Texas Instruments UC1724L

Overview

UC1724L from Texas Instruments is an isolated drive transmitter IC designed to drive high-side MOSFET gates in high-voltage H-bridge topologies using pulse transformers. It delivers 500mA source/sink output drive, operates from 8–35V, supports up to 600kHz switching, features under-voltage lockout (7.75V start-up), and transmits DC logic states across isolation barriers. It is used in industrial motor drives and isolated DC-DC converters.

For engineers reviewing the UC1724L datasheet, UC1724L pinout, UC1724L application, or UC1724L equivalent, key selection criteria include its transformer-coupled gate drive architecture, duty-cycle modulation for instantaneous response, –55°C to +125°C operating range, dual totem-pole output capability, and compatibility with low-cost pulse transformers in high-reliability power systems.

Technical Context

The UC1724L implements a retriggerable one-shot timing core with programmable frequency via external RT/CT components, enabling precise control of output pulse width and repetition rate. Its duty-cycle modulation scheme preserves DC logic levels across the isolation barrier without requiring separate bias windings or auxiliary supplies.

It integrates under-voltage lockout with 0.4–1.5V hysteresis to prevent erratic operation during brown-out conditions, and its dual high-current outputs are internally disabled until VIN exceeds the lockout threshold. Output rise/fall times are 30–90ns with no load, supporting fast-switching power stages.

Key Specifications

Pinout & Package

UC1724L is supplied in an 8-pin ceramic dual-inline package (CDIP), designated "J" suffix, with through-hole mounting and hermetic sealing for high-reliability applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolated gate drive transmitter applications.

Compared with UC2724DW and UC3724N, the UC1724L offers the widest temperature range (–55°C to +125°C), hermetic CDIP packaging for moisture resistance, and qualification for mission-critical industrial and aerospace gate drive applications - making it the only choice where thermal robustness and long-term stability are design requirements.

Availability

UC1724L is available at Aetrix Electronics and suitable for industrial motor drives, solar inverters, and high-reliability UPS systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for UC1724L 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The UC1724L belongs to TI's legacy Unitrode isolated gate drive transmitter family, engineered specifically for transformer-coupled, high-voltage H-bridge and half-bridge gate control in ruggedized power conversion systems.

FAQ

What is the function of the PHI input on the UC1724L?

The PHI input on the UC1724L is the primary logic control signal that determines the state of the dual output drivers. It accepts TTL/CMOS-compatible digital inputs (HIGH ≥2.0V, LOW ≤0.8V) and directly controls the duty-cycle modulated output waveform. The UC1724L uses this input to generate precisely timed, transformer-coupled drive pulses - enabling the UC1724L to transmit both AC transitions and steady-state DC logic levels across isolation boundaries without auxiliary biasing.

Does the UC1724L require external timing components?

Yes, the UC1724L requires two external passive components: a timing resistor (RT, connected to Pin 7) and a timing capacitor (CT, connected to Pin 8). These set the oscillator frequency and one-shot pulse width, with recommended values of 2kΩ–10kΩ for RT and 300pF–3nF for CT. The UC1724L's programmable timing allows frequency tuning from ~100kHz to 600kHz - a key feature distinguishing the UC1724L from fixed-frequency alternatives.

What is the purpose of the under-voltage lockout (UVLO) in the UC1724L?

The under-voltage lockout in the UC1724L disables both output drivers when the VIN supply drops below 7.75V (rising threshold), preventing erratic or partial gate drive that could cause shoot-through in H-bridge configurations. With 0.4–1.5V hysteresis, the UC1724L ensures clean, bounce-free re-enabling after brown-out recovery - a critical safety feature for high-voltage power systems where uncontrolled MOSFET conduction poses fire or failure risks.

Can the UC1724L drive SiC or GaN MOSFETs directly?

The UC1724L can drive low-to-medium gate charge SiC and GaN MOSFETs directly at frequencies up to 200kHz (with typical RT/CT), but higher-frequency operation (>300kHz) may require external gate buffers due to increased capacitive loading. Its 500mA peak source/sink current and 30–90ns no-load rise/fall times make the UC1724L suitable for many discrete wide-bandgap devices - however, gate drive strength should be verified against the specific Qg and Ciss of the target SiC/GaN FET in the final UC1724L-based design.

What package type does the UC1724L use, and why is it significant?

The UC1724L uses an 8-pin ceramic dual-inline package (CDIP), denoted by the "J" suffix. This hermetically sealed package provides superior moisture resistance, thermal stability, and long-term reliability compared to plastic DIP or SOIC variants - making it essential for aerospace, downhole, and military applications where extended temperature operation (–55°C to +125°C) and environmental resilience are mandatory. The UC1724L's CDIP construction directly supports its qualification for high-integrity power gate drive roles.