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National Semiconductor’s COP8 µC family, targeting cost-sensitive applications, is now available in a product line that potentially requires no external components. The new COP8SAx contains built-in EMI protection, power-on-reset circuitry, multi-input-wake-up, a Microwire/Plus serial interface, software-selectable I/O, 8 bytes of user-accessible storage, a watchdog timer, as many as 12 high-current outputs, and a direct LED drive. To help achieve low chip cost, National’s chip architects designed the COP8 with a serial architecture, including a 1-bit ALU and serial peripherals. This serial architecture reduces performance but offers smaller silicon. Also, fewer transistors switch at once, yielding low current, low EMI, and less di/dt.
The COP8SAx’s EMI protection comprises an RF choke, gradual-turn-on drivers, and an internal RC oscillator. The choke actively reduces current transients reaching the power supply and, in turn, the H-field emissions from the system. The output ports use gradual-turn-on drivers to reduce EMI and reduce the peak instantaneous current; however, these ports have slightly longer propagation delay than do standard drivers. The RC oscillator uses a power-supply filter to minimize the direct coupling of the oscillator frequency to the power supply.
Software-selectable I/O lets you select high or low output and tristate or pullup inputs on the fly. The COP8SAx’s 8-byte storage space is useful for storing configuration information, date codes, CRC values, and software revisions. When the COP8SAx’s security bit is set, this storage space is unprotected, whereas the regular program space is protected, preventing users from reading your coded intellectual property.
The COP8SAB with 2 kbytes of EPROM and 128 bytes of RAM and the COP8SAA with 1 kbyte EPROM and 64 bytes of RAM cost $1.50 and $1, respectively (10,000). The devices operate from 2.7 to 5.5V and are available in nine packages and pinouts. For software support, National provides a C compiler, an assembler, a linker, and a librarian. National also offers an evaluation-and-programming unit. Metalink (Chandler, AZ) provides an in-circuit emulator.—by Markus Levy
National Semiconductor, Santa Clara, CA. (800) 272-9959; http://www.national.com.
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