ina219 datasheet

C
BYPASS
0.1 F
(typical)
m
Supply Voltage
(INA219 Power Supply Range is
3V to 5.5V)
Data (SDA)
Clock (SCL)
´
Power Register
Current Register
I C
Interface
2
Voltage Register
V
IN+
R
F1
R
F2
R
PULLUP
3.3k
(typical)
W
R
PULLUP
3.3k
(typical)
W
V
IN-
ADC
PGA
INA219
GND
Power Bus
(0V to 26V)
Load
C
F
A0
A1
SDA
SCL
R
SHUNT
INA219
www.ti.com SBOS448G –AUGUST 2008–REVISED DECEMBER 2015
9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The INA219 is a current shunt and power monitor with an I
2
C- and SMBus-compatible interface. The device
monitors both a shunt voltage drop and bus supply voltage. Programmable calibration value, combined with an
internal multiplier, enable readouts of current and power.
9.2 Typical Application
Figure 28 shows a typical application circuit for the INA219. Use a 0.1-μF ceramic capacitor for power-supply
bypassing, placed as closely as possible to the supply and ground pins.
The input filter circuit consisting of R
F1
, R
F2
, and C
F
is not necessary in most applications. If the need for filtering
is unknown, reserve board space for the components and install 0-Ω resistors for R
F1
and R
F2
and leave C
F
unpopulated, unless a filter is needed (see Filtering and Input Considerations).
The pull-up resistors shown on the SDA and SCL lines are not needed if there are pullup resistors on these
same lines elsewhere in the system. Resistor values shown are typical: consult either the I
2
C or SMBus
specification to determine the acceptable minimum or maximum values and also refer to the Specifications for
Output Current Limitations.
Figure 28. Typical Application Circuit
9.2.1 Design Requirements
The INA219 measures the voltage across a current-sensing resistor (R
SHUNT
) when current passes through the
resistor. The device also measures the bus supply voltage, and calculates power when calibrated. This section
goes through the steps to program the device for power measurements, and shows the register results Table 8.
The Conditions for the example circuit is: Maximum expected load current = 15 A, Nominal load current = 10 A,
V
CM
= 12 V, R
SHUNT
= 2 mΩ, V
SHUNT
FSR = 40 mV (PGA = /1), and BRNG = 0 (VBUS range = 16 V).
9.2.2 Detailed Design Procedure
Figure 29 shows a nominal 10-A load that creates a differential voltage of 20 mV across a 2-mΩ shunt resistor.
The common mode is at 12 volts and the voltage present at the IN– pin is equal to the common-mode voltage
minus the differential drop across the resistor.
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