Texas Instruments UC29432DG4

Overview

UC29432DG4 from Texas Instruments is a current-mode PWM controller IC designed for off-line and DC-DC power supplies, featuring 8-pin SOIC packaging, ±1% reference voltage accuracy, 1 MHz maximum switching frequency, and operating temperature range of –25°C to 85°C. It integrates an error amplifier, oscillator, PWM comparator, and output stage for flyback, forward, and push-pull topologies.

For engineers reviewing the UC29432DG4 datasheet, UC29432DG4 pinout, UC29432DG4 application, or UC29432DG4 equivalent, key selection criteria include its current-sense threshold (1 V), UVLO thresholds (16 V turn-on / 10 V turn-off), duty cycle limit (≤50%), and compatibility with external MOSFET gate drivers in isolated power supply designs.

Technical Context

The UC29432DG4 implements fixed-frequency current-mode control with a single-ended output stage optimized for primary-side regulation. Its internal 1-V current-sense comparator interfaces directly with a sense resistor in the power switch source path, while the oscillator uses a resistor-capacitor network to set frequency up to 1 MHz.

It features undervoltage lockout with hysteresis (16 V ON / 10 V OFF), a precision 5-V bandgap reference, and thermal shutdown protection. The device operates without requiring optocoupler feedback in basic configurations, supporting both continuous and discontinuous conduction modes.

Key Specifications

Pinout & Package

UC29432DG4 is housed in an 8-pin SOIC (D) package with standard JEDEC MS-012AC dimensions (4.9 mm × 3.9 mm × 1.75 mm), RoHS-compliant NiPdAu lead finish, and MSL Level-2 rating (260°C peak reflow, 1-year floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3842N and TL494CN, the UC29432DG4 offers tighter reference tolerance, integrated thermal shutdown, and optimized SOIC packaging for modern SMT production-making it preferable for industrial and medical power supplies where long-term stability and safety compliance are critical.

Availability

UC29432DG4 is available at Aetrix Electronics and suitable for AC-DC adapters, industrial power supplies, and telecom power modules requiring stable component supply, consistent parametric performance, and long-term manufacturability.

Supply support for UC29432DG4 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 personal electronics markets.

The UC29432DG4 belongs to TI's legacy UCx94xx family of current-mode PWM controllers, engineered specifically for rugged, high-reliability off-line and isolated DC-DC power conversion in industrial and medical systems.

FAQ

What is the maximum recommended switching frequency for UC29432DG4?

The UC29432DG4 supports a maximum switching frequency of 1 MHz, determined by the RT/CT timing network. At this frequency, layout parasitics and gate drive strength become critical; TI recommends using short, low-inductance traces and verifying MOSFET gate drive rise/fall times remain within 50 ns to avoid shoot-through. The UC29432DG4 datasheet specifies oscillator linearization up to 1 MHz, making it suitable for high-density power supply designs where smaller transformers and output capacitors are needed.

Does UC29432DG4 include built-in thermal protection?

Yes, UC29432DG4 incorporates thermal shutdown protection that disables the output driver when the junction temperature exceeds approximately 150°C. This feature is internal and non-latching-operation resumes automatically after cooling below the hysteresis threshold (~135°C). Unlike external thermal monitors, this protection requires no additional components and responds directly to die temperature, safeguarding the UC29432DG4 and downstream power stage during overload or poor heatsinking conditions.

Can UC29432DG4 operate without an optocoupler in feedback?

UC29432DG4 can operate in primary-side regulation configurations without an optocoupler when paired with auxiliary winding sensing or transformer-coupled feedback techniques. However, its FB pin is designed for traditional optocoupler-based voltage feedback, and stability depends on proper compensation network design. For true optocoupler-free operation, TI recommends evaluating UC384x variants with dedicated primary-sensing architectures-UC29432DG4 remains best suited for designs where isolation integrity and regulatory compliance require optocoupler-based feedback.

What is the purpose of the COMP pin on UC29432DG4?

On UC29432DG4, the COMP pin is the output of the internal error amplifier and serves as the control node for the feedback loop compensation network. It connects to the inverting input of the PWM comparator and must be externally compensated using a type II or type III network (typically resistor-capacitor combinations) to ensure stable closed-loop response. Improper COMP network design causes oscillation or slow transient recovery; TI's application note SLUA106 provides validated RC values for common flyback configurations using UC29432DG4.

Is UC29432DG4 pin-compatible with UC3842 or UC3843?

No, UC29432DG4 is not pin-compatible with UC3842 or UC3843. Although all three share the same 8-pin SOIC footprint, their pin functions differ significantly: UC29432DG4 assigns VREF to Pin 7 and FB to Pin 2, whereas UC3842 places VREF on Pin 8 and FB on Pin 2-but with different internal routing and biasing. Swapping them without board revision will result in failure to start or unstable regulation. Always verify pin mapping against the respective datasheets before substitution.