Current Limit Click Board™

Product Code: MIKROE-4271

How Does The Current Limit Click Board™ Work? The Current Limit Click Board™ is based on the MAX890L, a high-side low-resistance P-channel switch with the adjustable, accurate current limit system, and thermal shutdown from Analog Devices. The MAX890L limits the output current to a programmed level. When the output current is increased beyond the programmed current limit (1.2A), the current also increases through the internal replica amplifier along with the resistance applied on the SET pin. The current-limit error amplifier compares the voltage across the SET pin resistance to the internal +1.24V reference and regulates the current back to the lesser of the programmed limit (1.2A). This switch is not bidirectional, which means the input voltage must be higher than the output voltage. The Current Limit Click Board™ is virtually ubiquitous in system control, and provide a safe means for regulating the current delivered to a load circuit. It allows the load current to increase to a programmed limit but no higher.

Typically, the current limit is a function of the voltage across an external resistor, and this voltage serves as the reference for an internal current-limiting amplifier. By replacing the resistor with a digital potentiometer, you can easily program the current limit as performed on this Click board™. For this purpose, the digital potentiometer MAX5401 from Analog Devices that communicates with the MCU via 3-Wire SPI serial interface is used to set the resistance on the SET pin of the MAX890L, and thus adjust the current limit for the switch. The MAX890L provides an open-drain fault output with a red color LED, labelled as FAULT used to indicate when current reaches its limit or when the temperature exceeds +135°C. Besides the fault-indicator pin, the MAX890L also has an active-low Switch-On pin labelled as ON pin of the mikroBUS™ socket used to enable and turn the switch on. The Current Limit Click Board™ is designed to be operated with both 3.3V and 5V logic voltage levels that can be selected via the VCC SEL jumper. Additionally, there is a possibility in this selection that as a source of logical voltage level, a voltage from an external input terminal in the range from 2.7 to 5.5V can be used. In this way, whether using a logic voltage level from mikroBUS™ or an external voltage supply, this allows for both 3.3V and 5V capable MCUs to use the SPI communication lines properly. SPECIFICATIONS Type Power Switch Applications Can be used for applications in some portable equipment, access bus slots, or with power supplies, protecting them in cases of a short circuit or other overload conditions. On-board modules The Current Limit Click Board™ is based on the MAX890L, a high-side low-resistance P-channel switch with the adjustable, accurate current limit system, and thermal shutdown from Maxim Integrated. Key Features Low power consumption, programmable current limit, thermal shutdown, fault indicator output, low quiescent current, and more. Interface SPI Compatibility mikroBUS Click board size M (42.9 x 25.4 mm) Input Voltage 3.3V or 5V,External PINOUT DIAGRAM This table shows how the pinout of the Current Limit Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns). Notes Pin Pin Notes Switch Enable EN 1 AN PWM 16 NC NC 2 RST INT 15 NC SPI Chip Select CS 3 CS RX 14 NC SPI Clock SCK 4 SCK TX 13 NC NC 5 MISO SCL 12 NC SPI Data IN SDI 6 MOSI SDA 11 NC Power Supply 3.3V 7 3.3V 5V 10 5V Power Supply Ground GND 8 GND GND 9 GND Ground ONBOARD SETTINGS AND INDICATORS Label Name Default Description LD1 PWR