Learn more about how current sense amplifiers work, when bi-directional current sense is needed, and discover STMicro’s portfolio of current sense amplifier solutions.
Overview
HOW DOES A CURRENT SENSE AMPLIFIER WORK?
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The working principle of a current sensing amplifier is based on Ohm's law. When load current flows through a shunt resistor (Rshunt) present on inputs, it generates a voltage drop called VSENSE. This voltage is generally small to limit power dissipation losses. VSENSE is then amplified with an internal instrumentation amplifier. The resulting output voltage (VOUT) is a voltage which is proportional to the Load current. It can then be processed with an ADC (analog-to-digital converter). |
WHEN IS BI-DIRECTIONAL CURRENT SENSE NEEDED?
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In some applications, current can flow into the load in both directions. This is the case for brushed motor control applications used in H-Bridge topologies, as shown in the diagram. The direction and speed of rotation of the motor can be determined by measuring the voltage drop across the shunt.
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Another example where bi-directional current sensing is required is brushless DC motor control, using inline current sense shunts on each of the three motor phases, as shown in the diagram. Inline phase current sensing is the best method to know precisely the phase current flowing into the motor. This current measurement offers the best information that can be used in feedback motor control, in order to optimize the motor performance.
Bi-directional current sense amplifiers utilize a VREF input pin in order to set the output reference anywhere within the power supply range.
Current Sense Amplifier Product Line Overview
Summary of bi-directional current sense amplifier part numbers
| Gain | Bandwidth | VICM | Supply | |
| TSC213 | x50 | 100 kHz | -0.3V to 26V | 2.7V to 26V |
| TSC210 | x200 | 25 kHz | -0.3V to 26V | 2.7V to 26V |
| TSC212 | x1000 | 6 kHz | -0.3V to 26V | 2.7V to 26V |
| TSC2010 | x20 | >1 MHz | -20V to +70V | 2.7V to 5.5V |
| TSC2011 | x60 | 600 kHz | -20V to +70V | 2.7V to 5.5V |
| TSC2012 | x100 | 390 kHz | -20V to +70V | 2.7V to 5.5V |
The TSC201x family supports precise measurement of faster signals and wider common mode input voltage range. The TSC21x family is well suited for extremely accurate measurement of slower signals.
The TSC201x and TSC21x devices are included in the ST 10-Year Longevity Commitment, with guaranteed availability until November 2029.
Competing Solutions
TSC201x Evaluation Board: STEVAL-AETKT1V1
- • Supports SMT and THT types of shunts
- • Allows simple set of VREF and standby pin by jumpers
- • Embeds RC filter
- • External wire connection
- • TSC201x on daughter board
TSC201x device Input offset voltage vs. input common mode with VCC = 5 V
Resources
Current Sensing Basics
ST Product Portfolio for Current Sensing
TSC210x and TSC21x Use Cases
Current Sensing Error Analysis
ST Evaluation Tools for Current Sensing
On Demand Webinar
Current Sense Amplifiers for Shunt-Based Current Sensing
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