Texas Instruments TPS56921PWPR

Overview

TPS56921PWPR from Texas Instruments is a 17 V, 9 A synchronous step-down DC/DC converter with integrated 26 mΩ/19 mΩ MOSFETs, I²C-compatible VID control (0.72–1.48 V in 10 mV steps), and peak current-mode control operating from 200 kHz to 1.6 MHz. It supports monotonic startup into pre-biased outputs and delivers ±1.5% output voltage accuracy over temperature for SoC core power applications.

For engineers reviewing the TPS56921PWPR datasheet, TPS56921PWPR pinout, TPS56921PWPR application, or TPS56921PWPR equivalent, key selection considerations include its dual regulation modes (external resistor divider or I²C VID), hiccup-mode overcurrent protection, thermal shutdown with 10°C hysteresis, and HTSSOP-20 PowerPAD™ package for high-density power delivery.

Technical Context

The TPS56921PWPR implements fixed-frequency peak current-mode control with internal slope compensation to prevent subharmonic oscillation across 0–100% duty cycle. Its error amplifier features 1300 µA/V transconductance and drives the COMP pin for loop compensation.

It supports two regulation architectures: external mode (VSENSE feedback with resistor divider, min 0.8 V) and internal mode (I²C VID control via SDA/SCL/A0/A1, 0.72–1.48 V). The RT/CLK pin enables either resistor-programmed switching frequency (200 kHz–1.6 MHz) or synchronization to an external clock's falling edge.

Key Specifications

Pinout & Package

TPS56921PWPR is housed in a thermally enhanced 20-pin HTSSOP package with exposed PowerPAD™ thermal pad (Pin 21), requiring solder connection to PCB ground plane for optimal thermal performance (θ_JCbot = 2.1°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS56921PWPR, TPS568215RNNR offers lower cost and simpler layout but forfeits I²C-based voltage agility, while MP2964GQKT-Z adds digital intelligence and wider VOUT flexibility at the expense of higher complexity and BOM cost.

Availability

TPS56921PWPR is available at Aetrix Electronics and suitable for SoC core power, digital TV mainboards, high-density server PSUs, and industrial FPGA power applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TPS56921PWPR 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 and embedded processing technologies, with decades of expertise in power management IC design.

The TPS56921PWPR belongs to TI's SWIFT™ synchronous buck converter product line, engineered for high-current, space-constrained applications demanding I²C programmability, robust protection, and thermal efficiency in consumer, computing, and industrial power systems.

FAQ

What is the maximum output voltage supported by TPS56921PWPR in I²C VID mode?

The TPS56921PWPR supports a maximum output voltage of 1.48 V in I²C VID mode, adjustable in precise 10 mV steps from 0.72 V to 1.48 V. When using VID control, the VOUT pin must be connected to the converter output, which enforces a hard 3.3 V upper limit on the regulated rail - though practical VID operation remains within the 0.72–1.48 V range per datasheet specification. This makes TPS56921PWPR ideal for low-voltage SoC and FPGA core supplies.

How does the TPS56921PWPR handle startup into a pre-biased output?

The TPS56921PWPR ensures monotonic startup into pre-biased outputs by disabling low-side MOSFET conduction until the SS pin voltage exceeds 1.4 V. This prevents reverse current flow from the output capacitor into the converter during power-up. The behavior is inherent to the control logic and requires no external circuitry - a key reliability feature for hot-swap and multi-rail systems where downstream rails may already be energized when TPS56921PWPR is enabled.

What thermal performance can be expected from the TPS56921PWPR in a standard 4-layer PCB?

In a standard 4-layer PCB per JEDEC JESD51-7 (3″ × 3″, 2 oz copper, 21 thermal vias under PowerPAD™), the TPS56921PWPR achieves θ_JA = 26°C/W and θ_JCbot = 2.1°C/W. At 9 A load and 12 V input, typical junction temperature rise is ~65°C above ambient - well within the –40°C to 125°C operating range. Proper soldering of the PowerPAD™ to a solid ground plane is mandatory to realize these values; insufficient thermal relief will degrade performance significantly.

Can the TPS56921PWPR operate with only PVIN powered and VIN floating?

No - the TPS56921PWPR requires a valid voltage on the VIN pin (4.5–17 V) to power its internal control circuitry, including the oscillator, error amplifier, and I²C interface. PVIN (1.6–17 V) supplies only the power switches. If VIN is left floating or below 4.5 V, the device will not initialize, regardless of PVIN status. Both rails must be present and within spec for normal operation; VIN cannot be omitted or replaced by PVIN.

What protection mechanisms does the TPS56921PWPR implement against overvoltage conditions?

The TPS56921PWPR implements overvoltage protection via its PWRGD comparator and control logic: when VSENSE exceeds 106% of the internal reference, PWRGD asserts low and the high-side MOSFET is immediately disabled. Recovery occurs only after VSENSE falls below 104% of VREF, preventing output overshoot during load dump or transient events. This hardware-level OV response operates independently of I²C commands and functions in both external and internal regulation modes.