Texas Instruments TPS56921PWP

Overview

TPS56921PWP 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 delivers ±1.5% output voltage accuracy over temperature in VID mode and supports monotonic startup into pre-biased outputs for SoC power rails.

For engineers reviewing the TPS56921PWP datasheet, TPS56921PWP pinout, TPS56921PWP application, or TPS56921PWP equivalent, key selection considerations include its dual regulation modes (external resistor divider or I²C), thermal hiccup protection, 2 µA shutdown current, PowerPAD™-enabled thermal performance, and compatibility with high-density power distribution systems requiring dynamic voltage scaling.

Technical Context

The TPS56921PWP implements fixed-frequency peak current mode control with internal slope compensation to prevent subharmonic oscillation across its full duty cycle range. Its error amplifier features 1300 µA/V transconductance and drives the COMP pin for loop compensation via external RC networks.

It supports dual regulation architectures: external mode uses VSENSE feedback with resistor dividers (min 0.8 V), while internal mode uses I²C commands via SDA/SCL and address pins A0/A1 to set VOUT between 0.72 V and 1.48 V in 10 mV increments - with automatic mode transition after first valid I²C write.

Key Specifications

Pinout & Package

TPS56921PWP is housed in a thermally enhanced 20-pin HTSSOP package with exposed PowerPAD™ (pin 21) that must be soldered to PCB ground for electrical integrity and thermal dissipation (θ_JA = 39.4°C/W, 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 TPS56921PWP, TPS568215PWP offers lower cost and identical package but forfeits I²C programmability, while LM27402SQ/NOPB provides wider input range and external FET control at the expense of BOM size and thermal design effort.

Availability

TPS56921PWP is available at Aetrix Electronics and suitable for SoC power, digital TV main rails, set-top box DDR memory, and high-density server PMBus rails requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TPS56921PWP 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 and manufacturing.

The TPS56921PWP belongs to TI's SWIFT™ synchronous buck converter product line, engineered specifically for high-current, dynamically scalable power delivery in space-constrained consumer and computing applications.

FAQ

What is the minimum output voltage achievable with TPS56921PWP in I²C VID mode?

The TPS56921PWP supports a minimum output voltage of 0.72 V in internal regulation (I²C VID) mode, adjustable in precise 10 mV increments up to 1.48 V. This range is enforced by the internal DAC and validated across –40°C to 125°C junction temperature. The 0.72 V floor enables compatibility with advanced low-voltage SoCs and FPGAs requiring sub-0.8 V core rails.

How does TPS56921PWP handle startup into a pre-biased output?

The TPS56921PWP ensures monotonic startup into pre-biased outputs by disabling low-side MOSFET sinking until the SS pin voltage exceeds 1.4 V. This prevents reverse current flow and output voltage collapse during hot-plug events. The behavior is hardware-enforced and independent of regulation mode - active in both external resistor and I²C VID configurations.

Can TPS56921PWP operate with different input voltages on PVIN and VIN pins?

Yes - TPS56921PWP supports split-rail operation: PVIN accepts 1.6–17 V to power the MOSFET stage, while VIN supplies 4.5–17 V to the control circuitry. This allows optimizing efficiency in low-input scenarios (e.g., 3.3 V PVIN for intermediate bus) while maintaining robust control logic bias. External resistors on EN configure independent UVLO thresholds for each rail.

What thermal performance can be expected from TPS56921PWP 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™), TPS56921PWP achieves θ_JA = 26°C/W and θ_JCbot = 2.1°C/W. At 9 A output and 12 V input, junction temperature rise remains ≤65°C above ambient - well within the 125°C max rating and enabling full-load operation without heatsinks in most consumer enclosures.

Does TPS56921PWP support synchronization to an external clock signal?

Yes - the RT/CLK pin supports CLK mode synchronization: applying an external clock signal to this pin causes TPS56921PWP to align its switching edge to the falling edge of that clock. Frequency must be 200–1600 kHz, and the pin automatically detects CLK mode when no resistor is present. This feature reduces beat frequencies and EMI in multi-rail systems sharing a common clock source.