Filter Protects microSD Memory Cards In Mobile Handsets

An interface protection filter guards against electrostatic discharge damage to the microSD flash memory card or to the hardware in mobile and computing devices. In addition, the CM1624 suppresses EMI electromagnetic interference while providing excellent digital signal integrity. The filter, which is a member of the Praetorian III product line, also features integrated pull-up resistors to eliminate the need for additional circuitry on the handset pc board. The CM1624 can support clock frequencies up to 96 MHz, rise/fall times as fast at 5 ns, and high levels of attenuation from 700 MHz to 3 GHz. The CM1624 pinout is optimized for the microSD interface standard and features 6 lines of EMI suppression with IEC 61000-4-2 +/-15 kV (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. Integrated 25-kohm pull-up resistors help detect the presence of the memory card. The microSD interface specification allows for a total capacitive loading budget of 40 pF, and features a specification 0-V DC capacitance of 20 pF and less than 12 pF at operating voltage. The CM1624-08DE protection filter comes in an RoHS-compliant microDFN16 package. Samples and production quantities are available now and are priced at $0.16 each in 3000-unit quantities. CALIFORNIA MICRO DEVICES CORP., Milpitas, CA. (800) 325-4966.