LT1990 ±250V Input Range G = 1, 10, Micropower, Difference Amplifier DESCRIPTIO U APPLICATIO S ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ U ■ The LT®1990 is a micropower precision difference amplifier with a very high common mode input voltage range. It has pin selectable gains of 1 or 10. The LT1990 operates over a ±250V common mode voltage range on a ±15V supply. The inputs are fault protected from common mode voltage transients up to ±350V and differential voltages up to ±500V. The LT1990 is ideally suited for both high side and low side current or voltage monitoring. Pin Selectable Gain of 1 or 10 High Common Mode Voltage Range: 85V Window (VS = 5V, 0V) ±250V (VS = ±15V) Common Mode Rejection Ratio: 70dB Min Input Protection to ±350V Gain Error: 0.28% Max PSRR: 82dB Min High Input Impedance: 2MΩ Differential, 500kΩ Common Mode Micropower: 120µA Max Supply Current Wide Supply Range: 2.7V to 36V –3dB Bandwidth: 100kHz Rail-to-Rail Output 8-Pin SO Package On a single 5V supply, the LT1990 has an adjustable 85V input range, 70dB min CMRR and draws less than 120µA supply current. The rail-to-rail output maximizes the dynamic range, especially important for single supplies as low as 2.7V. The LT1990 is specified for single 3V, 5V and ±15V supplies over both commercial and industrial temperature ranges. The LT1990 is available in the 8-pin SO package. FEATURES ■ ■ ■ ■ ■ ■ Battery Cell Voltage Monitoring High Voltage Current Sensing Signal Acquisition in Noisy Environments Input Protection Fault Protected Front Ends Level Sensing Isolation , LTC and LT are registered trademarks of Linear Technology Corporation. U ■ TYPICAL APPLICATIO Full-Bridge Load Current Monitor +VSOURCE 5V LT1990 900k 10k 8 7 – + 2 1M 3 1M 100k – RS 6 VOUT + VREF = 1.5V IL 4 IN –12V ≤ VCM ≤ 73V VOUT = VREF ± (10 • IL • RS) OUT LT6650 GND FB 10k 1nF 54.9k 40k 5 900k 40k 100k 20k 1 1990 TA01 1µF 1990f 1 LT1990 U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Notes 1, 2) Total Supply Voltage (V + to V –) ............................... 36V Input Voltage Range Continuous ...................................................... ±250V Transient (0.1s) ............................................... ±350V Differential ....................................................... ±500V Output Short-Circuit Duration (Note 3) ............ Indefinite Operating Temperature Range (Note 4) ...–40°C to 85°C Specified Temperature Range (Note 5) ....–40°C to 85°C Storage Temperature Range .................. –65°C to 150°C Lead Temperature (Soldering, 10 sec.)................. 300°C ORDER PART NUMBER TOP VIEW REF 1 8 GAIN1 –IN 2 7 V+ +IN 3 6 OUT V– 4 5 GAIN2 LT1990CS8 LT1990IS8 LT1990ACS8 LT1990AIS8 S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 150°C, θJA = 190°C/W 1990 1990A 1990I 1990AI 3V/5V ELECTRICAL CHARACTERISTICS VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6) SYMBOL PARAMETER CONDITIONS G Gain Pins 5 and 8 = Open Pins 5 and 8 = GND ∆G Gain Error VOUT = 0.5V to (+Vs) –0.75V LT1990, G = 1 LT1990A, G = 1 G = 10, VS = 5V, 0V VS = 5V, 0V; VOUT = 0.5V to 4.25V G=1 G = 10 GNL VCM CMRR Gain Nonlinearity Input Voltage Range Common Mode Rejection Ratio RTI (Referred to Input) VOS Offset Voltage, RTI en MIN TYP MAX UNITS 0.4 0.07 0.2 0.6 0.28 0.8 % % % 0.001 0.01 0.005 % % 25 80 47 V V V 1 10 Guaranteed by CMRR VS = 3V, 0V; VREF = 1.25V VS = 5V, 0V; VREF = 1.25V VS = 5V, 0V; VREF = 2.5V –5 –5 –38 VS = 3V, 0V (Note 7) VCM = –5V to 25V, VREF = 1.25V LT1990 LT1990A 60 70 68 75 dB dB VS = 5V, 0V VCM = –5V to 80V, VREF = 1.25V LT1990 LT1990A 60 70 68 75 dB dB VS = 5V, 0V (Note 7) VCM = –38V to 47V, VREF = 2.5V LT1990 LT1990A 60 70 68 75 dB dB G = 1, 10 0.8 3 mV Input Noise Voltage, RTI fO = 0.1Hz to 10Hz 22 µVP-P Noise Voltage Density, RTI fO = 1kHz 1 µV/√Hz 1990f 2 LT1990 3V/5V ELECTRICAL CHARACTERISTICS VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6) SYMBOL PARAMETER CONDITIONS MIN RIN Input Resistance Differential Common Mode PSRR Power Supply Rejection Ratio, RTI VS = 2.7V to 12.7V, VCM = VREF = 1.25V Minimum Supply Voltage Guaranteed by PSRR 2.4 2.7 80 TYP MAX UNITS 2 0.5 MΩ MΩ 92 dB V IS Supply Current (Note 8) 105 120 µA VOL Output Voltage Swing LOW –IN = V+, +IN = Half Supply (Note 8) 30 50 mV VOH Output Voltage Swing HIGH –IN = 0V, +IN = Half Supply VS = 3V, 0V, Below V+ VS = 5V, 0V, Below V+ 100 120 150 175 mV mV ISC Output Short-Circuit Current Short to GND (Note 9) Short to V+ (Note 9) BW Bandwidth (–3dB) SR AVREF 4 13 8 20 mA mA G=1 G = 10 100 6.5 kHz kHz Slew Rate G = 1, VS = 5V, 0V, VOUT = 0.5V to 4.5V 0.5 V/µs Settling Time to 0.01% 4V Step, G = 1, VS = 5V, 0V 45 µs Reference Gain to Output 1 ± 0.0007 The ● denotes the specifications which apply over the temperature range of 0°C ≤ TA ≤ 70°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS MIN ∆G Gain Error VOUT = 0.5V to (+VS) – 0.75V LT1990, G = 1 LT1990A, G = 1 G = 10 ● ● ● TYP MAX UNITS 0.65 0.33 0.90 % % % G/T Gain vs Temperature G = 1 (Note 10) G = 10 (Note 10) ● ● VCM Input Voltage Range Guaranteed by CMRR VS = 3V, 0V, VREF = 1.25V VS = 5V, 0V, VREF = 1.25V VS = 5V, 0V, VREF = 2.5V ● ● ● –5 –5 –37 VS = 3V, 0V (Note 7) VCM = –5V to 25V, VREF = 1.25V LT1990 LT1990A ● ● 58 68 dB dB VS = 5V, 0V VCM = –5V to 80V, VREF = 1.25V LT1990 LT1990A ● ● 58 68 dB dB VS = 5V, 0V (Note 7) VCM = –38V to 47V, VREF = 2.5V LT1990 LT1990A ● ● 58 68 dB dB VS = 3V, 0V G = 1, 10 ● ● 4.1 mV VS = 5V, 0V G = 1, 10 ● ● 4.1 mV CMRR VOS Common Mode Rejection Ratio, RTI Input Offset Voltage, RTI 2 7 10 20 ppm/°C ppm/°C 25 80 48 V V V 1990f 3 LT1990 3V/5V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of 0°C ≤ TA ≤ 70°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS VOS/T Input Offset Voltage Drift, RTI (Note 10) VOSH Input Offset Voltage Hysteresis, RTI PSRR Power Supply Rejection Ratio, RTI Minimum Supply Voltage Guaranteed by PSRR ● 2.7 IS Supply Current (Note 8) ● 150 µA VOL Output Voltage Swing LOW –IN = V+, +IN = Half Supply (Note 8) ● 60 mV VOH Output Voltage Swing HIGH –IN = 0V, +IN = Half Supply VS = 3V, 0V, Below V+ VS = 5V, 0V, Below V+ ● ● 180 205 mV mV Short to GND (Note 9) Short to V+ (Note 9) ● ● ISC Output Short-Circuit Current MIN TYP MAX UNITS ● 5 22 µV/°C (Note 11) ● 230 VS = 2.7V to 12.7V VCM = VREF = 1.25V G = 1, 10 ● µV 78 dB V 3 11 mA mA The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 85°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS ∆G Gain Error VOUT = 0.5V to (+VS) – 0.75V LT1990, G = 1 LT1990A, G = 1 G = 10 MIN ● ● ● TYP MAX UNITS 0.67 0.35 0.95 % % % G/T Gain vs Temperature G = 1 (Note 10) G = 10 (Note 10) ● ● VCM Input Voltage Range Guaranteed by CMRR VS = 3V, 0V, VREF = 1.25V VS = 5V, 0V, VREF = 1.25V VS = 5V, 0V, VREF = 2.5V ● ● ● –5 –5 –37 VS = 3V, 0V (Note 7) VCM = –5V to 25V, VREF = 1.25V LT1990 LT1990A ● ● 57 67 dB dB VS = 5V, 0V VCM = –5V to 80V, VREF = 1.25V LT1990 LT1990A ● ● 57 67 dB dB VS = 5V, 0V (Note 7) VCM = –38V to 47V, VREF = 2.5V LT1990 LT1990A ● ● 57 67 dB dB VS = 3V, 0V G = 1, 10 ● ● 4.5 mV VS = 5V, 0V G = 1, 10 ● ● 4.5 mV 22 µV/°C CMRR VOS Common Mode Rejection Ratio, RTI Input Offset Voltage, RTI 2 7 VOS/T Input Offset Voltage Drift, RTI (Note 10) ● 5 VOSH Input Offset Voltage Hysteresis, RTI (Note 11) ● 230 PSRR Power Supply Rejection Ratio, RTI VS = 2.7V to 12.7V VCM = VREF = 1.25V ● 76 10 20 ppm/°C ppm/°C 25 80 48 V V V µV dB 1990f 4 LT1990 3V/5V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 85°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS MAX UNITS Minimum Supply Voltage Guaranteed by PSRR ● 2.7 V Supply Current (Note 8) ● 170 µA VOL Output Voltage Swing LOW –IN = V+, +IN = Half Supply (Note 8) ● 70 mV VOH Output Voltage Swing HIGH –IN = 0V, +IN = Half Supply VS = 3V, 0V, Below V+ VS = 5V, 0V, Below V+ ● ● 200 225 mV mV Short to GND (Note 9) Short to V+ (Note 9) ● ● IS ISC Output Short-Circuit Current MIN TYP 2 8 mA mA ±15V ELECTRICAL CHARACTERISTICS VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6) SYMBOL PARAMETER CONDITIONS G Gain Pins 5 and 8 = Open Pins 5 and 8 = VREF ∆G Gain Error VOUT = ±10V LT1990, G = 1 LT1990A, G = 1 G = 10 GNL Gain Nonlinearity MIN TYP MAX UNITS 0.6 0.28 0.8 % % % 0.0008 0.002 0.005 0.02 % % 1 10 0.4 0.07 0.2 VOUT = ±10V G=1 G = 10 VCM Input Voltage Range Guaranteed by CMRR –250 CMRR Common Mode Rejection Ratio, RTI VCM = –250V to 250V LT1990 LT1990A 60 70 250 68 75 V dB dB VOS Offset Voltage, RTI G = 1, 10 0.9 en Input Noise Voltage, RTI fO = 0.1Hz to 10Hz 22 µVP-P Noise Voltage Density, RTI fO = 1kHz 1 µV/√Hz RIN Input Resistance Differential Common Mode PSRR Power Supply Rejection Ratio, RTI VS = ±1.35V to ±18V Minimum Supply Voltage Guaranteed by PSRR IS Supply Current VOUT Output Voltage Swing Short to V– ISC Output Short-Circuit Current BW Bandwidth SR Slew Rate G = 1, VOUT = ±10V Settling Time to 0.01% 10V Step, G = 1 AVREF Short to V+ Reference Gain to Output 82 5.2 mV 2 0.5 MΩ MΩ 100 dB ±1.2 ±1.35 V 140 180 µA V ±14.5 ±14.79 6 15 9 22 mA mA 105 7 kHz kHz 0.55 V/µs G=1 G = 10 0.3 60 µs 1 ± 0.0007 1990f 5 LT1990 ±15V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of 0°C ≤ TA ≤ 70°C. VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS ∆G Gain Error VOUT = ±10V LT1990, G = 1 LT1990A, G = 1 G = 10 GNL Gain Nonlinearity MIN MAX UNITS ● ● ● 0.65 0.33 0.9 % % % VOUT = ±10V G=1 G = 10 ● ● 0.0025 0.025 % % G/T Gain vs Temperature G = 1 (Note 10) G = 10 (Note 10) ● ● VCM Input Voltage Range Guaranteed by CMRR ● –250 CMRR Common Mode Rejection Ratio, RTI VCM = –250V to 250V LT1990 LT1990A ● ● 59 68 TYP 2 7 Input Offset Voltage, RTI G = 1, 10 ● VOS/T Input Offset Voltage Drift, RTI (Note 10) ● 5 VOSH Input Offset Voltage Hysteresis, RTI (Note 11) ● 250 PSRR Power Supply Rejection Ratio, RTI VS = ±1.35V to ±16V Minimum Supply Voltage Guaranteed by PSRR Supply Current VOUT Output Voltage Swing ISC Output Short-Circuit Current SR Slew Rate ppm/°C ppm/°C 250 V dB dB VOS IS 10 20 6.2 mV 22 µV/°C µV 80 dB ● ±1.35 V ● 230 µA ● ±14.4 Short to V+ ● ● 5 13 mA mA G = 1, VOUT = ±10V ● 0.25 V/µs Short to V– V 1990f 6 LT1990 ±15V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 85°C. VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS ∆G Gain Error VOUT = ±10V LT1990, G = 1 LT1990A, G = 1 G = 10 GNL Gain Nonlinearity MIN MAX UNITS ● ● ● 0.67 0.35 0.9 % % % VOUT = ±10V G=1 G = 10 ● ● 0.003 0.03 % % G/T Gain vs Temperature G = 1 (Note 10) G = 10 (Note 10) ● ● VCM Input Voltage Range Guaranteed by CMRR ● –250 CMRR Common Mode Rejection Ratio, RTI VCM = –250V to 250V LT1990 LT1990A ● ● 58 67 TYP 2 7 Input Offset Voltage, RTI G = 1, 10 ● VOS/T Input Offset Voltage Drift, RTI (Note 10) ● 5 VOSH Input Offset Voltage Hysteresis, RTI (Note 11) ● 250 PSRR Power Supply Rejection Ratio, RTI VS = ±1.35V to ±18V ● Minimum Supply Voltage Guaranteed by PSRR ● Supply Current VOUT Output Voltage Swing ISC Output Short-Circuit Current SR Slew Rate ppm/°C ppm/°C 250 V dB dB VOS IS 10 20 6.7 mV 22 µV/°C µV 78 dB ±1.35 V 280 µA ● ±14.3 V Short to V+ ● ● 3 10 mA mA G = 1, VOUT = ±10V ● 0.2 V/µs Short to V– Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: ESD (Electrostatic Discharge) sensitive device. Extensive use of ESD protection devices are used internal to the LT1990, however, high electrostatic discharge can damage or degrade the device. Use proper ESD handling precautions. Note 3: A heat sink may be required to keep the junction temperature below absolute maximum. Note 4: The LT1990C/LT1990I are guaranteed functional over the operating temperature range of – 40°C to 85°C. Note 5: The LT1990C is guaranteed to meet the specified performance from 0°C to70°C and 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 LT1990I is guaranteed to meet specified performance from –40°C to 85°C. Note 6: G = 10 limits are guaranteed by correlation to G = 1 tests and gain error tests at G = 10. Note 7: Limits are guaranteed by correlation to –5V to 80V CMRR tests. Note 8: VS = 3V limits are guaranteed by correlation to VS = 5V and VS = ±15V tests. Note 9: VS = 5V limits are guaranteed by correlation to VS = 3V and VS = ±15V tests. Note 10: This parameter is not 100% tested. Note 11: Hysteresis in offset voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower temperature. Offset voltage hysteresis is always measured at 25°C, but the IC is cycled to 85°C I-grade (or 70°C C-grade) or –40°C I-grade (0°C C-grade) before successive measurement. 1990f 7 LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Supply Current vs Supply Voltage 150 VREF = VOUT = 1.25V V – = 0V 200 160 TA = 25°C 140 TA = –40°C 120 TA = –55°C 100 80 SUPPLY CURRENT (µA) 60 130 120 110 100 90 80 40 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 60 –50 40 35 –25 0 25 50 75 TEMPERATURE (°C) 100 1990 G01 TA = 25°C TA = 25°C +1 SINKING (+IN = –2.5V) +0.1 TA = 125°C TA = –55°C +1 TA = 25°C +0.1 TA = –55°C +1 TA = 25°C 0 0.2 0.4 0.6 0.8 DIFFERENTIAL INPUT VOLTAGE (±V) MAXIMUM INPUT VOLTAGE (V) TA = –55°C TA = 25°C TA = 125°C SINK TA = 125°C –15 TA = –55°C –20 TA = 25°C –25 1.0 2 4 8 10 12 6 SUPPLY VOLTAGE (±V) 14 16 1990 G07 OUTPUT FULLY SATURATED G = 10 G = 1 2 4 6 8 10 12 SUPPLY VOLTAGE (±V) 300 VREF = 4V 150 VREF = 1.25V 100 VREF = 2.5V 50 VREF = 1.25V 0 VREF = 2.5V –50 16 1990 G06 V – = 0V TA = –40°C TO 85°C 200 14 Input Voltage Range vs Split Supply Voltage VREF = 0V TA = –40°C TO 85°C 200 100 0 –100 –200 VREF = 4V –100 0 V – +0.01 0 Input Voltage Range vs Single Supply Voltage 10 –10 +0.1 G = 10, V+IN = V –/10 G=1 G = 10 OUTPUT FULLY SATURATED 1990 G05 SOURCE 0 V–IN = 0V VREF = 0V NO LOAD TA = 25°C G = 1, V+IN = V – TA = –55°C V – +0.01 250 –5 –0.1 G = 10, V = V+/10 +IN TA = 125°C 25 5 G = 1, V+IN = V+ TA = 25°C Output Short-Circuit Current vs Supply Voltage 15 1990 G03 +0.1 4.0 100 V + –0.01 –1 TA = 125°C 0.5 1.0 1.5 2.0 2.5 3.0 3.5 DIFFERENTIAL INPUT VOLTAGE (±V) 0.01 0.1 1 10 OUTPUT CURRENT (mA) TA = 125°C 1990 G04 20 V – +0.01 0.001 Output Voltage Swing vs Supply Voltage TA = –55°C VS = ±2.5V G = 10 –0.1 NO LOAD OUTPUT VOLTAGE WITH RESPECT TO SUPPLY (V) TA = 25°C 0 V + –0.01 TA = 125°C –1 V – +0.01 125 OUTPUT SWING WITH RESPECT TO SUPPLY (V) TA = –55°C VS = ±2.5V G=1 –0.1 NO LOAD OUTPUT VOLTAGE WITH RESPECT TO SUPPLY (V) TA = 125°C –1 Output Voltage vs Input Voltage, G = 10 V + –0.01 OUTPUT SHORT-CIRCUIT CURRENT (mA) SOURCING (+IN = 2.5V) 1990 G02 Output Voltage vs Input Voltage, G = 1 –30 – 0.1 70 MAXIMUM INPUT VOLTAGE (V) SUPPLY CURRENT (µA) TA = 85°C VS = ±2.5V –IN = 0V G=1 TA = –55°C 140 TA = 125°C 180 V + – 0.01 VS = 5V, 0V OUTPUT VOLTAGE SWING WITH RESPECT TO SUPPLY (V) 220 Output Voltage Swing vs Load Current Supply Current vs Temperature 3 7 9 11 13 5 POSITIVE SUPPLY VOLTAGE (V) 15 1990 G08 –300 1 3 9 7 11 5 SUPPLY VOLTAGE (±V) 13 15 1990 G09 1990f 8 LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Common Mode Rejection Ratio vs Frequency Gain vs Frequency 50 VS = 5V, 0V 40 TA = 25°C VS = 5V, 0V TA = 25°C G = 1 OR 10 REFERRED TO INPUT 90 80 30 70 20 60 10 GAIN (dB) COMMON MODE REJECTION RATIO (dB) 100 50 40 0 G = 10 G=1 –10 –20 30 20 –30 10 –40 0 100 10k 1k FREQUENCY (Hz) –50 100 100k 200k 1k 10k 100k FREQUENCY (Hz) 1M 1990 G10 –3dB Bandwidth vs Supply Voltage, G = 1 120 8 1.0 TA = 25°C TA = 25°C RL = 10k TA = –55°C TA = –55°C FREQUENCY (kHz) TA = 125°C 100 0.8 7 105 TA = 25°C 95 90 85 80 TA = 25°C 6 SLEW RATE (V/µs) 110 FREQUENCY (kHz) Slew Rate vs Supply Voltage, G=1 –3dB Bandwidth vs Supply Voltage, G = 10 TA = 25°C 115 1990 G12 TA = 125°C 5 4 –SR 0.6 +SR 0.4 0.2 75 70 3 0 2 6 8 4 10 12 SUPPLY VOLTAGE (±V) 14 0 0 16 2 6 8 4 10 12 SUPPLY VOLTAGE (±V) 1990 G13 0 0.5 0.8 0.1 –SR SLEW RATE (V/µs) SLEW RATE (V/µs) +SR 0.2 0.6 +SR 0.4 0.2 0 0 2 8 6 10 12 4 SUPPLY VOLTAGE (±V) 14 16 1990 G16 14 16 0.6 VS = ±15V RL = 10k –SR 8 6 10 12 4 SUPPLY VOLTAGE (±V) Slew Rate vs Temperature G = 10 1.0 TA = 25°C RL = 10k 0.3 2 1990 G15 Slew Rate vs Temperature G=1 0.4 SLEW RATE (V/µs) 16 1990 G14 Slew Rate vs Supply Voltage, G = 10 0.5 14 0 –50 –25 VS = ±15V RL = 10k 0.4 0.3 –SR +SR 0.2 0.1 50 25 75 0 TEMPERATURE (°C) 100 125 1990 G17 0 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 1990 G18 1990f 9 LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Power Supply Rejection Ratio vs Frequency 70 G = 10 G=1 100 10 VS = 5V, 0V TA = 25°C 1 100 10k 1k FREQUENCY (Hz) 60 VS = 5V, 0V TA = 25°C G=1 50 40 30 G = 10 20 10 0 –10 –20 SETTLING TIME (µs) SETTLING TIME (µs) 280 0.01% OF STEP 0.01% OF STEP 0.1% OF STEP 0.01% OF STEP 260 0.01% OF STEP 240 220 200 0.1% OF STEP 180 0.1% OF STEP 160 8 140 –10 –8 –6 –4 –2 0 2 4 OUTPUT STEP (V) 10 VS = ±1.5V TO ±15V TA = 25°C 1000 100 6 8 1 10 10 100 1000 FREQUENCY (Hz) 10000 1990 G24 Overshoot vs Capacitive Load 30 VS = ±1.5V TO ±15V TA = 25°C G=1 VOUT = ±50mV GAIN = 1 RL = 10k 25 OVERSHOOT (%) NOISE VOLTAGE (10µV/DIV) 50 1990 G21 0.01 to 1Hz Noise Voltage REF 10 20 30 40 TIME AFTER POWER-UP (S) 1990 G23 0.1 to 10Hz Noise Voltage VS = ±1.5V TO ±15V TA = 25°C G=1 0 10000 1990 G22 NOISE VOLTAGE (10µV/DIV) –40 Voltage Noise Density vs Frequency VS = ±15V RL = 10k 300 50 6 –20 100k 200k 1k 10k FREQUENCY (Hz) 320 VS = ±15V RL = 10k 20 –10 –8 –6 –4 –2 0 2 4 OUTPUT STEP (V) 0 Settling Time vs Output Step, G = 10 60 0.1% OF STEP 20 1990 G20 Settling Time vs Output Step, G=1 30 40 –60 100 1990 G19 40 VS = ±15V TA = 25°C REFERRED TO INPUT –30 –40 10 100k 200k Warm-Up Drift vs Time 60 VOLTAGE NOISE DENSITY (nV/√Hz) OUTPUT IMPEDANCE (Ω) 1k POWER SUPPLY REJECTION RATIO (dB) 5k CHANGE IN OFFSET VOLTAGE (µV) Output Impedance vs Frequency REF 20 15 VS = 3V, 0V 10 VS = ±15V 5 0 1 2 3 4 5 6 TIME (S) 7 8 9 10 1990 G25 0 10 20 30 40 50 60 70 80 90 100 TIME (S) 1990 G26 10 100 1000 CAPACITIVE LOAD (pF) 10000 1990 G27 1990f 10 LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS GND 1990 G28 50µs/DIV 5V/DIV 1.5V VS = 3V, 0V G = 1, –1 RL = 10k VREF = 1.5V Large Signal Transient Response Small Signal Transient Response 50mV/DIV 50mV/DIV Small Signal Transient Response VS = ±15V G = 1, –1 RL = 10k VREF = GND GND 1990 G29 50µs/DIV VS = ±15V G = 1, –1 RL = 10k VREF = GND 50µs/DIV 1990 G30 W BLOCK DIAGRA R5 900k R7 10k 8 GAIN1 V+ 7 R1 1M R6 100k – –IN 2 R2 1M 6 OUT + +IN 3 V– 4 R10 10k R8 900k R3 40k 5 GAIN2 R4 40k 1 R9 100k 1990 SS REF U U U PI FU CTIO S REF (Pin 1): Reference Input. Sets the output level when the difference between the inputs is zero. –IN (Pin 2): Inverting Input. Connects a 1MΩ resistor to the op amp’s inverting input. Designed to permit high voltage operation. +IN (Pin 3): Noninverting Input. Connects a 1MΩ resistor to the op amp’s noninverting input. Designed to permit high voltage operation. V– (Pin 4): Negative Power Supply. Can be either ground (in single supply applications) or a negative voltage (in split supply applications). GAIN2 (Pin 5): Gain = 10 Select Input. Configures the amplifier for a gain of 10 when connected to the GAIN1 pin. The gain is equal to one when both GAIN2 and GAIN1 are open. See Applications section for additional functions. OUT (Pin 6): Output. VOUT = G • (V+IN – V–IN) + VREF, in the basic configuration. V+ (Pin 7): Positive Power Supply. Can range from 2.7V to 36V above the V– voltage. GAIN1 (Pin 8): Gain = 10 Select Input. Configures the amplifier for a gain of 10 when connected to the GAIN2 pin. The gain is equal to one when both GAIN1 and GAIN2 are open. See Applications section for additional functions. 1990f 11 LT1990 U W U U APPLICATIO S I FOR ATIO Primary Features The LT1990 is a complete gain-block solution for high input common mode voltage applications, incorporating a low power precision operational amplifier providing railto-rail output swing along with on-chip precision thin-film resistors for high accuracy. The Block Diagram shows the internal architecture of the part. The on-chip resistors form a modified difference amplifier including a reference port for introducing offset or other additive waveforms. With pin-strapping alone either unity gain or gain of 10 is produced with high precision. The resistor network is designed to produce internal common-mode voltage division of 27 so that a very large input range is available compared to the power supply voltage(s) used by the LT1990 itself. The LT1990 is ideally suited to situations where relatively small signals need to be extracted from high voltage circuits, as is the case in many current monitoring instrumentation applications for example. With the ability to accept a range of input voltages well outside the limits of the local power rails and its greater than 1MΩ input impedances, development of precision low power over-the-top and under-the-bottom instrumentation designs is greatly simplified with the LT1990 single chip solution over conventional discrete implementations. Classic Difference Amplifier Used in the basic difference amplifier topology where the gain G is pin-strap configurable to be unity or ten, the following relationship is realized: VO = G • (V+IN – V–IN) + VREF To operate in unity gain, the GAIN1 and GAIN2 pins are left disconnected. For G = 10 operation, the GAIN1 and GAIN2 pins are simply connected together or tied to a common potential such as ground or V –. The input common mode range capability is up to ±250V, governed by the following relationships: For G = 1 and G = 10 where GAIN1 and GAIN2 are only tied together (not grounded,etc): VCM+ ≤ 27 • V+ – 26 • VREF – 23 VCM– ≥ 27 • V – – 26 • VREF + 27 For G = 10 where GAIN1 and GAIN2 are tied to a common potential VGAIN: VCM+ ≤ 27 • V+ – 26 • VREF – 23 – VGAIN VCM– ≥ 27 • V– – 26 • VREF + 27 – VGAIN For split supplies over about ±11V, the full ±250V common mode range is normally available (with VREF a small fraction of the supply). With lower supply voltages, an appropriate selection of VREF can tailor the input common mode range to a specific requirement. As an example, the following low supply voltage scenarios are readily implemented with the LT1990: Supply VREF VCM Range +3V 1.25V –5V to 25V (e.g. 12V automotive environment) +5V 1.25V –5V to 80V (e.g. 42V automotive environment) +5V 4.00V –77V to 8V (e.g. telecom environment; use downward signaling) Configuring Other Gains An intermediate gain G ranging between 1 and 10 may be produced by placing an adjustable resistance between the GAIN1 and GAIN2 pins according to the following nominal relationship: RGAIN ≈ (180k/(G – 1)) – 20k While the expression is exact, the value is approximate because the absolute resistance of the internal network could vary on a unit-to-unit basis by as much as ±30% from the nominal figures and the external gain resistance is required to accommodate that deviation. Once adjusted, however, the gain stability is excellent by virtue of the –30ppm/°C typical temperature coefficient offered by the on-chip thin-film resistor process. Preserving and Enhancing Common Mode Rejection The basic difference amplifier topology of the LT1990 requires that source impedances seen by the input pins +IN and –IN, should be matched to within a few tens of ohms to avoid increasing common mode induced errors beyond the basic production limits of the part. Known source imbalances beyond that level should be compensated for by the addition of series resistance to the lower1990f 12 LT1990 U W U U APPLICATIO S I FOR ATIO impedance source. Also the source impedance of a signal connected to the REF pin must be on the order of a few ohms or less to preserve the high accuracy of the LT1990. While the LT1990 comes from the factory with an excellent CMRR, some precision applications with a large applied common mode voltage may require a method to trim out residual common mode error. This is easily accomplished by adding series resistance to each input, +IN and –IN, such that an adjustable resistance difference of ±1kΩ is provided. This is most easily realized by adding a fixed 1kΩ in series with one of the inputs, and a 2kΩ trimmer in series with the other as shown in Figure 1. The trim range of this configuration is ±0.1% for the internal gain resistor matching, so a much more finely resolved correction is available using the LT1990 than is realizable with ordinary discrete solutions. In applications where the input common mode voltage is relatively constant and large (perhaps at or beyond the supply range), this same configuration can be treated as an offset adjustment. 1k 2k Dual Differential-Input Arithmetic Block The internal resistor network topology of the LT1990 allows the GAIN1 and GAIN2 pins to be used as another differential input in addition to the normal +IN and –IN port. This can be a very useful function for implementing servo-loop differential error amplifiers, for example. In this mode of operation, the output is governed by the following relationship: VO = 10 • (V+IN – V–IN + VGAIN2 – VGAIN1) + VREF Unlike the main inputs, the GAIN1 and GAIN2 pins are clamped by substrate diodes and ESD structures, thus the operating voltage range of these pins is limited to V– – 0.2V to V– + 36V. If the GAIN inputs are brought beyond the operating input range, care must be taken to limit the input currents to less than 10mA to prevent damage to the device. Also, since the gain setting resistors associated with the GAIN1 and GAIN2 inputs are in the 10kΩ area, low source impedances are particularly important to preserve the precision of the LT1990. This dual differential input mode of operation is used in the circuit as shown in Figure 2. – LT1990 + Figure 1. Optional CMRR Trim This circuit is a high efficiency H-bridge driver that is PWM modulated to provide a controlled current to an electromagnet coil. Since the common mode voltage of the current sense resistor RS varies with operating current and the coil properties, a differential feedback is required. In this application, it was desirable to allow the control input to utilize the wide common mode range port (+IN and –IN) so that constraints on input referencing are eliminated. The GAIN1 and GAIN2 pins always operate within the supply range and both ports operate with a gain of 10 to develop the loop error. The LTC1923 provides the loop integrator and PWM functions of the servo. 1990f 13 LT1990 U W U U APPLICATIO S I FOR ATIO 10k PLLLPF RT RSLEW CT 330pF 82k VIN+ 100k 3 + 20k 2 100k – 10nF VDD 7 5 LT1990 REF 8 VDD G2 SDSYNC VREF 1µF VDD VREF 100k 6 G1 100k 10nF 4 CNTRL PDRVB EAOUT NDRVB 10µF MPA* L1 10µH 1 FB VIN– VDD LTC1923 ICOIL = (VIN+ – VIN)/(10 • RS) (i.e. ±1A FOR ±1V) 1µF 10k C1, C2, C3: TAIYO YUDEN JMK325BJ226MM-T (X7R) L1, L2: SUMIDA CDRH6D2B-220NC *MNA, MPA: SILICONIX Si9801 **MNB, MPB: SILICONIX Si9801 10k AGND 1µF PGND SS NDRVA ILIM PDRVA VSET CS + FAULT CS – VTHRM ITEC H/C VTEC C1 MNB** 22µF C3 22µF MPB** L2 10µH C2 22µF MNA* 0.1 TEC + TEC – RS 0.1 ICOIL ELECTROMAGNET COIL 1990 F02 Figure 2. PWM-Based ±1A Electromagnet Current Controller 1990f 14 LT1990 U PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN 7 6 5 .160 ±.005 .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP 1 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) 0°– 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN 2 .014 – .019 (0.355 – 0.483) TYP INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) .050 (1.270) BSC SO8 0303 1990f 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. 15 LT1990 U TYPICAL APPLICATIO Telecom Supply Current Monitor + LOAD IL Selectable Gain Amplifier 5V +V 48V 3 VIN+ – 3 7 + RS – 4 5 6 G1 VOUT 8 2 VIN– – 4 G1 1 5 6 VOUT 8 –V REF VREF 1 –77V ≤ VCM ≤ 8V VOUT = VREF – (10 • IL • RS) G2 LT1990 G2 LT1990 2 7 + 2N7002 REF VREF = 4V 4 IN 5 OUT LT6650 1 GND FB 2 1nF 174k GAIN_SEL (HI = 10X, LO = 1X) 2N7002 20k 1990 AI02 1990 AI01 1µF Bidirectional Controlled Current Source Boosted Bidirectional Controlled Current Source +V +V VCTL 3 7 + LT1990 2 – 4 1 REF –V 1k 6 CZT751 RSENSE VCTL 3 7 + ILOAD LT1990 2 ILOAD = VCTL/RSENSE ≤ 5mA EXAMPLE: FOR RSENSE =100Ω, OUTPUT IS 1mA PER 100mV INPUT – 6 + 10µF 4 RSENSE 1 REF 1990 AI03 ILOAD 1k CZT651 –V ILOAD = VCTL/RSENSE ≤ 100mA EXAMPLE: FOR RSENSE =10Ω, OUTPUT IS 1mA PER 10mV INPUT 1990 AI04 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1787 Precision High Side Current Sense Amplifier On-Chip Precision Resistor Array LT1789 Micropower Instrumentation Amplifier Micropower, Precision, G = 1 to 1000 LTC1921 Dual –48V Supply and Fuse Monitor Withstands ±200V Transients LT1991 High Accuracy Difference Amplifier Micropower, Precision, Pin Selectable G = –13 to 14 LT1995 30MHz, 1000V/µs Gain Selectable Amplifier Pin Selectable G = –7 to 8 LT6910 Single Supply Programmable Gain Amplifier Digitally Controlled, SOT-23, G = 0 to 100 1990f 16 LT/TP 0704 1K • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2004