Texas Instruments UCC21551BDWKR

Overview

UCC21551BDWKR from Texas Instruments is a reinforced-isolation dual-channel gate driver configured for half-bridge, dual high-side, or dual low-side operation. It delivers 4A peak source and 6A peak sink output current, supports up to 25V VDD output supply with 8V UVLO threshold, and operates across –40°C to +150°C junction temperature - enabling robust SiC and IGBT gate control in high-voltage DC-DC converters.

For engineers reviewing the UCC21551BDWKR datasheet, UCC21551BDWKR pinout, UCC21551BDWKR application, or UCC21551BDWKR equivalent, key selection criteria include its 125V/ns CMTI, programmable dead time via external resistor, fast enable for power sequencing, integrated UVLO on all supplies, and SOIC-14 package with 5kVRMS isolation barrier.

Technical Context

The UCC21551BDWKR implements galvanic isolation between input logic (VCCI/GND) and dual independent output stages (OUTA/VSSA/VDDB and OUTB/VSSB/VDDB), each with dedicated 8V UVLO protection and active pull-down capability. Its input stage accepts TTL/CMOS-compatible signals with internal pull-downs on INA, INB, and EN pins.

Dead time is resistor-programmable via DT pin (0–150Ω for interlock, 1.7–100kΩ for linear scaling), and propagation delay matching is ≤5ns over full temperature range. The device features integrated de-glitch filtering (rejects <5ns transients) and thermal derating per VDE safety limits for DWK package.

Key Specifications

Pinout & Package

UCC21551BDWKR uses a 14-pin SOIC (DWK) package with reinforced isolation barrier separating primary-side (VCCI, GND, INA, INB, EN, DT) and secondary-side (VDDA, VSSA, OUTA, VDDB, VSSB, OUTB) terminals. Pin 7 and Pins 12–13 are NC (no internal connection).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel isolated gate driver applications.

Compared with UCC21551ADWKR and UCC21551CDWKR, the UCC21551BDWKR provides optimal balance of noise immunity (8V UVLO), gate drive headroom (9.2V min VDD), and compatibility with common 12V auxiliary supplies - making it ideal for automotive and telecom DC-DC designs where 5V is too marginal and 12V is excessive.

Availability

UCC21551BDWKR is available at Aetrix Electronics and suitable for high-voltage DC-DC converters, automotive HVAC inverters, and uninterruptible power supplies requiring stable component supply, reinforced isolation certification, and extended temperature operation.

Supply support for UCC21551BDWKR 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 isolation and gate driver innovation.

The UCC21551x family was designed specifically for high-efficiency, high-power-density isolated power conversion - targeting SiC and GaN-based systems where timing precision, noise immunity, and thermal robustness are critical.

FAQ

What is the minimum VDD supply voltage for reliable operation of the UCC21551BDWKR?

The UCC21551BDWKR requires a minimum VDDA and VDDB supply voltage of 9.2V to ensure proper UVLO release and stable gate drive output. Below this threshold, the device remains disabled even if input signals are present - a safety feature preventing partial or weak turn-on of power switches that could cause shoot-through or thermal stress. This 9.2V specification is specific to the 'B' variant and differs from other members of the UCC21551x family.

How does the DT pin function on the UCC21551BDWKR, and what resistor values are supported?

The DT pin on the UCC21551BDWKR configures dead time interlock behavior: grounding it with 0–150Ω enables strict non-overlapping outputs; leaving it open or tying to VCCI disables interlock; connecting 1.7–100kΩ to GND sets programmable dead time (e.g., 10kΩ ≈ 100ns). TI explicitly warns against bypassing DT with >1nF capacitors, as this can destabilize timing. The UCC21551BDWKR's DT implementation is identical across the family but calibrated for its 8V UVLO operating point.

Does the UCC21551BDWKR support both high-side and low-side configurations simultaneously?

Yes, the UCC21551BDWKR supports simultaneous high-side and low-side operation in half-bridge mode - with OUTA driving the high-side switch (referenced to HV DC-link) and OUTB driving the low-side switch (referenced to power ground). Its reinforced isolation barrier allows independent floating supplies (VDDA/VSSA and VDDB/VSSB), eliminating the need for bootstrap diodes or level shifters. This capability is inherent to the UCC21551BDWKR's architecture and confirmed in TI's functional description and typical application schematic.

What is the maximum recommended switching frequency for the UCC21551BDWKR with a 1.8nF load?

With a 1.8nF capacitive load and 12V VDD, the UCC21551BDWKR achieves 8ns rise/fall times and maintains ≤5ns pulse-width distortion up to at least 3MHz - though practical limits depend on thermal design. At 500kHz, total supply current per channel is ~3.2mA (VDD=12V), well within the 450mW per-driver thermal limit. The UCC21551BDWKR's 33ns propagation delay and 125V/ns CMTI make it suitable for hard-switched topologies up to 2MHz and resonant converters beyond.

How does the UCC21551BDWKR handle power supply sequencing during startup?

The UCC21551BDWKR incorporates fast enable (EN) functionality and independent UVLO on VCCI, VDDA, and VDDB to manage power sequencing: EN must be high before outputs activate; VCCI must exceed 2.7V first to initialize logic; then VDDA/VDDB must reach their respective UVLO thresholds (8.5V for UCC21551BDWKR) before gate drive enables. This staged activation prevents shoot-through and ensures gate drivers are fully biased before accepting input commands - a core design feature of the UCC21551BDWKR validated in TI's application notes.