POWER AND LINEAR IC SOLUTIONS

Dual 400mA Regulator Suits Portable Products

Micrel’s MIC23250 is believed to be the industry’s smallest high-efficiency, dual 400mA, 4MHz PWM, synchronous buck step-down converter.



Housed in a tiny 2mm x 2mm, 10-lead MLF (MicroLeadFrame) package, the device is aimed at portable applications in which high efficiency, low output ripple and small size are crucial. The MIC23250 uses a proprietary switching method called Hyper Light Load™ that achieves high efficiency, very low output ripple, and fast transient response while using very small output capacitors.

The combination of high efficiency and fast transient response makes the MIC23250 an excellent choice to power the latest generation of low-voltage microprocessor cores and peripheral devices for mobile handsets, GPS, PDAs, Portable Media Players (PMPs) and other portable devices.

The MIC23250 requires only six external components while regulating two independent output rails. Designed for use with a 1µH inductor and a 4.7µF output capacitor, it enables system designs with heights of less than 1mm.

The device has a very low quiescent current of 35µA with both regulators operating, and can achieve over 85% efficiency at 1mA. At higher loads it attains peak efficiencies of up to 94%. Output voltage ripple is less than 3mV peak-to-peak in full Pulse Width Modulation (PWM) Continuous Conduction Mode (CCM). The transition between PWM CCM and Hyper Light Load, in which output ripple is 20mV, is automatic.

The MIC23250 integrates two synchronous rectified DC/DC converters, eliminating the need for external MOSFETs. It accommodates an input voltage range of 2.7V to 5.5V, and has fixed preset output voltage options down to 0.72V. An adjustable voltage version is also available. The device also includes integrated thermal shutdown and current limit protection, and a micropower shutdown mode to extend battery life in portable applications.

Micrel provides full design support for the MIC23250 range of devices, including application examples, circuit schematics and layout recommendations. A free evaluation card for a number of variants within the MIC23250 range is also available.

Features

• 4MHz, dual 400mA synchronous buck regulator
• PWM CCM and Hyper Light Load modes
• Input voltage range 2.7V to 5.5V
• Quiescent current down to 35µA
• Designed for use with 1µH inductor and 4.7µF capacitor
• Ultra-fast transient response
• Output ripple voltage down to 3mV
• Up to 94% efficiency
• Integrated MOSFETs
• Micropower shutdown
• Thermal shutdown and current limiting
• Thin MLF package

Applications

• Mobile handsets
• GPS
• PDAs
• PMPs
• WiFi/WiMax/WiBro modules
• Digital cameras
• Wireless LAN cards
• USB-powered devices

For further information, including how to obtain a Micrel Evaluation Board or the MIC23250 Datasheet, please click here