LTC6911CMS-1

LTC6911-1/LTC6911-2 Dual Matched Amplifiers with Digitally Programmable Gain in MSOP FEATURES s DESCRIPTIO s s s s s s s s s s 3-Bit Digital Gain Control: (Inverting Gains of 0, 1, 2, 5, 10, 20, 50 and 100V/V) -1 Option (Inverting Gains of 0, 1, 2, 4, 8, 16, 32 and 64V/V) -2 Option Two Matched Programmable Gain Amplifiers Channel-to-Channel Gain Matching of 0.1dB (Max) Rail-to-Rail Input Range Rail-to-Rail Output Swing Single or Dual Supply: 2.7V to 10.5V Total 11MHz Gain Bandwidth Product Input Noise: 10nV/√Hz Total System Dynamic Range to 120dB Input Offset Voltage: 2mV, Gain of 10 Low Profile 10-Lead MSOP Package The LTC®6911 is a family of low noise digitally programmable gain amplifiers (PGAs) that are easy to use and occupy very little PC board space. The matched gain of both channels is adjustable using a 3-bit parallel interface to select voltage gains of 0, 1, 2, 5, 10, 20, 50 and 100V/ V (LTC6911-1) and 0, 1, 2, 4, 8, 16, 32 and 64V/V (LTC6911-2). All gains are inverting. The LTC6911 family consists of two matched inverting 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, the LTC6911 family is offered in a 10-lead MSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. APPLICATIO S s s s s Data Acquisition Systems Dynamic Gain Changing Automatic Ranging Circuits Automatic Gain Control TYPICAL APPLICATIO V+ 2.7V TO 10.5V 7 0.1µF 9 DIGITAL INPUT GAIN IN V/V G2 G1 G0 LTC6911-1 LTC6911-2 000 0 0 001 –1 –1 010 –2 –2 011 –5 –4 100 –10 –8 101 –20 –16 110 –50 –32 111 –100 –64 VINA AGND ≥1µF 1 10 VOUTA = GAIN • VINA GAIN (dB) 2 LTC6911-X VINB 3 8 VOUTB = GAIN • VINB 691112 TA01 –10 100 4 G0 5 G1 6 G2 U Frequency Response (LTC6911-1) 50 40 VS = 10V, VIN = 5mVRMS GAIN OF –100 (DIGITAL INPUT 111) 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) GAIN OF –2 (DIGITAL INPUT 010) 0 GAIN OF –1 (DIGITAL INPUT 001) 1k 10k 100k FREQUENCY (Hz) 1M 10M 691112 TA02 U U sn691112 691112fs 1 LTC6911-1/LTC6911-2 ABSOLUTE (Note 1) AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW INA AGND INB G0 G1 1 2 3 4 5 10 9 8 7 6 OUTA V– OUTB V+ G2 Total Supply Voltage (V+ to V–) .............................. 11V Input Current ..................................................... ± 10mA Operating Temperature Range (Note 2) LTC6911C-1/LTC6911C-2 .................. – 40°C to 85°C LTC6911I-1/LTC6911I-2 .................... – 40°C to 85°C LTC6911H-1/LTC6911H-2 ................ – 40°C to 125°C Specified Temperature Range (Note 3) LTC6911C-1/LTC6911C-2 .................. – 40°C to 85°C LTC6911I-1/LTC6911I-2 .................... – 40°C to 85°C LTC6911H-1/LTC6911H-2 ................ – 40°C to 125°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 150°C, θJA = 230°C/W ORDER PART NUMBER LTC6911CMS-1 LTC6911IMS-1 LTC6911HMS-1 LTC6911CMS-2 LTC6911IMS-2 LTC6911HMS-2 MS PART MARKING LTAHK LTAHM LTBCF LTAHH LTAHJ LTBCG Consult LTC Marketing for parts specified with wider operating temperature ranges. GAI SETTI GS A D PROPERTIES Table 1 (LTC6911-1) NOMINAL VOLTAGE GAIN Volts/Volt (dB) 0 –120 –1 0 –2 6 –5 14 –10 20 –20 26 –50 34 –100 40 MAXIMUM LINEAR INPUT RANGE (VP-P) Dual 5V Single 5V Single 3V Supply Supply Supply 10 5 3 10 5 3 5 2.5 1.5 2 1 0.6 1 0.5 0.3 0.5 0.25 0.15 0.2 0.1 0.06 0.1 0.05 0.03 NOMINAL INPUT IMPEDANCE (kΩ) (Open) 10 5 2 1 1 1 1 DIGITAL INPUTS G1 G0 0 0 0 1 1 0 1 1 0 0 0 1 1 0 1 1 G2 0 0 0 0 1 1 1 1 Table 2 (LTC6911-2) DIGITAL INPUTS G1 G0 0 0 0 1 1 0 1 1 0 0 0 1 1 0 1 1 NOMINAL VOLTAGE GAIN Volts/Volt (dB) 0 –120 –1 0 –2 6 –4 12 –8 18.1 –16 24.1 –32 30.1 –64 36.1 MAXIMUM LINEAR INPUT RANGE (VP-P) Dual 5V Single 5V Single 3V Supply Supply Supply 10 5 3 10 5 3 5 2.5 1.5 2.5 1.25 0.75 1.25 0.625 0.375 0.625 0.3125 0.188 0.3125 0.156 0.094 0.156 0.078 0.047 NOMINAL INPUT IMPEDANCE (kΩ) (Open) 10 5 2.5 1.25 1.25 1.25 1.25 sn691112 691112fs G2 0 0 0 0 1 1 1 1 2 U W U U WW U W U U LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-1/LTC6911-2 Total Supply Voltage (VS) Supply Current per Channel CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX q MIN 2.7 H GRADE TYP MAX 10.5 2.1 2.5 3.1 3.1 12 60 20 100 30 190 10 50 10 90 20 180 ± 27 ± 35 3.25 4.00 5.00 5.00 35 125 45 190 60 290 25 90 35 175 45 270 UNITS V mA mA mA mA mV mV mV mV mV mV mV mV mV mV mV mV mA mA 2.7 2.1 2.5 3.1 3.1 12 60 20 100 30 190 10 50 10 90 20 180 ± 27 ± 35 2.45 0.55 0.75 – 4.30 55 55 60 80 75 80 12 16 2.5 10.5 3.15 3.75 4.65 4.65 30 110 40 170 50 260 20 80 30 160 40 250 VS = 2.7V, VINA = VINB = VAGND VS = 5V, VINA = VINB = VAGND VS = ±5V, VINA = VINB = 0V, Pins 4, 5, 6 = –4.5V or 5V VS = ±5V, VINA = VINB = 0V, Pin 4 = 4.5V, Pins 5, 6 = 0.5V VS = 2.7V, RL = 10k Tied to Mid Supply VS = 2.7V, RL = 500Ω Tied to Mid Supply VS = 5V, RL = 10k Tied to Mid Supply VS = 5V, RL = 500Ω Tied to Mid Supply VS = ±5V, RL = 10k Tied to 0V VS = ±5V, RL = 500Ω Tied to 0V q q q q q q q q q q q q q q q q q q q q q q q q q Output Voltage Swing LOW (Note 4) Output Voltage Swing HIGH (Note 4) VS = 2.7V, RL = 10k Tied to Mid Supply VS = 2.7V, RL = 500Ω Tied to Mid Supply VS = 5V, RL = 10k Tied to Mid Supply VS = 5V, RL = 500Ω Tied to Mid Supply VS = ±5V, RL = 10k Tied to 0V VS = ±5V, RL = 500Ω Tied to 0V Output Short-Circuit Current (Note 5) AGND Open-Circuit Voltage AGND (Common Mode) Input Voltage Range AGND Rejection (i.e., Common Mode Rejection or CMRR) Power Supply Rejection Ratio (PSRR) Slew Rate Signal Attenuation at Gain = 0 Setting Digital Input “High” Voltage VS = 2.7V VS = ±5V VS = 5V VS = 2.7V VS = 5V VS = ± 5V VS = 2.7V, VAGND = 1.1V to 1.6V VS = ±5V, VAGND = – 2.5V to 2.5V VS = 2.7V to ±5V VS = 5V, VOUTA = VOUTB = 1.1V to 3.9V VS = ±5V, VOUTA = VOUTB = ±1.4V Gain = 0 (Digital Inputs 000), f = 20kHz VS = 2.7V VS = 5V VS = ±5V VS = 2.7V VS = 5V VS = ±5V VS = 2.7V, Pins 4, 5, 6 = 2.43V VS = 5V, Pins 4, 5, 6 = 4.5V VS = ±5V, Pins 4, 5, 6 = 4.5V VS = 2.7V, Pins 4, 5, 6 = 0.27V VS = 5V, Pins 4, 5, 6 = 0.5V VS = ±5V, Pins 4, 5, 6 = 0.5V 2.55 1.60 3.65 3.20 2.45 0.55 0.75 – 4.30 50 50 57 2.5 2.55 1.60 3.65 3.20 V V V V dB dB dB V/µs V/µs dB V V V 80 75 80 12 16 – 120 q q q q q q q q q q q q q – 120 2.43 4.50 4.50 0.27 0.50 0.50 1 5 10 1 5 10 2.43 4.50 4.50 Digital Input “Low” Voltage 0.27 0.50 0.50 1 5 10 1 5 10 V V V µA µA µA µA µA µA Digital Input “High” Current Digital Input “Low” Current sn691112 691112fs 3 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-1 Only Voltage Gain (Note 6) CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q MIN H GRADE TYP MAX UNITS dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω VS = 2.7V, Gain = 2, RL = 10k VS = 2.7V, Gain = 5, RL = 10k VS = 2.7V, Gain = 10, RL = 10k VS = 2.7V, Gain = 10, RL = 500Ω VS = 2.7V, Gain = 20, RL = 10k VS = 2.7V, Gain = 50, RL = 10k VS = 2.7V, Gain = 100, RL = 10k VS = 2.7V, Gain = 100, RL = 500Ω VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω VS = 5V, Gain = 2, RL = 10k VS = 5V, Gain = 5, RL = 10k VS = 5V, Gain = 10, RL = 10k VS = 5V, Gain = 10, RL = 500Ω VS = 5V, Gain = 20, RL = 10k VS = 5V, Gain = 50, RL = 10k VS = 5V, Gain = 100, RL = 10k VS = 5V, Gain = 100, RL = 500Ω VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω VS = ±5V, Gain = 2, RL = 10k VS = ±5V, Gain = 5, RL = 10k VS = ±5V, Gain = 10, RL = 10k VS = ±5V, Gain = 10, RL = 500Ω VS = ±5V, Gain = 20, RL = 10k VS = ±5V, Gain = 50, RL = 10k VS = ±5V, Gain = 100, RL = 10k VS = ±5V, Gain = 100, RL = 500Ω –0.07 0 0.07 –0.11 –0.02 0.07 5.94 6.01 6.08 13.85 13.95 14.05 19.7 19.93 20.1 19.6 19.85 20.1 25.75 25.94 26.1 33.5 33.8 39.0 39.6 37.4 38.9 34.1 40.1 40.1 –0.08 0 0.07 –0.13 –0.02 0.07 5.93 6.01 6.08 13.8 13.95 14.05 19.65 19.93 20.1 19.45 19.85 20.1 25.65 25.94 26.1 33.4 38.8 36.5 33.8 39.6 38.9 34.1 40.1 40.1 –0.08 0.01 0.08 –0.11 –0.01 0.07 5.95 6.02 6.09 13.8 13.96 14.1 19.8 19.94 20.1 19.6 19.87 20.1 25.8 25.94 26.1 33.5 33.84 34.1 39.3 39.7 38.0 39.2 –0.06 0.01 –0.10 0.00 5.95 6.02 40.1 40.1 0.08 0.08 6.09 –0.09 0.01 0.08 –0.13 –0.01 0.07 5.94 6.02 6.09 13.78 13.96 14.1 19.75 19.94 20.1 19.45 19.87 20.1 25.75 25.94 26.1 33.4 33.84 34.1 39.1 37.0 39.7 39.2 40.1 40.1 0.08 0.08 6.09 –0.07 0.01 –0.11 0.00 5.94 6.02 13.8 13.96 14.1 19.8 19.94 20.1 19.7 19.91 20.1 25.8 25.95 26.1 33.7 33.87 34.1 39.4 39.8 38.8 39.5 –0.1 0.02 –0.1 0.02 –0.1 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.20 0.02 –1.00 0.02 40.2 40.1 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.20 1.00 13.79 13.96 14.1 19.75 19.94 20.1 19.60 19.91 20.1 25.75 25.95 26.1 33.60 33.87 34.1 39.25 39.8 38.00 39.5 –0.1 –0.1 –0.1 0.02 0.02 0.02 40.2 40.1 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.20 1.50 Channel-to-Channel Voltage Gain Match VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω VS = 2.7V, Gain = 2, RL = 10k VS = 2.7V, Gain = 5, RL = 10k VS = 2.7V, Gain = 10, RL = 10k VS = 2.7V, Gain = 10, RL = 500Ω VS = 2.7V, Gain = 20, RL = 10k VS = 2.7V, Gain = 50, RL = 10k VS = 2.7V, Gain = 100, RL = 10k VS = 2.7V, Gain = 100, RL = 500Ω –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.20 0.02 –1.50 0.02 sn691112 691112fs 4 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-1 Only Channel-to-Channel Voltage Gain Match CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX q q q q q q q q q q q q q q q q q q q q MIN –0.1 –0.1 –0.1 H GRADE TYP MAX 0.02 0.02 0.02 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 1.2 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 0.9 UNITS dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB ppm/°C ppm/°Cppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C dB dB dB VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω VS = 5V, Gain = 2, RL = 10k VS = 5V, Gain = 5, RL = 10k VS = 5V, Gain = 10, RL = 10k VS = 5V, Gain = 10, RL = 500Ω VS = 5V, Gain = 20, RL = 10k VS = 5V, Gain = 50, RL = 10k VS = 5V, Gain = 100, RL = 10k VS = 5V, Gain = 100, RL = 500Ω VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω VS = ±5V, Gain = 2, RL = 10k VS = ±5V, Gain = 5, RL = 10k VS = ±5V, Gain = 10, RL = 10k VS = ±5V, Gain = 10, RL = 500Ω VS = ±5V, Gain = 20, RL = 10k VS = ±5V, Gain = 50, RL = 10k VS = ±5V, Gain = 100, RL = 10k VS = ±5V, Gain = 100, RL = 500Ω –0.1 0.02 –0.1 0.02 –0.1 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.2 0.02 –0.8 0.02 –0.1 0.02 –0.1 0.02 –0.1 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.2 0.02 –0.6 0.02 2 –1.5 –11 –30 –38 –70 –140 1.0 1.0 0.2 1.0 0.4 3.0 3.0 108 107 93 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 0.8 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 0.6 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.2 –1.2 –0.1 –0.1 –0.1 0.02 0.02 0.02 0.02 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.2 –0.9 0.02 0.02 2 –1.5 –11 –30 –38 –70 –140 1.0 1.0 0.2 1.0 0.4 3.0 3.0 108 107 93 Gain Temperature Coefficient VS = 5V, Gain = 1, RL = Open VS = 5V, Gain = 2, RL = Open VS = 5V, Gain = 5, RL = Open VS = 5V, Gain = 10, RL = Open VS = 5V, Gain = 20, RL = Open VS = 5V, Gain = 50, RL = Open VS = 5V, Gain = 100, RL = Open Channel-to-Channel Gain Temperature VS = 5V, Gain = 1, RL = Open Coefficient Match VS = 5V, Gain = 2, RL = Open VS = 5V, Gain = 5, RL = Open VS = 5V, Gain = 10, RL = Open VS = 5V, Gain = 20, RL = Open VS = 5V, Gain = 50, RL = Open VS = 5V, Gain = 100, RL = Open Channel-to-Channel Isolation (Note 7) f = 200kHz VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 10, RL = 10k VS = 5V, Gain = 100, RL = 10k Gain = 1 Gain = 10 Gain = 1 Gain = 10 q q Offset Voltage Magnitude Referred to INA or INB Pins (Note 8) Offset Voltage Magnitude Drift Referred to INA or INB Pins (Note 8) 2.0 1.1 12 6.6 22 12 2.0 1.1 20 11 22 14 mV mV µV/°C µV/°C sn691112 691112fs 5 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-1 Only DC Input Resistance at INA or INB Pins (Note 9) DC VINA or VINB = 0V Gain = 0 Gain = 1 Gain = 2 Gain = 5 Gain > 5 Gain = 1 Gain = 2 Gain = 5 Gain > 5 DC VINA or VINB = 0V Gain = 0 Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX MIN H GRADE TYP MAX UNITS q q q q q q q q q >100 10 5 2 1 10 5 2 1 0.4 0.7 1.0 1.9 3.4 6.4 15 30 >100 10 5 2 1 10 5 2 1 0.4 0.7 1.0 1.9 3.4 6.4 15 30 18 6 11 7.5 12.3 8.5 6.1 5.2 5.0 4.5 3.8 28 19 14 12 11.5 10.8 9.9 – 90 0.003 – 82 0.008 18 MΩ kΩ kΩ kΩ kΩ Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω MHz µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz dB % dB % DC Input Resistance Match RINA – RINB DC Small-Signal Output Resistance at OUTA or OUTB Pins Gain-Bandwidth Product Wideband Noise (Referred to Input) Gain = 100, fIN = 200kHz f = 1kHz to 200kHz Gain = 0 (Output Noise Only) Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 f = 50kHz Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 Gain = 10, fIN = 10kHz, VOUT = 1VRMS Gain = 10, fIN = 100kHz, VOUT = 1VRMS q 7 11 7.5 12.3 8.5 6.1 5.2 5.0 4.5 3.8 28 19 14 12 11.5 10.8 9.9 – 90 0.003 – 82 0.008 Voltage Noise Density (Referred to Input) Total Harmonic Distortion sn691112 691112fs 6 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-2 Only Voltage Gain (Note 6) CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q MIN H GRADE TYP MAX UNITS dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω VS = 2.7V, Gain = 2, RL = 10k VS = 2.7V, Gain = 4, RL = 10k VS = 2.7V, Gain = 8, RL = 10k VS = 2.7V, Gain = 8, RL = 500Ω VS = 2.7V, Gain = 16, RL = 10k VS = 2.7V, Gain = 32, RL = 10k VS = 2.7V, Gain = 64, RL = 10k VS = 2.7V, Gain = 64, RL = 500Ω VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω VS = 5V, Gain = 2, RL = 10k VS = 5V, Gain = 4, RL = 10k VS = 5V, Gain = 8, RL = 10k VS = 5V, Gain = 8, RL = 500Ω VS = 5V, Gain = 16, RL = 10k VS = 5V, Gain = 32, RL = 10k VS = 5V, Gain = 64, RL = 10k VS = 5V, Gain = 64, RL = 500Ω VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω VS = ±5V, Gain = 2, RL = 10k VS = ±5V, Gain = 4, RL = 10k VS = ±5V, Gain = 8, RL = 10k VS = ±5V, Gain = 8, RL = 500Ω VS = ±5V, Gain = 16, RL = 10k VS = ±5V, Gain = 32, RL = 10k VS = ±5V, Gain = 64, RL = 10k VS = ±5V, Gain = 64, RL = 500Ω –0.07 0 0.07 –0.11 –0.02 0.07 5.94 6.01 6.08 11.9 12.02 12.12 17.80 18.00 18.15 17.65 17.94 18.15 23.8 24.01 24.25 29.7 30 30.2 36.2 36.2 35.3 35.8 34.2 35.3 –0.08 0 0.07 –0.13 –0.02 0.07 5.93 6.01 6.08 11.88 12.02 12.12 17.75 18.00 18.15 17.55 17.94 18.15 23.75 24.01 24.25 29.65 30 30.2 36.2 36.2 35.15 35.8 33.65 35.3 –0.08 0.00 0.08 –0.10 –0.01 0.08 5.96 6.02 6.1 11.85 12.02 12.15 17.85 18.01 18.15 17.65 17.96 18.15 23.85 24.02 24.15 29.70 30.02 30.2 35.5 35.9 34.7 35.6 –0.06 0.01 –0.10 0.00 5.96 6.02 36.3 36.1 0.08 0.08 6.1 –0.09 0.00 0.08 –0.12 –0.01 0.08 5.95 6.02 6.1 11.83 12.02 12.15 17.83 18.01 18.15 17.50 17.96 18.15 23.80 24.02 24.15 29.65 30.02 30.2 35.40 35.9 34.20 35.6 –0.07 0.01 –0.11 0.00 5.95 6.02 36.3 36.1 0.08 0.08 6.1 11.9 12.03 12.15 17.85 18.02 18.15 17.80 17.99 18.15 23.85 24.03 24.15 29.85 30 30.2 35.65 36.0 36.20 35.20 35.8 36.20 –0.1 0.02 –0.1 0.02 –0.1 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.2 0.02 –0.7 0.02 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 0.7 11.88 12.03 12.15 17.83 18.02 18.15 17.73 17.99 18.15 23.82 24.03 24.15 29.8 30 30.2 35.55 36.0 36.20 34.80 35.8 36.20 –0.1 –0.1 –0.1 0.02 0.02 0.02 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 1.0 Channel-to-Channel Voltage Gain Match VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω VS = 2.7V, Gain = 2, RL = 10k VS = 2.7V, Gain = 4, RL = 10k VS = 2.7V, Gain = 8, RL = 10k VS = 2.7V, Gain = 8, RL = 500Ω VS = 2.7V, Gain = 16, RL = 10k VS = 2.7V, Gain = 32, RL = 10k VS = 2.7V, Gain = 64, RL = 10k VS = 2.7V, Gain = 64, RL = 500Ω –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.15 0.02 –0.2 –1.0 0.02 0.02 sn691112 691112fs 7 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-2 Only CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX q q q q q q q q q q q q q q q q q q q q MIN H GRADE TYP MAX 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 2 –1 –7 –21 –28 –40 –115 0 –0.5 0.5 0.5 1.0 4.0 4.0 110 110 93 2.0 1.1 20 11 >100 10 5 2.5 1.25 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.80 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.60 UNITS dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C dB dB dB mV mV µV/°C µV/°C MΩ kΩ kΩ kΩ kΩ Gain Temperature Coefficient Channel-to-Channel Gain Temperature Coefficient Match Channel-to-Channel Isolation (Note 7) Offset Voltage Magnitude Referred to INA or INB Pins (Note 8) Offset Voltage Magnitude Drift Referred to INA or INB Pins (Note 8) DC Input Resistance at INA or INB Pins (Note 9) VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω VS = 5V, Gain = 2, RL = 10k VS = 5V, Gain = 4, RL = 10k VS = 5V, Gain = 8, RL = 10k VS = 5V, Gain = 8, RL = 500Ω VS = 5V, Gain = 16, RL = 10k VS = 5V, Gain = 32, RL = 10k VS = 5V, Gain = 64, RL = 10k VS = 5V, Gain = 64, RL = 500Ω VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω VS = ±5V, Gain = 2, RL = 10k VS = ±5V, Gain = 4, RL = 10k VS = ±5V, Gain = 8, RL = 10k VS = ±5V, Gain = 8, RL = 500Ω VS = ±5V, Gain = 16, RL = 10k VS = ±5V, Gain = 32, RL = 10k VS = ±5V, Gain = 64, RL = 10k VS = ±5V, Gain = 64, RL = 500Ω VS = 5V, Gain = 1, RL = Open VS = 5V, Gain = 2, RL = Open VS = 5V, Gain = 4, RL = Open VS = 5V, Gain = 8, RL = Open VS = 5V, Gain = 16, RL = Open VS = 5V, Gain = 32, RL = Open VS = 5V, Gain = 64, RL = Open VS = 5V, Gain = 1, RL = Open VS = 5V, Gain = 2, RL = Open VS = 5V, Gain = 4, RL = Open VS = 5V, Gain = 8, RL = Open VS = 5V, Gain = 16, RL = Open VS = 5V, Gain = 32, RL = Open VS = 5V, Gain = 64, RL = Open f = 200kHz VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 8, RL = 10k VS = 5V, Gain = 64, RL = 10k Gain = 1 Gain = 8 Gain = 1 Gain = 8 DC VINA or VINB = 0V Gain = 0 Gain = 1 Gain = 2 Gain = 4 Gain > 4 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.60 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.40 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 2 –1 –7 –21 –28 –40 –115 0 –0.5 0.5 0.5 1.0 4.0 4.0 110 110 93 2.0 1.1 12 6.8 >100 10 5 2.5 1.25 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.60 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.40 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.80 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.60 q q 22 12 22 14 q q q q q sn691112 691112fs 8 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS PARAMETER LTC6911-2 Only DC Input Resistance Match RINA – RINB CONDITIONS The q denotes the specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), RL = 10k to midsupply point, unless otherwise noted. C/I GRADES MIN TYP MAX q q q q MIN H GRADE TYP MAX 10 5 2 1 0.4 0.7 1.0 1.9 3.4 6.4 15 30 7.4 12.4 8.5 6.5 5.5 5.2 4.9 4.3 28.0 19.0 14.8 12.7 11.8 11.5 10.9 – 90 0.003 – 82 0.008 11 UNITS Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz dB % dB % MHz DC Small-Signal Output Resistance at OUTA or OUTB Pins Wideband Noise (Referred to Input) Voltage Noise Density (Referred to Input) Total Harmonic Distortion Gain = 1 Gain = 2 Gain = 4 Gain > 4 DC VINA or VINB = 0V Gain = 0 Gain = 1 Gain = 2 Gain = 4 Gain = 8 Gain = 16 Gain = 32 Gain = 64 f = 1kHz to 200kHz Gain = 0 (Output Noise Only) Gain = 1 Gain = 2 Gain = 4 Gain = 8 Gain = 16 Gain = 32 Gain = 64 f = 50kHz Gain = 1 Gain = 2 Gain = 4 Gain = 8 Gain = 16 Gain = 32 Gain = 64 Gain = 8, fIN = 10kHz, VOUT = 1VRMS Gain = 8, fIN = 100kHz, VOUT = 1VRMS 10 5 2 1 0.4 0.7 1.0 1.9 3.4 6.4 15 30 7.4 12.4 8.5 6.5 5.5 5.2 4.9 4.3 28.0 19.0 14.8 12.7 11.8 11.5 10.9 – 90 0.003 – 82 0.008 11 Gain-Bandwidth Product Gain = 64, fIN = 200kHz q 6 17 6 17 Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LTC6911C and LTC6911I are guaranteed functional over the operating temperature range of – 40°C to 85°C. The LTC6911H is guaranteed functional over the operating temperature range of – 40°C to 125°C. Note 3: The LTC6911C is guaranteed to meet specified performance from 0°C to 70°C. The LTC6911C is designed, characterized and expected to meet specified performance from – 40°C to 85°C but is not tested or QA sampled at these temperatures. LTC6911I is guaranteed to meet specified performance from – 40°C to 85°C. The LTC6911H is guaranteed to meet specified performance from –40°C to 125°C. Note 4: Output voltage swings are measured as differences between the output and the respective supply rail. Note 5: Extended operation with output shorted may cause junction temperature to exceed the 150°C limit and is not recommended. Note 6: Gain is measured with a DC large-signal test using an output excursion between approximately 30% and 70% of the total supply voltage. Note 7: Channel-to-channel isolation is measured by applying a 200kHz input signal to one channel so that its output varies 1VRMS and measuring the output voltage RMS of the other channel relative to AGND with its input tied to AGND. Isolation is calculated: IsolationA = 20 • log10 VOUTB V , IsolationB = 20 • log10 OUTA VOUTA VOUTB Note 8: Offset voltage referred to the INA or INB input is (1 + 1/G) times the offset voltage of the internal op amp, where G is the nominal gain magnitude. See Applications Information. Note 9: Input resistance can vary by approximately ±30% part-to-part at a given gain setting (input resistance match remains as specified). sn691112 691112fs 9 LTC6911-1/LTC6911-2 TYPICAL PERFOR A CE CHARACTERISTICS (LTC6911-1) LTC6911-1 Gain Shift vs Temperature 0.100 0.075 0.050 GAIN CHANGE (dB) VS = 5V OUTPUT UNLOADED GAIN = 100 40 –3dB FREQUENCY (MHz) GAIN (dB) 0.025 GAIN = 10 0 GAIN = 1 –0.025 –0.050 –0.075 –0.100 –50 –25 50 25 TEMPERATURE (°C) 0 75 100 6911 G01 LTC6911-1 Channel Isolation vs Frequency 120 CHANNEL-TO-CHANNEL ISOLATION (dB) 115 GAIN = 1 110 REJECTION (dB) 105 100 95 90 85 100k FREQUENCY (Hz) 6911 G04 VOLTAGE NOISE DENSITY (nV/√Hz) VS = 5V VOUT = 1VRMS GAIN = 10 GAIN = 100 LTC6911-1 Distortion vs Frequency with Light Loading (RL = 10k) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) –40 –50 –60 –70 VS = ± 2.5V VOUT = 1VRMS (2.83VP-P) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) –30 THD + NOISE (dB) GAIN = 100 GAIN = 10 –80 –90 –100 0 50k 100k FREQUENCY (Hz) 6911 G07 GAIN = 1 150k 10 UW LTC6911-1 Frequency Response 50 VS = 10V, VIN = 5mVRMS GAIN OF 100 (DIGITAL INPUT 111) LTC6911-1 –3dB Bandwidth vs Gain Setting 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 • • • • • • VIN = 5mVRMS • VS = 2.7V • VS = ± 5V 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) GAIN OF 2 (DIGITAL INPUT 010) 0 GAIN OF 1 (DIGITAL INPUT 001) 1k 10k 100k FREQUENCY (Hz) 1M 10M 6911 G02 • • 10 GAIN • • –10 100 • • 100 6911 G03 1 LTC6911-1 Power Supply Rejection vs Frequency 90 80 70 60 –SUPPLY 50 40 30 20 10 0 1M LTC6911-1 Noise Density vs Frequency VS = ±2.5V GAIN = 1 100 VS = ± 2.5V TA = 25°C INPUT REFERRED GAIN = 1 GAIN = 10 10 GAIN = 100 +SUPPLY 1k 10k 100k 1M FREQUENCY (Hz) 10M 6911 G05 1 1k 10k FREQUENCY (Hz) 100k 6911 G06 LTC6911-1 Distortion vs Frequency with Heavy Loading (RL = 500Ω) –30 –40 –50 GAIN = 10 –60 GAIN = 1 –70 –80 –90 –100 0 50k 100k FREQUENCY (Hz) 6911 G08 LTC6911-1 THD + Noise vs Input Voltage –20 –30 GAIN = 100 –40 GAIN = 10 –50 –60 –70 –80 –90 fIN = 1kHz –100 VS = ±5V GAIN = 1 BW = 100Hz TO 22kHz –110 10n 1m 0.1 1 10 INPUT VOLTAGE (VP-P) 6911 G09 VS = ± 2.5V VOUT = 1VRMS (2.83VP-P) GAIN = 100 200k 150k 200k sn691112 691112fs LTC6911-1/LTC6911-2 TYPICAL PERFOR A CE CHARACTERISTICS (LTC6911-2) LTC6911-2 Gain Shift vs Temperature 0.100 0.075 0.050 GAIN = 64 50 VS = 5V OUTPUT UNLOADED GAIN CHANGE (dB) GAIN (dB) 0.025 0 30 GAIN OF 32 GAIN OF 16 –3dB FREQUENCY (MHz) GAIN = 8 GAIN = 1 –0.025 –0.050 –0.075 –0.100 –50 –25 50 25 TEMPERATURE (°C) 0 75 100 6911 G010 LTC6911-2 Channel Isolation vs Frequency 120 CHANNEL-TO-CHANNEL ISOLATION (dB) 115 GAIN = 8 110 REJECTION (dB) GAIN = 1 105 100 95 90 85 100k FREQUENCY (Hz) 6911 G13 VOLTAGE NOISE DENSITY (nV/√Hz) VS = 5V VOUT = 1VRMS GAIN = 64 LTC6911-2 Distortion vs Frequency with Light Loading (RL = 10k) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) –30 –40 –50 –60 GAIN = 64 –70 GAIN = 8 –80 GAIN = 1 –90 –100 0 50k 100k FREQUENCY (Hz) 6911 G16 VS = ± 2.5V VOUT = 1VRMS (2.83VP-P) THD + NOISE (dB) 150k UW LTC6911-2 Frequency Response VS = ± 5V VIN = 10mVRMS LTC6911-2 –3dB Bandwidth vs Gain Setting 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 • • • • • • • • 1 10 GAIN 40 GAIN OF 64 VIN = 10mVRMS • VS = 2.7V • VS = ± 5V 20 GAIN OF 8 GAIN OF 4 10 GAIN OF 2 GAIN OF 1 0 –10 100 • • • • 100 6911 G12 1k 100k 10k FREQUENCY (Hz) 1M 10M 6911 G11 LTC6911-2 Power Supply Rejection vs Frequency 90 80 70 60 –SUPPLY 50 40 30 20 10 0 1M LTC6911-2 Noise Density vs Frequency VS = ±2.5V GAIN = 1 100 VS = ± 2.5V TA = 25°C INPUT REFERRED GAIN = 1 +SUPPLY GAIN = 8 10 GAIN = 64 1k 10k 100k 1M FREQUENCY (Hz) 10M 6911 G14 1 1k 10k FREQUENCY (Hz) 100k 6911 G15 LTC6911-2 Distortion vs Frequency with Heavy Loading (RL = 500Ω) –30 –40 –50 GAIN = 8 –60 –70 –80 –90 –100 0 50k 100k FREQUENCY (Hz) 6911 G17 LTC6911-2 THD + Noise vs Input Voltage –20 –30 –40 GAIN = 64 –50 GAIN = 8 –60 –70 –80 VS = ± 2.5V VOUT = 1VRMS (2.83VP-P) GAIN = 64 GAIN = 1 200k 150k 200k –90 fIN = 1kHz –100 VS = ±5V GAIN = 1 BW = 100Hz TO 22kHz –110 10n 1m 0.1 1 10 INPUT VOLTAGE (VP-P) 6911 G18 sn691112 691112fs 11 LTC6911-1/LTC6911-2 PI FU CTIO S INA (Pin 1): Analog Input. The input signal to the A channel amplifier of the LTC6911-X is the voltage difference between the INA and AGND pin. The INA pin connects internally to a digitally controlled resistance whose other end is a current summing point at the same potential as the AGND pin (Figure 1). At unity gain (digital input 001), the value of this input resistance is approximately 10kΩ and the INA pin voltage range is rail-to-rail (V+ to V–). At gain settings above unity, the input resistance falls. The linear input range at INA also falls inversely proportional to the programmed gain. Tables 1 and 2 summarize this behavior. The higher gains are designed to boost lower level signals with good noise performance. In the “zero” gain state (digital input 000), analog switches disconnect the INA pin internally and this pin presents a very high input resistance. The input may vary from rail to rail in the “zero” gain setting, but the output is insensitive to it and is forced to the AGND potential. G2 6 G1 5 V+ 10k AGND 2 MOS-INPUT OP AMP V– INB 3 691112 F01 INPUT R ARRAY Figure 1. Block Diagram sn691112 691112fs 12 – MOS-INPUT OP AMP + 10k + – U U U Circuitry driving the INA pin must consider the LTC6911-X’s input resistance, its lot-to-lot variance, and the variation of this resistance from gain setting to gain setting. Signal sources with significant output resistance may introduce a gain error as the source’s output resistance and the LTC6911-X’s input resistance form a voltage divider. This is especially true at higher gain settings where the input resistance is the lowest. In single supply voltage applications, it is important to remember that the LTC6911-X’s DC ground reference for both input and output is AGND, not V–. With increasing gains, the LTC6911-X’s input voltage range for an unclipped output is no longer rail-to-rail but diminishes inversely to gain, centered about the AGND potential. G0 4 CMOS LOGIC INA 1 INPUT R ARRAY FEEDBACK R ARRAY 10 OUTA 9 V– 8 OUTB 7 V+ FEEDBACK R ARRAY LTC6911-1/LTC6911-2 PI FU CTIO S AGND (Pin 2): Analog Ground. The AGND pin is at the midpoint of an internal resistive voltage divider, developing a potential halfway between the V+ and V– pins, with an equivalent series resistance to the pin of nominally 5kΩ (Figure 1). AGND is also the noninverting input to both the internal channel A and channel B amplifiers. This makes AGND the ground reference voltage for the INA, INB, OUTA and OUTB pins. Recommended analog ground plane connection depends on how power is applied to the LTC6911-X (see Figures 2, 3 and 4). Single power supply applications typically use V– for the system signal ground. The analog ground plane in single supply applications should therefore tie to V–, and the AGND pin should be bypassed to this ground plane by a high quality capacitor of at least 1µF (Figure 2). The AGND pin provides an internal analog reference voltage at half the V+ supply voltage. Dual supply applications with symmetrical supplies (such as ±5V) have a natural system ground plane potential of zero volts, which can be tied directly to the AGND pin, making the zero volt ground plane the input and output reference voltage for the LTC6911-X (Figure 3). Finally, if dual asymmetrical power supplies are used, the supply ground is still the natural ground plane voltage. To maximize signal swing V+ 0.1µF ANALOG GROUND PLANE SINGLE-POINT SYSTEM GROUND Figure 2. Single Supply Ground Plane Connection U U U capability with an asymmetrical supply, however, it is often desirable to refer the LTC6911-X’s analog input and output to a voltage equidistant from the two supply rails V+ and V–. The AGND pin will provide such a potential when open-circuited and bypassed with a capacitor (Figure 4). V– 0.1µF V+ 0.1µF 10 9 8 7 6 LTC6911-X 1 ANALOG GROUND PLANE 2 3 4 5 SINGLE-POINT SYSTEM GROUND DIGITAL GROUND PLANE (IF ANY) 691112 F03 Figure 3. Dual Supply Ground Plane Connection V– 0.1µF V+ 0.1µF 10 9 8 7 6 10 9 8 7 6 LTC6911-X LTC6911-X 1 2 3 4 + 5 1 ANALOG GROUND PLANE 2 3 4 5 ≥1µF V REFERENCE 2 V + + V– REFERENCE 2 ≥1µF DIGITAL GROUND PLANE (IF ANY) 691112 F02 SINGLE-POINT SYSTEM GROUND DIGITAL GROUND PLANE (IF ANY) 691112 F04 Figure 4. Asymmetrical Dual Supply Ground Plane Connection sn691112 691112fs 13 LTC6911-1/LTC6911-2 PI FU CTIO S In noise sensitive applications where AGND does not directly tie to a ground plane, as in Figures 2 and 4, it is important to AC-bypass the AGND pin. Otherwise, channel-to-channel isolation is degraded and wideband noise will enter the signal path from the thermal noise of the internal voltage divider resistors that present a Thévenin equivalent resistance of approximately 5kΩ. This noise can reduce SNR by at least 3dB at high gain settings. An external capacitor from AGND to the ground plane, whose impedance is well below 5kΩ at frequencies of interest, will filter and suppress this noise. A 1µF high quality capacitor is effective for frequencies down to 1kHz. Larger capacitors extend this suppression to lower frequencies. This issue does not arise in dual supply applications because the AGND pin ties directly to ground. In applications requiring an analog ground reference other than half the total supply voltage, the user can override the built-in analog ground reference by tying the AGND pin to a reference voltage within the AGND voltage range specified in the Electrical Characteristics table. The AGND pin will load the external reference with approximately 5kΩ returned to the half-supply potential. AGND should still be capacitively bypassed to a ground plane as noted above. Do not connect the AGND pin to the V– pin. INB (Pin 3): Analog Input. Refer to INA pin description. G0, G1, G2 (Pins 4, 5, 6): CMOS-Level Digital Gain Control Inputs. G2 is the most significant bit (MSB) and G0 is the least significant bit (LSB). These pins control the voltage gain settings for both channels (see Tables 1 and 2). Each channel’s gain cannot be set independent of the other channel. The logic input pins (G pins) are allowed to swing from V– to 10.5V above V–, regardless of V+ so long as the logic levels meet the minimum requirements specified in the Electrical Characteristics table. The G0, G1 and G2 pins are high impedance CMOS logic inputs, but have small pull-down current sources (10µF) near the chip, can create a high-Q LC resonance in the hundreds of kHz in the chip’s supplies or ground reference. This may impair circuit performance at those frequencies. A compact, carefully laid out printed circuit board with a good ground plane makes a significant difference in minimizing distortion and maximizing channel isolation. Finally, equipment to measure amplifier performance can itself add to distortion or noise floors. Checking for these limits with wired shorts from INA to OUTA and INB to OUTB in place of the chip is a prudent routine procedure. sn691112 691112fs W UU 17 LTC6911-1/LTC6911-2 TYPICAL APPLICATIO Expanding an ADC’s Dynamic Range Figure 5 shows a compact 2-channel data acquisition system for wide ranging input levels. This figure combines an LTC6911-X programmable amplifier (10-lead MSOP) with an LTC1865 analog-to-digital converter (ADC) in an 8-lead MSOP. This ADC has 16-bit resolution and a V+ 0.1µF 9 VINA AGND ≥ 1µF 1 2 VINB 3 Figure 5. Expanding a Dual Channel ADC’s Dynamic Range 18 U maximum sampling rate of 250ksps. An LTC6911-1, for example, expands the ADC’s input amplitude range by 40dB while operating from the same single 5V supply. The 499Ω resistor and 270pF capacitor couple cleanly between the LTC6911-X’s output and the switched-capacitor inputs of the LTC1865. 7 V+ 0.1µF 10 499Ω 270pF CH0 LTC6911-X CH1 8 499Ω 270pF GND LTC1865 SCK SDO SDI 691112 F05 VCC CONV ADC INTERFACE 691112 F05 4 5 6 GAIN CONTROL sn691112 691112fs LTC6911-1/LTC6911-2 PACKAGE DESCRIPTIO 5.23 (.206) MIN 0.50 0.305 ± 0.038 (.0197) (.0120 ± .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) GAUGE PLANE 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 0.127 ± 0.076 (.005 ± .003) MSOP (MS) 0603 NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.889 ± 0.127 (.035 ± .005) 3.20 – 3.45 (.126 – .136) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 10 9 8 7 6 0.497 ± 0.076 (.0196 ± .003) REF DETAIL “A” 0° – 6° TYP 12345 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 1.10 (.043) MAX 0.86 (.034) REF 4.90 ± 0.152 (.193 ± .006) 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 0.50 (.0197) BSC sn691112 691112fs 19 LTC6911-1/LTC6911-2 TYPICAL APPLICATIO Fully Differential Amplifier with Digitally Programmable Gain High Dynamic Range (PGA Input) –5V 0.1µF VIN+ VIN– VIN+ VIN– 5V 1 LTC1992-1 OR 7 2 LTC1992-2 OR 6 3 LTC1992-5 OR 5 4 LTC1992-10 8 –5V 1 2 LTC6911-1 OR 4 LTC6911-2 5 3 0.1µF 10 9 8 7 6 0.1µF RELATED PARTS PART NUMBER LT 1228 LT1251/LT1256 LTC1564 LTC6910 LTC6915 ® DESCRIPTION 100MHz Gain Controlled Transconductance Amplifier 40MHz Video Fader and Gain Controlled Amplifier 10kHz to 150kHz Digitally Controlled Filter and PGA Digitally Controlled Programmable Gain Amplifier in SOT-23 Digitally Controlled Programmable Instrumentation Amplifier with SPI Interface 20 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 q FAX: (408) 434-0507 q U 1 2 LTC6911-1 OR 4 LTC6911-2 5 3 10 9 8 7 6 0.1µF 5V 8 LTC1992-1 OR 2 7 LTC1992-2 OR 3 6 LTC1992-5 OR 0.1µF 4 5 LTC1992-10 1 –5V VOUT+ VOUT– G0 G1 G2 DIGITAL GAIN CONTROL 0.1µF High CMRR (Differential Input) –5V 0.1µF VOUT+ VOUT– 5V 0.1µF 691112 TA03 G0 G1 G2 DIGITAL GAIN CONTROL COMMENTS Differential Input, Continuous Analog Gain Control Two Input, One Output, Continuous Analog Gain Control Continuous Time, Low Noise 8th Order Filter and 4-Bit PGA Single Channel Version of the LTC6911 14 Bits of Gain Control sn691112 691112fs LT/TP 0104 1K • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 2004