Energy Meter

Designers face the challenge of keeping system costs down while still accomplishing this task. If this record-keeping portion of the system is tampered with, revenues collected from the end customer could be drastically reduced. To prevent the loss of billing data in the event of a power failure, this data is stored regularly into non-volatile memory—as often as once a minute or 525,600 writes per year. This means that a high-endurance memory such as an EEPROM or serial SRAM and a real-time clock that is accurate over temperature is required.

For reliable code and data storage, Microchip offers a broad range of NOR flash memory products, including Parallel Flash, SPI, and SQI^®. The various available densities, wide voltage and temperature ranges, and very small packages allow Microchip flash to excel in any metering application. SuperFlash products support cost-effective, non-volatile memory data storage solutions while offering industry-leading features coupled with fixed and fast program/erase times, ultra-low power consumption, high endurance, and excellent reliability.

Memory Features:

High endurance serial EEPROM up to 1M Erase/Write Cycles
I²C or SPI serial interface
Industry leading reliability
Wide operating voltage and temperature
SPI Serial SRAM has unlimited endurance
SRAM in small 8-pin package

SuperFlash^® Memory Features:

100 years data retention (JEDEC standard A103)
100K Endurance (JEDEC standard A117)
Small Sector Architecture
Fastest and Fixed Erase/Program times
Ultra low power consumption for battery operated applications
Execute-In-Place (XIP) capability with low latency
Support for high frequency/bandwidth
Cutting edge micro-packages available

Real-Time Clock/Calendar Features:

Current as low as 700nA max.
Operates to 1.3V
Battery switchover for backup power (Vbat)
Timestamps at power fail and restore
Wide digital trimming range
Event Detect input with switch debounce
Watchdog Timer
I²C or SPI serial interface available

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Technology

High Endurance Serial EEPROM & Serial SRAM Memory

Since data storage is a critical factor, a reliable memory such as a serial EEPROM has been the industry preference for many years. The 24xxx and 25xxx serial EEPROM devices support an I²C and SPI serial interface respectively. Further details at www.microchip.com/memory.

Flash Memory

For applications with higher density memory requirements, Microchip’s NOR flash memory products with patented and proprietary SuperFlash® nonvolatile flash memory cells are an ideal solution. SuperFlash memory uses a split-gate cell design and a thick-oxide tunneling injector to offer significant cost and reliability benefits to customers. Superior reliability of 100,000 cycles endurance and greater than 100 years of data retention ensures robust and reliable designs for meter applications. Small Sector Architecture enables a system to choose the right amount of data/code to be erased to update contents allowing seamless partition of program and data code occupying less memory space.

Microchip offers multiple interfaces to satisfy different design needs; Parallel Flash offers asynchronous random access through dedicated address bus. SQI™ flash memory reads and writes through a 4-bit multiplexed synchronous serial communication interface enables true low-pin count, high-bandwidth code execute-in-place applications. SPI Flash serial interface is a cost effective option to store the boot loader code, making it available for download into shadow memory upon power-up.

Memory Cell Structure

No over-erase problem
Low total power consumption during erase
Low leakage current during erase
Small sector architecture
Faster re-write times

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Real-Time Clock/Calendar

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Integration

The MCP794XX and MCP795XXX low-power real time clock/calendar devices feature non-volatile memory and can operate down to 1.3V through the backup supply connected to the VBAT input for timekeeping and SRAM retention only. As part of the power sense circuit, a time saver function is implemented to store the time when main power is lost and again when power is restored to log the time and duration of any power failure. A Watchdog Timer is included for applications outside the microcontroller.

Accuracy

Accuracy is needed over a wide temperature range; these RTCC devices were implemented with digital trimming to support a software temperature- compensated design. Through the use of an MCU and an external temperature sensor, the digital trimming registers can be updated with new calibration parameters when the temperature changes.

Unique ID

A 64-bit or 128-bit protected EEPROM space is available for a unique ID or MAC address to be programmed at the factory or by the end user.

Anti-Temper

To support anti-tampering requirements, two types of digital event detects were implemented in the MCP795XXX RTCC. One event detect input is high speed with a programmable pulse count that can identify the 1/4/16/32 pulses before sending an interrupt the MCU. The second event detect is low speed with a built-in debounce input filter to support noisy mechanical switches or the removal of a panel from the meter. Since the real-time clock is running all the time, the event detects operate all the time.

Learn more at www.microchip.com/RTCC.

Products

Serial EEPROM/SRAM Products Table

Product	Type	Bus	Speed	Density	Voltage	Features
24xx256	EEPROM	I²C	400 KHz to 1 MHz	256 KB	1.7V-5.5V	>1M Erase/Write cycles
24xx512	EEPROM	I²C	400 KHz to 1 MHz	512 KB	1.7V-5.5V	>1M Erase/Write cycles
25xx512	EEPROM	SPI	20 MHz	512 KB	1.8V-5.5V	>1M Erase/Write cycles
25xx1024	EEPROM	SPI	20 MHz	1 MB	1.8V-5.5V	>1M Erase/Write cycles
23K256	SRAM	SPI	20 MHz	256 KB	2.3V-3.6V	Unlimited Erase/Write cycles

Flash Memory Products

Product	Bus	Density (bits)	Operating Voltage	Typical Standby Current	Speed	Typical Program/Erase Endurance
SST25VF512A/010A	SPI	512K to 1M	2.7V to 3.6V	8µA	33 MHz	100K cycles
SST25VF020B/040B/080B	SPI	2M to 8M	2.7V to 3.6V	5µA	80 MHz	100K cycles
SST25VF016B/032B	SPI	16M to 32M	2.7V to 3.6V	5µA	up to 80 MHz	100K cycles
SST25VF064C	SPI	64M	2.7V to 3.6V	5µA	80 MHz	100K cycles
SST26VF016/032	SQI	16m to 32M	2.7V to 3.6V	5µA	80 MHz	100K cycles
SST39VF512/010/020/040	x8 Parallel	512K to 4M	2.7V to 3.6V	1µA	55ns, 70ns	100K cycles
SST39VF200A/400A	x16 Parallel	2M to 4M	2.7V to 3.6V	3µA	55ns, 70ns	100K cycles
SST39VF801C/802C	x16 Parallel	8M	2.7V to 3.6V	3µA	55ns, 70ns	100K cycles
SST39VF1601C/1602C	x16 Parallel	16M	2.7V to 3.6V	3µA	70ns	100K cycles
SST39VF3201C/3202C	x16 Parallel	32M	2.7V to 3.6V	3µA	70ns	100K cycles
SST38VF6401/2/3/4	x16 Parallel	64M	2.7V to 3.6V	3µA	70ns	100K cycles
SST39WF400B/800B	x16 Parallel	4M to 8M	1.65V to 1.95V	5µA	70ns	100K cycles
SST39WF1601/2	x16 Parallel	16M	1.65V to 1.95V	2µA	70ns	100K cycles

Serial Real-Time Clock/Calendar Products Table

Product	Bus	Speed	DIgital Trim Range	Memory	MAC Address	Vbat Min.	Current	Features
MCP79411	I²C	400 KHz	+/- 127 PPM	SRAM – 64 B EEPROM – 1 Kb Unique ID – 64 b	EUI-48	1.3V	700nA	Battery Switchover with Timestamp
MCP79412	I²C	400 KHz	+/- 127 PPM	SRAM – 64 B EEPROM – 1 Kb Unique ID – 64 b	EUI-64	1.3V	700nA	Battery Switchover with Timestamp
MCP795W21	I²C	10 MHz	+/- 255 PPM	SRAM – 64 B EEPROM – 1 Kb Unique ID – 128 b	EUI-48	1.3V	700nA	Battery Switchover with Timestamp, Event Detect Inputs, Watchdog Timer
MCP795W22	I²C	10 MHz	+/- 255 PPM	SRAM – 64 B EEPROM – 1 Kb Unique ID – 128 b	EUI-64	1.3V	700nA	Battery Switchover with Timestamp, Event Detect Inputs, Watchdog Timer

News & Events

Energy Meter

Memory Features:

SuperFlash® Memory Features:

Real-Time Clock/Calendar Features:

High Endurance Serial EEPROM & Serial SRAM Memory

Flash Memory

Memory Cell Structure

Real-Time Clock/Calendar

Integration

Accuracy

Unique ID

Anti-Temper

Serial EEPROM/SRAM Products Table

Flash Memory Products

Serial Real-Time Clock/Calendar Products Table

SuperFlash^® Memory Features: