RGXR

Overview

TPS621351RGXR from Texas Instruments is a high-accuracy, synchronous step-down DC-DC converter with DCS-Control™ topology, delivering up to 4 A continuous output current across an input range of 3 V to 17 V and adjustable output voltage from 0.8 V to 12 V. It features ±1% output voltage accuracy in PWM mode, 18 µA typical quiescent current, and forced PWM or automatic PWM/PFM operation - optimized for connected-standby power delivery in mobile and embedded computers.

For engineers reviewing the TPS621351RGXR datasheet, TPS621351RGXR pinout, TPS621351RGXR application, or TPS621351RGXR equivalent, key selection considerations include its 2.5 MHz nominal switching frequency in forced PWM mode, active output discharge absence (distinguishing it from TPS62135), VSEL/FB2 voltage scaling capability, and 3 mm × 2 mm VQFN-11 package with thermal performance validated at R_θJA = 38.4 °C/W.

Technical Context

The TPS621351RGXR implements DCS-Control™ - a hybrid regulation architecture combining fast comparator-based transient response with internal voltage feedback compensation for stable operation using low-ESR ceramic capacitors. Its control loop supports seamless transition between PWM and PFM modes without output voltage disturbance.

Unlike the TPS62135, the TPS621351RGXR omits active output discharge; its VSEL pin enables dynamic output voltage scaling via FB2's internal switch to GND; MODE pin selects between forced PWM (2.5 MHz) and adaptive AEE™-enabled PWM/PFM operation; and PG provides open-drain power-good signaling with 93–98% V_OUT threshold hysteresis.

Key Specifications

Pinout & Package

TPS621351RGXR is housed in a thermally enhanced 3-mm × 2-mm VQFN-11 package (RGX) with exposed thermal pad, rated for −40 °C to +125 °C operating junction temperature and supporting 38.4 °C/W junction-to-ambient thermal resistance on standard 4-layer PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter applications.

Compared with TPS62135RGXR, the TPS621351RGXR removes output discharge to simplify design where fast shutdown decay isn't required; versus TPS621361RGXR, it delivers higher switching frequency for compact layouts but with slightly higher quiescent current - making it optimal for space-constrained digital POL applications.

Availability

TPS621351RGXR is available at Aetrix Electronics and suitable for mobile computing power rails, gaming console core supplies, SSD drive power management, and industrial embedded controller POL requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for TPS621351RGXR 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-efficiency DC-DC conversion.

The TPS621351RGXR belongs to TI's DCS-Control™ synchronous buck converter family, engineered specifically for high-density, low-quiescent-power point-of-load applications in portable and embedded systems where efficiency across light-to-heavy loads is critical.

FAQ

What is the key functional difference between TPS621351RGXR and TPS62135RGXR?

The TPS621351RGXR lacks the active output discharge feature present in the TPS62135RGXR. When disabled, TPS62135 actively discharges V_OUT through an internal 100-Ω switch, while TPS621351RGXR leaves V_OUT floating. This makes TPS621351RGXR suitable for applications where residual output voltage after shutdown is acceptable or managed externally. All other electrical specifications, pinout, and package are identical between the two parts.

Does TPS621351RGXR support 100% duty-cycle operation, and what is its practical benefit?

Yes, TPS621351RGXR supports true 100% duty-cycle operation - maintaining regulation even when input voltage drops to ~15% above the output voltage. This extends usable battery life in single- or dual-cell Li-ion systems by allowing deeper discharge before brownout. The feature activates automatically when minimum off-time (~80 ns) is reached, holding the high-side FET continuously on while disabling the low-side FET - preserving regulation without external components.

How does the VSEL pin function in TPS621351RGXR, and what design flexibility does it provide?

The VSEL pin on TPS621351RGXR controls an internal switch connecting FB2 to GND. When VSEL is high, this switch closes, placing an additional resistor in parallel with the lower FB divider leg - effectively increasing the output voltage. This enables two discrete, user-selectable output voltages (e.g., 1.2 V and 1.8 V) using one TPS621351RGXR and a simple logic signal, eliminating the need for multiple regulators or complex digital control in multi-voltage domain systems.

What thermal performance can be expected from TPS621351RGXR in a standard PCB layout?

In a standard 4-layer PCB layout with 6 thermal vias under the exposed pad, TPS621351RGXR achieves R_θJA = 38.4 °C/W and R_θJB = 7.6 °C/W. At 4 A load and 12 V input, junction temperature rise above ambient is approximately 62 °C - well within the +125 °C maximum rating. For extended high-temperature operation, adding copper pour and extra thermal vias further reduces thermal resistance, enabling full 4-A output at +85 °C ambient without derating.

Can TPS621351RGXR be used with ceramic output capacitors smaller than 22 µF?

Yes - TPS621351RGXR is optimized for low-ESR ceramic capacitors, with minimum recommended output capacitance of 6 µF (per spec table). While 22 µF is typical for 3.3 V outputs to ensure <1% ripple under 4-A transients, designs with lower current or relaxed ripple budgets may use 10 µF or even 6 µF. Stability is maintained across the full 6–200 µF range, verified with 0805/1206 X7R/X5R MLCCs - enabling compact, cost-effective filtering without tantalum or polymer alternatives.