AS8267 datasheet(2/136 Pages) AMSCO

2 / 136 page

Data Sheet AS8267 / AS8268

Revision 1.0, 19-Jun-07

Page 2 of 136

1kByte volatile data memory. The meter system

designer also has the option of an additional

external EEPROM memory, which is selectable in

size from 1kByte to 32kByte (in binary steps).

Program and data stored in the on-chip non-volatile

Flash memory can be secured by password

protection, in addition to an attack counter which

‘locks’ access after 5 unauthorised attacks.

An on-chip programmable watchdog timer (WDT) is

available to automatically initiate a system reset if

a regular ‘hold-off’ signal is not detected.

The system timing and real time clock (RTC) has a

dedicated external battery supply pin (VDD_BAT),

enabling the oscillator and RTC to continue

operation during ‘power-down’. The RTC may be

digitally calibrated for oscillator frequency

accuracy.

The on-chip temperature sensor provides the meter

designer the option of temperature compensation

for any of the measured parameters or functional

blocks provided, over the full operating temperature

range of the device.

The LCD Driver (LCDD) block enables the display

of information provided by the microcontroller,

directly to the LCD. Two dedicated data register

banks are provided to simplify programming,

particularly in the case where scrolled display data

is required.

The programmable multi-purpose I/O pins (MPIO)

may be independently configured as inputs or

outputs. All the I/O pins are programmable for data

direction, pull-up/pull-down resistors and drive

strength (4mA/8mA). Typical functions may include

LED energy consumption pulse output, energy

direction and fault condition indication depending

on current 1 or current 2 being active for the

energy calculation, push button for display

scrolling, mains isolation relay control for

prepayment meters, optical interface etc.

An on-chip analog ground buffer (ABUF) and

voltage reference (VREF) ensures that no external

circuitry is required. A power-supply monitor (PSM)

provides a reset, when VDD falls below a safe

operating threshold.

A reset pin (RES_N) is available for external

system reset.

The AS8267 / AS8268 ICs are available in LQFP64

plastic package.

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