PWM controller simplifies multiple-output supplies

Leveraging its leading high performance analogue manufacturing capabilities, Texas Instruments has developed an innovative power management IC for high density, low output voltage convertors.

Leveraging its leading high performance analogue manufacturing capabilities, Texas Instruments has developed an innovative power management IC for high density, low output voltage convertors.

The new secondary-side, synchronous pulsewidth modulation (PWM) controller simplifies design of applications with multiple output power supplies, such as telecom and data communications modules, industrial supplies, computer, test and medical instrumentation and merchant power supplies.

TI's UCC2540 voltage-mode, synchronous buck controller is the first secondary-side control device with dual +/-3A TrueDrive outputs to allow design of multiple power stages that can deliver currents up to 50A and output voltages as low as 0.7V.

Capable of supporting a wide input supply voltage range of 2.7 to 35V, the flexible controller can operate from a 3.3V bus, compared with competing devices that run from a 5V or higher voltages.

The device drives two external N-channel MOSFETs synchronously at a switching frequency up to 1MHz to deliver high current at high efficiencies, while minimising sizes of inductors and capacitors.

Ideal for generating auxiliary outputs as a secondary-side post regulator (SSPR) for multiple output power supplies, the UCC2540 controller achieves higher power efficiency than today's designs that use a single SSPR transistor or magnetic amplifier designs.

In addition, the UCC2540 can be used in two-stage, cascaded topologies as the local secondary-side controller for the main output in isolated, high-performance DC/DC convertors.

The controller can take synchronisation input directly from a pulsed-rectified voltage from the secondary winding device or from a pulse transmission from the primary side PWM controller.

The UCC2540 is the first device to include a tracking function to allow sequencing of two or more outputs, an essential feature needed for multiple-output power supplies.

Multiple UCC2540 controllers can be stacked to provide multiple outputs, and each output can be sequenced to another in simultaneous, ratiometric or sequential modes.

Incorporating TI's proprietary Predictive Gate Drive technology, the UCC2540 improves overall power efficiency by up to 4%, and helps eliminate body diode conduction and reverse recovery losses in synchronous rectifiers.

The UCC2540 also has a 1% accuracy reference tolerance over line, load and temperature variations.

The controller also attains optimum compensation and fast transient response by integrating a high-speed error amplifier.

The UCC2540 is shipping in volume today from TI and its authorised distributors.

The device is rated for operation from -40 to +105C, and is available in a 20-pin, thermally enhanced, HTSSOP PowerPAD package.

Suggested resale pricing is $1.85 in quantities of 1000 units.

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