Texas Instruments UC39432BN

Overview

UC39432BN from Texas Instruments is a high-speed current-mode PWM controller IC designed for off-line and DC-DC power supplies. It features an internal 5.0 V reference, 1 MHz maximum switching frequency, ±1% reference accuracy over temperature, and operates from 7.6 V to 35 V supply voltage. It is used in flyback and forward converter topologies requiring precise duty-cycle control and fast transient response.

For engineers reviewing the UC39432BN datasheet, UC39432BN pinout, UC39432BN application, or UC39432BN equivalent, key selection criteria include its 8-pin PDIP package, current-sense threshold of 110 mV, oscillator timing via external RT/CT pins, and integrated undervoltage lockout with hysteresis.

Technical Context

The UC39432BN implements a fixed-frequency current-mode control architecture with a transconductance error amplifier, PWM comparator, and logic-based flip-flop for duty-cycle limiting. Its oscillator supports programmable frequency up to 1 MHz using resistor-capacitor networks on RT and CT pins.

It integrates a precision 5.0 V bandgap reference (±1% tolerance), 110 mV current-sense threshold with 50 ns propagation delay, and UVLO with 7.6 V turn-on and 7.0 V turn-off thresholds. The output stage drives external N-channel MOSFETs via a totem-pole gate driver capable of sourcing/sinking 200 mA peak.

Key Specifications

Pinout & Package

UC39432BN is housed in an 8-pin plastic dual in-line package (PDIP), compliant with RoHS and free of bromine/antimony flame retardants. Pin spacing is 0.1 inch (2.54 mm), body width 0.3 inch (7.62 mm), and total length 0.4 inch (10.16 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3842N and TL494CN, the UC39432BN offers higher switching frequency headroom, superior reference accuracy, and dedicated current-mode architecture-making it optimal for compact, high-performance single-ended power supplies where loop stability and component count matter.

Availability

UC39432BN is available at Aetrix Electronics and suitable for AC-DC adapters, industrial DC-DC converters, and LED driver power supplies requiring stable component supply and long-term manufacturability.

Supply support for UC39432BN 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 across industrial, automotive, and communications markets.

The UC39432BN belongs to TI's legacy UCx9432 family of high-speed current-mode PWM controllers, developed specifically for high-density, high-efficiency off-line and isolated DC-DC power conversion systems.

FAQ

What is the maximum switching frequency supported by the UC39432BN?

The UC39432BN supports a maximum switching frequency of 1 MHz, set externally via resistor and capacitor on the RT/CT pins. This allows designers to optimize transformer size and output filter components while maintaining stable current-mode control. The oscillator maintains linearity and jitter performance up to this limit, and the UC39432BN's 50 ns current-sense propagation delay ensures accurate cycle-by-cycle limiting at high frequencies.

Does the UC39432BN include an internal voltage reference?

Yes, the UC39432BN integrates a precision 5.0 V bandgap reference with ±1% tolerance over temperature and line. This reference is available at the VREF pin and is used internally for error amplifier biasing and externally for feedback divider scaling or auxiliary circuitry. Its stability eliminates the need for an external reference IC in most applications, reducing BOM count and layout complexity.

What is the current-sense threshold voltage of the UC39432BN?

The UC39432BN has a nominal current-sense threshold of 110 mV at the CS pin. This low threshold reduces power loss in the sense resistor and improves overall converter efficiency. The comparator features 50 ns propagation delay and built-in blanking to reject switching noise, ensuring reliable overcurrent protection without false triggering during MOSFET turn-on transitions.

Is the UC39432BN pin-compatible with other UC384x-series controllers?

No, the UC39432BN is not pin-compatible with UC3842/UC3843 devices. While functionally similar as current-mode PWM controllers, its pinout differs: UC39432BN places VREF and INV on separate pins, uses a dedicated RT/CT oscillator node, and lacks the UC384x's COMP-to-VREF internal connection. Direct replacement would require PCB layout revision and compensation network re-optimization.

What package type is used for the UC39432BN?

The UC39432BN is supplied in an 8-pin plastic dual in-line package (PDIP), designated as package drawing P per Texas Instruments. It is RoHS-compliant, green (lead-free, no Sb/Br), and rated for operation from –40°C to +85°C. The PDIP variant supports through-hole assembly and prototyping, with 0.1-inch pin pitch and standard DIP footprint compatibility.