INA220 datasheet(15/35 Pages) TI

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Simple Current Shunt Monitor Usage

Programming the INA220

Supply

Load

10W

FILTER

10W

FILTER

0.1 Fto1 F

CeramicCapacitor

Current

Shunt

Data(SDA)

3.3VSupply

Clock(SCL)

PowerRegister

CurrentRegister

Two-Wire

Interface

VoltageRegister

IN+

ADC

INA220

GND

SupplyVoltage

IN-

BUS

INA220

www.ti.com ............................................................................................................................................................. SBOS459B – JUNE 2009 – REVISED JUNE 2009

sampling rate (>1MHz). Filter using the lowest

available. Testing has demonstrated that the addition

possible series resistance and ceramic capacitor.

of 10

Ω resistors in series with each input of the

Recommended values are 0.1

µF to 1.0µF. Figure 19

INA220 sufficiently protects the inputs against dV/dt

shows the INA220 with an additonal filter added at

failure up to the 26V rating of the INA220. These

the input.

resistors have no significant effect on accuracy.

Overload conditions are another consideration for the

INA220 inputs. The INA220 inputs are specified to

(No Programming Necessary)

tolerate 26V across the inputs. A large differential

The INA220 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

exceed the 26V differential and common-mode rating

Without

programming,

current

measured

of the INA220. Inductive kickback voltages are best

reading the shunt voltage. The Current Register and

dealt with by zener-type transient-absorbing devices

Power Register are only available if the Calibration

(commonly

called

transzorbs)

combined

with

sufficient energy storage capacitance.

In applications that do not have large energy storage

electrolytics on one or both sides of the shunt, an

The default power-up states of the registers are

input

overstress

condition

may

result

from

shown in the INA220 register descriptions section of

excessive dV/dt of the voltage applied to the input. A

this data sheet. These registers are volatile, and if

hard physical short is the most likely cause of this

programmed to other than default values, must be

event, particularly in applications with no large

re-programmed at every device power-up. Detailed

electrolytics present. This problem occurs because an

information on programming the Calibration Register

excessive dV/dt can activate the ESD protection in

specifically is given in the section, Programming the

the INA220 in systems where large currents are

INA220 Power Measurement Engine.

Figure 19. INA220 with Input Filtering

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INA220 Datasheet(PDF) 15 Page - Texas Instruments

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