Highly Integrated Mixed-Signal Memory IC Saves Board Space, Reduces Cost, and Speeds Designs
DALLAS, TX—May 9, 2007—Dallas Semiconductor, a wholly owned subsidiary of Maxim Integrated Products (NASDAQ: MXIM), introduces the DS28DG02, a new memory device with unprecedented integration of mixed-signal and nonvolatile memory functions.
Through high integration of functions and capabilities, the DS28DG02 provides typically a 20% savings in PCB space and 30% savings in cost. Manufacturers of end-equipment will have a reduced bill-of-materials for lower production costs and increased equipment reliability through fewer components. The product designer will realize a reduced design cycle from simplified hardware complexity and a single device for software interaction. With its unmatched array of capabilities, this new memory device is applicable for a broad range of applications in communication, medical, consumer, and industrial end equipment.
The Limitations of Traditional Memory Circuits
"Prior to the availability of the DS28DG02, equipment designers typically used up to four discrete ICs to implement equivalent functionality," noted Scott Jones, Business Director for the Company's mixed-signal memory products. These four discrete devices included an EEPROM, real-time clock (RTC), port expander, and CPU supervisor/monitor. If a designer integrated ROM ID and an active backup battery monitor, yet more discrete components were normally required. The hardware design of such a discrete implementation was further complicated by factors including multidevice bus interfacing, power-supply bypass filtering, and increased PCB layout effort. The software design effort for that discrete approach was similarly complicated through configuration and control of multiple devices.
Compared to the complexities of the traditional discrete solution, the integrated approach of the DS28DG02 with its memory array and single set of control/status registers is immediately appealing.
Unmatched Integration in a Memory Device
The DS28DG02's integration is a matrix of capabilities not found in any other single device. The circuit has a 2kb EEPROM array which meets the size requirements to store system configuration, calibration, operational settings, etc., required by most applications. In addition, page boundary-programmable write-protection modes are provided to safeguard stored data.
Twelve bidirectional, user-programmable GPIO channels offer a high level of flexibility and convenience for adapting to a wide range of applications. The GPIOs can be configured as input or output, open drain or push-pull, and can be programmed through the EEPROM registers to power up in a defined state. Additionally, the GPIOs can sink up to 22mA when operating at 3.3V, which makes them ideal for LED on/off direct control.
The DS28DG02's RTC provides a BCD formatted clock/calendar with a programmable time/calendar alarm. Of particular benefit for portable electronic devices, the RTC can be powered from an external backup power source, such as a lithium coin cell, in the absence of VCC power.
The DS28DG02 is the first device to provide a user-programmable, supervisory function that "actively" monitors the health of the backup battery. Jones explained that: "It is critical for most applications that the RTC and alarm functions operate reliably when running on backup power. An energy-depleted coin cell would be a catastrophic condition, which would essentially cause the RTC oscillator and associated timekeeping and alarm functions to stop." While operating under VCC power, the battery monitor periodically tests the backup source and generates an alarm interrupt if the battery condition is out of spec.
"The DS28DG02's battery monitoring actively protects the device, not just passively alerts when the power source has completely failed and when it is too late to take preventive action." Jones added. The active battery monitor applies a 10 microamp (typ) test load with 1-second duration to the battery each hour. It then follows with a battery terminal voltage comparison to a programmable test point; the comparison range is programmable from 1.75V to 2.5V with 0.25V increments. An interrupt output is generated if the terminal voltage is below the programmed threshold.
Jones explained: "The measurement of the terminal voltage of an unloaded backup battery does not really provide useful information. For example, the no-load terminal voltage of a fully depleted 3V lithium coin cell will typically measure in the 3V range. This misleading measurement incorrectly indicates capacity to deliver backup power, information which could have disastrous effects for the end user."
Additional DS28DG02 supervisory functions include a voltage monitor and watchdog timer, both with reset outputs. The voltage monitor is factory-programmed to generate a 328ms (typ) reset at 3.3V, -5% with 2.5% accuracy over the operating range. The monitor's reset output can also be used as a pushbutton input/output with debounce. The watchdog is user-programmable with timeout options ranging from 0.2s to 1.64s (typ).
Finally, for equipment and applications that require a unique electronic serial number, the DS28DG02 provides a factory-programmed 64-bit ROM ID unique to each device. This 64-bit ID can be used to serialize a piece of equipment for tracking by manufacturing or to generate a unique node ID for networked environments.
Serial communication with the DS28DG02 is performed over the industry standard SPI™ interface at speeds up to 2MHz.
The Range of Applications Is Wide
Because of its diverse capabilities, low manufacturing cost, and tight integration, the DS28DG02 will fit into a broad range of end-equipment applications. Examples include medical instruments, base stations and data communication equipment, servers, vending equipment, asset tracking systems, process control, Point-of-Sale (POS) equipment, building lighting, and energy control.
The standard device operates at 3.3V, ±5%. Other versions are available that operate at 5V, 3V, 2.5V, and some with 5% and 10% trip point options. The DS28DG02 is specified over the -40°C to +85°C industrial temperature range. Package options include 28-pin TSSOP and 36-pin, 6mm x 6mm TQFN. Pricing starts at $1.81 (1,000-up, FOB USA). For more information please visit: http://www.maxim-ic.com/Memory-IC
SPI is a trademark of Motorola, Inc.
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