Texas Instruments UC3638N

Overview

UC3638N from Texas Instruments is a high-speed, dual-channel PWM controller IC designed for precision motor control and power conversion systems. It features two independent PWM comparators with 1.2V internal reference, 500kHz maximum switching frequency, ±1% duty cycle accuracy over temperature, and operates across 0°C to 70°C. It is used in brushless DC motor drives requiring synchronized gate drive timing and current-mode feedback.

For engineers reviewing the UC3638N datasheet, UC3638N pinout, UC3638N application, or UC3638N equivalent, key selection considerations include its dual-comparator architecture, fixed 1.2V reference tolerance, PDIP-20 thermal performance at 70°C ambient, and compatibility with external oscillator or sync input for multi-phase interleaving.

Technical Context

The UC3638N implements two fully independent PWM channels with separate error amplifiers, current-sense comparators, and latch logic-enabling asymmetric or interleaved operation without cross-talk. Each channel supports peak-current-mode control with programmable slope compensation via external resistor.

It integrates a precision 1.2V bandgap reference (±1% initial tolerance), undervoltage lockout (UVLO) with 16V turn-on/10V turn-off thresholds, and thermal shutdown at 150°C. The device accepts external clock synchronization up to 500kHz and provides open-collector output drivers capable of sinking 200mA per channel.

Key Specifications

Pinout & Package

UC3638N is housed in a 20-pin plastic dual in-line package (PDIP-N), 0.300" wide, with 0.100" lead pitch. The package has no exposed thermal pad and is RoHS-compliant with NiPdAu lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-PWM controller applications.

Compared with UC3846N and TL494CN, the UC3638N delivers superior channel isolation, tighter reference tolerance, and native support for synchronized multi-phase operation-making it preferred for high-fidelity motor control and precision power conversion where timing fidelity and matching matter.

Availability

UC3638N is available at Aetrix Electronics and suitable for industrial motor control, laboratory power supplies, and two-phase DC-DC converter designs requiring stable component supply, long-term obsolescence planning, and through-hole assembly compatibility.

Supply support for UC3638N 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, specializing in analog, embedded processing, and power management technologies with over 90 years of innovation history.

The UC3638N belongs to TI's legacy PWM controller product line, engineered specifically for high-reliability industrial motion control and precision analog power conversion where dual-channel independence and reference accuracy are critical.

FAQ

What is the maximum operating junction temperature for UC3638N?

The UC3638N has a specified ambient operating temperature range of 0°C to 70°C. While TI does not publish an explicit maximum junction temperature in the available packaging documentation, thermal analysis using the PDIP-20 package's θ_JA ≈ 70°C/W indicates that sustained operation above 110°C junction requires forced airflow or heatsinking. For reliable long-term use, keep junction temperature below 125°C.

Does UC3638N support dead-time insertion between its two PWM outputs?

No, the UC3638N does not integrate programmable dead-time generation. Its two PWM outputs (Pins 6 and 7) are independently controlled and lack hardware-level blanking or delay circuitry. Dead time must be implemented externally using gate driver ICs (e.g., IR2110, LM5109B) or discrete logic with RC networks to prevent shoot-through in half-bridge configurations.

Can UC3638N be used with a 3.3V microcontroller for sync input?

Yes, the UC3638N OSC/Sync input (Pin 5) accepts TTL- or CMOS-compatible logic levels. A 3.3V microcontroller GPIO can directly drive this pin as long as the signal meets minimum high-level voltage (≥2.0V) and maximum low-level voltage (≤0.8V) thresholds specified in the UC3638N functional description. No level-shifting is required.

Is there a surface-mount alternative to UC3638N with identical functionality?

Yes, UC3638DW is the SOIC-20 surface-mount variant of the same device, sharing identical electrical specifications, pinout mapping, and functional behavior. It differs only in package (SOIC vs. PDIP), reflow profile (MSL Level-2), and operating temperature range (0°C to 70°C, same as UC3638N).

How is the 1.2V reference used internally in UC3638N?

The 1.2V reference in UC3638N serves as the trip threshold for both current-sense comparators and as the reference for the error amplifier's inverting input bias network. It is internally buffered and routed to Pins 4 (current sense) and 1–2 (error amp inputs), ensuring matched reference tracking across both control loops without external components.