DC566A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 566
DIGITALLY CONTROLLED PROGRAMMABLE GAIN AMPLIFIER
LTC6910
DESCRIPTION
Demonstration circuits 566A-A, -B and -C, feature the
easy to use, rail-to-rail input and output LTC6910 series of Low Noise Programmable Gain Amplifier
(PGA) parts. The inverting gain is set by changing the
positions of three onboard jumpers: G0, G1 and G2 to
set the 3-bit programming code. Demo Circuit 566AA is for the LTC6910–1 with gains of 0, 1, 2, 5, 10,
20, 50, 100 V/V. Demo Circuit 566A-B is for the
LTC6910–2 with gains of 1, 2, 4, 8, 16, 32, and 64
V/V. Demo Circuits 566A-C is for the LTC6910–3 with
gains of 1, 2, 3, 4, 5, 6 and 7 V/V.
All three-demo boards have input jumpers to select
between AC or DC coupling of the input, and a jumper
to select operation with a single or dual supply. Typical applications include data acquisition systems, dynamic gain changing, automatic ranging circuits and
automatic gain control. The LTC6910 family can op50
40
VS = 10V, VIN = 5mVRMS
GAIN OF 100 (DIGITAL INPUT 111)
40
30
GAIN (dB)
GAIN (dB)
30 GAIN OF 50 (DIGITAL INPUT 110)
GAIN OF 20 (DIGITAL INPUT 101)
20
GAIN OF 10 (DIGITAL INPUT 100)
10 GAIN OF 5 (DIGITAL INPUT 011)
1k
10k
100k
FREQUENCY (Hz)
Performance Summary (TA = 25°C)
PARAMETER
CONDITION
VALUE
Supply Voltage Range
V+ to V–
2.7V to 10.5V
Gain Accuracy
Gain Dependent (see Data
Sheet)
Typical
±0.05dB at
Gain = 1
and ±0.4 dB at
Gain = 100
Slew Rate
Vs = ±2.5V, VOUT = ±1.4V
12V/µs
Vs = ±5V, VOUT = ±1.4V
16V/µs
20
VS = ±5V
VIN = 10mVRMS
GAIN OF 7
GAIN OF 6
15
GAIN OF 64
GAIN OF 32
10
GAIN OF 16
GAIN OF 4
10 GAIN OF 2
GAIN OF 5
GAIN OF 4
GAIN OF 3
5 GAIN OF 2
0
GAIN OF 1
GAIN OF 1
0
GAIN OF 1 (DIGITAL INPUT 001)
–10
100
Table 1.
20 GAIN OF 8
GAIN OF 2 (DIGITAL INPUT 010)
0
Design files for this circuit board are available. Call
the LTC factory.
GAIN (dB)
50
erate from single or split supplies from 2.7V to 10.5V
total between V+ and V-.
1M
10M
6910 G02
Figure 1. LTC6910-1 Frequency Response
–10
100
–5
1k
100k
10k
FREQUENCY (Hz)
1M
10M
69102 TA02
Figure 2. LTC6910-2 Frequency Response
VS = ±5V
VIN = 10mVRMS
–10
10k
100
1k
100k
FREQUENCY (Hz)
1M
10M
69103 TA02
Figure 3. LTC6910-3 Frequency Response
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 566
DIGITALLY CONTROLLED PROGRAMMABLE GAIN AMPLIFIER
Figure 4. Proper Measurement Equipment Setup
QUICK START PROCEDURE
The 566 family of Demonstration boards allow for
easy evaluation of the performance of the LTC6910
series of PGAs. Refer to Figure 4 for proper measurement equipment setup and follow the procedure
given below:
1.
The jumper settings given in this procedure set the
gain to a value of –1 (the LTC6910-X is an inverting
amplifier), for other gain values refer to Gain Table
2, 3 or 4 which matches the Demo Circuit, 566-A, B, or -C. To set the gain to a value of –1 set:
Place jumpers in the following positions:
G0: Set to Logic 1
Supply Jumper:
G1: Set to Logic 0
SINGLE for Single Supply
DUAL for Dual Supply
G2: Set to Logic 0
2.
Input Jumper (IN):
NOTE: Make
sure that the input voltage does not
exceed 11V total between V+ and V–.
DC for DC Coupling
AC for AC Coupling
3.
Set a function generator to output a 1kHz 1VP–P
signal.
4.
Set the input jumper to give the desired input coupling, AC or DC.
f–3dB = 1/(2πC7RINPUT)
C7 = 10µF, RINPUT is the nominal input impedance and depends on the gain setting,
see Table 2, 3, or 4.
With the power off, connect the input power supply
to V+, V- and AGND as required.
2
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 566
DIGITALLY CONTROLLED PROGRAMMABLE GAIN AMPLIFIER
5.
Turn on the power supply and connect the signal
generator to the IN BNC, or turrets as shown in
Figure 4.
6.
Monitor the output (BNC or test point) with an oscilloscope to observe a 1kHz 1VP–P signal.
Table 2.
7.
Using Tables 2, 3 or 4 set the gain as desired and
set the input to within the nominal linear input
range. Example: For a dual 5V supply operation
and a gain equal to five, the input to an LTC6910-1
should be set equal to or less than 2VP-P (see Table
2).
DC566A–A Gain Settings And Properties LTC6910-1
NOMINAL VOLTAGE GAIN
G2
G1
G0
1
0
0
NOMINAL LINEAR INPUT RANGE (VP–P)
SINGLE 5V
SUPPLY
SINGLE 3V
SUPPLY
NOMINAL INPUT IMPEDANCE
(KΩ)
VOLTS/VOLT
(dB)
DUAL 5V
SUPPLY
0
0
-120
10
5
3
OPEN
0
1
-1
0
10
5
3
10
0
1
0
-2
6
5
2.5
1.5
5
0
1
1
-5
14
2
1
0.6
2
1
0
0
–10
20
1
0.5
0.3
1
1
0
1
-20
26
0.5
0.25
0.15
1
1
1
0
-50
34
0.2
0.1
0.06
1
1
1
1
-100
40
0.1
0.05
0.3
1
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 566
DIGITALLY CONTROLLED PROGRAMMABLE GAIN AMPLIFIER
Table 3.
DC566A–B Gain Settings And Properties LTC6910-2
NOMINAL VOLTAGE GAIN
G2
G1
G0
1
0
0
NOMINAL LINEAR INPUT RANGE (VP–P)
NOMINAL INPUT IMPEDANCE
(K•)
VOLTS/VOLT
(dB)
DUAL 5V
SUPPLY
SINGLE 5V
SUPPLY
SINGLE 3V
SUPPLY
0
0
-120
10
5
3
OPEN
0
1
-1
0
10
5
3
10
0
1
0
-2
6
5
2.5
1.5
5
0
1
1
-4
12
2.5
1.25
0.75
2.5
1
0
0
-8
18.06
125
0.625
0.375
1.25
1
0
1
-16
24.08
0.625
0.313
0.188
1.25
1
1
0
-32
30.1
0.313
0.156
0.094
1.25
1
1
1
-64
36.12
0.156
0.078
0.047
1.25
Table 4.
DC566A–C Gain Settings And Properties LTC6910-3
NOMINAL VOLTAGE GAIN
G2
G1
G0
1
0
0
NOMINAL LINEAR INPUT RANGE (VP–P)
NOMINAL INPUT IMPEDANCE
(K•)
VOLTS/VOLT
(dB)
DUAL 5V
SUPPLY
SINGLE 5V
SUPPLY
SINGLE 3V
SUPPLY
0
0
-120
10
5
3
OPEN
0
1
-1
0
10
5
3
10
0
1
0
-2
6
5
2.5
1.5
5
0
1
1
-3
9.5
3.33
1.67
1
3.3
1
0
0
-4
12
2.5
1.25
0.75
2.5
1
0
1
-5
14
2
1
0.6
2
1
1
0
-6
15.6
1.67
0.83
0.5
1.7
1
1
1
-7
16.9
1.43
0.71
0.43
1.4
4
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 566
DIGITALLY CONTROLLED PROGRAMMABLE GAIN AMPLIFIER
5
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