MIKROE BUCK Click is a buck switching regulator that accepts a wide input voltage range of up to 40V and steps it down to 3.3V or 5V. The Click carries the LT3976 from Analog Devices, 40V, 5A, 2MHz step-down switching regulator with 3.3µA quiescent current. BUCK Click communicates with the target microcontroller over the following pins on the mikroBUS™ line: PWM, INT, RS, CS.

Note: When all the usual conditions and proper cooling are met BUCK click can supply up to 5A of load current.

The LT3976 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 40V. Low quiescent current design consumes only 3.3µA of supply current while regulating with no load. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mV in a typical application.

The LT3976 can supply up to 5A of load current and has current limit foldback to limit power dissipation during short-circuit. A low dropout voltage of 500mV is maintained when the input voltage drops below the programmed output voltage, such as during automotive cold crank.

There are two onboard screw terminals, one for connecting the external input supply, and the other for the output. There is also a multiplexer which chooses the resistor used for setting the switching frequency.

The multiplexer is used for selecting one of the four different resistors. Each of these resistors, if selected, sets different switching frequency:

A0 A1 Selects resistor Switching frequency [MHz]

• 0 0 R7 = 130k 0.4
• 0 1 R8 = 32.4k 1.2
• 1 0 R9 = 54.9k 0.8
• 1 1 R10 = 21.5k 1.6

• Interface: GPIO
• Compatibility: mikroBUS™
• Dimensions: 57.15 x 25.4mm
• Input Voltage: 3.3V or 5V

• Schematic
• MAX4634 Datasheet
• GitHub