INA226 Ultra-Precise I2C Output Current, Voltage and Power Monitor

The INA226 is a current and power monitor chip with high-accuracy ADC and a resolution of 16bit. It features I2C and SMBUS-compatible interfaces for easy integration and monitors both shunt voltage drop and bus voltage drop. Programmable calibration value, conversion times, and averaging, combined with an internal multiplier enables direct readout of current in amperes and power in watts. The INA226 senses current on common-mode bus voltages that can vary from 0 V to 36 V, independent of the supply voltage. The device operates from a single 2.7 V to 5.5 V supply, drawing a typical 330 µA of supply current. The device is specified over the operating temperature range between -40°C and +125°C and features up to 16 programmable addresses on the I2C-compatible interface.

 

INA226 Pinout Configuration

PIN NAME	PIN NO.	I/O	DESCRIPTION
A0	2	Digital input	Address pin. Connect to GND, SCL, SDA, or VS. Table 2 shows pin settings and corresponding addresses.
A1	1	Digital input	Address pin. Connect to GND, SCL, SDA, or VS. Table 2 shows pin settings and corresponding addresses.
Alert	3	Digital output	Multi-functional alert, open-drain output.
GND	7	Analog	Ground.
IN+	10	Analog input	Connect to the supply side of the shunt resistor.
IN–	9	Analog input	Connect to the load side of the shunt resistor.
SCL	5	Digital input	Serial bus clock line, open-drain input.
SDA	4	Digital I/O	Serial bus data line, open-drain input/output.
VBUS	8	Analog input	Bus voltage input.
VS	6	Analog	Power supply, 2.7 V to 5.5 V.

 

Features

• Senses bus voltages from 0 V to 36 V
• High-side or low-side sensing
• High accuracy
• 0.1% gain error (max)
• 10 µV offset (max)         
• Reports current, voltage, and power
• Configurable averaging options
• 16 programmable addresses
• Operates from 2.7 V to 5.5 V power supply
• 10-pin, DGS (VSSOP) package

 

Note: Complete technical details can be found in the INA226’s datasheet at this page’s end.

 

How To Use INA226?

The schematics below shows the typical application circuit diagram of INA226.

The INA226 device performs two measurements on the power-supply bus of interest. The voltage developed from the load current that flows through a shunt resistor creates a shunt voltage that is measured at the IN+ and IN– pins. The device can also measure the power supply bus voltage by connecting this voltage to the VBUS pin. The differential shunt voltage is measured with respect to the IN–pin while the bus voltage is measured with respect to the ground. The device is typically powered by a separate supply that can range from 2.7 V to 5.5 V. The bus that is being monitored can range in voltage from 0 V to 36 V, based on the fixed 1.25-mV LSB for the Bus Voltage Register that a full-scale register results in a 40.96 V value.

Functional Block Diagram

 

Applications

• Servers
• Telecom equipment
• Computing
• Power management
• Battery chargers
• Power supplies
• Test equipment

 

Absolute Maximum Ratings

		MIN	MAX	UNIT
VVS	Supply voltage		6	V
Analog Inputs, IN+, IN–	Differential (VIN+ – VIN-)(2)	–40	40	V
Common-Mode (VIN+ + VIN-) / 2	–0.3	40
VVBUS		–0.3	40	V
VSDA		GND – 0.3	6	V
VSCL		GND – 0.3	VVS + 0.3	V
IIN	Input current into any pin		5	mA
IOUT	Open-drain digital output current		10	mA
TJ	Junction temperature		150	°C
Tstg	Storage temperature range	–65	150	°C

 

DC Characteristics

PARAMETER		TEST CONDITIONS	MIN	TYP	MAX	UNIT
INPUT
	Shunt voltage input range		–81.9175		81.92	mV
	Bus voltage input range(1)		0		36	V
CMRR	Common-mode rejection	0 V ≤ VIN+ ≤ 36 V	126	140		dB
VOS	Shunt offset voltage, RTI(2)			±2.5	±10	μV
	Shunt offset voltage, RTI(2) vs temperature	–40°C ≤ TA ≤ 125°C		0.02	0.1	μV/°C
PSRR	Shunt offset voltage, RTI(2) vs Power supply	2.7 V ≤ VS ≤ 5.5 V		2.5		μV/V
VOS	Bus offset voltage, RTI(2)			±1.25	±7.5	mV
	Bus offset voltage, RTI(2) vs temperature	–40°C ≤ TA ≤ 125°C		10	40	μV/°C
PSRR	Bus offset voltage, RTI(2) vs power supply			0.5		mV/V
IB	Input bias current (IIN+, IIN– pins)			10		μA
	VBUS input impedance			830		kΩ
	Input leakage (3)	(IN+ pin) + (IN– pin),Power-down mode		0.1	0.5	μA
DC ACCURACY
	ADC native resolution			16		Bits
	1 LSB step size	Shunt voltage		2.5		μV
Bus voltage		1.25		mV
	Shunt voltage gain error			0.02%	0.10%
	Shunt voltage gain error vs temperature	–40°C ≤ TA ≤ 125°C		10	50	ppm/°C
	Bus voltage gain error			0.02%	0.10%
	Bus voltage gain error vs temperature	–40°C ≤ TA ≤ 125°C		10	50	ppm/°C
	Differential nonlinearity			±0.1		LSB
SMBus
	SMBus timeout(4)			28	35	ms

 

2D Model and Dimensions