Texas Instruments UC3709N

Overview

UC3709N from Texas Instruments is a dual high-speed FET driver IC designed to rapidly switch the capacitive gates of power MOSFETs in switching power supplies and motor drives. It delivers ±1.5 A peak source/sink current, achieves 40 ns rise/fall times into 1000 pF, operates from 5 V to 40 V, and includes thermal shutdown protection - enabling robust gate drive in industrial DC-DC converters.

For engineers reviewing the UC3709N datasheet, UC3709N pinout, UC3709N application, or UC3709N equivalent, this device is evaluated for TTL-compatible input logic, 30 V output swing capability, low quiescent current (7–12 mA), and compatibility with legacy MMH0026/DS0026 layouts in 8-pin DIP configurations.

Technical Context

The UC3709N uses a high-speed Schottky bipolar process with a totem-pole output stage optimized to minimize cross-conduction current spikes during switching transitions. Its inverting logic inputs accept standard TTL voltage levels (0.8 V logic low, 2.2 V logic high) and tolerate up to 5.5 V input voltage.

Internally, it integrates a 5-V regulator for biasing and a thermal sense circuit triggering shutdown at ~155°C junction temperature. The device supports operation across 0°C to 70°C ambient, with absolute maximum supply voltage rated at 40 V and peak transient output current limited to ±1.5 A in the N-package variant.

Key Specifications

Pinout & Package

The UC3709N is housed in an 8-pin plastic dual in-line package (PDIP, package code P), 0.3-inch width, with 0.1-inch lead pitch. Pin 1 is marked by a notch or dot; leads are tin-lead (NIPDAU) finish, RoHS-compliant, and rated for solder reflow per Level-2-260°C-1 year.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual high-speed FET driver applications.

Compared with UC2709N and TC4427CPA, the UC3709N offers the lowest quiescent current in its family and integrated thermal safety - making it optimal for cost-sensitive commercial power supplies where ambient temperature stays within 0°C–70°C and reliability under transient overload is critical.

Availability

UC3709N is available at Aetrix Electronics and suitable for switch-mode power supplies, motor drive half-bridges, and industrial DC-DC converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for UC3709N 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 heritage in power IC design and manufacturing excellence.

The UC3709N belongs to TI's legacy UCx709 dual FET driver product line, engineered specifically for cost-effective, high-reliability gate driving in commercial-grade switching power conversion systems.

FAQ

What is the maximum gate capacitance the UC3709N can drive with 40 ns rise/fall times?

The UC3709N achieves 40 ns rise and fall times into a 1000 pF capacitive load, as specified in the datasheet under typical switching characteristics. This corresponds to driving gate capacitances typical of 60–100 V MOSFETs with Qg ≈ 20–30 nC at 12–20 V VGS. For larger gate charges, rise/fall times scale linearly - e.g., 2000 pF yields ~80 ns - and layout inductance must be minimized to preserve edge fidelity. The UC3709N remains effective up to ~3000 pF with acceptable performance degradation.

Does the UC3709N support non-inverting logic inputs?

No, the UC3709N features inverting logic inputs exclusively: a high input drives the corresponding output low, and a low input drives it high. This is inherent to its internal architecture and cannot be reconfigured. If non-inverting behavior is required, an external inverter (e.g., SN74LVC1G04) must be placed between the controller and UC3709N INPUT A/B pins. The UC3709N datasheet confirms inverting functionality across all operating conditions and variants.

Can the UC3709N be used in a high-side floating configuration?

No, the UC3709N is a ground-referenced driver and lacks a floating high-side supply or level-shifting capability. Its outputs are referenced to the same GROUND pin (Pin 3), so it cannot directly drive high-side N-channel MOSFETs in a bootstrapped or isolated half-bridge. For high-side drive, use dedicated high-side drivers (e.g., IRS21844) or isolated gate drivers. The UC3709N is intended for low-side or dual low-side configurations, such as synchronous buck bottom switches or H-bridge low-side legs.

What is the thermal resistance (θJA) of the UC3709N PDIP package?

The UC3709N in the PDIP (P) package has a junction-to-ambient thermal resistance (θJA) of 90°C/W, measured on a standard 5-inch² FR4 PCB with 1 oz copper, per TI's Thermal Resistance Table. This value assumes no added heatsinking; actual θJA improves significantly with copper pour, thermal vias, or small clip-on heatsinks. For continuous 1.5 A peak output operation, derating is required above ~55°C ambient to stay within the 125°C max junction temperature limit.

Is the UC3709N pin-compatible with the MMH0026 or DS0026?

Yes, the UC3709N is explicitly documented as pin-compatible with the MMH0026 and DS0026 in the datasheet. All share the same 8-pin DIP footprint, identical pin functions (including N/C on Pins 1 and 5), and compatible input/output voltage ranges. However, the UC3709N draws significantly lower quiescent current and includes thermal shutdown - features absent in the older 0026-series devices - making it a functional upgrade with no PCB changes required.