Datasheet

INA226
www.ti.com SBOS547 –JUNE 2011
Simple Current Shunt Monitor Usage
(No Programming Necessary)
The INA226 can be used without any programming if it is only necessary to read a shunt voltage drop and bus
voltage with the default power-on reset configuration and continuous conversion of shunt and bus voltage.
Without programming the INA226 Calibration Register, the device is unable to provide either a valid current or
power value, because these outputs are both derived using the values loaded into the Calibration Register.
Default INA226 Settings
The default power-up states of the registers are shown in the INA226 Register Descriptions section of this data
sheet. These registers are volatile, and if programmed to a value other than the default values shown in Table 2,
they must be re-programmed at every device power-up. Detailed information on programming the Calibration
Register specifically is given in the Configure/Measure/Calculate Example section and calculated based on
Equation 1.
REGISTER INFORMATION
The INA226 uses a bank of registers for holding configuration settings, measurement results, minimum/maximum
limits, and status information. Table 2 summarizes the INA226 registers; refer to Figure 1 for an illustration of the
registers.
Table 2. Summary of Register Set
POINTER
ADDRESS POWER-ON RESET
HEX REGISTER NAME FUNCTION BINARY HEX TYPE
(1)
All-register reset, shunt voltage and bus
0 Configuration Register voltage ADC conversion times and 01000001 00100111 4127 R/W
averaging, operating mode.
1 Shunt Voltage Shunt voltage measurement data. 00000000 00000000 0000 R
2 Bus Voltage Bus voltage measurement data. 00000000 00000000 0000 R
Contains the value of the calculated
3 Power
(2)
00000000 00000000 0000 R
power being delivered to the load.
Contains the value of the calculated
4 Current
(2)
current flowing through the shunt 00000000 00000000 0000 R
resistor.
Sets full-scale range and LSB of current
5 Calibration and power measurements. Overall 00000000 00000000 0000 R/W
system calibration.
Alert configuration and conversion ready
6 Mask/Enable 00000000 00000000 0000 R/W
flag.
Contains the limit value to compare to
7 Alert Limit 00000000 00000000 0000 R/W
the selected Alert function.
Contains unique die identification
FF Die ID ASCII ASCII R
number.
(1) Type: R = Read-Only, R/W = Read/Write.
(2) The Current Register defaults to '0' because the Calibration Register defaults to '0', yielding a zero current and power value until the
Calibration Register is programmed.
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