Datasheet

INA226
SBOS547 –JUNE 2011 www.ti.com
DATA OUTPUT REGISTERS
Shunt Voltage Register 01h (Read-Only)
The Shunt Voltage Register stores the current shunt voltage reading, V
SHUNT
. Negative numbers are represented
in twos complement format. Generate the twos complement of a negative number by complementing the
absolute value binary number and adding 1. Extend the sign, denoting a negative number by setting the MSB =
'1'.
Example: For a value of V
SHUNT
= –80mV:
1. Take the absolute value: 80mV
2. Translate this number to a whole decimal number (80mV ÷ 2.5µV) = 32000
3. Convert this number to binary = 111 1101 0000 0000
4. Complement the binary result = 000 0010 1111 1111
5. Add '1' to the complement to create the twos complement result = 000 0011 0000 0000
6. Extend the sign and create the 16-bit word: 1000 0011 0000 0000 = 8300h
If averaging is enabled, this register displays the averaged value. Full-scale range = 81.92mV (decimal = 7FFF);
LSB: 2.5μV.
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
Bus Voltage Register 02h (Read-Only)
(1)
The Bus Voltage Register stores the most recent bus voltage reading, V
BUS
.
If averaging is enabled, this register displays the averaged value. Full-scale range = 40.96V (decimal = 7FFF);
LSB = 1.25mV.
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.
Power Register 03h (Read-Only)
If averaging is enabled, this register displays the averaged value.
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
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.
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