Texas Instruments UCC37321D

Overview

UCC37321D from Texas Instruments is an inverting 9-A low-side MOSFET driver with enable function, designed to interface PWM controllers with power N-channel MOSFETs in high-dV/dt switching applications. It delivers ±9 A peak output current at the Miller plateau, achieves 20-ns typical rise/fall times with 10-nF load, and operates from 4.5 V to 15 V supply across –40°C to +105°C.

For engineers reviewing the UCC37321D datasheet, UCC37321D pinout, UCC37321D application, or UCC37321D equivalent, key selection criteria include its inverting logic configuration, industry-standard SOIC-8 package with dual VDD/PGND/AGND pins, thermal resistance of 42°C/W (θjc), and enable-input hysteresis for noise-immune control in SMPS and motor drive systems.

Technical Context

The UCC37321D implements a hybrid TrueDrive output stage-paralleling bipolar and MOSFET transistors-to deliver high peak current precisely during the Miller plateau region where gate charge demands are greatest. Its input threshold remains TTL/CMOS-compatible across the full 4.5–15 V supply range, with 1.2 V (min) low-level and 2.2 V (typ) high-level thresholds.

Enable functionality is implemented on Pin 3 with internal 100-kΩ pull-up to VDD, active-high logic, and 0.55-V typical hysteresis-ensuring robust immunity against ground bounce and supply ripple. The device separates AGND (control-side reference) and PGND (power-side reference) to minimize switching-induced noise coupling into logic inputs.

Key Specifications

Pinout & Package

The UCC37321D is housed in an 8-pin SOIC (D) package with 3.91 mm × 4.90 mm body size and exposed thermal pad not connected internally. Dual VDD (Pins 1 & 8) and separated AGND (Pin 4) / PGND (Pin 5) require dedicated low-inductance routing per TI layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-side MOSFET driver applications.

Compared with UCC37321D, UCC37321DR offers identical performance in automated manufacturing, while TPS2828DBVR trades 4.5× lower peak current and no enable for 60% smaller footprint-making it viable only in thermally relaxed, low-power designs where 9-A drive is unnecessary.

Availability

UCC37321D is available at Aetrix Electronics and suitable for switch mode power supplies, motor controllers, and Class-D switching amplifiers requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceable sourcing.

Supply support for UCC37321D 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The UCC37321D belongs to TI's high-speed power driver product line, engineered specifically for demanding gate-drive applications where Miller current, thermal efficiency, and noise immunity are critical-such as server PSUs, EV onboard chargers, and industrial servo drives.

FAQ

What is the logic configuration of the UCC37321D?

The UCC37321D is an inverting low-side MOSFET driver: when the IN pin is high, the OUT pin goes low, and vice versa. This configuration is explicitly defined in the device logic table (Table 8-1) and optimized for driving N-channel synchronous rectifiers in buck-derived topologies. The UCC37321D differs from the non-inverting UCC37322D, and this inversion behavior is intrinsic to the UCC37321D silicon design-not configurable via external components.

Does the UCC37321D require external pull-up or pull-down resistors on the IN or ENBL pins?

No, the UCC37321D does not require external pull-up or pull-down resistors on IN or ENBL. The ENBL pin has an internal 100-kΩ pull-up resistor to VDD, enabling standard operation when left unconnected. The IN pin has no internal biasing but is designed for direct connection to logic outputs with defined high/low states; adding external resistors is unnecessary and may degrade noise immunity or timing margins. TI's datasheet confirms both pins operate reliably without external biasing under recommended conditions.

Can the UCC37321D drive a MOSFET with 200 nC total gate charge?

Yes, the UCC37321D can effectively drive a MOSFET with 200 nC total gate charge. With ±9 A peak output current and 20-ns rise/fall times into 10-nF loads, the UCC37321D delivers sufficient Miller plateau current to fully charge/discharge high-Qg devices within practical switching periods. For example, at 9 A, 200 nC is transferred in ~22 ns-well within the UCC37321D's capability. Layout optimization (short traces, proper decoupling) is essential to maintain performance at this gate charge level.

What is the maximum allowable supply voltage for the UCC37321D?

The absolute maximum supply voltage for the UCC37321D is 16 V, but the recommended operating range is 4.5 V to 15 V per Section 7.3 of the datasheet. Operation at 15 V maximizes peak output current and switching speed, while operation below 4.5 V risks insufficient drive strength and increased propagation delay. Exceeding 16 V-even momentarily-may cause permanent damage, as confirmed in the Absolute Maximum Ratings table (Section 7.1).

How does the UCC37321D handle ground separation between AGND and PGND?

The UCC37321D mandates physical separation of AGND (Pin 4) and PGND (Pin 5) to isolate control-side and power-side return paths. Per TI's layout guidelines, these grounds must connect via a single thick copper trace directly beneath the device to prevent noise coupling. AGND references IN and ENBL inputs, while PGND carries high di/dt output current; improper grounding causes input threshold instability and erratic switching. This dual-ground architecture is a core design feature of the UCC37321D-not optional-and is validated in all TI reference designs.