Texas Instruments UCC3976PW

Overview

UCC3976PW from Texas Instruments is a half-bridge resonant piezoelectric transformer (PZT) controller IC for CCFL backlight power supplies, operating from 3 V to 13.5 V, delivering dual out-of-phase MOSFET gate drive outputs (OUTP/OUTN), featuring programmable VCO frequency control via OSC pin, open-lamp fault protection, and 15-µA shutdown current. It targets narrow-profile LCD backlighting in portable electronics.

For engineers reviewing the UCC3976PW datasheet, UCC3976PW pinout, UCC3976PW application, or UCC3976PW equivalent, key selection considerations include its fixed 50% duty cycle with anti-cross-conduction timing, half-bridge topology support only, PZT-specific regulation via frequency sweep, and TSSOP-8 package compatibility with space-constrained display power designs.

Technical Context

The UCC3976PW implements a precision window comparator-based voltage-controlled oscillator (VCO) with thresholds at 0.7 V and 1.7 V on the OSC pin, enabling lamp-strike and regulation via frequency sweep from high to low across a user-programmed range. Its error amplifier compares FB (inverting input) to a 1.5-V internal reference to generate COMP voltage that directly modulates VCO frequency.

It integrates dual CMOS drivers: OUTP drives an external P-channel MOSFET while OUTN drives an N-channel MOSFET, both operating at fixed 50% duty cycle with built-in dead time (250 ns typical) to prevent shoot-through. The OPEN/SD pin serves dual functions-open-lamp detection (threshold 1.5 V) and shutdown activation (>2.5 V)-with retry logic up to seven attempts before error shutdown.

Key Specifications

Pinout & Package

UCC3976PW is housed in an 8-pin TSSOP (PW) package, 3.0 mm × 4.4 mm, 0.65 mm pitch, thermally enhanced for compact display power stages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC3976PW, UCC3977PW enables higher PZT gain via push-pull drive but increases component count and layout area, while UCC2976PW offers identical performance with extended thermal qualification-making UCC3976PW the most cost- and space-efficient choice for standard notebook and portable display applications.

Availability

UCC3976PW is available at Aetrix Electronics and suitable for notebook computers, portable instrument displays, and medical handheld devices requiring stable component supply and long-term production continuity.

Supply support for UCC3976PW 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 focused on analog and embedded processing technologies, with broad portfolio spanning power management, signal chain, and interface solutions.

The UCC3976PW belongs to TI's dedicated CCFL/PZT controller product line, engineered specifically for resonant piezoelectric transformer-based backlight power supplies in space- and efficiency-constrained portable electronics.

FAQ

What topology does the UCC3976PW support?

The UCC3976PW supports only the resonant half-bridge topology for driving piezoelectric transformers. It is not compatible with flyback (UCC3975PW) or push-pull (UCC3977PW) configurations. Its OUTP and OUTN drivers are specifically configured for complementary P/N-MOSFET switching with built-in dead time, and its functional block diagram, pin assignments, and application schematics in the SLUS499A datasheet confirm exclusive half-bridge implementation.

How does the UCC3976PW regulate CCFL lamp current?

The UCC3976PW regulates lamp current by controlling the operating frequency of the resonant half-bridge stage. It senses lamp current via the RCS resistor, filters it through the RFB/CFB network into the FB pin, and uses the error amplifier to generate a COMP voltage that sweeps the VCO frequency downward until the lamp strikes and current stabilizes at the setpoint. This frequency-based regulation leverages the PZT's gain-vs-frequency characteristic, as detailed in Figures 9 and 11 of the SLUS499A datasheet.

What is the function of the OPEN/SD pin on the UCC3976PW?

The OPEN/SD pin on the UCC3976PW serves two distinct functions: open-lamp fault detection (triggered at 1.4–1.6 V) and low-power shutdown activation (triggered above 2.5 V). During startup, it initiates a 7-attempt retry sequence on open-lamp condition; in normal operation, pulling it above 2.5 V places UCC3976PW into 15-µA shutdown mode, and pulling it below 0.5 V resumes operation. This dual-role pin eliminates need for separate fault and enable circuitry.

What package type is used for the UCC3976PW?

The UCC3976PW is packaged in an 8-pin TSSOP (Thin Shrink Small Outline Package), designated "PW" in TI's ordering nomenclature. Its mechanical dimensions are 3.0 mm × 4.4 mm with 0.65 mm lead pitch, and it is available taped and reeled (e.g., UCC3976TRPW for 2500-unit reels), as specified in the "Available Options" table on page 4 of the SLUS499A datasheet.

Does the UCC3976PW provide protection against MOSFET cross-conduction?

Yes, the UCC3976PW provides hardware-enforced anti-cross-conduction protection via its integrated dead-time generator. The OUTP and OUTN drivers are synchronized with a guaranteed 250-ns minimum dead time between transitions, ensuring that the P-channel and N-channel external MOSFETs are never simultaneously on. This is explicitly stated in the "Output" section of the Electrical Characteristics table (page 4) and confirmed in the functional block diagram (Figure 4) and state diagram (Figure 5) of the SLUS499A datasheet.