Electronic Design

Semtech Adds New Power Management Controllers for Notebook CPU and GPU Applications

Camarillo, Calif.:
Semtech Corp. announced the SC457 and SC458 power supply controllers with digitally controlled output and fast transient performance for processors and graphics chips used in notebook computers.

With a built-in 7-bit DAC, the output voltage of the SC457 and SC458 can be digitally programmed in 12.5-mV steps from 0.3 V up to 1.5 V for precision control over output voltages. Both devices have a programmable DAC slew rate to minimize transient currents and audible noise. Additionally, the devices feature a power-save function that boosts efficiency at light loads to extend battery life.

The single-phase SC457 can drive up to 30 A and is packaged in an MLP5x5-32pin (5-mm × 5-mm) package so it is ideal for ultra small, lightweight notebook computers that need low-voltages for long battery life. The 60-A, dual-phase SC458 can seamlessly switch between single- and dual-phase operation for very efficient operation with no disturbance on the output voltage. The SC458 is provided in an MLP7x7-44pin (7-mm × 7-mm) package. Both devices are lead free and WEEE and RoHS compliant.

The SC457 and SC458 feature a very fast hysteretic voltage regulation scheme for a transient response of less than 10µs. The use of hysteretic topology allows increased design flexibility and simplicity because it ensures the output is very stable and requires no equivalent series resistance (ESR). This architecture also minimizes output capacitance, reducing component counts, minimizing board footprint and lowering cost.

"The SC457 and SC458 are a new generation of dedicated controllers for notebook processors, and with their battery-saving features, fast transient response and digital output programmability, we believe they offer dramatic added value over general purpose controllers," said Nejo Necar, Vice President of Marketing for Semtech's Power Management Group. "These controllers give notebook designers a substantive choice to meet the needs of notebook families, with a single-phase device for ultra lightweight notebooks, and a dual-phase device for desktop replacement models."

For high efficiency, the SC457 and SC458 utilize Semtech's proprietary Smart Drive technology, which lowers ringing on the phase node and high-side FET gate node to keep efficiency high while reducing EMI and eliminating the need for snubbers or gate resistors. Additionally, the SC458's current sensing system is based on Semtech's Combi-Sense technology that eliminates the need for lossy, external sense resistors, thus keeping efficiency high and reducing cost.

Both devices have a complete set of protection mechanisms including programmable current limit, output over-voltage protection, input under-voltage lockout and over-temperature protection.

Key Features of the SC457 and SC458:

  • Input voltage: 5 V and 5 V to 25 V
  • Digitally programmed output voltage: 0.3 V to 1.5 V (12.5-mV steps)
  • Hysteretic control for fast transient response
  • Low ESR capacitance compliant
  • Supports ceramic decoupling solutions
  • Default 1.2-V boot voltage
  • Soft OFF state
  • Active voltage positioning
  • Dynamic current sharing on SC458

Pricing and Availability
The SC457 and SC458 are available immediately in production quantities. The SC457 is priced at $1.94 each in 1,000-piece lots. The SC458 is priced at $2.80 each in 1,000-piece lots. Data sheets, volume pricing, and delivery quotes, as well as evaluation kits and samples, are available by contacting Semtech.

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