ANA311
High-side current sense amplifier with 60V common-mode range, 10x/50x/100x gain options, and low offset voltage.
Product Overview
Description
The ANA311 is a precision high-side current sense amplifier capable of measuring current with common-mode voltages up to 60V.
Integrated gain resistors provide accurate 10x, 50x, or 100x amplification with less than 1% gain error and 100μV offset voltage.
Wide 2.5V to 60V supply range and low 150μA supply current make it suitable for battery and industrial applications.
Product Series
ANA
Primary Application
Battery current monitoring
Key Features
- Wide common-mode range (2.5V to 60V)
- Three gain options (10x, 50x, 100x)
- Low offset voltage (100μV)
- High accuracy (0.5% gain error)
- Single resistor current sensing
- Low supply current (150μA)
- Wide supply voltage range
- AEC-Q100 qualified
Specifications
| Common-Mode Range | 2.5V to 60V |
|---|---|
| Gain Options | 10V/V, 50V/V, 100V/V (pin-selectable) |
| Gain Error | 0.5% maximum |
| Offset Voltage | 100μV maximum |
| Bandwidth | 200kHz (at 10x gain) |
| Supply Voltage | 2.5V to 60V |
| Supply Current | 150μA typical |
| Input Bias Current | 10μA typical |
| Operating Temperature | -40°C to +125°C |
| Package | SOT23-5, SOIC-8 |
Applications
Battery current monitoring
Battery and charging management
Power supply current limiting
Power conversion and supply
Motor current sensing
Motor drive and control systems
Solar panel monitoring
Renewable energy systems
LED current control
Industrial automation and control
Automotive load monitoring
Automotive and EV electronics
FAE Expert Insights
"The ANA311 is my standard recommendation for high-side current sensing up to 60V. The integrated gain resistors eliminate the precision resistor network required by discrete solutions, saving BOM cost and PCB area. The 100μV offset is excellent for low-side current sensing - with a 10mΩ sense resistor, you can measure currents down to 10mA with 1% accuracy. I've used this part in battery management systems, motor drives, and solar inverters with excellent results. The pin-selectable gain is valuable - use 10x for high-current applications (reduces output voltage but improves bandwidth), and 100x for low-current precision measurement. For automotive applications, the AEC-Q100 qualification provides confidence in reliability. One design tip: keep the sense resistor traces short and Kelvin-connected to minimize parasitic resistance errors."
Precision high-side current sense with integrated gain and wide common-mode range
— Michael Chen, BeiLuo
Frequently Asked Questions
How do I calculate the sense resistor value for ANA311?
Sense resistor calculation: R_sense = V_out_max / (I_max × Gain). For example: Maximum current to measure = 5A, ADC input range = 3.3V, using 50x gain. R_sense = 3.3V / (5A × 50) = 13.2mΩ (use 10mΩ standard). Power dissipation in resistor: P = I² × R = 5² × 0.01 = 0.25W (use 0.5W or 1W resistor for safety margin). Output voltage at 5A: V_out = 5A × 0.01Ω × 50 = 2.5V. Resolution with 12-bit ADC: 5A / 4096 = 1.22mA per LSB. For lower current applications, use higher gain (100x) or larger sense resistor.
Calculate R_sense based on max current and desired output voltage. Use standard value with adequate power rating. Consider power dissipation vs resolution trade-off.
What is the advantage of high-side vs low-side current sensing?
High-side sensing advantages: 1) Detects load shorts to ground, 2) Maintains ground reference for load (important for communication interfaces), 3) Can monitor current during sleep mode (no ground interruption), 4) Suitable for automotive where chassis is ground. Disadvantages: 1) Requires amplifier with high common-mode range, 2) Slightly higher cost, 3) Common-mode rejection requirements. Low-side advantages: 1) Simpler amplifier requirements (near-zero common-mode), 2) Lower cost, 3) Easier layout. Disadvantages: 1) Load ground is raised by sense voltage (can cause ground loops), 2) Cannot detect ground shorts, 3) Interrupts ground path during sensing. ANA311 enables high-side sensing with integrated high common-mode amplifier.
Use high-side for automotive and systems requiring intact ground. Use low-side for cost-sensitive applications where ground disturbance is acceptable.
How do I minimize errors in current sense measurements?
Error minimization techniques: 1) Use Kelvin (4-wire) connection to sense resistor - separate current-carrying and sense traces. 2) Choose sense resistor with low temperature coefficient (<50ppm/°C) to minimize drift. 3) Place sense resistor close to amplifier inputs to reduce noise pickup. 4) Use proper PCB layout - wide traces for high current, short traces for sense connections. 5) Add filtering if needed - RC filter at output (not at input) to avoid affecting common-mode rejection. 6) Calibrate offset and gain in software for highest accuracy. 7) Consider self-heating - derate resistor power or use larger package. ANA311's 100μV offset and 0.5% gain error provide excellent baseline accuracy.
Use Kelvin connection and low-TCR resistor. Implement software calibration for highest accuracy. Filter at output if noise is an issue.
Can ANA311 measure bidirectional current?
ANA311 is unidirectional - it measures current flowing in one direction only. For bidirectional current sensing (e.g., battery charge/discharge), you have two options: 1) Use ANA312 which supports bidirectional sensing with offset output (V_out = V_ref ± I × R_sense × Gain). 2) Add external offset to ANA311 output using a voltage divider and op-amp. For option 2: Bias ANA311 output at VCC/2 using resistor divider, then use differential amplifier to remove offset. With 5V supply and 50x gain: Zero current output = 2.5V, positive current increases voltage, negative current decreases voltage. Ensure ADC can handle the full output range including offset.
Use ANA312 for native bidirectional support. Or add external offset circuit to ANA311 for bidirectional measurement with single-supply ADC.
What PCB layout considerations are important for current sensing?
PCB layout for current sensing: 1) Use Kelvin connection - separate pads for current path and sense connections. Route sense traces as differential pair to amplifier inputs. 2) Keep sense traces short and away from switching noise sources. 3) Use wide traces for high-current path to minimize parasitic resistance. 4) Place sense resistor close to amplifier to minimize noise pickup. 5) Use solid ground plane under amplifier for noise reduction. 6) Add vias near sense resistor pads for thermal management. 7) Avoid vias in sense traces - they add resistance and inductance. 8) Consider thermal effects - keep sense resistor away from heat sources. ANA311's high PSRR helps reject common-mode noise, but good layout is still essential.
Use Kelvin connection with short sense traces. Keep away from switching noise. Use adequate copper for high-current paths.