INA226-Q1

SBOS743 – JULY 2015

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7.6.2 Shunt Voltage Register (01h) (Read-Only)

in two's complement format. Generate the two's complement of a negative number by complementing the

absolute value binary number and adding 1. An MSB = '1' denotes a negative number.

1. Take the absolute value: 80 mV

2. Translate this number to a whole decimal number (80 mV ÷ 2.5 µV) = 32000

3. Convert this number to binary = 0111 1101 0000 0000

4. Complement the binary result = 1000 0010 1111 1111

5. Add '1' to the complement to create the two's complement result = 1000 0011 0000 0000 = 8300h

If averaging is enabled, this register displays the averaged value.

Full-scale range = 81.92 mV (decimal = 7FFF); LSB: 2.5

μV.

Table 10. Shunt Voltage Register (01h) (Read-Only) Description

BIT #

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

BIT

SIGN

SD14

SD13

SD12

SD11

SD10

SD9

SD8

SD7

SD6

SD5

SD4

SD3

SD2

SD1

SD0

NAME

POR

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

VALUE

The Bus Voltage Register stores the most recent bus voltage reading, VBUS.

If averaging is enabled, this register displays the averaged value.

Full-scale range = 40.96 V (decimal = 7FFF); LSB = 1.25 mV.

Table 11. Bus Voltage Register (02h) (Read-Only) Description

BIT #

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

BIT

—

BD14

BD13

BD12

BD11

BD10

BD9

BD8

BD7

BD6

BD5

BD4

BD3

BD2

BD1

BD0

NAME

POR

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

VALUE

(1)

D15 is always zero because bus voltage can only be positive.

7.6.4 Power Register (03h) (Read-Only)

If averaging is enabled, this register displays the averaged value.

The Power Register LSB is internally programmed to equal 25 times the programmed value of the Current_LSB.

The Power Register records power in Watts by multiplying the decimal values of the Current Register with the

decimal value of the Bus Voltage Register according to Equation 4.

Table 12. Power Register (03h) (Read-Only) Description

BIT #

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

BIT

PD15

PD14

PD13

PD12

PD11

PD10

PD9

PD8

PD7

PD6

PD5

PD4

PD3

PD2

PD1

PD0

NAME

POR

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

VALUE

7.6.5 Current Register (04h) (Read-Only)

If averaging is enabled, this register displays the averaged value.

The value of the Current Register is calculated by multiplying the decimal value in the Shunt Voltage Register

with the decimal value of the Calibration Register, according to Equation 3.

24

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