LTC6912_15 Datasheet, PDF (1/24 Pages) Linear Technology – Dual Programmable Gain Amplifiers with Serial Digital Interface

FEATURES
■ _{2 Channels with Independent Gain Control}
LTC6912-1: (0, 1, 2, 5, 10, 20, 50, and 100V/V)
LTC6912-2: (0, 1, 2, 4, 8, 16, 32, and 64V/V)
■ _{Offset Voltage = 2mV Max (–40°C to 85°C)}
■ _{Channel-to-Channel Gain Matching of 0.1dB Max}
■ _{3-Wire SPI}^TM _Interface
■ _{Extended Gain-Bandwidth at High Gains}
■ _{Wired-OR Outputs Possible (2:1 Analog MUX}
Function)
■ _{Low Power Hardware Shutdown (GN-16 Only,}
2µA Max at 2.7V)
■ _{Rail-to-Rail Input Range}
■ _{Rail-to-Rail Output Swing}
■ _{Single or Dual Supply: 2.7V to 10.5V Total}
■ _{Input Noise: 12.6nV/√Hz}
■ _{Total System Dynamic Range to 115dB}
■ _{16-Pin GN (SSOPU) or 12-Pin DFN Package Options}
APPLICATIO S
■ _{Data Acquisition Systems}
■ _{Dynamic Gain Changing}
■ _{Automatic Ranging Circuits}
■ _{Automatic Gain Control}
LTC6912
Dual Programmable
Gain Amplifiers with
Serial Digital Interface
DESCRIPTIO
The LTC^®6912 is a family of dual channel, low noise,
digitally programmable gain amplifiers (PGA) that are
easy to use and occupy very little PC board space. 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 ); and 0, 1, 2, 4,
8, 16, 32, and 64V/V (LTC6912-2). All gains are inverting.
The LTC6912 family 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, the LTC6912-X
family is offered in tiny SSOP and DFN-12 Packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
A Dual, Matched Low Noise PGA (16-Lead SSOP Package)
3V
0.1µF
12
14
V⁺
V^–
2 INA
V_INA
1µF
3
AGND
OUT A 15
V_OUTA = GAIN_A • V_INA
LTC6912-X
V_INB ^{4 INB}
OUT B
13
V_OUTB = GAIN_B • V_INB
3-WIRE
SPI
INTERFACE
5
SHDN
6
CS/LD
7
DATA
8
CLK
CHB
SHDN
CS/LD
D_IN
CHA
DGND
10
D_OUT
9
6912 TA01a
LTC6912-2
Frequency Response
40
GAIN OF 64
30 ^{GAIN OF 32}
GAIN OF 16
V_S = ±2.5V
V_IN = 10mV_RMS
20 GAIN OF 8
GAIN OF 4
10
GAIN OF 2
0 ^{GAIN OF 1}
–10
0.1 1
10 100 1000 10000
FREQUENCY (kHz)
6912 TA01b
6912fa
1