GainAMP Click

GainAMP click carries the LTC6912 dual channel, low noise, digitally programmable gain amplifier (PGA), from Analog Devices. The click is designed to work on either 3.3V or 5V power supply. It communicates with the target MCU over SPI interface, with additional functionality provided by the following pins on the mikroBUS™ line: AN, RST.

GainAMP click also features three pairs of screw terminals and a power indication LED.

How it works

The gains for both channels are independently programmable, using a 3-wire SPI interface to select voltage gains of 0, 1, 2, 5, 10, 20, 50, and 100V/V (LTC6912-1). All gains are inverting.

The LTC®6912 consists of 2 matched amplifiers with rail-to-rail outputs. When operated with unity gain, they will also process rail-to-rail input signals.

A half-supply reference generated internally at the AGND pin supports single power supply applications. Operating from single or split supplies from 2.7V to 10.5V total.

Programmable gain amplifier

A programmable-gain amplifier (PGA) is an electronic amplifier whose gain can be controlled externally (by analog or digital signals).

Specifications

Pinout diagram

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

Notes	Pin					Pin	Notes
Analog input	AN_IN	1	AN	PWM	16	NC
Shut down	SHDN	2	RST	INT	15	NC
Chip select	SPI_CS	3	CS	TX	14	NC
SPI Clock Input	SPI_CLK	4	SCK	RX	13	NC
	NC	5	MISO	SCL	12	NC
SPI Master Output Slave Input	SPI_MOSI	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

Maximum ratings

Jumpers and settings

Programming

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

The gains for both channels are independently programmable using an SPI interface to select voltage gains. The example controls channel A, increasing and decreasing gain with input buttons.

Code snippet

The code snippet demonstrates a simple usage of the helper function.

01 void main()
02 {
03     system_init();
04 
05     gain_amp_set(GAIN_AMP_NOMINAL_0, GAIN_AMP_SW_SHUTDOWN);
06 
07     while( 1 )
08     {
09         if(Button(&GPIOE_IDR, 9, 100, 1)) 
10         {
11             byte = gain_amp_set(++gain & 0x07, GAIN_AMP_SW_SHUTDOWN);
12             GPIOD_ODR = (GPIOD_ODR & 0xFF00) | byte;
13         }
14         if(Button(&GPIOE_IDR, 8, 100, 1)) 
15         {
16             byte = gain_amp_set(--gain & 0x07, GAIN_AMP_SW_SHUTDOWN);
17             GPIOD_ODR = (GPIOD_ODR & 0xFF00) | byte;
18         }
19     }
20 }