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Single-Chip Data-Acq Family Blossoms

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Analog Devices Extends Its Microconverter Family to Include Large Memory and Higher Speed Core Integrating 12- or 16-bit A/D Converters and D/A Converters With an 8052 MCU Core and 62 kbytes of Flash/EE Memory Norwood, Mass.--Analog Devices, Inc. announced five new MicroConverters and their associated QuickStart evaluation kits, adding to its extensive family of data-acquisition systems on a chip. These new devices preserve the signature A/D converter precision, enhancing the MicroConverter family by offering an eight-fold increase in on-chip memory—facilitating larger programs and C-programming. Each device offers 62 kbytes of flash/EE program memory, 8 kbytes of flash/EE data memory, and 2304 bytes of data RAM. A comprehensive suite of peripherals includes precision A/D converters, voltage-output D/A converters, PWM/sigma-delta outputs, temperature sensor, and reference. Also included are a watchdog timer, time-interval counter, serial I/O ports (I²C, SPI, and UART), and three timers/counters—timer 3 facilitates an accurate baud-rate generator at up to 524 kbaud. The ADuC831 and ADuC841—drop in replacements for the ADuC812—are for use in applications where larger memory and/or higher core speed are required. They differ in that the ADuC831 has a 12-clock-per-instruction core and a 16 MHz max clock rate, while the ADuC841 has a 1-clock-per-instruction core and a max clock rate of 16 MHz at 3 V and 25 MHz at 5 V. The high-frequency clock is supplied externally. The ADuC832 and ADuC842 are identical to the ADuC831/41 respectively, except that they operate from a 32 kHz crystal, with an on-chip PLL generating the high-frequency clock. The ADuC831/32 have an 8-channel 200 ksamples/s A/D converter and a 100 ppm/°C reference. The ADuC841/42 offer a higher throughput 8-channel A/D converter (up to 400 ksamples/s), a more accurate reference (20 ppm/°C), an enhanced I²C interface, and higher core speed. The ADuC836 is an expanded-memory version of the ADuC816. It includes dual 16-bit sigma-delta A/D converters, a 12-bit D/A converter, temperature sensor, reference, and the same digital peripheral set as detailed above. For 24-bit performance, the ADuC824/34 provides a fully compatible upgrade path. All parts are packaged in a 52-lead plastic quad flatpack and in the smaller (8 mm × 8 mm) chip-scale package. Integration, precision, and low power make these parts ideal for smart/remote sensor interface in industrial, instrumentation (including portable), and automotive applications, as well as for monitoring/control of critical parameters in communications infrastructure such as base stations and optical transceivers. Pricing and Availability Available now, the ADuC8xx are priced per unit in 10,000 quantities as follows: the ADuC831/2 are priced at $7.22 the ADuC841/2 are priced at $7.95 the ADuC836 are priced at $8.11

Makers of 8-bit microcontrollers are always under pressure to expand addressable memory space. It's plain that Analog Devices Inc. (ADI) is letting no memory grass grow under its data-converter feet, as evidenced by these new family upgrades. Although price and availability are given, these converters are, however, still listed with preliminary datasheets on ADI's Web site. Nonetheless, it's plain to see where ADI is taking these devices as it presumably also benefits from the higher digital integration that permits somewhat smaller die sizes, even with feature-size-constrained analog circuits on-chip. The ADuC831 and ADuC832 are the fundamental building blocks in the new series, and are billed by ADI as smart transducer front-ends. That's especially significant to support IEEE-1451.2-compatible networked transducers. (Click here to try out a tutorial on IEEE-1451.) Note that the ADuC832 is functionally the same as the ' 831, except that it clocks at 16.77 MHz, derived from an El Cheapo 32 kHz external watch crystal. The IC has an on-chip PLL to support that. For its part, the nearly identical ADuC831 requires an external quartz crystal, or an external clock signal, in the range of 1 MHz to 16 MHz. Operable from either 3 V or 5 V, both of these power-managed ICs pack self-calibrating multi-channel 12-bit A/D converters, dual D/A converters, and 8-bit 8052-type microcontroller cores. The Venerable 8052 ADI is wise to use the 8052, as it's almost universally accepted in the industry, and there are many codesmiths familiar with it, to say nothing of the gobs of reusable code out there. In this iteration, the core is 8051-instruction-set-compatible, but offers a performance level of 12 clock periods per machine cycle. The ADuC831 and ' 832 also pack 62 kbytes of flash for program memory and 4 kbytes for data. They also have a 256-byte scratchpad RAM and 2 kbytes of extended RAM. On the analog side, both ICs include power-supply monitors and bandgap references. Digital peripherals include a UART, two 16-bit D/A converters, and a dual-output 16-bit pulse-width modulator. There's also a watchdog timer, an interval counter, three available timer/counters, and a dedicated timer for baud-rate generation only. Serial I/O ports support the I²C serial interface popularized by Philips, as mentioned in the press release, as well as the Motorola-derived Serial Peripheral Interface (SPI) protocol. The chips' on-chip UARTs also permit you to upgrade firmware as well as access the IC's debug modes. You can also enter a single-pin emulation mode. Speaking of emulation, these chips are supported by ADI's QuickStar development system. 25 MHz RISCs Let's turn to the ADuC841 and ADuC842 devices. They're also characterized by ADI as smart transducer front-ends, but they pack single-cycle 25 MHz 8-bit 8051 instruction-set-compatible controllers on-chip. The ADuC841 micro is actually an optimized 8052 core that can crank through 25 MIPS (peak). The fact that these ICs tout 1-clock-per-instruction cores makes them quite RISC-like. The ' 842 has a 16 MHz core. Like the ADuC832, this chip operates from a 32 kHz crystal with an on-chip PLL in conjunction with a programmable divider chain generating the CPU's 16.77 MHz clock. The microcontroller offers up to 16 MIPS peak performance. Like the other ICs in ADI's rollout, there are also three serial I/O ports supporting SPI and I²C communications as well as UART functions. On the ADuC812 and ADuC831, the serial interfaces shared some of the same pins, and ADI maintains this scheme on its ADuC841 to ensure backward compatibility. However, you can optionally operate the I²C separately on two pins (SPI uses the standard pinout). 16-bit Converters As the press release notes, ADI's ADuC836 is essentially an expanded-memory version of the forerunner ADuC816. But, unlike the 12-bit A/D converters found on the ADuC831, ' 832, ' 841, and ' 842 devices, the ' 836 packs dual and totally independent 16-bit sigma-delta A/D converters. At its output is a 12-bit D/A converter. By the way, ADI's ADuC824 and ' 834 provide an upgrade path for 24-bit performance. At the chip's front end, the two A/D converters can act in primary and auxiliary conversion roles. In addition, the chip includes a temperature sensor and a programmable-gain amplifier. The PGA aids the measurement of low-level signals. The A/D converters, with on-chip digital filtering and programmable output data rates, abet the measurement of wide-dynamic-range low-frequency signals. With their high levels of integration, and versions that can run over the -40°C to +125°C extended military temperature range, these reasonably priced data-converter-on-a-chip devices should find sockets not only in smart-sensor applications but in a variety of data-collection and industrial measuring and control schemes. The chip-scale packaged (CSP) flavors are particularly intriguing, especially for ultra-compact and portable designs.

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