GainAMP click
PID: MIKROE-2555
Weight: 25 g
GainAMP click
carries the LTC®6912 dual channel, low noise, digitally programmable gain
amplifier (PGA). 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).
Key features
LTC®6912 gain amplifier
o
2 Channels with Independent Gain Control
o
3‐Wire SPI Interface
o
Extended Gain‐Bandwidth at High Gains
o
Rail‐to‐Rail Input Range
o
Rail‐to‐Rail Output Swing
o
Single or Dual Supply: 2.7V to 10.5V Total
Screw terminals for input and output
SPI interface
3.3V or 5V power supply
Specification
Product Type Amplifier
Data Acquisition Systems, Dynamic Gain Changing, Automatic Ranging
Applications
Circuits, Automatic Gain Control.
MCU
LTC®6912 dual channel gain amplifier
Rail-to-Rail Output Swing, Rail-to-Rail Input Range, 2 Channels with
Key Features
Independent Gain Control, Three pairs of screw terminals, 3-wire SPI interface
Interface
SPI
Power Supply 3.3V or 5V
Compatibility mikroBUS
Click board
S (28.6 x 25.4 mm)
size
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
mikroBUS
tm
Pin
Notes
Analog input
AN_IN 1
AN
Shut down
SHDN
2
RST
CS
PWM
16
NC Not connected
INT
15
NC Not connected
TX
14
NC Not connected
RX
13
NC Not connected
SCL
12
NC Not connected
SDA
11
NC Not connected
5V
10 +5V
Power supply
GND
9 GND
Ground
Chip select
SPI_CS 3
SPI Clock Input
SPI_CLK 4
SCK
Not connected
NC
5
MISO
SPI Master Output Slave Input
SPI_MOSI 6
MOSI
Power supply
Ground
+3.3V
GND
7
3.3V
8
GND
Maximum ratings
Description
Total Supply Voltage (V+ to V–)
Input Current
Operating Temperature Range –40°C
85°C
Min Typ Max Unit
11V V
±10
mA
Jumpers and settings
Designator Name Default Position Default Option
JP1
JP2
JP3
AN_sel ON
V+
V‐
Left
Left
AN
VCC
GND
Description
Analog input jumper.
V+ selection.
V‐ selection.
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
}
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