Mikroe BUCK click - DC to DC Step Down Switching Regulator with 40V Max Input Voltage

Product ID: 7657
Mikroe buck click 9402391181
$36.99 In Stock

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 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.

LT3976 regulator features

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.

How the click works

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


Type Buck
Applications Automotive battery regulation, portable devices, industrial supplies, etc.
On-board modules LT3976 step-down switching regulator, MAX4634 4-channel CMOS analog multiplexer
Key Features Thermal shutdown protection, output voltage can be set to 3.3V or 5V, 4 possible switching frequencies
Interface GPIO
Input Voltage 3.3V or 5V
Click board size L (57.15 x 25.4 mm)

Pinout diagram

This table shows how the pinout on BUCK click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes Pin Mikrobus logo.png Pin Notes
NC 1 AN PWM 16 A1 Multiplexer A1 pin 
Multiplexer A0 pin  A0 2 RST INT 15 PG Open drain output of an internal comparator
Enable IC EN 3 CS TX 14 NC
Power supply +3.3V 7 3.3V 5V 10 +5V Power supply
Ground GND 8 GND GND 9 GND Ground

Jumpers and settings

Designator Name Default Position Default Option Description
JP1 VOUT SEL Right 3V3 Output Voltage Selection 3V3/5V, left position 5V, right position 3V3.
JP2 VCC SEL Left 3V3 Power Supply Voltage Selection toward host MCU 3V3/5V; left position 3V3, right position 5V


Code examples for BUCK click, written for MikroElektronika hardware and compilers are available on Libstock.

Code snippet

This code enables the buck regulator and detects if the voltage is within 8.4% of final regulation voltage.

01 void systemInit()
02 {
03     UART1_Init(9600);
04 }
06 void Buck_Init()
07 {
08     GPIO_Digital_Output( &GPIOC_BASE, _GPIO_PINMASK_2 );
09     GPIO_Digital_Output( &GPIOD_BASE, _GPIO_PINMASK_13 );
10     GPIO_Digital_Output( &GPIOA_BASE, _GPIO_PINMASK_0 );
11     GPIO_Digital_Input ( &GPIOD_BASE, _GPIO_PINMASK_10 );
12     BUCK_ENABLE_PIN = 1;
13     MUX_A0_PIN = 0;
14     MUX_A1_PIN = 0;   
15 }
17 void Buck_Task()
18 {
19     if (PG_PIN == 1)
20     {
21         UART1_Write_text("Vout is within the final 8.4% of final regulation voltage");
22         UART1_Write_Text( "rn" );
23         delay_ms(1000);
24     }
26 }
28 void main()
29 {
30     systemInit();
31     Buck_Init();
33    while( 1 )
34     {
35         Buck_Task();
36     }
37 }