ina219 datasheet

ADC
´
´
ShuntVoltage
Channel
BusVoltage
Channel
PGA
(InConfigurationRegister)
ShuntVoltage
(1)
DataRegisters
Full-ScaleCalibration
(2)
Current
(1)
BusVoltage
(1)
Power
(1)
NOTES:
(1)Read-only
(2)Read/write
INA219
www.ti.com SBOS448G –AUGUST 2008–REVISED DECEMBER 2015
8 Detailed Description
8.1 Overview
The INA219 is a digital current sense amplifier with an I
2
C- and SMBus-compatible interface. It provides digital
current, voltage, and power readings necessary for accurate decision-making in precisely-controlled systems.
Programmable registers allow flexible configuration for measurement resolution as well as continuous-versus-
triggered operation. Detailed register information appears at the end of this data sheet, beginning with Table 2.
See the Functional Block Diagram section for a block diagram of the INA219 device.
8.2 Functional Block Diagram
8.3 Feature Description
8.3.1 Basic ADC Functions
The two analog inputs to the INA219, IN+ and IN–, connect to a shunt resistor in the bus of interest. The INA219
is typically powered by a separate supply from 3 to 5.5 V. The bus being sensed can vary from 0 to
26 V. There are no special considerations for power-supply sequencing (for example, a bus voltage can be
present with the supply voltage off, and vice-versa). The INA219 senses the small drop across the shunt for
shunt voltage, and senses the voltage with respect to ground from IN– for the bus voltage. Figure 13 shows this
operation.
When the INA219 is in the normal operating mode (that is, MODE bits of the Configuration register are set to
111), it continuously converts the shunt voltage up to the number set in the shunt voltage averaging function
(Configuration register, SADC bits). The device then converts the bus voltage up to the number set in the bus
voltage averaging (Configuration register, BADC bits). The Mode control in the Configuration register also
permits selecting modes to convert only voltage or current, either continuously or in response to an event
(triggered).
All current and power calculations are performed in the background and do not contribute to conversion time;
conversion times shown in the Electrical Characteristics: can be used to determine the actual conversion time.
Power-Down mode reduces the quiescent current and turns off current into the INA219 inputs, avoiding any
supply drain. Full recovery from Power-Down requires 40 μs. ADC Off mode (set by the Configuration register,
MODE bits) stops all conversions.
Writing any of the triggered convert modes into the Configuration register (even if the desired mode is already
programmed into the register) triggers a single-shot conversion. Table 6 lists the triggered convert mode settings.
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