SA9106A

sames

5/14

Pin

Pin

Designation

Description

PLCC

DIP

31

39

TP39

Manufacturer's Test Pins (Leave unconnected)

32

40

TP40

1

TP1

4

TP4

5

TP5

9

TP9

12

TP12

37

TP37

38

TP38

44

TP44

PIN DESCRIPTION (Continued)

FUNCTIONAL DESCRIPTION

The SA9106A is a CMOS mixed signal Analog/Digital integrated circuit, which performs

bidirectional power calculations across a power range of 1000:1, to an overall accurancy

of better than 1% (± 1 count). An on-chip LED display driver directly drives a 5 digit (7

segment) LED display. The measured power is displayed in Watts.

The integrated circuit comprises of all the required functions such as two oversampling

A/D converters for the voltage and current sense inputs, power calculation and energy

integration. Internal offsets are eliminated through the use of cancellation procedures.

1.

Power Calculation

In the Application Circuit (Figure 1), the voltage drop across the shunt will be

between 0 and 50mV (0 to 80A through a shunt resistor of 625µ

Ω). This voltage is

converted to a current of between 0 and 16µA, by means of resistors R

The current sense input saturates at an input current of ±25µA peak.

For the voltage sense input, the mains voltage (230VAC) is divided down through

a divider to 14V. The resulting current into the A/D converter input is set at 14µA

at nominal mains voltage, via resistor R4 (1M

Ω).

In this configuration, with a mains voltage of 230 V and a current of 80A, the

displayed power is 18 400 Watts.

2.

LED Display Driver

The SA9106A has an on-chip LED display driver capable of driving 5 digit (7

segment) common cathode digits as well as a sign LED.

The sign LED is addressed by DIG [5], the most significant digit by DIG [4] and the

least significant digit by DIG [0].

The position of the segments a, b, c, d, e, f and g are shown in the diagram below: