Current-Sense Amplifier and Comparators Detect Over-Currents on Rails up to 26V

Texas Instruments (TI) introduced the what the company claims to be the smallest current-sense amplifier in a leaded package and the smallest, most accurate comparators with an internal 1.2V or 0.2V reference.

Offered in industry-leading package options, TI says that the INA185 current-sense amplifier (see functional diagram above), and open-drain TLV4021 and push-pull TLV4041 comparators enable the design of smaller, simpler and more integrated systems while maintaining high performance.

In addition, coupling the amplifier with one of the comparators produces the smallest, highest performing over-current detection solution in the industry.

INA185 Current-sense amplifier

TI optimized these new devices for a variety of personal electronics, enterprise, industrial, and communications applications, including notebooks, peripherals, and docking stations

INA185 Current-Sense Amplifier

The INA185 bidirectional current sense amplifier (also called a current-shunt monitor) is used in cost-sensitive, space-constrained applications. This device senses voltage drop across a current-sense resistor at common-mode voltages from -0.2V to +26V, independent of the supply voltage. The INA185 integrates a matched resistor gain network in four, fixed-gain device options: 20V/V, 50V/V, 100V/V, or 200V/V. This matched gain resistor network minimizes gain error and reduces the temperature drift.

INA185 operates from a single 2.7V to 5.5V power supply. It draws a maximum supply current of 260µA and features high slew rate and bandwidth, making this device an excellent choice for many power-supply and motor-control applications.

The INA185 is available in a low profile 6-pin, SOT-563 package, and it has a body size of size of 2.56mm2, including the device pins. All device options are specified over the extended operating temperature range of -40°C to +125°C.

Advantages of INA185

Reduce overall system size:

The small-outline transistor (SOT)-563 package measuring 1.6mm by 1.6mm (2.5mm2), the amplifier is said to be 40% smaller than the closest competitive leaded packages.

Improve system efficiencies:

A 55µV input offset enables higher precision measurements at low currents, the INA185 enables the use of lower-value shunt resistors to cut system power consumption.

Additionally, its 350kHz bandwidth and 2V/µS slew rate enable phase-current reproduction to enhance motor efficiency and save system power.

Increase performance and protection:

The precisely matched resistive gain network in the amplifier enables a maximum gain error as low as 0.2%, which contributes to robust performance over temperature and process variations.

The device's typical response time of 2µS enables fast fault detection to prevent system damage.

INA185 Features

• SOT-563 package (1.6mm × 1.6mm)
  • 39% smaller footprint than SC70
  • 0.55mm package height
• Common-mode range (V_CM): -0.2V to +26V
• High bandwidth: 350kHz (A1 devices)
• Offset voltage:
  • ±55µV (max) at V_CM = 0V
  • ±100µV (max) at V_CM = 12V (A4 device)
• Output slew rate: 2V/µs
• Bidirectional current-sensing capability
• Accuracy:
  • ±0.2% maximum gain error (A1, A2, A3)
  • 0.5-µV/°C maximum offset drift
• Gain options:
  • 20V/V (A1 devices)
  • 50V/V (A2 devices)
  • 100V/V (A3 devices)
  • 200V/V (A4 devices)
• Quiescent current: 260µA (max)

TLV4021 and TLV4041 Comparators

The TLV40x1 devices are low-power, high-accuracy comparators with precision thresholds. They feature a propagation delay of 360ns. The comparators are available in a DSBGA package measuring 0.73mm × 0.73mm, making the TLV40x1 applicable for space-critical designs like portable or battery-powered electronics where low-power and fast response to operating condition changes is required.

DSBGA package

The combination of factory-trimmed switching thresholds and precision hysteresis make the TLV40x1 appropriate for voltage and current monitoring in harsh, noisy environments where slow moving input signals must be converted into clean digital outputs. Likewise, brief glitches on the input are rejected, thereby ensuring stable output operation without false triggering.

The TLV40x1R1/2 are available in multiple configurations allowing the achievement of the desired output response. For example, the TLV4021 and TLV4031 feature an open-drain output stage while the TLV4041 and TLV4051 feature a push-pull output stage.

Furthermore, the TLV4021 and TLV4041 offer a non-inverting input, while the TLV4031 and TLV4051 have an inverting input.

Available in die-size ball-grid array (DSBGA) 0.73mm by 0.73mm package, the comparators' integrated voltage reference saves board space while supporting precise voltage monitoring, which optimizes system performance.

Lower power, longer battery life:

The comparators can monitor voltages as low as the 0.2V internal reference, and they feature a high threshold accuracy of 1% across a full temperature range from -40°C to +125°C. Low 2.5µA quiescent current delivers extended battery life for smart, connected devices.

Speedy response:

Fast propagation delay as low as 450nS reduces latency, enabling power-conscious systems to monitor signals and quickly respond to fault conditions.

Smallest, fastest overcurrent detection solution

15% smaller, 50 times faster:

When using both the INA185 and the TLV4021 or TLV4041, engineers can shrink their total footprint to enable smaller systems. In combination, these devices can create the smallest, highest-performing overcurrent detection solution that is 15% smaller and 50 times faster than competitive devices.

System protection:

Coupling the amplifier with one of the comparators supports over-current detection on rails as high as 26V, delivering more headroom for better current spike management.

These new devices join TI's small-size amplifier portfolio, which enables the design of smaller systems while maintaining high performance.

Features of TLV4021 and TLV4041

• Wide supply voltage range: 1.6V to 5.5V
• Adjustable thresholds down to 0.2V and 1.2V
• Fixed threshold of 3.2V
• High threshold accuracy
  • 0.5% at 25°C
  • 1% over temperature
• Low quiescent current: 2µA
• Propagation delay: 360ns
• Push-pull and open-drain output options
• Known startup conditions
• Non-inverting and inverting input options
• Precision hysteresis
• Temperature range: -40°C to +125°C
• Packages:
  • 0.73mm × 0.73mm DSBGA (4-bump)

Package, availability, and pricing

Production quantities of the INA185 are now available through the TI store and authorized distributors in a SOT-563 package, measuring 1.6mm by 1.6mm. Pricing starts at US$0.65 in 1,000-unit quantities.

Production quantities of the push-pull TLV4041 and pre-production samples of the open-drain TLV4021 comparators are now available through the TI store and authorized distributors in a DSBGA package, measuring 0.73mm by 0.73mm. Pricing for each comparator starts at US$0.39 in 1,000-unit quantities.

The company has also released evaluation modules INA185EVM and TLV4021-41EVM available for $25.00 each from the TI store and from authorized distributors.