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Driver Solutions in 2mm x 2mm Package |
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SAN JOSE, Calif. - (October 14, 2003) Micrel has released two new small sized DC/DC boost converters optimized for driving white LEDs in cellular, PDA, GPS, digital still camera and camcorder applications. Micrel Semiconductor (NASDAQ: MCRL), is an industry leader in analog, power management and high-speed communications integrated circuits.
The MIC2287 is similar to the MIC2289, except it operates with an external Schottky diode. The MIC2287 is best suited for higher power applications that would benefit by sharing the IC power dissipation with an external Schottky diode. The MIC2287 is available in a 2mm x 2mm MLF-8L package, as well as a low profile Thin SOT23-5L package. Both devices operate with a 2.5V to 10V input voltage range, making them suitable for 1- and 2-cell Li Ion applications. Their output voltage achieves up to 34V, allowing the MIC2287/9 to power up to 8 white LEDs in series. The devices have a high 500mA switch current rating, allowing them to provide the higher current necessary in applications such as camera flash LED drivers. The MIC2287/9 implement high frequency 1.2MHz PWM control, allowing small external components and low noise operation. The constant frequency PWM control of the MIC2287/9 significantly reduces input ripple and noise compared to variable-frequency PFM boost converter solutions. In many cases, this allows designers to reduce their input capacitance from 10uF to 1uF. The low input ripple is especially important in reducing noise injected into the main power line in sensitive RF applications such as cellular phones. The MIC2287/9 offer a high level of safety with three levels of over-voltage protection (OVP). The OVP feature protects the IC and external components in case of fault conditions which would cause the boost regulator to generate uncontrolled high voltages. Many other solutions require external OVP circuitry, or only offer a single high-voltage OVP. The three MIC2287/9 OVP options of 15V, 24V and 34V give customers the flexibility to use lower cost and smaller size low-voltage-rating output capacitors. "The MIC2287 and MIC2289 literally boost Micrel's strength in the portable market. These devices save valuable board space without sacrificing either efficiency or noise performance. The devices achieve over 80% efficiency across the Li Ion battery voltage range, saving valuable battery life. This compares to many charge-pump solutions that claim high efficiency at a single input voltage but actually have efficiency values as low as 60% across the normal battery voltage range. Additionally, the MIC2287/9 feature a tight line regulation of <1%, meaning the LED current will not change with input voltage, giving a constant brightness across the life of the battery," says Tony Grizelj, Micrel's marketing manager for power products. The MIC2287 is available in 2mm x 2mm MLF-8L and Thin SOT23-5L package options. The device is priced at $1.06 and $1.13 in 1,000-piece quantities, respectively. The MIC2289 is available in the 2mm x 2mm MLF-8L package. The device is priced at $1.22 in 1,000-piece quantities. Samples are available from stock, and production quantities are stock to 12 weeks ARO. Summary of Features & Applications: MIC2287 / MIC2289 White LED Driver ICs
Applications
Micrel Semiconductor is a leading manufacturer of advanced, high performance communications, clock management, Ethernet switch and physical layer transceiver, mixed signal, analog and power ICs. These products include devices for fiber-optic telecommunications and networking, cellular telephones, servers, portable computer systems, computer peripherals, process control systems, consumer electronics and power supplies. # # # MLF and MicroLead Frame are trademarks of Amkor Technology. For additional information, contact:
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The MIC2289 offers the smallest total size PWM DC/DC boost solution available in the market. The MIC2289 is available in a tiny 2mm x 2mm MLF-8L package with a high level of protection and performance features. The MIC2289 requires only four external components to provide a complete white LED driver solution. The low component count is achieved by integrating the external Schottky diode normally required with boost regulators, saving precious board area and cost.