Datasheet

INA219
SBOS448F –AUGUST 2008– REVISED SEPTEMBER 2011 www.ti.com
Simple Current Shunt Monitor Usage
Overload conditions are another consideration for the
(No Programming Necessary)
INA219 inputs. The INA219 inputs are specified to
tolerate 26V across the inputs. A large differential
The INA219 can be used without any programming if
scenario might be a short to ground on the load side
it is only necessary to read a shunt voltage drop and
of the shunt. This type of event can result in full
bus voltage with the default 12-bit resolution, 320mV
power-supply voltage across the shunt (as long the
shunt full-scale range (PGA = ÷8), 32V bus full-scale
power supply or energy storage capacitors support it).
range, and continuous conversion of shunt and bus
It must be remembered that removing a short to
voltage.
ground can result in inductive kickbacks that could
Without programming, current is measured by
exceed the 26V differential and common-mode rating
reading the shunt voltage. The Current Register and
of the INA219. Inductive kickback voltages are best
Power Register are only available if the Calibration
dealt with by zener-type transient-absorbing devices
Register contains a programmed value.
(commonly called transzorbs) combined with
sufficient energy storage capacitance.
Programming the INA219
In applications that do not have large energy storage
The default power-up states of the registers are
electrolytics on one or both sides of the shunt, an
shown in the INA219 register descriptions section of
input overstress condition may result from an
this data sheet. These registers are volatile, and if
excessive dV/dt of the voltage applied to the input. A
programmed to other than default values, must be
hard physical short is the most likely cause of this
re-programmed at every device power-up. Detailed
event, particularly in applications with no large
information on programming the Calibration Register
electrolytics present. This problem occurs because an
specifically is given in the section, Programming the
excessive dV/dt can activate the ESD protection in
INA219 Power Measurement Engine .
the INA219 in systems where large currents are
available. Testing has demonstrated that the addition
of 10Ω resistors in series with each input of the
INA219 sufficiently protects the inputs against dV/dt
failure up to the 26V rating of the INA219. These
resistors have no significant effect on accuracy.
16 Submit Documentation Feedback Copyright © 2008–2011, Texas Instruments Incorporated
Product Folder Link(s): INA219