LTC6912IDE-1

LTC6912 Dual Programmable Gain Amplifiers with Serial Digital Interface DESCRIPTIO The LTC®6912 is a family of dual channel, low noise, 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 SPITM 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 VINA 1µF 2 INA OUT A 15 VOUTA = GAINA • VINA 30 3 GAIN (dB) AGND LTC6912-X 20 GAIN OF 8 GAIN OF 4 10 GAIN OF 2 GAIN OF 1 VINB 4 INB OUT B 13 VOUTB = GAINB • VINB 0 SHDN 3-WIRE SPI INTERFACE CS/LD DATA CLK 5 6 7 8 CHB SHDN CS/LD DIN CHA DGND DOUT 10 9 6912 TA01a –10 0.1 1 10 100 1000 FREQUENCY (kHz) 10000 6912 TA01b U U U LTC6912-2 Frequency Response VS = ±2.5V VIN = 10mVRMS 6912fa 1 LTC6912 ABSOLUTE (Note 1) AXI U RATI GS 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 V –) ............................... 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 TJMAX = 125°C, θJA = 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 WW U W TOP VIEW NC 1 INA 2 AGND 3 INB 4 SHDN 5 CS/LD 6 DIN 7 CLK 8 16 NC 15 OUT A 14 V – 13 OUT B 12 V + 11 NC 10 DGND 9 DOUT GN PACKAGE 16-LEAD NARROW PLASTIC SSOP TJMAX = 150°C, θJA = 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 (VP-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 (VP-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 TA = 25°C. VS = 5V, AGND = 2.5V, Gain = 1, RL = 10k to midsupply point, unless otherwise noted. PARAMETER Total Supply Voltage (VS) Supply Current per Channel Both Amplifiers Active (Gain = 1) VS = 2.7V, VINA = VINB = VAGND VS = 5V, VINA = VINB = VAGND VS = ±5V, VINA = VINB = 0V Both Amplifiers Inactive (State 1000) VS = 2.7V, VINA = VINB = VAGND VS = 5V, VINA = VINB = VAGND VS = ±5V, VINA = VINB = 0V VS = 2.7V, VSHDN = 2.43V VS = 5V, VSHDN = 4.5V VS = ±5V, VSHDN = 4.5V CONDITIONS ● ● ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS MIN 2.7 C, I GRADES TYP MAX 10.5 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 2.75 3.0 3.5 255 325 750 2 10 50 30 110 40 170 50 260 20 80 30 160 40 250 MIN 2.7 H GRADE TYP MAX 10.5 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 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 Supply Current per Channel (Software Shutdown) Total-Supply Current (Hardware Shutdown, GN-16 Package Only) Output Voltage Swing LOW (Note 4) VS = 2.7V, RL = 10k Tied to Midsupply Point ● VS = 2.7V, RL = 500Ω Tied to Midsupply Point ● VS = 5V, RL = 10k Tied to Midsupply Point VS = 5V, RL = 500Ω Tied to Midsupply Point VS = ±5V, RL = 10k Tied to 0V VS = ±5V, RL = 500Ω Tied to 0V ● ● ● ● Output Voltage Swing HIGH (Note 4) VS = 2.7V, RL = 10k Tied to Midsupply Point ● VS = 2.7V, RL = 500Ω Tied to Midsupply Point ● VS = 5V, RL = 10k Tied to Midsupply Point VS = 5V, RL = 500Ω Tied to Midsupply Point VS = ±5V, RL = 10k Tied to 0V VS = ±5V, RL = 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 VS = 2.7V VS = ±5V VS = Single 5V Supply, VSHDN = 0.5V VS = Single 5V Supply, VSHDN = 4.5V VS = Single 2.7V Supply VS = Single 5V Supply VS = ±5V VS = 2.7V, VAGND = 1.1V to 1.6V VS = ±5V, VAGND = – 2.5V to 2.5V Gain = 1 VS = 5V, VOUTA = VOUTB = 1.1V to 3.9V VS = ±5V, VOUTA = VOUTB = ±1.4V Gain = 10 (–1), Gain = 8 (–2) VS = 5V, VOUTA = VOUTB = 1.1V to 3.9V VS = ±5V, VOUTA = VOUTB = ±1.4V 2.45 0.55 0.75 –4.3 55 55 60 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 80 75 80 12 16 20 26 –120 –120 Power Supply Rejection Ratio (PSRR) VS =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 VS = Single 2.7V VS = Single 5V VS = ±5V VS = Single 2.7V VS = Single 5V VS = ±5V VS = Single 2.7V VS = Single 5V VS = ±5V VS = Single 2.7V VS = Single 5V VS = ±5V 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, RL = 10k to midsupply point, unless otherwise noted. MIN ● ● ● ● ● ● C, I GRADES 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 2.43 4.5 4.5 0.27 0.5 0.5 0.2 1 1 0.2 1 1 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.27 0.5 0.5 0.2 1 1 0.2 1 1 V V V µA µA µA µA µA µA Specifications for the LTC6912-1 ONLY Voltage Gain (Note 6) 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 –0.11 5.94 13.85 19.7 19.55 25.75 33.5 39.2 37.3 –0.08 –0.11 5.95 13.8 19.8 19.6 25.78 33.5 39.3 37.75 –0.06 –0.10 5.95 13.8 19.78 19.68 25.78 33.65 39.4 38.6 0 –0.02 6.01 13.95 19.93 19.85 25.94 33.8 39.6 38.9 0.01 –0.01 6.02 13.96 19.94 19.87 25.94 33.84 39.7 39.2 0.01 0 6.02 13.96 19.94 19.91 25.95 33.87 39.8 39.5 0.07 0.07 6.08 14.05 20.1 20.05 26.1 34.05 40.0 39.7 0.08 0.07 6.09 14.1 20.1 20.1 26.08 34.1 40.1 39.85 0.08 0.08 6.09 14.1 20.08 20.05 26.08 34.05 40.2 39.9 –0.08 –0.13 5.93 13.8 19.65 19.35 25.65 33.40 39.0 36.20 –0.09 –0.13 5.94 13.78 19.75 19.45 25.75 33.4 39.1 36.6 –0.07 –0.11 5.94 13.79 19.75 19.58 25.73 33.60 39.25 37.6 0 –0.02 6.01 13.95 19.93 19.85 25.94 33.8 39.6 38.9 0.01 –0.01 6.02 13.96 19.94 19.87 25.94 33.84 39.7 39.2 0.01 0 6.02 13.96 19.94 19.91 25.95 33.87 39.8 39.5 0.07 0.07 6.08 14.05 20.1 20.05 26.1 34.05 40.0 39.7 0.08 0.07 6.09 14.1 20.1 20.1 26.08 34.1 40.1 39.85 0.08 0.08 6.09 14.1 20.08 20.05 26.08 34.05 40.2 39.9 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 6912fa 5 LTC6912 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, RL = 10k to midsupply point, unless otherwise noted. PARAMETER Channel-to-Channel Voltage Gain Match (Note 6) CONDITIONS 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 Gain Temperature Coefficient (Note 6) 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 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 f = 200kHz, VS = 5V, Gain = 1, RL = 10k VS = 5V, Gain = 10, RL = 10k VS = 5V, Gain = 100, RL = 10k ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS MIN –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.2 –1.0 –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 C, I GRADES 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 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 2 –1.5 –11 –30 –40 –70 –140 1 1 0.2 –1 –1 –3 –3 113 108 89 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 1.0 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 MIN –0.1 –0.1 –0.1 –0.15 –0.15 –0.2 –0.15 –0.15 –0.2 –1.5 –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 H GRADE TYP ±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 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 2 –1.5 –11 –30 –40 –70 –140 1 1 0.2 –1 –1 –3 –3 113 108 89 MAX 0.1 0.1 0.1 0.15 0.15 0.2 0.15 0.15 0.2 1.5 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 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 6912fa Specifications for the LTC6912-1 ONLY Channel-to-Channel Gain Temperature Coefficient Match (Gain Specified in dB’s) (Note 6) Channel-to-Channel Isolation (Note 7) 6 LTC6912 ELECTRICAL CHARACTERISTICS PARAMETER Offset Voltage Magnitude (Internal Op-Amp, Note 8) Offset Voltage Magnitude Referred to INA or INB Pins (Note 8) Input Offset Voltage Drift, Internal Op Amp DC Input Resistance at INA or INB Pins (Note 9) DC VINA or VINB = 0V Gain = 0 State = 8, Software Shutdown Gain = 1 Gain = 2 Gain = 5 Gain > 5 Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 Gain = 1 Gain = 2 Gain = 5 Gain > 5 ● ● ● ● ● ● ● ● ● ● 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, RL = 10k to midsupply point, unless otherwise noted. CONDITIONS Gain = 1 Gain = 1 Gain = 10 ● ● ● MIN C, I SUFFIXES TYP MAX 0.125 0.25 0.14 6 2 3.5 2 MIN H SUFFIX TYP 0.125 0.25 0.14 10 MAX 3.5 6.5 4 UNITS mV mV mV µV/°C Specifications for the LTC6912-1 ONLY >10 >10 10 5 2 1 85 90 100 120 130 150 190 10 5 5 5 0.4 0.7 1.0 1.9 3.4 6.4 15 30 >1 18 33 8.9 15.6 11.1 8.3 7.4 7.0 6.7 6.3 50 16 >10 >10 10 5 2 1 95 100 110 130 140 160 200 10 5 5 5 0.4 0.7 1.0 1.9 3.4 6.4 15 30 >1 33 8.9 15.6 11.1 8.3 7.4 7.0 6.7 6.3 50 MΩ MΩ kΩ kΩ kΩ kΩ ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω MΩ MHz µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS DC Input Resistance Drift at INA or INB Pins (Note 9) DC Input Resistance Match RINA-RINB DC Small Signal Output Resistance DC VINA or VINB = 0V at OUT A or OUT B Pins Gain = 0 Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 State = 8, Software Shutdown Gain Bandwidth Product Wideband Noise (Referred to Input) Gain = 100 f = 1kHz to 200kHz Gain = 0 (Output Noise only) Gain = 1 Gain = 2 Gain = 5 Gain = 10 Gain = 20 Gain = 50 Gain = 100 ● ● 6912fa 7 LTC6912 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, RL = 10k to midsupply point, unless otherwise noted. PARAMETER Voltage Noise Density (Referred to Input) CONDITIONS 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 Specifications for the LTC6912-2 ONLY Voltage Gain (Note 6) 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 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS MIN C, I GRADES TYP MAX MIN H GRADE TYP MAX UNITS Specifications for the LTC6912-1 ONLY 35.6 24.8 19.1 16.7 16 15.4 15.1 –90 0.003 –82 0.008 –0.07 –0.11 5.94 11.9 17.8 17.65 23.8 29.7 35.4 34.15 –0.08 –0.1 5.95 11.85 17.85 17.65 23.85 29.70 35.5 34.6 –0.06 –0.1 5.95 11.9 17.85 17.80 23.85 29.85 35.65 35.15 0 –0.02 6.01 12.02 18.0 17.94 24.01 30.0 35.8 35.3 0 –0.01 6.02 12.02 18.01 17.96 24.02 30.02 35.9 35.6 0.01 0 6.02 12.03 18.02 17.99 24.03 30.0 36.0 35.8 0.07 0.07 6.08 12.12 18.15 18.15 24.25 30.2 36.2 36.0 0.08 0.08 6.09 12.15 18.15 18.15 24.15 30.2 36.25 36.0 0.08 0.08 6.09 12.15 18.15 18.15 24.15 30.2 36.20 36.10 –0.08 –0.13 5.93 11.88 17.75 17.50 23.75 29.65 35.15 33.40 –0.09 –0.12 5.94 11.83 17.83 17.50 23.80 29.65 35.40 33.8 –0.07 –0.11 5.94 11.88 17.83 17.73 23.82 29.8 35.55 34.45 35.6 24.8 19.1 16.7 16 15.4 15.1 –90 0.003 –82 0.008 0 –0.02 6.01 12.02 18.0 17.94 24.01 30.0 35.8 35.3 0 –0.01 6.02 12.02 18.01 17.96 24.02 30.02 35.9 35.6 0.01 0 6.02 12.03 18.02 17.99 24.03 30.0 36.0 35.8 0.07 0.07 6.08 12.12 18.15 18.15 24.25 30.2 36.2 36.0 0.08 0.08 6.09 12.15 18.15 18.15 24.15 30.2 36.25 36.0 0.08 0.08 6.09 12.15 18.15 18.15 24.15 30.20 36.20 36.10 nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz 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 Total Harmonic Distortion 6912fa 8 LTC6912 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, RL = 10k to midsupply point, unless otherwise noted. PARAMETER Channel-to-Channel Voltage Gain Match (Note 6) CONDITIONS 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 Gain Temperature Coefficient (Note 6) 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 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS MIN –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.2 –0.7 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.6 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.4 C, I GRADES 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 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 2 –4 –10 –24 –30 –40 –120 0 –0.5 0 0 –1 –4 –4 117 110 92 0.125 2 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.2 0.7 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.6 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.4 MIN –0.1 –0.1 –0.1 –0.15 –0.15 –0.2 –0.15 –0.15 –0.2 –1.0 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.8 –0.1 –0.1 –0.1 –0.15 –0.15 –0.15 –0.15 –0.15 –0.15 –0.6 H GRADE TYP ±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 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 ±0.02 2 –4 –10 –24 –30 –40 –120 0 –0.5 0 0 –1 –4 –4 117 110 92 0.125 MAX 0.1 0.1 0.1 0.15 0.15 0.2 0.15 0.15 0.2 1.0 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.8 0.1 0.1 0.1 0.15 0.15 0.15 0.15 0.15 0.15 0.6 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 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 Specifications for the LTC6912-2 ONLY Channel-to-Channel Gain Temperature Coefficient Match (Note 6) Channel-to-Channel Isolation (Note 7) Offset Voltage Magnitude (Internal Op-Amp, Note 8) 3.5 mV 6912fa 9 LTC6912 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, RL = 10k to midsupply point, unless otherwise noted. PARAMETER Offset Voltage Magnitude Referred to INA or INB Pins (Note 8) Input Offset Voltage Drift, Internal Op Amp DC Input Resistance at INA or INB Pins (Note 9) DC VINA or VINB = 0V Gain = 0 State = 8, Software Shutdown Gain = 1 Gain = 2 Gain = 4 Gain > 4 Gain = 1 Gain = 2 Gain = 4 Gain = 8 Gain = 16 Gain = 32 Gain = 64 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 State = 8, Software Shutdown 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 ● ● ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS CONDITIONS Gain = 1 Gain = 8 MIN ● ● C, I GRADES TYP MAX 0.25 0.14 6 3.5 2 MIN H GRADE TYP 0.25 0.14 10 MAX 6.5 4 UNITS mV mV µV/°C Specifications for the LTC6912-2 ONLY >10 >10 10 5 2.5 1.25 85 90 95 120 130 140 170 10 5 5 5 0.4 0.7 1.0 1.9 3.4 6.4 15 30 >1 17 30 8.1 13.8 9.6 7.5 6.4 6.0 5.8 5.6 50 15 >10 >10 10 5 2.5 1.25 95 100 105 130 140 150 180 10 5 5 5 0.4 0.7 1.0 1.9 3.4 6.4 15 30 >1 30 8.1 13.8 9.6 7.5 6.4 6.0 5.8 5.6 50 MΩ MΩ kΩ kΩ kΩ kΩ ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C ppm/°C Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω Ω MΩ MHz µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS µVRMS DC Input Resistance Drift at INA or INB Pins (Note 9) DC Input Resistance Match RINA-RINB DC Small Signal Output Resistance at OUT A or OUT B Pins ● ● Gain Bandwidth Product Wideband Noise (Referred to Input) 6912fa 10 LTC6912 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, RL = 10k to midsupply point, unless otherwise noted. PARAMETER Voltage Noise Density (Referred to Input) CONDITIONS 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 MIN C, I GRADES TYP MAX MIN H GRADE TYP MAX UNITS ELECTRICAL CHARACTERISTICS Specifications for the LTC6912-2 ONLY 31.1 22.8 17 14.6 13.2 12.9 12.6 –84 0.006 –82 0.008 31.1 22.8 17 14.6 13.2 12.9 12.6 –84 0.006 –82 0.008 nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz nV/√Hz dB % dB % Total Harmonic Distortion SERIAL I TERFACE SPECIFICATIO S SYMBOL VIH VIL VOH VOL t1 t2 t3 t4 t5 t6 t7 t8 t9 t1 t2 t3 t4 t5 t6 t7 t8 t9 PARAMETER Digital Input High Voltage Digital Input Low Voltage Digital Output High Voltage Digital Output Low Voltage DIN Valid to CLK Setup DIN Valid to CLK Hold CLK Low CLK High CS/LD Pulse Width LSB CLK to CS/LD CS/LD Low to CLK DOUT Output Delay CLK Low to CS/LD Low DIN Valid to CLK Setup DIN Valid to CLK Hold CLK Low CLK High CS/LD Pulse Width LSB CLK to CS/LD CS/LD Low to CLK DOUT Output Delay CLK Low to CS/LD Low CL = 15pF CL = 15pF Sourcing 500µA Sinking 500µA CONDITIONS ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Digital I/O Logic Levels, All Digital I/O Voltage Referenced to DGND 2 0.8 V+ – 0.3 0.3 60 0 100 100 60 60 30 125 0 30 0 50 50 40 40 20 85 0 V V V V ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns 6912fa Serial Interface Timing, V + = 2.7V ~ 4.5V, V – = 0V (Note 10) Serial Interface Timing, V + = 4.5V ~ 5.5V, V – = 0V (Note 10) U U MIN TYP MAX UNITS 11 LTC6912 SERIAL I TERFACE SPECIFICATIO S SYMBOL t1 t2 t3 t4 t5 t6 t7 t8 t9 PARAMETER DIN Valid to CLK Setup DIN Valid to CLK Hold CLK High CLK Low CS/LD Pulse Width LSB CLK to CS/LD CS/LD Low to CLK DOUT Output Delay CLK Low to CS/LD Low t1 CLK CONDITIONS ● ● ● ● ● ● ● Serial Interface Timing, Dual ±4.5V ~ ±5.5V Supplies (Note 10) 30 0 50 50 40 40 20 85 0 ns ns ns ns ns ns ns ns ns CL = 15pF t2 t4 DIN D3 D2 CS/LD t8 DOUT D4 D3 D2 PREVIOUS BYTE Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LTC6912-1C and LTC6912-1I are guaranteed functional over the operating temperature range of –40°C to 85°C. The LTC6912-1H is guaranteed functional over the operating temperature range of –40°C to 125°C. Note 3: The LTC6912-1C is guaranteed to meet specified performance from 0°C to 70°C. The LTC6912-1C 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. The LTC6912-1I is guaranteed to meet specified performance from –40°C to 85°C. The LTC6912-1H 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 for GN package and 125°C for a DFN package is not recommended. Note 6: Gain is measured with a large signal DC test using an output excursion between approximately 30% and 70% of supply voltage. 12 U U MIN TYP MAX UNITS ● ● t3 t6 t7 t9 D31 D0 t5 D7 • • • D4 D3 D31 D0 D7 • • • D4 CURRENT BYTE D3 6912 TD 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: IsolationB = 20 • log10(VOUTA/VOUTB) or IsolationA = 20 • log10(VOUTB/VOUTA) High channel-to-channel isolation is strongly dependent on proper circuit layout. See Applications Information. Note 8: Offset voltage referred to the INA or INB input is (1 + 1/|GAIN|) times the offset voltage of the internal op amp, where GAIN is the nominal gain magnitude. The typical offset voltage values are for 25°C only. See Applications Information. Note 9: Input resistance can vary by approximately ±30% part-to-part at a given gain setting. Note 10: Guaranteed by design, not subject to test. Note 11: States 13, 14 and 15 (binary 11xx) are not used. Programming a channel to states 8 or higher will configure that particular channel into a low power shutdown state. In addition, programming a channel into state 15 (binary 1111) will cause that particular channel to draw up to 20mA of supply current and is not recommended. 6912fa LTC6912 TYPICAL PERFOR A CE CHARACTERISTICS LTC6912-1 Frequency Response 50 40 30 GAIN (dB) 20 10 0 –10 GAIN OF 100 GAIN OF 50 GAIN OF 20 GAIN OF 10 GAIN OF 5 GAIN OF 2 GAIN OF 1 CHANNEL-TO-CHANNEL GAIN MATCH (dB) VS = ±5V VIN = 10mVRMS 0.10 0.05 0 –0.05 –0.10 –0.15 –0.20 0.1 1 10 100 1000 FREQUENCY (Hz) 10000 6912 G02 GAIN OF 1 –3dB FREQUENCY (MHz) 1 10 100 1000 FREQUENCY (kHz) LTC6912-1 Channel Isolation vs Frequency 125 CHANNEL-TO-CHANNEL ISOLATION (dB) 120 115 110 105 100 95 90 85 80 100 FREQUENCY (kHz) 6912 G04 VOLTAGE NOISE DENSITY (nV/√HZ) VS = ±5V VOUT = 1VRMS GAIN OF 1 REJECTION (dB) GAIN OF 10 GAIN OF 100 LTC6912-1 Distortion vs Frequency with Light Loading THD-AMPLITUDE BELOW FUNDAMENTAL (dB) RL = 10k V = ±2.5V –55 S VOUT = 1VRMS (2.83)VP-P –60 –65 GAIN OF 100 –70 –75 GAIN OF 10 –80 GAIN OF 1 –85 –90 0 50 100 150 FREQUENCY (kHz) 200 6912 G07 THD-AMPLITUDE BELOW FUNDAMENTAL (dB) –50 THD PLUS NOISE (dB) UW 10000 6912 G01 LTC6912-1 Channel Gain Matching vs Frequency VS = ±5V VIN = 10mVRMS GAIN OF 100 GAIN OF 10 6 LTC6912-1 –3dB Bandwidth vs Gain Setting VIN = 10mVRMS VS = ±5V 1 VS = 2.7V 1 10 GAIN (V/V) 100 6912 G03 LTC6912-1 Power Supply Rejection vs Frequency 90 80 70 60 50 40 30 20 10 1000 0 1 10 100 1000 FREQUENCY (kHz) 10000 6912 G05 LTC6912-1 Noise Density vs Frequency VS = 5V GAIN = 1 100 GAIN OF 1 GAIN OF 10 GAIN OF 100 10 +SUPPLY –SUPPLY 1 VS = ±2.5V TA = 25°C INPUT REFERRED 1 10 FREQUENCY (kHz) 100 6912 G06 LTC6912-1 Distortion vs Frequency with Heavy Loading –30 GAIN OF 100 –40 –50 GAIN OF 10 –60 –70 –80 –90 GAIN OF 1 RL = 500Ω VS = ±2.5V VOUT = 1VRMS (2.83)VP-P 0 50 100 150 FREQUENCY (kHz) 200 6912 G08 LTC6912-1 THD Plus Noise vs Input Voltage –30 –40 –50 –60 –70 –80 GAIN OF 10 GAIN OF 100 VS = ±5V –90 RL = 10k fIN = 1kHz GAIN OF 1 BW = 22kHz –100 0.001 0.01 0.1 1 10 INPUT VOLTAGE (VP-P) 6912 G09 6912fa 13 LTC6912 TYPICAL PERFOR A CE CHARACTERISTICS LTC6912-1 Hardware Shutdown Total Supply Current vs Temperature HARDWARE SHUTDOWN (GN-16 ONLY) TOTAL SUPPLY CURRENT (µA) TOTAL SUPPLY CURRENT (µA) 10 VS = 5V VS = ±5V TOTAL SUPPLY CURRENT (mA) 1 VS = 2.7V VS = 3V 0.1 –50 –25 50 25 75 0 TEMPERATURE (°C) LTC6912-1 Gain Shift vs Temperature (Light Load) 0.10 0.05 GAIN CHANGE (dB) GAIN CHANGE (dB) 0 –0.05 –0.10 GAIN OF 1 GAIN OF 10 –0.5 GAIN OF 100 –1.0 GAIN (dB) GAIN OF 100 –0.15 –0.20 –0.25 –50 –25 50 25 75 0 TEMPERATURE (°C) LTC6912-2 Channel Gain Matching vs Frequency 0.100 CHANNEL-TO-CHANNEL GAIN MATCH (dB) 0.075 0.050 0.025 0 –0.025 –0.050 –0.075 –0.100 1 10 GAIN OF 1 GAIN OF 8 GAIN OF 64 6.0 –3dB FREQUENCY (MHz) CHANNEL-TO-CHANNEL ISOLATION (dB) VS = ±5V VIN = 10mVRMS RL = 10kΩ 1000 100 FREQUENCY (kHz) 14 UW VS = ±5V 100 6912 G10 LTC6912-1 Software Shutdown Total Supply Current vs Temperature 700 BOTH AMPLIFIERS IN SOFTWARE SHUTDOWN 600 RL = 10k 500 400 300 200 100 –50 –25 VS = 2.7V VS = 5V 5.00 LTC6912-1 Total Supply Current vs Temperature (Both Amplifiers Active) BOTH AMPLIFIERS 4.75 PROGRAMMED TO GAIN = 1 RL = 10k 4.50 4.25 VS = 5V 4.00 3.75 3.50 3.25 VS = 2.7V VS = ±5V 125 50 25 75 0 TEMPERATURE (°C) 100 125 3.00 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) 6912 G11 6912 G12 LTC6912-1 Gain Shift vs Temperature (Heavy Load) VS = 5V RL = 10k 0.5 VS = 5V RL = 500Ω 0 GAIN OF 1 GAIN OF 10 30 40 LTC6912-2 Frequency Response GAIN OF 64 GAIN OF 32 GAIN OF 16 20 GAIN OF 8 GAIN OF 4 10 GAIN OF 2 GAIN OF 1 VS = ±5V VIN = 10mVRMS 0 100 125 –1.5 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 –10 1 10 100 1000 FREQUENCY (kHz) 10000 6912 G14a 6912 G13 6912 G14 LTC6912-2 –3dB Bandwidth vs Gain Setting 8.0 VS = ±5V VS = 2.7V VIN = 10mVRMS 125 120 115 110 105 100 95 90 85 LTC6912-2 Channel Isolation vs Frequency GAIN = 1 VS = 5V VOUT = 1VRMS 4.0 GAIN = 8 2.0 GAIN = 64 1.0 0.8 0.6 0.4 10000 6912 G15 1 10 GAIN (V/V) 100 6912 G16 80 100 FREQUENCY (kHz) 1000 6912 G17 6912fa LTC6912 TYPICAL PERFOR A CE CHARACTERISTICS LTC6912-2 Power Supply Rejection vs Frequency 90 80 70 VS = 5V GAIN = 1 100 VOLTAGE NOISE DENSITY (nV/Hz) VS = ±2.5V TA = 25°C INPUT REFERRED THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) REJECTION (dB) 60 50 40 30 20 10 0 1 10 1000 100 FREQUENCY (kHz) 10000 6912 G18 +SUPPLY –SUPPLY LTC6912-2 Distortion vs Frequency with Heavy Loading (RL = 500Ω) THD (AMPLITUDE BELOW FUNDAMENTAL) (dB) –30 –40 –50 GAIN = 8 –60 –70 –80 –90 GAIN = 1 VS = ±2.5V VOUT = 1VRMS (2.83VP-P) GAIN = 64 –30 –40 TOTAL SUPPLY CURRENT (µA) THD + NOISE (dB) 0 50 100 150 FREQUENCY (kHz) LTC6912-2 Software Shutdown Total Supply Current vs Temperature 800 BOTH AMPLIFIERS PROGRAMMED TO STATE = 8 700 R = 10k L 600 500 VS = 5V 400 300 200 100 –50 –25 VS = 2.7V VS = 5V 6.0 5.5 5.0 TOTAL SUPPLY CURRENT (mA) TOTAL SUPPLY CURRENT (A) GAIN CHANGE (dB) 50 25 75 0 TEMPERATURE (°C) UW 6912 G21 LTC6912-2 Noise Density vs Frequency –50 –55 –60 –65 –70 –75 –80 –85 –90 LTC6912-2 Distortion vs Frequency with Light Loading (RL = 10k) VS = ±2.5V VOUT = 1VRMS (2.83VP-P) GAIN = 1 GAIN = 8 GAIN = 64 10 GAIN = 64 GAIN = 8 GAIN = 1 1 1 10 FREQUENCY (kHz) 100 6912 G19 0 50 100 150 FREQUENCY (kHz) 200 6912 G20 LTC6912-2 THD + Noise vs Input Voltage LTC6912-2 Hardware Shutdown Total Supply Current vs Temperature HARDWARE SHUTDOWN (GN-16 ONLY) VS = ±5V 10 VS = 5V –50 –60 GAIN = 64 GAIN = 8 –70 –80 –90 VS = 5V RL = 10k fIN = 1kHz 0.01 0.1 1 INPUT VOLTAGE (VP-P) 10 6912 G22 1 VS = 2.7V GAIN = 1 VS = 3V 200 –100 0.001 0.1 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 6912 G22A LTC6912-2 Total Supply Current vs Temperature (Both Amplifiers Active) BOTH AMPLIFIERS ACTIVE : GAIN = 1 RL = 10k 0.100 0.075 VS = ±5V 0.050 0.025 0 –0.025 –0.050 –0.075 –0.100 –0.125 3.5 3.0 –50 –25 –0.150 –0.175 LTC6912-2 Gain Shift vs Temperature (Light Load) VS = 5V RL = 10k GAIN = 1 VS = 5V 4.5 4.0 VS = 2.7V GAIN = 8 GAIN = 64 100 125 50 25 75 0 TEMPERATURE (°C) 100 125 –0.200 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 6912 G23 6912 G24 6912 G25 6912fa 15 LTC6912 TYPICAL PERFOR A CE CHARACTERISTICS LTC6912-2 Gain Shift vs Temperature (Heavy Load) 0.25 GAIN = 1 VS = 5V RL = 500 GAIN CHANGE (dB) PI FU CTIO S INA, INB: Analog Inputs. The input signal to the A channel amplifier of the LTC6912-X is the voltage difference between the INA pin and AGND pin. Likewise, the input signal to the B channel amplifier of the LTC6912-X is the voltage difference between the INB pin and AGND pin. The INA (or INB) 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, the value of this input resistance is approximately 10kΩ and the INA (or INB) 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 and INB 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 (state = 0), or in software shutdown (state = 8) analog switches disconnect the INA or INB pin internally and this pin presents a very high input resistance. In the “zero” gain state (state = 0), the input may vary from rail to rail but the output is insensitive to it and is forced to the AGND potential. Circuitry driving the INA and INB pins must consider the LTC6912-X’s input resistance, its process 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 LTC6912X’s input resistance forms a voltage divider. This is especially true at higher gain settings where the input resistance is the lowest. In single supply voltage applications, the LTC6912-X’s DC ground reference for both input and output is AGND, not V –. With increasing gains, the LTC6912-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. NC INA 1 2 INPUT R ARRAY V+ – 100k AGND 3 100k V– MOS INPUT OP AMP + 13 OUT B – MOS INPUT OP AMP + 15 OUT A 14 V – 16 NC 16 UW 0 GAIN = 8 –0.25 GAIN = 64 –0.50 –0.75 –1.00 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 6912 G26 U U U FEEDBACK R ARRAY INB 4 INPUT R ARRAY CHANNEL A 12 V+ FEEDBACK R ARRAY CHANNEL B 11 NC LOWER NIBBLE 8-BIT LATCH UPPER NIBBLE V+ 10 DGND 9 Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 8-BIT SHIFT-REGISTER DOUT SHDN CS/LD DATA CLK 5 6 7 8 6912 BD Figure 1. GN-16 Block Diagram 6912fa LTC6912 PI FU CTIO S AGND: 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. In normal operation, the AGND pin has an equivalent input resistance of nominally 50k (Figure 1). In order to reduce the quiescent supply current in hardware shutdown (SHDN pin pulled to V +, GN-16 only), the equivalent series resistance of this pin significantly increases (to a value on the order of 800kΩ with 5V supplies, but is highly supply voltage, temperature, and process dependent). AGND is 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 LTC6912-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 0.1µF (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, in which the AGND pin can be directly tied to, making the zero volt ground plane the input and output reference voltage for the LTC6912-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 ANALOG GROUND PLANE V+ REFERENCE 1 2 2 ≥ 0.1µF 3 4 5 6 SERIAL INTERFACE 7 8 16 LTC6912-X 15 14 13 12 11 10 9 DIGITAL GROUND PLANE 6912 F02 Figure 2. Single Supply Ground Plane Connection U U U asymmetrical supply, however, it is often desirable to refer the LTC6912-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). In noise sensitive applications where AGND does not tie directly 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 which present a Thévenin equivalent resistance of approximately 50kΩ. This noise can reduce SNR by at least 15dB at high gain settings. An external capacitor from AGND to the ground plane, whose impedance is well below 50kΩ at frequencies of interest, will filter and suppress this noise. A 0.1µF high quality capacitor is effective for frequencies down to 1kHz. Larger capacitors will 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 with the AGND voltage range specified in the Electrical Characteristics Table. The AGND pin will load the external reference with approximately 50kΩ 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. ANALOG GROUND PLANE 1 2 3 LTC6912-X 16 15 14 V – 13 12 V + 11 10 9 DIGITAL GROUND PLANE 6912 F03 0.1µF 0.1µF 0.1µF V+ SINGLE-POINT SYSTEM GND 4 5 6 SERIAL INTERFACE 7 8 SINGLE-POINT SYSTEM GND Figure 3. Symmetrical Dual Supply Ground Plane Connection 6912fa 17 LTC6912 PI FU CTIO S ANALOG GROUND PLANE V+ + V– REFERENCE 1 2 2 ≥ 0.1µF 3 4 5 6 SERIAL INTERFACE 7 8 16 LTC6912-X 15 14 V – 13 12 V + 11 10 9 DIGITAL GROUND PLANE 6912 F04 Figure 4. Asymmetrical Dual Supply Ground Plane Connection SHDN (GN-16 ONLY): CMOS Compatible Logic Hardware Shutdown Input. The LTC6912-X has two shutdown modes. One is a software shutdown state which can be software programmed into either Channel A, Channel B, or both. The software shutdown, when programmed to a particular channel (state = 8), will disable that channel’s amplifier and tri-state open its analog input and analog output. The serial interface, however is still active. A hardware shutdown occurs when the SHDN pin is pulled to the positive rail. In this condition, both amplifiers and serial interface are disabled. The SHDN pin is 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 SHDN pin is a high impedance CMOS logic input, but has a small pull-down current source (10µF) near the chip, can create a parasitic high-Q LC resonant circuit in the hundreds of kHz range 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. Finally, equipment to measure performance can itself introduce 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. an integrating lowpass loop with capacitor C2 to set the programmable upper corner frequency. The LT1884 also supports rail-to-rail output swings over the total supply voltage range of 2.7V to 10.5V. AC coupling through capacitor C1 establishes a fixed low frequency corner of 1Hz, which can be adjusted by changing C1. Alternatively, shorting C1 makes the amplifier DC coupled. If DC gain is not needed, the AC coupling cap C1 serves to suppress several error sources: any shift in DC levels, low frequency noise, and DC offset voltages (not including the LT1884’s low internal offset). R2 15.8k C2 1µ F 1M BANDWIDTH CONTROL PGA R GAINB INB LTC6912-1 CHANNEL B 1 TO ≤ 2π R1C1 1 R2 )C2 2π ( GAINB OUTB R W U UU – 1/2 LT1884 VOUT + 1/2 LT1884 6912 F07 6912fa LTC6912 PACKAGE DESCRIPTIO 0.65 ± 0.05 3.50 ± 0.05 1.70 ± 0.05 2.20 ± 0.05 (2 SIDES) 0.25 ± 0.05 3.30 ± 0.05 (2 SIDES) 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING PROPOSED TO BE A VARIATION OF VERSION (WGED) IN JEDEC PACKAGE OUTLINE M0-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS .254 MIN .0165 ± .0015 RECOMMENDED SOLDER PAD LAYOUT .007 – .0098 (0.178 – 0.249) .016 – .050 (0.406 – 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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 DE/UE Package 12-Lead Plastic DFN (4mm × 3mm) (Reference LTC DWG # 05-08-1695) 4.00 ± 0.10 (2 SIDES) R = 0.20 TYP 3.00 ± 0.10 (2 SIDES) 1.70 ± 0.10 (2 SIDES) PIN 1 NOTCH (UE12/DE12) DFN 0603 7 R = 0.115 TYP 0.38 ± 0.10 12 PIN 1 TOP MARK (NOTE 6) PACKAGE OUTLINE 0.200 REF 0.75 ± 0.05 6 0.25 ± 0.05 3.30 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .045 ± .005 .189 – .196* (4.801 – 4.978) 16 15 14 13 12 11 10 9 .009 (0.229) REF .150 – .165 .229 – .244 (5.817 – 6.198) .150 – .157** (3.810 – 3.988) .0250 BSC 1 .015 ± .004 × 45° (0.38 ± 0.10) 0° – 8° TYP .0532 – .0688 (1.35 – 1.75) 23 4 56 7 8 .004 – .0098 (0.102 – 0.249) .008 – .012 (0.203 – 0.305) TYP .0250 (0.635) BSC GN16 (SSOP) 0204 6912fa 23 LTC6912 TYPICAL APPLICATIO CHANNEL A INPUT 1µ F CHANNEL B INPUT 3-WIRE SPI INTERFACE MUX OPERATION: IF THE LOWER NIBBLE (Q3, Q2, Q1, Q0) IS (1, 0, 0, 0) THEN OUTA IS IN TRI-STATE AND THE UPPER NIBBLE (Q7, Q6, Q5, Q4) CONTROLS THE ACTIVE CHANNEL B. IF THE UPPER NIBBLE IS (1, 0, 0, 0) THEN OUTB IS IN TRI-STATE AND THE LOWER NIBBLE CONTROLS ACTIVE CHANNEL A. RELATED PARTS PART NUMBER LT1228 LT1251/LT1256 LTC1564 LTC6910-1/-2/-3 LTC6911-1/-2 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 Dual Digitally Controlled Programmable Gain Amplifier in MSOP-10 Zero Drift Instrumentation Amp with Digitally Programmable Gain 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 Programmable Gain Amplifier, 3-Bit Parallel Digital Interface Dual Programmable Gain Amplifiers, 3-Bit Parallel Digital Interface Gains 0 - 4096V/V, 116dB CMRR 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com U A 2:1 PGA MUX V+ 12 V+ 0.1µF 14 V– 2 INA OUT A 15 VOUT (TO ADC) 3 AGND LTC6912-X 4 INB OUT B 13 SHDN CS/LD DATA CLK 5 6 7 8 CHB SHDN CS/LD DIN CHA DGND DOUT 10 9 6912 TA02 6912fa LT/LT 1005 REV A • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2004