SA9106A
PIN DESCRIPTION (Continued)
Pin
PLCC
Pin
DIP
Designation
Description
Manufacturer's Test Pins (Leave unconnected)
31
32
1
39
40
TP39
TP40
TP1
4
TP4
5
TP5
9
TP9
12
37
38
44
TP12
TP37
TP38
TP44
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 625µΩ). This voltage is
converted to a current of between 0 and 16µA, by means of resistors R1 and R2.
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 (1MΩ).
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:
5/14
sames
SAMES [ SAMES ]
