Data Sheet AS8118

Revision 1.8, 15-Feb-05

Page 3 of 30

Pin Description

Pin No.

Pin Name

Description

1

VP

Positive input for the voltage channel. VP is a differential input with VN. The differential voltage

should be set at

±150mV peak for rated voltage conditions. VP is an analog input pin.

2

VN

Negative input for the voltage channel. VN is a differential input with VP. VN is usually tied to 0V

potential (VSSA). VN is an analog input pin.

3

TM

On ‘power up’, the test mode input defines the operation mode of the device. Either ‘Normal

Operation’, or ‘Calibration’ modes may be selected. TM has an on-chip pull down resistor and

should be left unconnected during ‘Normal Operation’. TM must be set to logic ‘1’ at ‘power up’ to

set the device in ‘Calibration’ mode.

4

VSSA

Negative analog supply. VSSA is the ground reference for the analog circuitry.

5

PROG

Programming pin for calibration procedure. PROG is an analog input pin which must be left

unconnected during normal operation. Note: PROG must not be connected to VSS.

6

VSSD

Negative digital supply. VSSD is the ground reference for the digital circuitry.

7

DIRO

Direction output provides indication of the direction of current flow through the current sensor.

This digital input/output has an on-chip pull down resistor and provides logic ‘0’ for positive

power and logic ‘1’ for negative power. DIRO is used as an input during the programming cycle.

This output may be directly connected to a LED and is capable of driving 4mA.

8

CAL

Fast energy pulse output for calibration. CAL pulse rate is programmable and dependent upon

the selected MON/MOP frequency.

9

MOP

Positive motor drive signal. MOP and MON are low frequency outputs for directly driving a two

phase stepper motor. The frequency of the MOP/MON outputs is programmable to suite all

industry standards and is capable of driving 10mA.

10

MON

Negative motor drive signal. MON and MOP are low frequency outputs for directly driving a two

phase stepper motor. The frequency of the MOP/MON outputs is programmable to suite all

industry standards and is capable of driving 10mA.

11

LED

This output may be connected to an LED to display energy consumption. LED is a digital output,

which is programmable to a desired pulse rate. All the industry standard pulse rates are

available. This output is capable of driving 10mA.

12

VDDD

Positive digital supply. VDDD provides the supply voltage for the digital circuitry. The required

supply voltage is 5V

±10%.

13

XOUT

See XIN below, for the connection of a crystal or ceramic resonator. When an external clock is

applied to XIN, XOUT is not connected.

14

XIN

A 3.579545 MHz crystal or ceramic resonator may be connected across XIN and XOUT without

the need for external load capacitors. Alternatively, an external clock signal may be applied to

XIN.

15

VDDA

Positive analog supply. VDDA provides the supply voltage for the analog circuitry. The required

supply voltage is 5V

±10%.

16

DIRI

Direction input pin for selecting unidirectional or bi-directional energy measurement mode. When

DIRI is at logic ‘0’, the IC is set in unidirectional mode. When DIRI is at logic ‘1’ the IC is in bi-

directional mode. In default mode, when DIRI is not connected, the IC is in bi-directional mode.

DIRI is a digital input with an on-chip pull-up resistor.

17

IP

Positive input for the current channel. IP is a differential input with IN. The input gain is

programmable depending on the desired current sensor. The maximum differential voltage is

±150mV peak (Gain = 4). IP is an analog input pin.

18

IN

Negative input for the current channel. IN is a differential input with IP. The input gain is

programmable depending on the desired current sensor. IN is usually at 0V potential. IN is an

analog input pin.