Texas Instruments TPS65251-2RHAR

Overview

TPS65251-2RHAR from Texas Instruments is a triple-output synchronous buck converter IC for multi-rail power management in 4.5–18 V input systems. It integrates three high-current DC/DC converters (3 A on Buck 1, 2 A on Buck 2 and Buck 3), supports adjustable switching frequency (300 kHz–2.2 MHz), features independent enable/soft-start/current-limit pins per channel, and delivers regulated outputs from 0.8 V to VIN−1 V - used in automotive infotainment and set-top box power trees.

For engineers reviewing the TPS65251-2RHAR datasheet, TPS65251-2RHAR pinout, TPS65251-2RHAR application, or TPS65251-2RHAR equivalent, key selection criteria include per-channel current capability (3 A/2 A/2 A), 180° out-of-phase Buck 1 vs Buck 2/3 operation to reduce input ripple, factory-programmed 32-ms PGOOD reset timing, and VQFN-40 (6 mm × 6 mm) thermal performance with R_θJA = 32.7°C/W.

Technical Context

The TPS65251-2RHAR implements peak current-mode control with internal slope compensation across all three buck stages, enabling stable loop response with simple RC compensation networks on COMP pins. Each channel uses integrated high-side (95 mΩ Buck 1; 120 mΩ Buck 2/3) and low-side (50 mΩ Buck 1; 80 mΩ Buck 2/3) MOSFETs, eliminating external switch requirements.

It supports dual operating modes: forced PWM for consistent EMI profile and automatic PFM/PWM transition (via LOW_P pin) for light-load efficiency optimization. Input ripple is minimized by fixed 180° phase shift between Buck 1 and Buck 2, while Buck 2 and Buck 3 operate in-phase - a topology confirmed in the functional block diagram and timing analysis.

Key Specifications

Pinout & Package

VQFN-40 (RHA) package, 6.00 mm × 6.00 mm body, exposed thermal pad connected to GND. Pin pitch: 0.5 mm. RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple-buck power management applications.

Compared with TPS65251-1RHAR and TPS65251-3RHAR, the TPS65251-2RHAR provides the shortest factory-programmed PGOOD reset interval (32 ms), enabling faster system boot in latency-sensitive consumer electronics while retaining identical thermal, electrical, and layout compatibility.

Availability

TPS65251-2RHAR is available at Aetrix Electronics and suitable for set-top boxes, automotive infotainment systems, and digital video recorders requiring stable component supply, long-term lifecycle support, and production-grade thermal validation.

Supply support for TPS65251-2RHAR 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 over 50 years of innovation in high-reliability power conversion solutions.

The TPS65251-x family is designed for multi-rail consumer and automotive power management, integrating three high-current synchronous buck converters with independent control, sequencing, and thermal protection in a compact VQFN package.

FAQ

What is the factory-programmed PGOOD reset time for TPS65251-2RHAR?

The TPS65251-2RHAR has a factory-programmed PGOOD reset time of 32 ms - distinct from TPS65251-1RHAR (1000 ms) and TPS65251-3RHAR (256 ms). This value is fixed and non-adjustable; it defines the minimum duration after all three buck outputs reach ≥90% regulation before the open-drain PGOOD pin is pulled high. The TPS65251-2RHAR uses this timing to coordinate fast-boot sequences in consumer electronics.

How does the 180° out-of-phase operation between Buck 1 and Buck 2 reduce input ripple in TPS65251-2RHAR?

In the TPS65251-2RHAR, Buck 1 and Buck 2 operate 180° out-of-phase while Buck 2 and Buck 3 run in-phase. This interleaving reduces the RMS input ripple current by canceling harmonic components - verified in the device's functional description and typical application schematics. The result is up to 40% smaller required input capacitance and lower EMI filter cost compared to in-phase operation, directly improving system size and EMC compliance.

Can TPS65251-2RHAR support different output voltages on each buck channel?

Yes, the TPS65251-2RHAR supports independent output voltages per channel using external resistor dividers on FB1, FB2, and FB3 pins. Each feedback network references the internal 0.8 V precision bandgap, enabling outputs from 0.8 V to VIN−1 V. For example: Buck 1 can be set to 1.2 V (SoC core), Buck 2 to 1.8 V (memory), and Buck 3 to 3.3 V (I/O) - all simultaneously, with ±2% regulation accuracy across temperature and line conditions.

What is the maximum continuous current rating for each buck channel in TPS65251-2RHAR?

The TPS65251-2RHAR specifies 3 A continuous output current for Buck 1, and 2 A continuous output current for both Buck 2 and Buck 3 - confirmed in the "Features" section and Electrical Characteristics table. These ratings assume proper PCB layout, thermal management (R_θJA = 32.7°C/W), and recommended external components (e.g., 4.7 µH inductors, 68 µF output capacitors). Peak current capability reaches 3.5 A (Buck 1) and 2.5 A (Buck 2/3) with appropriate RLIM resistor selection.

How is switching frequency configured on TPS65251-2RHAR - resistor or external clock?

The TPS65251-2RHAR supports both methods: switching frequency is set either by an external resistor from ROSC to GND (300 kHz–2.2 MHz range) or synchronized to an external clock applied to the SYNC pin (0.2–2.2 MHz range). When using SYNC, the external clock must exceed the internal oscillator frequency to ensure reliable locking; the SYNC pin is ignored during startup and only engages after PGOOD assertion. Both configurations maintain current-mode control stability and phase relationships.