Sunday, May 27, 2018
Publication Date: 09/1/2009
Archive >  September 2009 Issue >  New Products > 

Calif. Micro Launches MicroSD Interface Filter
MicroSD interface protection.
Milpitas, CA — California Micro Devices has launched its CM1624, an application-specific microSD (micro Secure Digital) interface protection filter for mobile and computing devices. The popular microSD flash memory card is increasingly used in portable devices to allow users to store or use data across different devices.

The CM1624 protects the microSD memory card user interface against ESD damage to the card or to the hardware, and suppresses EMI while providing excellent digital signal integrity. It is a member of the company's Praetorian III® product line which reportedly combines outstanding filter performance with minimal line capacitance. The CM1624 also incorporates integrated pull-up resistors, eliminating the need for additional circuitry on the handset PCB and saving additional BOM costs.

Inductor-based filter solutions offer the highest level of digital signal integrity available. The CM1624 can support clock frequencies up to 96MHz, rise/fall times as fast at 5nSec, and high levels of attenuation from 700MHz to 3GHz. The device's pinout is optimized for the microSD interface standard and provides 6 lines of EMI suppression with IEC 61000-4-2 ±15kV (contact) integrated ESD protection, one line of through-package ESD protection for the Vcc line, and two additional discrete ESD diodes for related functions such as Card Detect. In addition, CMD has integrated 25kΩ pull-up resistors to help detect the presence of the memory card. As process geometries used in manufacturing baseband and applications processors migrate to increasingly smaller feature sizes, system operating voltages are also becoming lower so that the amount of capacitive loading on the data lines has become a major concern for handset designers. The microSD interface specification allows for a total capacitive loading budget of 40pF and traditional filter architectures consume too much of this tight design parameter. The CM1624 spec is 0VDC capacitance of 20pF, and less than 12pF at operating voltage — said to be the lowest level of capacitance available in EMI filters designed for the microSD interface. The lower filter line capacitance affords handset designers greater design latitude with respect to PCB routing and improved ease of design.

Contact: California Micro Devices Corp., 490 N. McCarthy Blvd., #100, Milpitas, CA 95035 800-325-4966 or 408-263-3214 fax: 408-263-7846 Web:

search login