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