This high-speed, low-side over-current detection solution is implemented with a single zero-drift fast-settling amplifier (OPA388) and one high-speed comparator (TLV3201). This circuit is designed for applications that monitor fast current signals and over-current events, such as current detection in motors and power supply units.
The OPA388 is selected for its widest bandwidth with ultra-low offset and fast slew rate. These parameters allow the circuit to be a well-balanced, high-speed solution in order to accurately detect high frequency current components. In applications that only require average current detection, devices with less bandwidth can be used like the LPV821. In applications that require faster response time, devices with larger bandwidth can be used like the THS4521.
The TLV3201 is selected for its fast response due to its small propagation delay of 40 ns and rise time of 4.8 ns. This allows the comparator to quickly respond and alert the system of an over-current event all within the transient response time requirement. The push-pull output stage also allows the comparator to directly interface with the logic levels of the micro-controller. The TLV3201 also has low power consumption with a quiescent current of 40 µA.
Typically for low-side current detection, the amplifier across the sense resistor can be used in a non-inverting configuration. The application circuit shown, however, uses the OPA388 as a differential amplifier across the sense resistor. This provides a true differential measurement across the shunt resistor and can be beneficial in cases where the supply ground and load ground are not necessarily the same.
Dedicated current sense amplifiers can also be an option for high-speed current detection. The trade-offs for each option should be taken into account when deciding on a current sense solution. Integrated solutions can provide larger bandwidth and savings on board space, but can be more costly and offer limited customization. Discrete solutions can be lower cost and easily customizable, but could require precision resistors to increase measurement precision.
Download PDF: High-Speed-Overcurrent-Detection
Source: Texas Instrument
Reference Design Description
The Motion Sensing & LED Control Reference Design demonstrates how to use Zilog’s Z8FS040 ZMOTION MCU with the IXYS LDS8710 High-Efficiency LED Driver and explains how to implement features such as ambient light detection and LED dimming in addition to passive infrared motion detection. It also illustrates how the combined capabilities of both products are an exceptional choice for energy management functions in applications ranging from low-power displays and backlighting to ambient room lighting control.
- Integrated passive infrared (PIR) motion sensing and LED control combined in a single 8-pin Zilog MCU
- Self-contained, single-board solution for motion sensing and LED control
- Motion detection adapts to various lenses with simple header file changes
- Selectable power source of either two AA batteries or an external power supply with operating voltage in the 2.7 V to 3.6 V range
- Ability to switch high-intensity LEDs on and off in response to motion
- Controls LED brightness from three sources:
- Console command
- Potentiometer (control source depends on software build)
- Ambient light
Source: EEWeb Design Library
In many of the project applications and testing applications, Variable DC Power supplies are used. Sometimes it happens that one can not find an AC power socket nearby testing circuit. Also, Power supplies are usually AC powered and are bulky, because of their voltage transformers, to bring anywhere near testing circuit or equipment. Hence, Portable Variable DC Power Supply is required which helps people become mobile in doing electronic projects that will need power supplies.
This project uses a voltage regulator and a potentiometer that allows the user to change the output voltage between 2 volts to 25 volts. It is also equipped with a small seven segment display which acts a voltage meter which lets the user to know how much voltage is being supplied by the regulator. Powered by a 9V battery, this project gives mobility in making circuit projects. It also includes a banana jack that accommodates plugs that can help attach it to different applications.
Source: Portable Variable Power Supply