The INA791x is a voltage output, current sense amplifier with an integrated shunt resistor of 400μΩ. The INA791x is designed to monitor bidirectional current over a common-mode range of –4V to 110V, independent of the supply voltage. Adjustable gain option assists in optimizing the system dynamic range. The integration of the Kelvin connected shunt resistor with a zero-drift chopped amplifier provides calibration equivalent measurement accuracy, ultra-low temperature drift performance of 35ppm/°C, and an optimized layout for the sensing resistor.
This device operates from a single 2.7V to 5.5V power supply, drawing a maximum of 3.75mA of supply current. All versions are specified over the extended operating temperature range (–40°C to +125°C), and are available in a 15-pin VQFN package.
PIN | Type | DESCRIPTION | |
---|---|---|---|
NAME | NO. | ||
ALERT | 14 | Digital Out | Open-drain temperature alert |
FB | 12 | Analog Input | Gain adjustment feedback; connect to resistor divider to adjust device gain |
GND | 5 | Analog | Ground |
IN– | 9 | Analog Input | Kelvin connection to internal shunt on load side and negative amplifier input |
IN+ | 1 | Analog Input | Kelvin connection to internal shunt on supply side and positive amplifier input |
IS– | 8 | Analog Input | Connect to load |
IS+ | 15 | Analog Input | Connect to supply |
NC | 2 | – | Connect to IN+ (Pin 1) |
NC | 4, 6, 7 | – | Connect to ground or leave unconnected |
NC | 10 | – | Connect to IN– (Pin 9) |
OUT | 11 | Analog Output | Output voltage |
REF | 13 | Analog Input | Reference voltage, 0V to VS |
VS | 3 | Analog | Power supply, 2.7V to 5.5V |
MIN | MAX | UNIT | ||
---|---|---|---|---|
Supply voltage (Vs) | 6 | V | ||
Analog Inputs, VIN+, VIN- (2) | Differential (VIN+) - (VIN-) | –12 | 12 | V |
Common-mode | GND – 20 | 120 | V | |
Analog input (REF) | Analog input (REF) | GND – 0.3 | Vs + 0.3 | V |
Analog input (FB) | Analog input (FB) | GND – 0.3 | Vs + 0.3 | V |
Analog output (OUT) | Analog output (OUT) | GND – 0.3 | Vs + 0.3 | V |
Digital output (ALERT) | Temperature Alert Output | GND – 0.3 | Vs + 0.3 | V |
TA | Operating Temperature | –55 | 150 | °C |
TJ | Junction temperature | 150 | °C | |
Tstg | Storage temperature | –65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) | ±2000 | V |
Charged device model (CDM), per ANSI/ESDA/JEDEC JS-002, all pins(2) | ±1000 |
MIN | NOM | MAX | UNIT | ||
---|---|---|---|---|---|
VCM | Common-mode input range | –4 | 110 | V | |
VS | Operating supply range | 2.7 | 5.5 | V | |
ISENSE | Continuous Current | –50 | 50 | A | |
VREF | Reference voltage range | 0 | VS | V | |
VFB | Feed-back voltage range | 0 | VS | V | |
TA | Ambient temperature | –40 | 125 | °C |
THERMAL METRIC(1) | INA791x | UNIT | |
---|---|---|---|
DEK (VQFN) | |||
15 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 28.7 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 8.3 | °C/W |
RθJB | Junction-to-board thermal resistance(2) | 30.8 | °C/W |
ΨJT | Junction-to-top characterization parameter(2) | 1.1 | °C/W |
ΨJB | Junction-to-board characterization parameter(2) | 8.4 | °C/W |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
INPUT | ||||||
VCM | Common-mode input range | VIN+ = –4V to 110V, ISENSE = 0A, TA = –40°C to +125°C |
–4 | 110 | V | |
CMRR | Common-mode rejection ratio | VIN+ = –4V to 110V, ISENSE = 0A, TA = –40°C to +125°C, INA791A |
±25 | ±79 | µA/V | |
VIN+ = –4V to 110V, ISENSE = 0A, TA = –40°C to +125°C, INA791B |
±790 | ±2500 | ||||
CMRR | Common-mode rejection ratio | f = 50kHz | ±56 | mA/V | ||
Ios | Offset current, input referred | ISENSE = 0A, INA791A | ±5 | ±30 | mA | |
ISENSE = 0A, INA791B | ±62.5 | ±375 | ||||
dIos/dT | Offset current drift | ISENSE = 0A, TA = –40°C to +125°C, INA791A |
0.125 | ±0.625 | mA/°C | |
ISENSE = 0A, TA = –40°C to +125°C, INA791B |
0.250 | ±1.25 | ||||
PSRR | Power supply rejection ratio | VS = 2.7V to 5.5V, VREF = 1V, ISENSE = 0A, INA791A | 0.25 | ±2.5 | mA/V | |
VS = 2.7V to 5.5V, VREF = 1V, ISENSE = 0A, INA791B | 2.5 | ±25 | ||||
IB | Total input bias current | IB++ IB-, ISENSE = 0A | ±50 | ±80 | ±100 | µA |
IFB | Feed-back current | ISENSE = 0A | ±1.3 | nA | ||
ISENSE = 0A, TA = –40°C to +125°C | ±5 | |||||
INTEGRATED SHUNT RESISTOR | ||||||
RSHUNT | Internal Kelvin shunt resistance | IN+ to IN-, TA = 25°C | 350 | 400 | 500 | µΩ |
Pin to pin package resistance | IS+ to IS-, TA = 25°C | 450 | 560 | 650 | µΩ | |
Pin to pin package inductance | IS+ to IS-, TA = 25°C | 2 | nH | |||
ISENSE | Maximum Continuous Current | TA = –40°C to +125°C | ±50 | A | ||
Short time overload change | ISENSE = 120A for 5 seconds | ± 0.05 | % | |||
Change due to temperature cycle | –65°C to 150°C, 500 cycles | ± 0.1 | % | |||
Shunt resistance change to solder heat | 260°C solder, 10 seconds | ± 0.1 | % | |||
High temperature exposure change | 1000 hours, TA = 150°C | ± 0.15 | % | |||
OUTPUT | ||||||
G | Gain | INA791A, INA791B, | 20 | mV/A | ||
G | System Gain error (shunt + amplifier) (1) | GND + 50mV ≤ VOUT ≤ VS – 200mV, TA = 25°C, INA791A |
±0.05 | ±0.35 | % | |
GND + 50mV ≤ VOUT ≤ VS – 200mV, TA = 25°C, INA791B |
±0.1 | ±1 | ||||
G | System Gain error (shunt + amplifier) | TA = –40°C to +125°C, INA791A | ±0.5 | ±35 | ppm/°C | |
TA = –40°C to +125°C, INA791B | ±10 | ±75 | ||||
Non-Linearity Error | GND + 10mV ≤ VOUT ≤ VS – 200mV | ±0.01 | % | |||
RVRR | Reference voltage rejection ratio (input - referred) | ±2.5 | ±12.5 | mA/V | ||
Maximum capacitive load | No sustained oscillation | 0.5 | nF | |||
VOLTAGE OUTPUT | ||||||
Swing to Vs Power Supply Rail | RL = 10kΩ to GND, VREF = VS, Adjustable Gain = 4, TA = –40°C to +125°C | VS – 0.05 | VS – 0.2 | V | ||
Swing to Ground | RL = 10kΩ to GND, Adjustable Gain = 4, VREF = GND, TA = –40°C to +125°C | VGND + 5 | VGND + 20 | mV | ||
Swing to Ground | RL = 10kΩ to GND, VREF = GND, TA = –40°C to +125°C | VGND + 1 | VGND + 5 | mV | ||
FREQUENCY RESPONSE | ||||||
BW | Bandwidth (current sense amplifier) | –3dB Bandwidth, VFB = VOUT | 1 | MHz | ||
–3dB Bandwidth, Adjustable Gain = 4 | 0.5 | MHz | ||||
Settling time (current sense amplifier input to out) | VIN+, VIN- = 48V, VOUT = 1.5V to 3.5V, Output settles to 1% |
1.5 | µs | |||
VIN+, VIN- = 48V, Adjustable Gain = 4, VOUT = 0.5V to 4.5V, Output settles to 1% | 2.5 | µs | ||||
VIN+, VIN- = 48V, VOUT = 1.5V to 3.5V, Output settles to 5% |
1 | µs | ||||
VIN+, VIN- = 48V, Adjustable Gain = 4, VOUT = 0.5V to 4.5V, Output settles to 5% | 2 | µs | ||||
SR | Slew Rate | VFB = VOUT | 1.8 | V/µs | ||
Adjustable Gain = 4 | 1.5 | V/µs | ||||
NOISE | ||||||
Current Noise Density | 150 | µA/√Hz | ||||
POWER SUPPLY | ||||||
IQ | Quiescent current | 3.5 | 3.75 | mA | ||
TA = –40°C to +125°C | 4 | mA | ||||
TEMPERATURE | ||||||
Alert | Thermal Alert Threshold | Rpullup = 10kΩ, | 160 | °C | ||
AlertLO | Thermal Alert Threshold Swing to Ground | Rpullup = 10kΩ, | 200 | mV |
The INA791x features a precision current sensing solution with 400µΩ current-sensing EZShunt™ technology resistor and supports common-mode voltages up to 110V. The internal amplifier features a precision zero-drift topology with excellent common-mode rejection ratio (CMRR). High-precision measurements are enabled by matching the shunt resistor value and the current-sensing amplifier gain across temperature, thus providing a highly-accurate, system-calibrated method for measuring current. The high-speed current-sensing amplifier helps output settle fast after the common-mode transients. Flexibility of adjustable gain with two external resistors allows for the optimization of the desired full-scale output voltage based on the target current range expected in the application.
The INA791x features an integrated EZShunt™ technology current-sensing resistor that provides accurate measurements over the entire specified temperature range of –40°C to +125°C. The integrated current-sensing resistor provides measurement stability over temperature, and simplifies printed circuit board (PCB) layout and board constraint difficulties common in high-precision measurements.
The onboard current-sensing resistor is designed as a 4-wire (or Kelvin) connected resistor that enables accurate measurements through a force-sense connection. Internally connected amplifier input pins (IN– and IN+) to the sense pins of the shunt resistor eliminates many instances of parasitic impedance commonly found in typical very-low sensing-resistor level measurements. The INA791x is system-calibrated to make sure that the current-sensing resistor and current-sensing amplifier are both precisely matched to one another. The in-package integrated sensing resistor must be used with the internal current-sensing amplifier to achieve the optimized system gain specification.
The INA791x has approximately 550µΩ of package resistance. Of this total package resistance, 400µΩ resistance from the Kelvin-connected current-sensing resistor is used by the amplifier. The power dissipation requirements of the system and package are based on the total 550µΩ package resistance between the IS+ and IS– pins.
The heat dissipated across the package when current flows through the device ultimately determines the maximum current that can be safely handled by the package. The current consumption of the silicon is relatively low, leaving the total package resistance to carry the high load current as the primary contributor to the total power dissipation of the package. The maximum safe-operating current level shown in Figure 6-2 is set to make sure that the heat dissipated across the package is limited so that no damage occurs to the resistor or the package, or that the internal junction temperature of the silicon does not exceed a 165°C limit.
External factors, such as ambient temperature, external air flow, and PCB layout, contribute to how effectively the device dissipates heat. The internal heat is developed as a result of the current flowing through the total package resistance of 550µΩ.
The INA791x features a physical shunt resistance that is able to withstand current levels higher than the continuous handling limit of 50A without sustaining damage to the current-sensing resistor or the current-sensing amplifier, if the excursions are brief. Figure 6-3 shows the short-circuit duration curve for the INA791x.