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.
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 (SSOP) or 12-Pin DFN Package Options
Data Acquisition Systems
Dynamic Gain Changing
Automatic Ranging Circuits
Automatic Gain Control
APPLICATIO S
■
■
■
■
TYPICAL APPLICATIO
3V
12
V
+
A Dual, Matched Low Noise PGA (16-Lead SSOP Package)
0.1µF
14
V
–
40
GAIN OF 64
GAIN OF 32
GAIN OF 16
V
INA
1µF
2
INA
OUT A
15
V
OUTA
= GAIN
A
• V
INA
30
3
GAIN (dB)
AGND
LTC6912-X
20 GAIN OF 8
GAIN OF 4
10
GAIN OF 2
GAIN OF 1
V
INB
4
INB
OUT B
13
V
OUTB
= GAIN
B
• V
INB
0
SHDN
3-WIRE
SPI
INTERFACE
CS/LD
DATA
CLK
5
6
7
8
CHB
SHDN
CS/LD
D
IN
CHA
DGND
D
OUT
10
9
6912 TA01a
–10
0.1
1
10
100
1000
FREQUENCY (kHz)
10000
6912 TA01b
U
U
U
LTC6912-2
Frequency Response
V
S
=
±2.5V
V
IN
= 10mV
RMS
6912fa
1
LTC6912
ABSOLUTE
(Note 1)
AXI U RATI GS
V
–
) ...............................
Specified Temperature Range (Note 3)
LTC6912C-1, LTC6912C-2 ..................–40°C to 85°C
LTC6912I-1, LTC6912I-2 .....................–40°C to 85°C
LTC6912H-1, LTC6912H-2
(GN-16 Only) .....................................–40°C to 125°C
Storage Temperature Range ..................–65°C to 150°C
UE Package ....................................... –65°C to 125°C
Lead Temperature (Soldering, 10sec)................... 300°C
Total Supply Voltage (V
+
to
11V
Input Current ......................................................
±10mA
Operating Temperature Range (Note 2)
LTC6912C-1, LTC6912C-2 ..................–40°C to 85°C
LTC6912I-1, LTC6912I-2 .....................–40°C to 85°C
LTC6912H-1, LTC6912H-2
(GN-16 Only) .....................................–40°C to 125°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
INA
AGND
INB
CS/LD
DIN
CLK
1
2
3
4
5
6
13
12 OUTA
11 V
–
10 OUTB
9
8
7
V
+
DGND
DOUT
UE12 PACKAGE
12-LEAD (4mm
×
3mm) PLASTIC DFN
EXPOSED PAD IS CONNECTED TO V
–
(PIN 13),
MUST BE SOLDERED TO PCB
T
JMAX
= 125°C,
θ
JA
= 160°C/W
ORDER PART
NUMBER
LTC6912CDE-1
LTC6912IDE-1
LTC6912CDE-2
LTC6912IDE-2
DFN PART*
MARKING
69121
69121
69122
69122
Order Options
Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
2
U
U
W
W W
U
W
TOP VIEW
NC 1
INA 2
AGND 3
INB 4
SHDN 5
CS/LD 6
D
IN
7
CLK 8
16 NC
15 OUT A
14 V
–
13 OUT B
12 V
+
11 NC
10 DGND
9
D
OUT
GN PACKAGE
16-LEAD NARROW PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 120°C/W
ORDER PART
NUMBER
LTC6912CGN-1
LTC6912IGN-1
LTC6912HGN-1
LTC6912CGN-2
LTC6912IGN-2
LTC6912HGN-2
GN PART
MARKING
69121
6912I1
6912H1
69122
6912I2
6912H2
6912fa
LTC6912
GAI SETTI GS A D PROPERTIES
Table 1. LTC6912-1 GAIN SETTINGS AND PROPERTIES
UPPER/LOWER
NIBBLE
Q7
Q3
0
0
0
0
0
0
0
0
1
1
Q6
Q2
0
0
0
0
1
1
1
1
0
1
Q5
Q1
0
0
1
1
0
0
1
1
X
X
Q4
Q0
0
1
0
1
0
1
0
1
X
X
NOMINAL
VOLTAGE GAIN
Volts/Volt
0
–1
–2
–5
–10
–20
–50
–100
0
dB
–120
0
6
14
20
26
34
40
–120
MAXIMUM LINEAR INPUT RANGE (V
P-P
)
Dual 5V
Supply
10
10
5
2
1
0.5
0.2
0.1
10
Not Used (Note 11)
Single 5V
Supply
5
5
2.5
1
0.5
0.25
0.1
0.05
5
Single 3V
Supply
3
3
1.5
0.6
0.3
0.15
0.06
0.03
3
NOMINAL INPUT NOMINAL OUTPUT
IMPEDANCE (kΩ) IMPEDANCE (Ω)
(Open)
10
5
2
1
1
1
1
(Open)
Not Used
0.4
0.7
3.4
3.4
3.4
6.4
15
30
(Open)
Table 2. LTC6912-2 GAIN SETTINGS AND PROPERTIES
UPPER/LOWER
NIBBLE
Q7
Q3
0
0
0
0
0
0
0
0
1
1
Q6
Q2
0
0
0
0
1
1
1
1
0
1
Q5
Q1
0
0
1
1
0
0
1
1
X
X
Q4
Q0
0
1
0
1
0
1
0
1
X
X
NOMINAL
VOLTAGE GAIN
Volts/Volt
0
–1
–2
–4
–8
–16
–32
–64
0
dB
–120
0
6
12
18.1
24.1
30.1
36.1
–120
MAXIMUM LINEAR INPUT RANGE (V
P-P
)
Dual 5V
Supply
10
10
5
2.5
1.25
0.625
0.3125
0.156
10
Not Used (Note 11)
Single 5V
Supply
5
5
2.5
1.25
0.625
0.3125
0.156
0.078
5
Single 3V
Supply
3
3
1.5
0.75
0.375
0.188
0.094
0.047
3
NOMINAL INPUT NOMINAL OUTPUT
IMPEDANCE (kΩ) IMPEDANCE (Ω)
(Open)
10
5
2.5
1.25
1.25
1.25
1.25
(Open)
Not Used
0.4
0.7
3.4
3.4
3.4
6.4
15
30
(Open)
U
U
U
6912fa
3
LTC6912
The
●
denotes the specifications that apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
= 5V, AGND = 2.5V, Gain = 1, R
L
= 10k to midsupply point, unless
otherwise noted.
PARAMETER
Total Supply Voltage (V
S
)
Supply Current per Channel
Both Amplifiers Active (Gain = 1)
V
S
= 2.7V, V
INA
= V
INB
= V
AGND
V
S
= 5V, V
INA
= V
INB
= V
AGND
V
S
=
±5V,
V
INA
= V
INB
= 0V
Both Amplifiers Inactive (State 1000)
V
S
= 2.7V, V
INA
= V
INB
= V
AGND
V
S
= 5V, V
INA
= V
INB
= V
AGND
V
S
=
±5V,
V
INA
= V
INB
= 0V
V
S
= 2.7V, V
SHDN
= 2.43V
V
S
= 5V, V
SHDN
= 4.5V
V
S
=
±5V,
V
SHDN
= 4.5V
CONDITIONS
●
●
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
C, I GRADES
MIN
TYP
MAX
2.7
1.75
2.0
2.25
150
200
265
0.3
3.6
20
12
60
20
100
30
190
10
50
15
90
20
180
±27
±35
2.45
0.55
0.75
–4.3
55
55
60
80
75
80
12
16
20
26
●
●
H GRADE
MIN
TYP
MAX
2.7
1.75
2.0
2.25
150
200
265
0.3
3.6
20
12
50
20
90
30
80
10
50
15
80
20
180
±27
±35
10.5
3.0
3.25
3.75
280
350
750
5
10
50
35
125
45
190
60
290
25
90
35
175
45
270
UNITS
V
mA
mA
mA
µA
µA
µA
µA
µA
µA
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mA
mA
Specifications for Both the LTC6912-1 and the LTC6912-2
10.5
2.75
3.0
3.5
255
325
750
2
10
50
30
110
40
170
50
260
20
80
30
160
40
250
Supply Current per Channel
(Software Shutdown)
Total-Supply Current
(Hardware Shutdown,
GN-16 Package Only)
Output Voltage Swing LOW
(Note 4)
V
S
= 2.7V, R
L
= 10k Tied to Midsupply Point
●
V
S
= 2.7V, R
L
= 500Ω Tied to Midsupply Point
●
V
S
= 5V, R
L
= 10k Tied to Midsupply Point
V
S
= 5V, R
L
= 500Ω Tied to Midsupply Point
V
S
=
±5V,
R
L
= 10k Tied to 0V
V
S
=
±5V,
R
L
= 500Ω Tied to 0V
●
●
●
●
Output Voltage Swing HIGH
(Note 4)
V
S
= 2.7V, R
L
= 10k Tied to Midsupply Point
●
V
S
= 2.7V, R
L
= 500Ω Tied to Midsupply Point
●
V
S
= 5V, R
L
= 10k Tied to Midsupply Point
V
S
= 5V, R
L
= 500Ω Tied to Midsupply Point
V
S
=
±5V,
R
L
= 10k Tied to 0V
V
S
=
±5V,
R
L
= 500Ω Tied to 0V
●
●
●
●
●
●
●
●
●
●
●
●
●
Output Short-Circuit Current
(Note 5)
AGND Open-Circuit Voltage
(GN-16 Package Only)
AGND (Common Mode)
Input Voltage Range
AGND Rejection (i.e., Common
Mode Rejection or CMRR)
Slew Rate
V
S
= 2.7V
V
S
=
±5V
V
S
= Single 5V Supply, V
SHDN
= 0.5V
V
S
= Single 5V Supply, V
SHDN
= 4.5V
V
S
= Single 2.7V Supply
V
S
= Single 5V Supply
V
S
=
±5V
V
S
= 2.7V, V
AGND
= 1.1V to 1.6V
V
S
=
±5V,
V
AGND
= –2.5V to 2.5V
Gain = 1
V
S
= 5V, V
OUTA
= V
OUTB
= 1.1V to 3.9V
V
S
=
±5V,
V
OUTA
= V
OUTB
=
±1.4V
Gain = 10 (–1), Gain = 8 (–2)
V
S
= 5V, V
OUTA
= V
OUTB
= 1.1V to 3.9V
V
S
=
±5V,
V
OUTA
= V
OUTB
=
±1.4V
2.5
2.65
2.55
1.6
3.65
3.2
2.45
0.55
0.75
–4.3
50
50
57
2.5
2.65
2.55
1.6
3.65
3.2
V
V
V
V
V
dB
dB
dB
V/µs
V/µs
V/µs
V/µs
dB
dB
80
75
80
12
16
20
26
–120
–120
Power Supply Rejection Ratio (PSRR) V
S
=2.7V to
±5V
Signal Attenuation at Gain = 0 Setting
Signal Attenuation in Software
Shutdown
Gain = 0 (Digital Inputs 0000),
f = 200kHz
(State = 1000)
–120
–120
6912fa
4
LTC6912
ELECTRICAL CHARACTERISTICS
PARAMETER
SHDN Input High Voltage
(GN-16 Package Only)
SHDN Input Low Voltage
(GN-16 Package Only)
SHDN Pin 5, Input High Current
(GN-16 Package Only)
SHDN Pin 5, Input Low Current
(GN-16 Package Only)
CONDITIONS
V
S
= Single 2.7V
V
S
= Single 5V
V
S
=
±5V
V
S
= Single 2.7V
V
S
= Single 5V
V
S
=
±5V
V
S
= Single 2.7V
V
S
= Single 5V
V
S
=
±5V
V
S
= Single 2.7V
V
S
= Single 5V
V
S
=
±5V
The
●
denotes the specifications that apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
= 5V, AGND = 2.5V, Gain = 1, R
L
= 10k to midsupply point, unless
otherwise noted.
C, I GRADES
MIN
TYP
MAX
●
●
●
●
●
●
MIN
2.43
4.5
4.5
H GRADE
TYP
MAX
UNITS
V
V
V
Specifications for Both the LTC6912-1 and the LTC6912-2
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