LTC6911CMS-2#TRPBF

LTC6911-1/LTC6911-2 Dual Matched Amplifiers with Digitally Programmable Gain in MSOP U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 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. 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 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. U APPLICATIO S ■ ■ Data Acquisition Systems Dynamic Gain Changing Automatic Ranging Circuits Automatic Gain Control TYPICAL APPLICATIO V+ 2.7V TO 10.5V 0.1µF Frequency Response (LTC6911-1) 7 DIGITAL INPUT GAIN IN V/V G2 G1 G0 LTC6911-1 LTC6911-2 0 0 0 0 0 0 0 1 –1 –1 0 1 0 –2 –2 0 1 1 –5 –4 1 0 0 –10 –8 1 0 1 –20 –16 1 1 0 –50 –32 1 1 1 –100 –64 50 9 40 VINA AGND 10 1 VOUTA = GAIN • VINA ≥1µF 2 LTC6911-X VS = 10V, VIN = 5mVRMS GAIN OF –100 (DIGITAL INPUT 111) 30 GAIN OF –50 (DIGITAL INPUT 110) GAIN (dB) ■ U ■ GAIN OF –20 (DIGITAL INPUT 101) 20 GAIN OF –10 (DIGITAL INPUT 100) 10 GAIN OF –5 (DIGITAL INPUT 011) VINB 3 8 VOUTB = GAIN • VINB 691112 TA01 4 G0 5 G1 6 G2 GAIN OF –2 (DIGITAL INPUT 010) 0 GAIN OF –1 (DIGITAL INPUT 001) –10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 691112 TA02 sn691112 691112fs 1 LTC6911-1/LTC6911-2 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) 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 TOP VIEW INA AGND INB G0 G1 10 9 8 7 6 1 2 3 4 5 OUTA V– OUTB V+ G2 MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 150°C, θJA = 230°C/W ORDER PART NUMBER MS PART MARKING LTC6911CMS-1 LTC6911IMS-1 LTC6911HMS-1 LTC6911CMS-2 LTC6911IMS-2 LTC6911HMS-2 LTAHK LTAHM LTBCF LTAHH LTAHJ LTBCG Consult LTC Marketing for parts specified with wider operating temperature ranges. U U U GAI SETTI GS A D PROPERTIES Table 1 (LTC6911-1) G2 0 0 0 0 1 1 1 1 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 –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 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 Table 2 (LTC6911-2) G2 0 0 0 0 1 1 1 1 DIGITAL INPUTS G1 G0 0 0 0 1 1 0 1 1 0 0 0 1 1 0 1 1 sn691112 691112fs 2 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS The ● 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. PARAMETER CONDITIONS C/I GRADES MIN TYP MAX MIN H GRADE TYP MAX UNITS 2.7 2.7 10.5 V LTC6911-1/LTC6911-2 Total Supply Voltage (VS) ● 10.5 Supply Current per Channel 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 ● ● ● ● 2.1 2.5 3.1 3.1 3.15 3.75 4.65 4.65 2.1 2.5 3.1 3.1 3.25 4.00 5.00 5.00 mA mA mA mA Output Voltage Swing LOW (Note 4) VS = 2.7V, RL = 10k Tied to Mid Supply VS = 2.7V, RL = 500Ω Tied to Mid Supply ● ● 12 60 30 110 12 60 35 125 mV mV VS = 5V, RL = 10k Tied to Mid Supply VS = 5V, RL = 500Ω Tied to Mid Supply ● ● 20 100 40 170 20 100 45 190 mV mV VS = ±5V, RL = 10k Tied to 0V VS = ±5V, RL = 500Ω Tied to 0V ● ● 30 190 50 260 30 190 60 290 mV mV VS = 2.7V, RL = 10k Tied to Mid Supply VS = 2.7V, RL = 500Ω Tied to Mid Supply ● ● 10 50 20 80 10 50 25 90 mV mV VS = 5V, RL = 10k Tied to Mid Supply VS = 5V, RL = 500Ω Tied to Mid Supply ● ● 10 90 30 160 10 90 35 175 mV mV VS = ±5V, RL = 10k Tied to 0V VS = ±5V, RL = 500Ω Tied to 0V ● ● 20 180 40 250 20 180 45 270 mV mV Output Short-Circuit Current (Note 5) VS = 2.7V VS = ±5V ● ● ±27 ±35 AGND Open-Circuit Voltage VS = 5V ● 2.45 AGND (Common Mode) Input Voltage Range VS = 2.7V VS = 5V VS = ±5V ● ● ● 0.55 0.75 – 4.30 AGND Rejection (i.e., Common Mode Rejection or CMRR) VS = 2.7V, VAGND = 1.1V to 1.6V VS = ±5V, VAGND = – 2.5V to 2.5V ● ● 55 55 Power Supply Rejection Ratio (PSRR) VS = 2.7V to ±5V ● 60 Slew Rate VS = 5V, VOUTA = VOUTB = 1.1V to 3.9V VS = ±5V, VOUTA = VOUTB = ±1.4V Signal Attenuation at Gain = 0 Setting Gain = 0 (Digital Inputs 000), f = 20kHz ● Digital Input “High” Voltage VS = 2.7V VS = 5V VS = ±5V ● ● ● Digital Input “Low” Voltage VS = 2.7V VS = 5V VS = ±5V ● ● ● Digital Input “High” Current 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 ● ● ● 1 5 10 1 5 10 µA µA µA Digital Input “Low” Current 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 ● ● ● 1 5 10 1 5 10 µA µA µA Output Voltage Swing HIGH (Note 4) 2.5 ±27 ±35 2.55 2.45 1.60 3.65 3.20 0.55 0.75 – 4.30 80 75 50 50 80 57 12 16 – 120 2.5 mA mA 2.55 V 1.60 3.65 3.20 V V V 80 75 dB dB 80 dB 12 16 V/µs V/µs – 120 2.43 4.50 4.50 dB 2.43 4.50 4.50 V V V 0.27 0.50 0.50 0.27 0.50 0.50 V V V sn691112 691112fs 3 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS The ● 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. PARAMETER CONDITIONS C/I GRADES MIN TYP MAX MIN H GRADE TYP MAX UNITS LTC6911-1 Only Voltage Gain (Note 6) Channel-to-Channel Voltage Gain Match VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω ● ● –0.07 0 0.07 –0.11 –0.02 0.07 –0.08 0 0.07 –0.13 –0.02 0.07 dB dB VS = 2.7V, Gain = 2, RL = 10k ● 5.94 6.01 5.93 6.08 dB VS = 2.7V, Gain = 5, RL = 10k ● 13.85 13.95 14.05 13.8 13.95 14.05 dB VS = 2.7V, Gain = 10, RL = 10k VS = 2.7V, Gain = 10, RL = 500Ω ● ● 19.7 19.93 20.1 19.6 19.85 20.1 19.65 19.93 20.1 19.45 19.85 20.1 dB dB VS = 2.7V, Gain = 20, RL = 10k ● 25.75 25.94 26.1 25.65 25.94 26.1 dB VS = 2.7V, Gain = 50, RL = 10k ● 33.5 33.8 34.1 33.4 33.8 34.1 dB VS = 2.7V, Gain = 100, RL = 10k VS = 2.7V, Gain = 100, RL = 500Ω ● ● 39.0 39.6 37.4 38.9 40.1 40.1 38.8 36.5 39.6 38.9 40.1 40.1 dB dB VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω ● ● –0.08 0.01 0.08 –0.11 –0.01 0.07 –0.09 0.01 0.08 –0.13 –0.01 0.07 dB dB VS = 5V, Gain = 2, RL = 10k ● 5.95 6.02 5.94 6.09 dB VS = 5V, Gain = 5, RL = 10k ● 13.8 13.96 14.1 13.78 13.96 14.1 dB VS = 5V, Gain = 10, RL = 10k VS = 5V, Gain = 10, RL = 500Ω ● ● 19.8 19.94 20.1 19.6 19.87 20.1 19.75 19.94 20.1 19.45 19.87 20.1 dB dB VS = 5V, Gain = 20, RL = 10k ● 25.8 25.94 26.1 25.75 25.94 26.1 dB VS = 5V, Gain = 50, RL = 10k ● 33.5 33.84 34.1 33.4 33.84 34.1 dB VS = 5V, Gain = 100, RL = 10k VS = 5V, Gain = 100, RL = 500Ω ● ● 39.3 39.7 38.0 39.2 40.1 40.1 39.1 37.0 39.7 39.2 40.1 40.1 dB dB VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω ● ● –0.06 0.01 –0.10 0.00 0.08 0.08 –0.07 0.01 –0.11 0.00 0.08 0.08 dB dB VS = ±5V, Gain = 2, RL = 10k ● 5.95 6.02 6.09 5.94 6.09 dB VS = ±5V, Gain = 5, RL = 10k ● 13.8 13.96 14.1 13.79 13.96 14.1 dB VS = ±5V, Gain = 10, RL = 10k VS = ±5V, Gain = 10, RL = 500Ω ● ● 19.8 19.94 20.1 19.7 19.91 20.1 19.75 19.94 20.1 19.60 19.91 20.1 dB dB VS = ±5V, Gain = 20, RL = 10k ● 25.8 25.95 26.1 25.75 25.95 26.1 dB VS = ±5V, Gain = 50, RL = 10k ● 33.7 33.87 34.1 33.60 33.87 34.1 dB VS = ±5V, Gain = 100, RL = 10k VS = ±5V, Gain = 100, RL = 500Ω ● ● 39.4 39.8 38.8 39.5 40.2 40.1 39.25 39.8 38.00 39.5 40.2 40.1 dB dB VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω ● ● –0.1 0.02 –0.1 0.02 0.1 0.1 –0.1 –0.1 0.02 0.02 0.1 0.1 dB dB VS = 2.7V, Gain = 2, RL = 10k ● –0.1 0.02 0.1 –0.1 0.02 0.1 dB VS = 2.7V, Gain = 5, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 2.7V, Gain = 10, RL = 10k VS = 2.7V, Gain = 10, RL = 500Ω ● ● –0.15 0.02 –0.15 0.02 0.15 0.15 –0.15 0.02 –0.15 0.02 0.15 0.15 dB dB VS = 2.7V, Gain = 20, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 2.7V, Gain = 50, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 2.7V, Gain = 100, RL = 10k VS = 2.7V, Gain = 100, RL = 500Ω ● ● –0.20 0.02 –1.00 0.02 0.20 1.00 –0.20 0.02 –1.50 0.02 0.20 1.50 dB dB 6.08 6.09 6.01 6.02 6.02 sn691112 691112fs 4 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS The ● 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. PARAMETER CONDITIONS C/I GRADES MIN TYP MAX MIN H GRADE TYP MAX UNITS LTC6911-1 Only Channel-to-Channel Voltage Gain Match Gain Temperature Coefficient VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω ● ● –0.1 0.02 –0.1 0.02 0.1 0.1 –0.1 –0.1 0.02 0.02 0.1 0.1 dB dB VS = 5V, Gain = 2, RL = 10k ● –0.1 0.02 0.1 –0.1 0.02 0.1 dB VS = 5V, Gain = 5, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 5V, Gain = 10, RL = 10k VS = 5V, Gain = 10, RL = 500Ω ● ● –0.15 0.02 –0.15 0.02 0.15 0.15 –0.15 0.02 –0.15 0.02 0.15 0.15 dB dB VS = 5V, Gain = 20, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 5V, Gain = 50, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 5V, Gain = 100, RL = 10k VS = 5V, Gain = 100, RL = 500Ω ● ● –0.2 0.02 –0.8 0.02 0.2 0.8 –0.2 –1.2 0.02 0.02 0.2 1.2 dB dB VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω ● ● –0.1 0.02 –0.1 0.02 0.1 0.1 –0.1 –0.1 0.02 0.02 0.1 0.1 dB dB VS = ±5V, Gain = 2, RL = 10k ● –0.1 0.02 0.1 –0.1 0.02 0.1 dB VS = ±5V, Gain = 5, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = ±5V, Gain = 10, RL = 10k VS = ±5V, Gain = 10, RL = 500Ω ● ● –0.15 0.02 –0.15 0.02 0.15 0.15 –0.15 0.02 –0.15 0.02 0.15 0.15 dB dB VS = ±5V, Gain = 20, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = ±5V, Gain = 50, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = ±5V, Gain = 100, RL = 10k VS = ±5V, Gain = 100, RL = 500Ω ● ● –0.2 0.02 –0.6 0.02 0.2 0.6 –0.2 –0.9 0.2 0.9 dB dB 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 Offset Voltage Magnitude Referred to INA or INB Pins (Note 8) Gain = 1 Gain = 10 Offset Voltage Magnitude Drift Referred to INA or INB Pins (Note 8) Gain = 1 Gain = 10 ● ● 0.02 0.02 2 –1.5 –11 –30 –38 –70 –140 2 –1.5 –11 –30 –38 –70 –140 ppm/°C ppm/°Cppm/°C ppm/°C ppm/°C ppm/°C ppm/°C 1.0 1.0 0.2 1.0 0.4 3.0 3.0 1.0 1.0 0.2 1.0 0.4 3.0 3.0 ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C 108 107 93 108 107 93 dB dB dB 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 The ● 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. PARAMETER C/I GRADES MIN TYP MAX CONDITIONS MIN H GRADE TYP MAX UNITS 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 ● ● ● ● ● >100 10 5 2 1 >100 10 5 2 1 DC Input Resistance Match RINA – RINB Gain = 1 Gain = 2 Gain = 5 Gain > 5 ● ● ● ● 10 5 2 1 10 5 2 1 Ω Ω Ω Ω DC Small-Signal Output Resistance at OUTA or OUTB Pins DC VINA or VINB = 0V Gain = 0 Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 0.4 0.7 1.0 1.9 3.4 6.4 15 30 0.4 0.7 1.0 1.9 3.4 6.4 15 30 Ω Ω Ω Ω Ω Ω Ω Ω Gain-Bandwidth Product Gain = 100, fIN = 200kHz Wideband Noise (Referred to Input) f = 1kHz to 200kHz Gain = 0 (Output Noise Only) Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 7.5 12.3 8.5 6.1 5.2 5.0 4.5 3.8 7.5 12.3 8.5 6.1 5.2 5.0 4.5 3.8 µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS Voltage Noise Density (Referred to Input) f = 50kHz Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 28 19 14 12 11.5 10.8 9.9 28 19 14 12 11.5 10.8 9.9 nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz Total Harmonic Distortion Gain = 10, fIN = 10kHz, VOUT = 1VRMS – 90 0.003 – 90 0.003 dB % Gain = 10, fIN = 100kHz, VOUT = 1VRMS – 82 0.008 – 82 0.008 dB % ● 7 11 18 6 11 MΩ kΩ kΩ kΩ kΩ 18 MHz sn691112 691112fs 6 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS The ● 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. PARAMETER CONDITIONS C/I GRADES MIN TYP MAX MIN H GRADE TYP MAX UNITS LTC6911-2 Only Voltage Gain (Note 6) Channel-to-Channel Voltage Gain Match VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω ● ● –0.07 0 0.07 –0.11 –0.02 0.07 –0.08 0 0.07 –0.13 –0.02 0.07 dB dB VS = 2.7V, Gain = 2, RL = 10k ● 5.94 6.01 5.93 dB VS = 2.7V, Gain = 4, RL = 10k ● 11.9 12.02 12.12 11.88 12.02 12.12 dB VS = 2.7V, Gain = 8, RL = 10k VS = 2.7V, Gain = 8, RL = 500Ω ● ● 17.80 18.00 18.15 17.65 17.94 18.15 17.75 18.00 18.15 17.55 17.94 18.15 dB dB VS = 2.7V, Gain = 16, RL = 10k ● 23.8 24.01 24.25 23.75 24.01 24.25 dB VS = 2.7V, Gain = 32, RL = 10k ● 29.7 30.2 29.65 30.2 dB VS = 2.7V, Gain = 64, RL = 10k VS = 2.7V, Gain = 64, RL = 500Ω ● ● 35.3 35.8 34.2 35.3 36.2 36.2 35.15 35.8 33.65 35.3 36.2 36.2 dB dB VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 1, RL = 500Ω ● ● –0.08 0.00 0.08 –0.10 –0.01 0.08 –0.09 0.00 0.08 –0.12 –0.01 0.08 dB dB VS = 5V, Gain = 2, RL = 10k ● 5.96 6.02 5.95 dB VS = 5V, Gain = 4, RL = 10k ● 11.85 12.02 12.15 11.83 12.02 12.15 dB VS = 5V, Gain = 8, RL = 10k VS = 5V, Gain = 8, RL = 500Ω ● ● 17.85 18.01 18.15 17.65 17.96 18.15 17.83 18.01 18.15 17.50 17.96 18.15 dB dB VS = 5V, Gain = 16, RL = 10k ● 23.85 24.02 24.15 23.80 24.02 24.15 dB VS = 5V, Gain = 32, RL = 10k ● 29.70 30.02 30.2 29.65 30.02 30.2 dB VS = 5V, Gain = 64, RL = 10k VS = 5V, Gain = 64, RL = 500Ω ● ● 35.5 35.9 34.7 35.6 36.3 36.1 35.40 35.9 34.20 35.6 36.3 36.1 dB dB VS = ±5V, Gain = 1, RL = 10k VS = ±5V, Gain = 1, RL = 500Ω ● ● –0.06 0.01 –0.10 0.00 0.08 0.08 –0.07 0.01 –0.11 0.00 0.08 0.08 dB dB VS = ±5V, Gain = 2, RL = 10k ● 5.96 6.02 6.1 5.95 6.1 dB VS = ±5V, Gain = 4, RL = 10k ● 11.9 12.03 12.15 11.88 12.03 12.15 dB VS = ±5V, Gain = 8, RL = 10k VS = ±5V, Gain = 8, RL = 500Ω ● ● 17.85 18.02 18.15 17.80 17.99 18.15 17.83 18.02 18.15 17.73 17.99 18.15 dB dB VS = ±5V, Gain = 16, RL = 10k ● 23.85 24.03 24.15 23.82 24.03 24.15 dB VS = ±5V, Gain = 32, RL = 10k ● 29.85 30.2 dB VS = ±5V, Gain = 64, RL = 10k VS = ±5V, Gain = 64, RL = 500Ω ● ● 35.65 36.0 36.20 35.20 35.8 36.20 35.55 36.0 36.20 34.80 35.8 36.20 dB dB VS = 2.7V, Gain = 1, RL = 10k VS = 2.7V, Gain = 1, RL = 500Ω ● ● –0.1 0.02 –0.1 0.02 –0.1 –0.1 0.02 0.02 dB dB VS = 2.7V, Gain = 2, RL = 10k ● –0.1 0.02 0.1 –0.1 0.02 0.1 dB VS = 2.7V, Gain = 4, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 2.7V, Gain = 8, RL = 10k VS = 2.7V, Gain = 8, RL = 500Ω ● ● –0.15 0.02 –0.15 0.02 0.15 0.15 –0.15 0.02 –0.15 0.02 0.15 0.15 dB dB VS = 2.7V, Gain = 16, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 2.7V, Gain = 32, RL = 10k ● –0.15 0.02 0.15 –0.15 0.02 0.15 dB VS = 2.7V, Gain = 64, RL = 10k VS = 2.7V, Gain = 64, RL = 500Ω ● ● –0.2 0.02 –0.7 0.02 0.2 0.7 –0.2 –1.0 0.2 1.0 dB dB 30 30 6.08 6.1 30.2 0.1 0.1 29.8 6.01 30 6.02 6.02 30 0.02 0.02 6.08 6.1 0.1 0.1 sn691112 691112fs 7 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS The ● 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. PARAMETER CONDITIONS C/I GRADES MIN TYP MAX MIN H GRADE TYP MAX –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 UNITS LTC6911-2 Only 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 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.02 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 22 12 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 22 14 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 sn691112 691112fs 8 LTC6911-1/LTC6911-2 ELECTRICAL CHARACTERISTICS The ● 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. PARAMETER LTC6911-2 Only DC Input Resistance Match RINA – RINB DC Small-Signal Output Resistance at OUTA or OUTB Pins Wideband Noise (Referred to Input) Voltage Noise Density (Referred to Input) Total Harmonic Distortion C/I GRADES MIN TYP MAX CONDITIONS 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 Gain-Bandwidth Product Gain = 64, fIN = 200kHz 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. ● 6 MIN H GRADE TYP MAX UNITS 10 5 2 1 10 5 2 1 Ω Ω Ω Ω 0.4 0.7 1.0 1.9 3.4 6.4 15 30 0.4 0.7 1.0 1.9 3.4 6.4 15 30 Ω Ω Ω Ω Ω Ω Ω Ω 7.4 12.4 8.5 6.5 5.5 5.2 4.9 4.3 7.4 12.4 8.5 6.5 5.5 5.2 4.9 4.3 µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS 28.0 19.0 14.8 12.7 11.8 11.5 10.9 – 90 0.003 – 82 0.008 11 28.0 19.0 14.8 12.7 11.8 11.5 10.9 – 90 0.003 – 82 0.008 11 nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz dB % dB % MHz 17 6 17 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 U W TYPICAL PERFOR A CE CHARACTERISTICS (LTC6911-1) LTC6911-1 Gain Shift vs Temperature 50 0.075 GAIN OF 100 (DIGITAL INPUT 111) 30 GAIN OF 50 (DIGITAL INPUT 110) 0.025 GAIN = 10 GAIN (dB) GAIN CHANGE (dB) 40 GAIN = 100 0.050 VS = 10V, VIN = 5mVRMS 0 GAIN = 1 GAIN OF 20 (DIGITAL INPUT 101) 20 GAIN OF 10 (DIGITAL INPUT 100) –0.025 10 GAIN OF 5 (DIGITAL INPUT 011) –0.050 GAIN OF 2 (DIGITAL INPUT 010) 0 –0.075 –0.100 –50 –25 –3dB FREQUENCY (MHz) VS = 5V OUTPUT UNLOADED 0 50 25 TEMPERATURE (°C) 75 GAIN OF 1 (DIGITAL INPUT 001) –10 100 100 10k 100k FREQUENCY (Hz) 1k 1M LTC6911-1 Channel Isolation vs Frequency GAIN = 1 70 GAIN = 10 100 95 +SUPPLY 60 –SUPPLY 50 40 30 GAIN = 100 20 90 10 1k 1M 10k FREQUENCY (Hz) 100k 1M FREQUENCY (Hz) –50 GAIN = 100 –60 –70 GAIN = 10 –80 GAIN = 1 –90 –100 0 50k 100k 150k 200k FREQUENCY (Hz) –30 •• •• 10 GAIN –40 • • 100 VS = ±2.5V TA = 25°C INPUT REFERRED GAIN = 1 GAIN = 10 10 GAIN = 100 10k FREQUENCY (Hz) 100k 6911 G06 LTC6911-1 THD + Noise vs Input Voltage –20 VS = ±2.5V VOUT = 1VRMS (2.83VP-P) –30 GAIN = 100 GAIN = 100 –40 GAIN = 10 –50 GAIN = 10 –60 GAIN = 1 –70 –80 –50 –60 –70 –80 –90 –90 –100 0 50k 100k 150k 200k FREQUENCY (Hz) 6911 G07 • • 1 1k 10M THD + NOISE (dB) –40 100 LTC6911-1 Distortion vs Frequency with Heavy Loading (RL = 500Ω) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) LTC6911-1 Distortion vs Frequency with Light Loading (RL = 10k) VS = ±2.5V VOUT = 1VRMS (2.83VP-P) • 6911 G05 6911 G04 –30 • 6911 G03 0 85 100k • LTC6911-1 Noise Density vs Frequency VS = ±2.5V GAIN = 1 80 REJECTION (dB) CHANNEL-TO-CHANNEL ISOLATION (dB) 90 110 105 VIN = 5mVRMS • VS = 2.7V • VS = ±5V • 1 LTC6911-1 Power Supply Rejection vs Frequency VS = 5V VOUT = 1VRMS 115 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 6911 G02 6911 G01 120 10M VOLTAGE NOISE DENSITY (nV/√Hz) 0.100 LTC6911-1 –3dB Bandwidth vs Gain Setting LTC6911-1 Frequency Response 6911 G08 fIN = 1kHz –100 VS = ±5V GAIN = 1 BW = 100Hz TO 22kHz –110 10n 1m 0.1 1 10 INPUT VOLTAGE (VP-P) 6911 G09 sn691112 691112fs 10 LTC6911-1/LTC6911-2 U W TYPICAL PERFOR A CE CHARACTERISTICS (LTC6911-2) LTC6911-2 Gain Shift vs Temperature 50 0.100 GAIN OF 32 30 0.025 GAIN (dB) GAIN = 8 0 GAIN = 1 –0.025 –3dB FREQUENCY (MHz) 40 GAIN OF 64 GAIN = 64 0.050 GAIN OF 16 20 GAIN OF 8 GAIN OF 4 10 GAIN OF 2 –0.050 GAIN OF 1 0 –0.075 –25 0 50 25 TEMPERATURE (°C) 75 –10 100 100 1k 100k 10k FREQUENCY (Hz) 1M LTC6911-2 Channel Isolation vs Frequency 70 GAIN = 8 GAIN = 1 100 GAIN = 64 95 +SUPPLY 60 –SUPPLY 50 40 30 20 90 10 1k 1M 10k FREQUENCY (Hz) 100k 1M FREQUENCY (Hz) –40 –50 –60 GAIN = 64 –70 GAIN = 8 –80 GAIN = 1 –90 –100 0 100 50k 100k 150k 200k 6911 G16 • • •• • 10 GAIN –30 100 GAIN = 8 10 GAIN = 64 10k FREQUENCY (Hz) LTC6911-2 THD + Noise vs Input Voltage –20 –30 GAIN = 64 –40 –50 GAIN = 8 –60 GAIN = 1 –70 –80 –90 –100 0 50k 100k 6911 G15 VS = ±2.5V VOUT = 1VRMS (2.83VP-P) –40 • VS = ±2.5V TA = 25°C INPUT REFERRED 1 1k 10M 100k 150k 200k FREQUENCY (Hz) FREQUENCY (Hz) • • GAIN = 1 LTC6911-2 Distortion vs Frequency with Heavy Loading (RL = 500Ω) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) LTC6911-2 Distortion vs Frequency with Light Loading (RL = 10k) VS = ±2.5V VOUT = 1VRMS (2.83VP-P) • 6911 G14 6911 G13 –30 • 6911 G12 0 85 100k • LTC6911-2 Noise Density vs Frequency VS = ±2.5V GAIN = 1 80 REJECTION (dB) CHANNEL-TO-CHANNEL ISOLATION (dB) 90 110 105 VIN = 10mVRMS • VS = 2.7V • VS = ±5V • 1 LTC6911-2 Power Supply Rejection vs Frequency VS = 5V VOUT = 1VRMS 115 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 6911 G11 6911 G010 120 10M VOLTAGE NOISE DENSITY (nV/√Hz) –0.100 –50 THD + NOISE (dB) GAIN CHANGE (dB) VS = ±5V VIN = 10mVRMS VS = 5V OUTPUT UNLOADED 0.075 LTC6911-2 –3dB Bandwidth vs Gain Setting LTC6911-2 Frequency Response 6911 G17 GAIN = 64 –50 GAIN = 8 –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 G18 sn691112 691112fs 11 LTC6911-1/LTC6911-2 U U U 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. 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. G2 G1 G0 6 5 4 CMOS LOGIC INA 1 INPUT R ARRAY FEEDBACK R ARRAY – MOS-INPUT OP AMP V+ 10 OUTA + 10k 9 V– AGND 2 + 10k V– MOS-INPUT OP AMP 8 OUTB – 7 V+ INB 3 691112 F01 INPUT R ARRAY FEEDBACK R ARRAY Figure 1. Block Diagram sn691112 691112fs 12 LTC6911-1/LTC6911-2 U U U 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 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 10 9 8 7 1 2 3 SINGLE-POINT SYSTEM GROUND SINGLE-POINT SYSTEM GROUND ≥1µF 6 2 3 4 5 DIGITAL GROUND PLANE (IF ANY) 691112 F03 Figure 3. Dual Supply Ground Plane Connection V– 0.1µF 6 10 9 V+ 0.1µF 8 7 6 4 5 LTC6911-X 4 5 1 + ANALOG GROUND PLANE 7 ANALOG GROUND PLANE LTC6911-X 1 8 LTC6911-X V+ 0.1µF 10 9 V+ 0.1µF V REFERENCE 2 DIGITAL GROUND PLANE (IF ANY) 691112 F02 Figure 2. Single Supply Ground Plane Connection ANALOG GROUND PLANE SINGLE-POINT SYSTEM GROUND 2 3 V + + V– REFERENCE 2 ≥1µF DIGITAL GROUND PLANE (IF ANY) 691112 F04 Figure 4. Asymmetrical Dual Supply Ground Plane Connection sn691112 691112fs 13 LTC6911-1/LTC6911-2 U U U 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 17 LTC6911-1/LTC6911-2 U 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+ 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. 0.1µF 7 9 V+ 0.1µF VINA AGND 1 10 499Ω VCC 270pF ≥1µF 2 LTC1865 LTC6911-X 3 8 GND 499Ω SCK SDO CH1 VINB CONV CH0 SDI 691112 F05 270pF ADC INTERFACE 691112 F05 4 5 6 GAIN CONTROL Figure 5. Expanding a Dual Channel ADC’s Dynamic Range sn691112 691112fs 18 LTC6911-1/LTC6911-2 U PACKAGE DESCRIPTIO MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.50 0.305 ± 0.038 (.0197) (.0120 ± .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.497 ± 0.076 (.0196 ± .003) REF 10 9 8 7 6 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 1 2 3 4 5 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.86 (.034) REF 1.10 (.043) MAX 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 0.50 (.0197) BSC 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 sn691112 691112fs 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. 19 LTC6911-1/LTC6911-2 U TYPICAL APPLICATIO Fully Differential Amplifier with Digitally Programmable Gain High Dynamic Range (PGA Input) –5V 0.1µF VIN+ 1 10 2 9 VIN– 3 LTC6911-1 OR 4 LTC6911-2 5 1 5V 8 7 6 0.1µF 8 LTC1992-1 OR 2 7 LTC1992-2 OR 3 6 LTC1992-5 OR 0.1µF 4 5 LTC1992-10 –5V 0.1µF VOUT+ VOUT– G0 G1 G2 DIGITAL GAIN CONTROL High CMRR (Differential Input) –5V VIN+ VIN– 5V 0.1µF 0.1µF 8 1 LTC1992-1 OR 7 2 LTC1992-2 OR 6 3 LTC1992-5 OR 5 4 LTC1992-10 –5V 1 10 2 9 LTC6911-1 OR 4 LTC6911-2 5 3 0.1µF 8 5V VOUT+ VOUT– 7 6 0.1µF 691112 TA03 G0 G1 G2 DIGITAL GAIN CONTROL RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT 1228 100MHz Gain Controlled Transconductance Amplifier Differential Input, Continuous Analog Gain Control LT1251/LT1256 40MHz Video Fader and Gain Controlled Amplifier Two Input, One Output, Continuous Analog Gain Control LTC1564 10kHz to 150kHz Digitally Controlled Filter and PGA Continuous Time, Low Noise 8th Order Filter and 4-Bit PGA LTC6910 Digitally Controlled Programmable Gain Amplifier in SOT-23 Single Channel Version of the LTC6911 LTC6915 Digitally Controlled Programmable Instrumentation Amplifier with SPI Interface 14 Bits of Gain Control ® sn691112 691112fs 20 Linear Technology Corporation LT/TP 0104 1K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com  LINEAR TECHNOLOGY CORPORATION 2004