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Chip customizes power management for cellphones

Posted: 06 Jun 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Vince Biancomano? Semtech? SC905? power management IC?

Semtech Corp.'s SC905 family of power management ICs feature nine ultralow dropout (ULDO) regulators that individually source from 80-300mA for cellphone applications.

The chip features five low-noise ULDOs for analog power, four general purpose ULDOs for digital power, and a battery charger IC interface. Each UDLO's output current and output noise is specifically optimized to match the handset's baseband functions: Microprocessor core, analog, keypad, receiver, transmitter, VCO, PLL, camera and vibrator motor. The SC905 and SC905A also include battery charger IC control when paired with Semtech's standalone battery chargers to provide a complete, cost-effective power regulation solution.

"Smart phone designs constantly add new features that require more power rails than supplied by power management ICs. Cellphone designers want a power solution that gives them the freedom to accommodate new loads or voltage levels and that fits in increasingly smaller designs," said Ven Shan, vice president of marketing for power management products at Semtech. "The SC905 and SC905A are mini PMICs that are I2C programmable to generate the output voltages for enabling compact, feature-rich cell phone designs."

Five of the ULDOs on the SC905 can generate low noise outputs in the 2.55V to 2.9V range to power noise-sensitive analog circuitry such as audio, radio frequency or oscillator circuits. Three of the other regulators generate outputs in the 1.35-2.9V range and are designed for powering digital circuits. One additional ULDO can drive up to 150mA (between 1.35-2.9V) to be used as a general supply or as a vibrator motor supply.

The SC905A offers the same combination of low noise and general purpose ULDOs, but offers expanded input/output voltage ranges for select ULDOs (output range up to 3.3V) allowing it to support a larger variety of CDMA chipsets. The SC905A also contains a dedicated enable pin for the vibrator motor regulator and transceiver output.

The devices come with a power-on control pin for on/off control of the baseband processor, oscillator, keypad and audio. Two other pins are available to power up the device when connected to a battery charger or hands-free kit. The SC905 and SC905A feature six independent input supply pins for connection from either the battery directly or other power sources, minimizing regulator input-to-output voltage drops and improving overall efficiency.

The SC905 and SC905A, in a 5-by-5 mm MLP-32 package, are available immediately in production quantities and are priced at $2.44 each in 1,000-piece lots. Semtech offers comprehensive design assistance, including field- and factory-based support.

- Vince Biancomano

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