AS8218 datasheet(2/123 Pages) AMSCO

2 / 123 page

Data Sheet AS8218 / AS8228

Revision 3.0, 31-May-06

Page 2 of 123

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 during

‘power-down’. The RTC may be digitally calibrated

for oscillator frequency accuracy.

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 the display data

needs to be scrolled.

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 AS8218 / AS8228 ICs are available in LQFP64

plastic packages.

AS8218 Datenblatt(PDF) 2 Page - ams AG