LT1999CS8-10#PBF

LT1999-10/LT1999-20/ LT1999-50 High Voltage, Bidirectional Current Sense Amplifier Features Description Buffered Output with 3 Gain Options: 10V/V, 20V/V, 50V/V nn Gain Accuracy: 0.5% Max nn Input Common Mode Voltage Range: –5V to 80V nn AC CMRR > 80dB at 100kHz nn Input Offset Voltage: 1.5mV Max nn –3dB Bandwidth: 2MHz nn Smooth, Continuous Operation Over Entire Common Mode Range nn 4kV HBM Tolerant and 1kV CDM Tolerant nn Low Power Shutdown 5.5V VCM = –5V VSHDN = 0.5V, 0V < VCM < 80V l l l 100 –2.35 137.5 –1.95 0.001 175 –1.5 2.5 μA mA μA IOS Input Offset Current IOS = I(+IN) – I(–IN) (Note 8) VCM > 5.5V VCM = –5V VSHDN = 0.5V, 0V < VCM < 80V l l l –1 –10 –2.5 1 10 2.5 μA μA μA PSRR Supply Rejection Ratio V+ = 4.5V to 5.5V l 68 77 dB CMRR Sense Input Common Mode Rejection VCM = –5V to 80V VCM = –5V to 5.5V VCM = 12V, 7VP-P, f = 100kHz, VCM = 0V, 7VP-P, f = 100kHz l l l l 96 96 75 80 105 120 90 100 dB dB dB dB en Differential Input Referred Noise Voltage Density f = 10kHz f = 0.1Hz to 10Hz 97 8 nV/√Hz μVP-P REFRR REF Pin Rejection, V+ = 5.5V ΔVREF = 3.0V ΔVREF = 3.25V ΔVREF = 3.25V dB dB dB LT1999-10 LT1999-20 LT1999-50 l l l 62 62 62 70 70 70 VSHDN = 0.5V l l 60 0.15 80 0.4 100 0.65 kΩ MΩ VSHDN = 0.5V l l 2.45 1 2.5 2.5 2.55 2.75 V V 1.25 1.125 1.125 V+ – 1.25 V+ – 1.125 V+ – 1.125 V V V RREF REF Pin Input Impedance VREF Open Circuit Voltage VREFR REF Pin Input Range (Note 9) LT1999-10 LT1999-20 LT1999-50 l l l ISHDN Pin Pull-Up Current V+ = 5.5V, VSHDN = 0V l –6 V+ – 0.5 –2 μA VIH SHDN Pin Input High l VIL SHDN Pin Input Low l f3dB Small Signal Bandwidth SR Slew Rate ts Settling Time due to Input Step, ΔVOUT = ±2V 0.5% Settling 2.5 μs tr Common Mode Step Recovery Time ΔVCM = ±50V, 20ns (Note 10) LT1999-10 LT1999-20 LT1999-50 0.8 1 1.3 μs μs μs VS Supply Voltage (Note 11) IS Supply Current VCM > 5.5V VCM = –5V V+ = 5.5V, VSHDN = 0.5V, VCM > 0V RO Output Impedance ΔIO = ±2mA ISRC Sourcing Output Current RLOAD = 50Ω to GND ISNK Sinking Output Current VOUT LT1999-10 LT1999-20 LT1999-50 l V 0.5 4.5 l l l V 2 2 1.2 MHz MHz MHz 3 V/μs 5 5.5 V 1.55 5.8 3 1.9 7.1 10 mA mA μA 40 mA 0.15 6 RLOAD = 50Ω to V+ l 15 26 40 mA Swing Output High (with Respect to V+) RLOAD = 1kΩ to Mid-Supply RLOAD = Open l l 125 5 250 125 mV mV Swing Output Low (with Respect to V–) RLOAD = 1kΩ to Mid-Supply RLOAD = Open l l 250 150 400 225 mV mV tON Turn-On Time VSHDN = 0V to 5V 1 μs tOFF Turn-Off Time VSHDN = 5V to 0V 1 μs 4 31 Ω l 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, –55°C < TA < 150°C for MP-grade parts, otherwise specifications are at TA = 25°C. V+ = 5V, GND = 0V, VCM = 12V, VREF = floating, VSHDN = floating, unless otherwise specified. See Figure 2. SYMBOL PARAMETER CONDITIONS VSENSE Full-Scale Input Sense Voltage (Note 7) VSENSE = V+IN – V–IN LT1999-10 LT1999-20 LT1999-50 VCM CM Input Voltage Range MAX UNITS l l l –0.35 –0.2 –0.08 MIN TYP 0.35 0.2 0.08 V V V l –5 80 V RIN(DIFF) Differential Input Impedance ΔVINDIFF = ±2V/GAIN l 6.4 8 RINCM CM Input Impedance ΔVCM = 5.5V to 80V ΔVCM = –5V to 4.5V l l 5 3.6 20 4.8 VOSI Input Referred Voltage Offset ±500 l –750 –2000 ΔVOSI /ΔT Input Referred Voltage Offset Drift AV Gain LT1999-10 LT1999-20 LT1999-50 l l l 9.95 19.9 49.75 9.6 kΩ 6 MΩ kΩ 750 2000 μV μV 8 10 20 50 μV/°C 10.05 20.1 50.25 V/V V/V V/V AV Error Gain Error ΔVOUT = ±2V l –0.5 ±0.2 0.5 % IB Input Bias Current I(+IN) = I(–IN) (Note 8) VCM > 5.5V VCM = –5V VSHDN = 0.5V, 0V < VCM < 80V l l l 100 –2.35 137.5 –1.95 0.001 180 –1.5 10 μA mA μA IOS Input Offset Current IOS = I(+IN) – I(–IN) (Note 8) VCM > 5.5V VCM = –5V VSHDN = 0.5V, 0V < VCM < 80V l l l –1 –10 –10 1 10 10 μA μA μA PSRR Supply Rejection Ratio V+ = 4.5V to 5.5V l 68 77 dB CMRR Sense Input Common Mode Rejection VCM = –5V to 80V VCM = –5V to 5.5V VCM = 12V, 7VP-P, f = 100kHz, VCM = 0V, 7VP-P, f = 100kHz l l l l 96 96 75 80 105 120 90 100 dB dB dB dB en Differential Input Referred Noise Voltage Density f= 10kHz f = 0.1Hz to 10Hz 97 8 nV/√Hz μVP-P REFRR REF Pin Rejection, V+ = 5.5V ΔVREF = 2.75V ΔVREF = 3.25V ΔVREF = 3.25V dB dB dB LT1999-10 LT1999-20 LT1999-50 l l l 62 62 62 70 70 70 VSHDN = 0.5V l l 60 0.15 80 0.4 100 0.65 kΩ MΩ VSHDN = 0.5V l l 2.45 0.25 2.5 2.5 2.55 2.75 V V 1.5 1.125 1.125 V+ – 1.25 V+ – 1.125 V+ – 1.125 V V V RREF REF Pin Input Impedance VREF Open Circuit Voltage VREFR REF Pin Input Range (Note 9) LT1999-10 LT1999-20 LT1999-50 l l l ISHDN Pin Pull-Up Current V+ = 5.5V, VSHDN = 0V l –6 V+ – 0.5 VIH SHDN Pin Input High l VIL SHDN Pin Input Low l f3dB Small Signal Bandwidth SR Slew Rate tS Settling Time Due to Input Step, ΔVOUT = ±2V –2 μA V 0.5 V LT1999-10 LT1999-20 LT1999-50 2 2 1.2 MHz MHz MHz 3 V/μs 0.5% Settling 2.5 μs 1999fd For more information www.linear.com/LT1999 5 LT1999-10/LT1999-20/ LT1999-50 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, –55°C < TA < 150°C for MP-grade parts, otherwise specifications are at TA = 25°C. V+ = 5V, GND = 0V, VCM = 12V, VREF = floating, VSHDN = floating, unless otherwise specified. See Figure 2. SYMBOL PARAMETER CONDITIONS MIN tr Common Mode Step Recovery Time ΔVCM = ±50V, 20ns (Note 10) LT1999-10 LT1999-20 LT1999-50 VS Supply Voltage (Note 11) IS Supply Current VCM > 5.5V VCM = –5V V+ = 5.5V, VSHDN = 0.5V, VCM > 0V TYP MAX 0.8 1 1.3 l 4.5 l l l UNITS μs μs μs 5 5.5 V 1.55 5.8 3 1.9 7.1 25 mA mA μA 40 mA RO Output Impedance ΔIO = ±2mA ISRC Sourcing Output Current RLOAD = 50Ω to GND l 3 ISNK Sinking Output Current RLOAD = 50Ω to V+ l 10 26 40 mA VOUT Swing Output High (with Respect to V+) RLOAD = 1kΩ to Mid-Supply RLOAD = Open l l 125 5 250 125 mV mV Swing Output Low (with Respect to V –) RLOAD = 1kΩ to Mid-Supply RLOAD = Open l l 250 150 400 225 mV mV tON Turn-On Time VSHDN = 0V to 5V 1 μs tOFF Turn-Off Time VSHDN = 5V to 0V 1 μs Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Pin 2 (+IN) and Pin 3 (–IN) are protected by ESD voltage clamps which have asymmetric bidirectional breakdown characteristics with respect to the GND pin (Pin 5). These pins can safely support common mode voltages which vary from –5.25V to 88V without triggering an ESD clamp. Note 3: Exposure to differential sense voltages exceeding the normal operating range for extended periods of time may degrade part performance. A heat sink may be required to keep the junction temperature below the Absolute Maximum Rating when the inputs are stressed differentially. The amount of power dissipated in the LT1999 due to input overdrive can be approximated by: PDISS = ( V+IN − V−IN )2 8kΩ Note 4: A heat sink may be required to keep the junction temperature below the absolute maximum rating. Note 5: The LT1999C/LT1999I are guaranteed functional over the operating temperature range –40°C to 85°C. The LT1999H is guaranteed functional over the operating temperature range –40°C to 125°C. The LT1999MP is guaranteed functional over the operating temperature range –55°C to 150°C. Junction temperatures greater than 125°C will promote accelerated aging. The LT1999 has a demonstrated typical life beyond 1000 hours at 150°C. Note 6: The LT1999C is guaranteed to meet specified performance from 0°C to 70°C. The LT1999C 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 LT1999I is guaranteed to meet specified performance from –40°C to 85°C. The LT1999H is guaranteed to meet specified performance from –40°C to 125°C. The LT1999MP is guaranteed to meet specified performance from –55°C to 150°C. 6 0.15 31 Ω Note 7: Full-scale sense (VSENSE) gives indication of the maximum differential input that can be applied with better than 0.5% gain accuracy. Gain accuracy is degraded when the output saturates against either power supply rail. VSENSE is verified with V+ = 5.5V, VCM = 12V, with the REF pin set to it’s voltage range limits. The maximum VSENSE is verified with the REF pin set to it’s minimum specified limit, verifying the gain error is less than 0.5% at the output. The minimum VSENSE is verified with the REF pin set to its maximum specified limit, verifying the gain error at the output is less than 0.5%. See Note 9 for more information. Note 8: IB is defined as the average of the input bias currents to the +IN and –IN pins (Pins 2 and 3). A positive current indicates current flowing into the pin. IOS is defined as the difference of the input bias currents. IOS = I(+IN) – I(–IN) Note 9: The REF pin voltage range is the minimum and maximum limits that ensures the input referred voltage offset does not exceed ±3mV over the I, C, and H temperature ranges, and ±3.5mV over the MP temperature range. Note 10: Common mode recovery time is defined as the time it takes the output of the LT1999 to recover from a 50V, 20ns input common mode voltage transition, and settle to within the DC amplifier specifications. Note 11: Operating the LT1999 with V+ < 4.5V is possible, although the LT1999 is not tested or specified in this condition. See the Applications Information section. 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Typical Performance Characteristics Supply Current vs Input Common Mode 7 Supply Current vs Temperature 1.8 V+ = 5V 6 VSHDN = OPEN VINDIFF = 0V VCM = 12V 150°C 130°C 90°C 25°C –45°C –55°C 3.5 1.7 5 3.0 3 2 IS (mA) 2.5 4 IS (mA) IS (mA) Supply Current vs Supply Voltage 4.0 1.6 V+ = 5.5V 1.5 VCM = 12V 2.0 1.5 V+ = 4.5V 1.0 1 0.5 0 –5 5 15 25 35 45 VCM (V) 55 65 1.4 –55 –30 75 80 20 45 70 95 TEMPERATURE (°C) 0 120 145 0 2 3 SUPPLY VOLTAGE (V) 1 10 V+ = 5V VCM = 12V 8 1 Shutdown Input Bias Current vs Input Common Mode 1000 VSHDN = 0V VINDIFF = 0V VCM = 12V V+ = 5V VSHDN = 0V VSENSE = 0V TA = 150°C TA =130°C 6 V+ = 5.5V 4 TA =110°C IB (nA) IS (µA) IS (mA) 100 TA = 150°C TA = 90°C 10 0.01 0.001 TA = 25°C 0 1 TA = 70°C TA = –55°C 3 2 VSHDN (V) 4 0 –55 –30 5 –5 20 45 70 95 TEMPERATURE (°C) 1999 G04 146 V+ = 5V IMPEDANCE (kΩ) IB (µA) IB (mA) VCM = 80V 140 138 VCM = 5.5V 136 –1.5 5 15 25 35 45 VCM (V) 55 65 75 80 1999 G07 132 –55 –30 –5 100 80 1999 G06 1000 100 DIFFERENTIAL INPUT IMPEDANCE 10 134 –5 60 40 VCM (V) COMMON MODE INPUT IMPEDANCE 10000 142 –1.0 20 100000 VSHDN = OPEN VINDIFF = 0V 144 V+ = 5V –0.5 0 Input Impedance vs Input Common Mode Voltage Input Bias Current vs Temperature 0 –2.0 1 120 145 1999 G05 Input Bias Current vs Input Common Mode 0.5 V+ = 4.5V 2 5 1999 G03 Shutdown Supply Current vs Temperature 0.1 4 1999 G02 1999 G01 Supply Current vs SHDN Pin Voltage 10 –5 20 45 70 95 TEMPERATURE (°C) 120 145 1999 G08 1 –5 5 15 25 35 45 VCM (V) 55 65 75 1999 G09 1999fd For more information www.linear.com/LT1999 7 LT1999-10/LT1999-20/ LT1999-50 Typical Performance Characteristics Input Referred Voltage Offset vs Temperature and Gain Option 1500 Input Referred Voltage Offset vs Input Common Mode Voltage 1500 VCM = 12V 12 UNITS PLOTTED 1000 1000 500 VOSI (µV) 500 VOSI (µV) V+ = 5V TA = 25°C 12 UNITS PLOTTED 0 0 –500 –500 –1000 –1500 –55 –30 –5 LT1999-10 LT1999-20 LT1999-50 –1000 LT1999-10 LT1999-20 LT1999-50 20 45 70 95 TEMPERATURE (°C) –1500 120 145 –5 5 15 25 1999 G10 25 GAIN GAIN (dB) 135 30 90 25 45 20 0 VOUT = 0.5VP-P AT 1kHz 10 100 1000 FREQUENCY (kHz) 135 GAIN 90 45 PHASE 15 0 –90 5 –90 –135 0 0 –5 180 –45 –45 1 1999 G11 10 5 –10 –5 –180 10000 –135 VOUT = 0.5VP-P AT 1kHz 1 10 LT1999-50 Small Signal Frequency Response 1999 G13 135 90 45 PHASE 20 0 15 –45 10 –90 5 GAIN ERROR (%) 25 VOUT = 0.5VP-P AT 1kHz 10 100 1000 FREQUENCY (kHz) –180 10000 LT1999-10 LT1999-20 LT1999-50 –5 20 45 70 95 TEMPERATURE (°C) 120 145 1999 G14 8 0 –0.25 –0.25 –0.50 –55 –30 V+ = 5V TA = 25°C 12 UNITS PLOTTED 0.25 0 –135 1 0.50 VCM = 12V 12 UNITS PLOTTED 0.25 PHASE (DEG) GAIN (dB) 30 0 0.50 GAIN ERROR (%) GAIN 35 Gain Error vs Input Common Mode Voltage Gain Error vs Temperature 180 –180 10000 100 1000 FREQUENCY (kHz) 1999 G12 40 75 PHASE (DEG) PHASE 35 PHASE (DEG) 15 180 GAIN (dB) 30 10 65 55 LT1999-20 Small Signal Frequency Response LT1999-10 Small Signal Frequency Response 20 35 45 VCM (V) 1999 G15 –0.50 LT1999-10 LT1999-20 LT1999-50 –5 5 15 25 35 45 VCM (V) 55 65 75 1999 G16 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Typical Performance Characteristics LT1999-10 Pulse Response LT1999-20 Pulse Response VOUT 4.5 0.075 4.0 0 –0.025 OUTPUT ERROR 1.0 1999 G20 TIME (1µs/DIV) VOUT (V) 2.5 0.15 VOUT 0.10 3.0 0.05 2.5 0 2.0 –0.050 1.5 –0.075 1.0 –0.100 0.5 –0.05 OUTPUT ERROR OUTPUT ERROR (V) 0.025 0.20 3.5 0.050 OUTPUT ERROR (V) VOUT (V) 0.100 3.0 0.5 VSENSE (0.1V/DIV) VSENSE (0.2V/DIV) VSENSE (0.5V/DIV) 4.5 1.5 1999 G19 TIME (2µs/DIV) LT1999-20 2V Step Response Settling Time LT1999-10 2V Step Response Settling Time 2.0 VOUT 1999 G18 TIME (2µs/DIV) VOUT (1V/DIV) VOUT 1999 G17 3.5 VOUT (1V/DIV) VOUT (1V/DIV) VOUT 4.0 VSENSE VSENSE VSENSE TIME (2µs/DIV) LT1999-50 Pulse Response –0.01 –0.15 –1 0 1 2 3 4 5 6 TIME (1µs/DIV) 7 8 9 10 –0.20 1999 G21 LT1999-50 2V Step Response Settling Time 0.500 4.0 0.375 VOUT 0 2.0 –0.125 OUTPUT ERROR –0.250 –0.375 1.0 TIME (1µs/DIV) LT1999-10 LT1999-20 LT1999-50 LT1999-10 LT1999-20 LT1999-50 100 1999 G22 –0.500 80 80 CMRR (dB) 2.5 OUTPUT ERROR (V) 0.125 0.5 100 CMRR vs Frequency 120 0.250 3.0 1.5 120 CMRR (dB) 3.5 VOUT (V) CMRR vs Frequency 4.5 60 40 40 VCM = 12V 20 V+ = 5V TA = 25°C 6 UNITS PLOTTED 0 1000 1 10 100 FREQUENCY (kHz) 60 VCM = 0V V+ = 5V TA = 25°C 6 UNITS PLOTTED 20 10000 1999 G23 0 1 10 100 1000 FREQUENCY (kHz) 10000 1999 G24 1999fd For more information www.linear.com/LT1999 9 LT1999-10/LT1999-20/ LT1999-50 Typical Performance Characteristics LT1999-10 Common Mode Rising Edge Step Response LT1999-10 Common Mode Falling Edge Step Response VCM , tRISE ≈ 20ns VOUT (0.5V/DIV) VCM (25V/DIV) VCM (25V/DIV) VOUT (0.5V/DIV) VCM , tFALL ≈ 20ns VOUT VOUT 1999 G25 TIME (0.5µs/DIV) 1999 G26 TIME (0.5µs/DIV) LT1999-20 Common Mode Rising Edge Step Response LT1999-20 Common Mode Falling Edge Step Response VOUT (0.5V/DIV) VCM , tFALL ≈ 20ns VOUT VCM (25V/DIV) VCM (25V/DIV) VOUT (0.5V/DIV) VCM , tRISE ≈ 20ns VOUT 1999 G27 TIME (0.5µs/DIV) 1999 G28 TIME (0.5µs/DIV) LT1999-50 Comm Step Response LT1999-50 Common Mode Falling Edge Step Response VCM tRISE
20ns VOUT (0.5V/DIV) VCM , tFALL ≈ 20ns VCM (25V/DIV) VCM (25V/DIV) VOUT (0.5V/DIV) VCM , tRISE ≈ 20ns VOUT VOUT (0.5 V / div) LT1999-50 Common Mode Rising Edge Step Response TIM VOUT TIME (0.5µs/DIV) 10 1999 G29 TIME (0.5µs/DIV) 1999 G30 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Typical Performance Characteristics LT1999 Input Referred Noise Density vs Frequency Short-Circuit Current vs Temperature 1000 3.0 40 30 SINKING REF PIN VOLTAGE (V) ISC (mA) 100 10 0 –10 –20 SOURCING 0.1 1 10 FREQUENCY (kHz) 1000 10000 –5 20 45 70 95 TEMPERATURE (°C) 1999 G31 0 1.5 1.0 V+ = 5V 0 –55 –30 –5 120 145 20 45 70 95 TEMPERATURE (°C) Turn-On/Turn-Off Time vs SHDN Voltage V+ = 5V VCM = 12V VCM = 12V IS (1mA/DIV) TA = 150°C TA = 25°C TA = –55°C SHDN PIN VOLTAGE (5V/DIV) IS –1 –2 SHUTDOWN –3 VSHDN –4 6 0 1 2 3 VSHDN (V) 4 5 1999 G35 TIME (1µs/DIV) 1999 G34 VOUT vs VSENSE Over the Sense ABSMAX Range VOUT vs VSENSE 6 VREF = 2.5V 5 4 4 3 3 VOUT (V) 5 2 1 VOUT PHASE REVERSAL FOR VSENSE < –25V 2 1 LT1999-10 LT1999-20 LT1999-50 0 –1 –0.25 120 145 1999 G33 1999 G32 SHDN Pin Current vs SHDN Pin Voltage and Temperature ISHDN (µA) 0.01 –40 –55 –30 SHDN MODE 2.0 0.5 –30 10 0.001 ACTIVE MODE 2.5 20 VOUT (V) NOISE DENSITY (nV/√Hz) REF Open Circuit Voltage vs Temperature –0.15 0.05 –0.05 VSENSE (V) 0.15 0.25 LT1999-10 LT1999-20 LT1999-50 0 VREF = 2.5V –1 –60 –30 1999 G36 0 VSENSE (V) 30 60 1999 G37 1999fd For more information www.linear.com/LT1999 11 LT1999-10/LT1999-20/ LT1999-50 Pin Functions (LT1999-XX/LT1999-XXF) V+ (Pins 1, 4/Pin 4): Power Supply Voltage. Pins 1 and 4 are tied internally together. The specified range of operation is 4.5V to 5.5V, but lower supply voltages (down to approximately 4V) is possible although the LT1999 is not tested or characterized below 4.5V. See the Applications Information section. OUT (Pin 7/Pin 7): Voltage Output. VOUT = AV •(VSENSE ± VOSI), where AV is the gain, and VOSI is the input referred offset voltage. The output amplifier has a low impedance output and is designed to drive up to 200pF capacitive loads directly. Capacitive loads exceeding 200pF should be decoupled with an external resistor of at least 100Ω. +IN (Pin 2/Pin 1): Positive Sense Input Pin. SHDN (Pin 8/Pin 8): Shutdown Pin. When pulled to within 0.5V of GND (Pin 5), will place the LT1999 into low power shutdown. If the pin is left floating, an internal 2µA pullup current source will place the LT1999 into the active (amplifying) state. –IN (Pin 3/Pin 2): Negative Sense Input Pin. NC (NA/Pin 3) GND (Pin 5/Pin 5): Ground Pin. REF (Pin 6/Pin 6): Reference Pin Input. The REF pin sets the output common mode level and is set halfway between V+ and GND using a divider made of two 160k resistors. The default open circuit potential of the REF pin is mid-supply. It can be overdriven by an external voltage source cable of driving 80k to a mid-supply potential (see the Electrical Characteristics table for its specified input voltage range). 12 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Block Diagram V+ LT1999 2µA V+ 1 2 3 4k V+ RG 2 – + 0.8k 4k V+ 2µA 0.8k 4k 8 SHDN + – 0.8k RG – + 7 V+ 7 V+ 160k 0.8k 4k 1 8 SHDN + – V+ LT1999-XXF 160k 6 3 NC 6 160k 160k V+ V+ 5 4 5 4 1999 BD 1999 BD Figure 1. Simplified Block Diagram Test Circuit V+ LT1999 + – VCM + – + – + – 4k V + + 0.8k VIN(DIFF) – 4k 3 V+ 5V 8 V SHDN SHDN 2 + – 2µA 1 0.8k 4k 1 V+ 5V VCM RG – + + – V+ + – 4k 2 7 V OUT V+ 3 160k 6 160k 4 2µA 0.8k VREF 0.8k 8 V SHDN SHDN VIN(DIFF) + – V+ LT1999F + – RG – + 7 V OUT V+ NC 160k 6 0.1µF V+ 5V 5 0.1µF 160k 4 VREF 0.1µF 5 0.1µF 1999 F02 1999 F02 Figure 2. Test Circuit 1999fd For more information www.linear.com/LT1999 13 LT1999-10/LT1999-20/ LT1999-50 Applications Information The LT1999 current sense amplifier provides accurate bidirectional monitoring of current through a user-selected sense resistor. The voltage generated by the current flowing in the sense resistor is amplified by a fixed gain of 10V/V, 20V/V or 50V/V (LT1999-10, LT1999-20, or LT1999-50 respectively) and is level shifted to the OUT pin. The voltage difference and polarity of the OUT pin with respect to REF (Pin 6) indicates magnitude and direction of the current in the sense resistor. Theory of Operation Refer to the Block Diagram (Figure 1). Case 1: V+ < VCM < 80V For input common mode voltages exceeding the power supply, one can assume D1 of Figure 1 is completely off. The sensed voltage (VSENSE) is applied across Pin 2 (+IN) and Pin 3 (–IN) to matched resistors R+IN and R– IN (nominally 4k each). The opposite ends of R+IN and R– IN are forced to equal potentials by transconductor GIN, which convert the differentially sensed voltage into a sensed current. The sensed current in R+IN and R– IN is combined, level-shifted, and converted back into a voltage by transresistance amplifier AO and resistor RG. Amplifier AO provides high open loop gain to accurately convert the sensed current back into a voltage and to drive external loads. The theoretical output voltage is determined by the sensed voltage (VSENSE), and the ratio of two on-chip resistors: VOUT − VREF = VSENSE • RG RIN Case 2: –5V < VCM < V+ For common mode inputs which transition or are set below the supply voltage, diode D1 will turn on and will provide a source of current through R+S and R –S to bias the inputs of transconductance amplifier GIN at least 2.25V above GND. The transition is smooth and continuous; there are negligible changes to either gain or amplifier voltage offset. The only difference in amplifier operation is the bias currents provided by D1 through R+S and R– S are steered through the input pins, otherwise amplifier operation is identical. The inputs to transconductance amplifier GIN are still forced to equal potentials forcing any differential voltages appearing at the +IN and –IN pins into a differential current. This differential current is combined, level-shifted, and converted back into a voltage by trans-resistance amplifier AO and Resistor RG. Resistors R+S and R– S are trimmed to match R+IN and R– IN respectively, to prevent common mode to differential conversion from occurring (to the extent of the matched trim) when the input common mode transitions below V+. As described in case 1, the output is determined by the sense voltage and the ratio of two on-chip resistors: VOUT − VREF = VSENSE • RG RIN where where RIN = The voltage difference between the OUT pin and the REF pin represent both polarity and magnitude of the sensed voltage. The noninverting input of amplifier AO is biased by a resistive 160k to 160k divider tied between V+ and GND to set the default REF pin bias to mid-supply. R +IN + R −IN nominally 4k 2 RIN = R +IN + R −IN 2 For the LT1999-10, RG is nominally 40k. For the LT1999-20, RG is nominally 80k, and for the LT1999-50, RG is nominally 200k. 14 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Applications Information Input Common Mode Range –2.0 With the V+ supply configured within the specified and tested range (4.5V < V+ < 5.5V), the LT1999’s common mode range extends from –5V to 80V. Pushing +IN and –IN beyond the limits specified in the Absolute Maximum table can turn on the voltage clamps designed to protect the +IN and –IN pins during ESD events. It is possible to operate the LT1999 on power supplies as low as 4V (although it is not tested or specified below 4.5V). Operating the LT1999 on supplies below 4V will produce erratic behavior. When operating the LT1999 with supplies as low as 4V, the common mode range for inputs which extend below GND is reduced. Refer to the Block Diagram (Figure 1). For inputs driven below V+, diode D1 conducts. For proper operation, the input to the transconductor V(G+IN) must be biased at approximately 2.25V above the GND pin. V(G+IN) sits on the centertap of a voltage divider comprised of R+S and R+IN V(G –IN) likewise sits in the middle of the voltage divider comprised of R – S , and R–IN). The voltage on V(G+IN) input is given by the following equation: V(G +IN) = V +IN• ( ) R +S R +IN + V + −VD1 • R +S + R +IN R +S + R +IN Setting V(G+IN) = 2.25V, the ratio (R+IN /R+S) to 5, and VD1 equal to 0.8V (cold temperatures), a plot of the lower input common mode range plotted against supply is shown in Figure 3. –2.5 VCM(LOWER LIMIT) (V) The LT1999 was optimized for high common mode rejection. Its input stage is balanced and fully differential, designed to amplify differential signals and reject common mode signals. There is negligible crossover distortion due to sense voltage reversals. The amplifier is most linear in the zero-sense region. BELOW GROUND INPUT COMMON MODE RANGE LIMITED BY V+ SUPPLY VOLTAGE –3.0 –3.5 –4.0 BELOW GROUND INPUT COMMON MODE RANGE LIMITED BY ESD CLAMPS –4.5 –5.0 –5.5 –6.0 TYPICAL ESD CLAMP VOLTAGE 4 4.25 4.5 5 4.75 SUPPLY VOLTAGE (V) 5.25 5.5 1999 F03 Figure 3. Lower Input Common Mode vs Supply Voltage Output Common Mode Range The LT1999’s output common mode level is set by the voltage on the REF pin. The REF pin sits in the middle of a 160k to 160k voltage divider connected between V+ and GND which sets the default open circuit potential of the REF pin to mid-supply. It can be overdriven by an external voltage source capable of driving 80k tied to a mid-supply potential. See the Electrical Characteristics table for the REF pin’s specified input voltage range. Differential sampling of the OUT pin with respect the REF pin provides the best noise immunity. Measurements of the output voltage made differentially with respect to the REF pin will provide the highest power supply and common mode rejection. Otherwise, power supply or GND pin disturbances are divided by the REF pin’s voltage divider and appear directly at the noninverting input of the transresistance amplifier AO and are not rejected. If not driven by a low impedance ( 5V, OUT will be at 5V. In the range of 4V < –IN < 5V, OUT may go to either V+ or GND, depending on the voltage applied to +IN. The open input (–IN) is biased internal to the IC to one diode below V+. 3 NC YES The circuit behaves normally. 4 V+ YES The circuit will behave as if powered off. 5 GND YES OUT, REF will float up towards 3.9V. 6 REF YES The circuit behaves normally with more broadband noise on OUT. BEHAVIOR 7 OUT YES No VOUT signal. 8 SHDN YES The low power shutdown feature will not function, otherwise the circuit behaves normally in the active state. FMEA information in this document (not limited to, but including the description of behavior under specific pin-connection conditions) is provided for convenience only. Ultimately, the end-user is responsible for verifying proper and reliable operation in each actual application. Linear Technology assumes no liability whatsoever with providing this information. 1999fd For more information www.linear.com/LT1999 19 LT1999-10/LT1999-20/ LT1999-50 Applications Information Fuse Monitor The inputs can be overdriven without fear of damaging the LT1999. This makes the LT1999 ideal for monitoring fuses if either +IN or –IN are shorted to ground while the other is at the full common mode supply voltage (see Figure 6). If the fuse in Figure 6 opens with the +IN tied to the positive supply, the load will pull –IN to GND. The output will be forced to the positive V+ supply rail. If it is desired that the output be near ground if the fuse opens, it is a simple matter of swapping the inputs. Precautions should be followed: First, when the inputs are stressed differentially due to the fuse blowing open, a large voltage drop will be placed across the +IN to –IN pins, dissipating VS V+ LT1999 2µA 1 VSHDN + – 4k V+IN 2 VOUT VREF STEERING DIODE V+ FUSE 8 SHDN ILOAD LOAD Finally, the user should be aware that in fuse monitoring applications with the sense voltage (VSENSE = V+IN – V–IN) being driven in excess of –25V, the output of the LT1999 will undergo phase reversal (see Figure 7). V+ 5V ON OFF power in the precision on-chip input resistors. Precaution should be taken to prevent junction temperatures from exceeding the Absolute Maximum ratings (see Note 3 in the Electrical Characteristics section). Secondly, if the load is inductive, and the fuse blows open without a clamp diode, energy stored in the inductive load will be dissipated in the LT1999, which could cause damage. A simple steering diode as shown in Figure 6 will prevent this from happening, and will protect the LT1999 from damage. VSHDN RG – + 0.8k 7 VOUT V+ RSENSE V–IN 3 4k 0.8k 160k 6 V+ 5V 160k 4 VREF 0.1µF 5 0.1µF 1999 F05 Figure 6. Using the LT1999 to Monitor a Fuse VOUT (1V/DIV) VOUT PHASE REVERSAL FOR VSENSE < –25V VREF = 2.5V –60 –45 –30 –15 0 15 VSENSE (V) 30 45 60 1999 F06 Figure 7. A Plot of the LT1999’s Output Voltage vs VSENSE (VSENSE = V+IN – V– IN). In Applications Where the Sense Voltage Is Driven in Excess of –25V, the Output of the LT1999 Will Undergo Phase Reversal 20 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Typical Applications Solenoid Current Monitor Bidirectional PWM Motor Monitor The solenoid of Figure 8 consists of a coil of wire in an iron case with permeable plunger that acts as a movable element. When the MOSFET turns on, the diode is reversed biased off, and current flows through RSENSE to actuate the solenoid. If the MOSFET is turned off, the current in the MOSFET is interrupted, but the energy stored in the solenoid causes the diode to turn on and current to freewheel in the loop consisting of the diode, RSENSE and the solenoid. Pulse width modulation is commonly used to efficiently vary the average voltage applied across a DC motor. The H-bridge topology of Figure 10 allows full 4-quadrant control: clockwise control, counter-clockwise control, clockwise regeneration, and counter-clockwise regeneration. The LT1999 in conjunction with a non-inductive current shunt is used to monitor currents in the rotor. The LT1999 can be used to detect stuck rotors, provide detection of overcurrent conditions in general, or provide current mode feedback control. Figure 8 shows the LT1999 monitoring currents in a ground referenced solenoid used when the coil is hard tied to the case, and is tied to ground. Figure 9 shows a supply referenced solenoid whose coil is insulated from the case. The LT1999 will interface equally well to either of these two configurations. VS V+ LT1999 V+ 5V 2µA 1 V+IN + – 4k 2 V + 0.8k VSHDN RG – + 7 VOUT V–IN 4k 3 5V V+ 0.8k 160k 6 0.1µF 160k 4 VREF 2.5V VOUT V+IN (10V/DIV) V+ RSENSE SOLENOID 8 SHDN VOUT (0.5V/DIV) OFF ON Figure 11 shows a plot of the output voltage of the LT1999. SOLENOID RELEASES SOLENOID PLUNGER PULLS IN V+IN 5 0.1µF 1999 F07a TIME (50ms/DIV) 1999 F07b Figure 8. Solenoid Current Monitor for Ground Tied Solenoid. The Common Mode Inputs to the LT1999 Switch Between VS and One Diode Drop Below Ground 1999fd For more information www.linear.com/LT1999 21 LT1999-10/LT1999-20/ LT1999-50 Typical Applications V+ LT1999 VS 1 2µA V+ SOLENOID V+IN + – 4k 2 + V 0.8k – + 7 VOUT 3 5V 4 4k V+ 0.8k 160k 6 VREF 160k 0.1µF 2.5V VOUT V+IN (10V/DIV) V–IN ON VSHDN RG V+ RSENSE OFF 8 SHDN VOUT (0.5V/DIV) 5V SOLENOID RELEASES SOLENOID PLUNGER PULLS IN V+IN 5 0.1µF 1999 F08a TIME (50ms/DIV) 1999 F08b Figure 9. Solenoid Current Monitor for Non-Grounded Solenoids. This Circuit Performs the Same Function as Figure 7 Except One End of the Solenoid Is Tied to VS. The Common Mode Voltage of Inputs of the LT1999 Switch Between Ground and One Diode Drop Above VS 22 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Typical Applications 5V V+ 10µF V+ LT1999-20 1 2µA SHDN + – 24V 4k 2 V+IN C4 1000µF 0.8k 80k V–IN 3 0.1µF – + 7 4k 0.8k 160k 6 160k 5V V+ 5V OUTA DIRECTION VOUT VREF 0.1µF 5 4 PWM INPUT VSHDN V+ VBRIDGE H-BRIDGE RSENSE 0.025Ω 1999 F09 24V MOTOR OUTB BRAKE INPUT GND Figure 10. Armature Current Monitor for DC Motor Applications VOUT 2.5V V+IN (20V/DIV) VOUT (2V/DIV) PWM IN V+ 8 V+IN TIME (20µs/DIV) 1999 F10 Figure 11. LT1999 Output Waveforms for the Circuit of Figure 10 1999fd For more information www.linear.com/LT1999 23 LT1999-10/LT1999-20/ LT1999-50 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660 Rev G) 3.00 ±0.102 (.118 ±.004) (NOTE 3) 0.889 ±0.127 (.035 ±.005) 0.254 (.010) 8 7 6 5 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) DETAIL “A” 0.52 (.0205) REF 0° – 6° TYP GAUGE PLANE 5.10 (.201) MIN 3.20 – 3.45 (.126 – .136) 1 0.53 ±0.152 (.021 ±.006) DETAIL “A” 4 0.86 (.034) REF 0.18 (.007) 0.65 (.0256) BSC 0.42 ± 0.038 (.0165 ±.0015) TYP 2 3 1.10 (.043) MAX SEATING PLANE RECOMMENDED SOLDER PAD LAYOUT 0.22 – 0.38 (.009 – .015) TYP 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 0.65 (.0256) BSC 0.1016 ±0.0508 (.004 ±.002) MSOP (MS8) 0213 REV G S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610 Rev G) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 .010 – .020 × 45° (0.254 – 0.508) NOTE: 1. DIMENSIONS IN 2 .053 – .069 (1.346 – 1.752) 0°– 8° TYP .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) 4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE 24 5 .150 – .157 (3.810 – 3.988) NOTE 3 1 RECOMMENDED SOLDER PAD LAYOUT .016 – .050 (0.406 – 1.270) 6 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP .008 – .010 (0.203 – 0.254) 7 3 4 .004 – .010 (0.101 – 0.254) .050 (1.270) BSC SO8 REV G 0212 1999fd For more information www.linear.com/LT1999 LT1999-10/LT1999-20/ LT1999-50 Revision History REV DATE DESCRIPTION A 5/11 Revised +IN and –IN pin descriptions in Pin Functions section 12 B 3/12 C 2/15 PAGE NUMBER Revised Voltage Output Swing Low specification (VOUT) under a loaded condition of 1kΩ to mid-supply. 4, 6 Updated Figure 4 to multicolor. 16 Addition of MSOP Pinout Option Engineered for FMEA All Correction to AV Specification for LT1999-50 from 48.75 to 49.75 5 Update to Pin Functions to include Pinout Option Engineered for FMEA Addition of New Application Information "Pinout Option Engineered for FMEA" Addition of Figure 5 and Renumbering of Figures 6 to 11 D 6/15 12 18, 19 18 to 23 Addition of Table 1 and Table 2 19 LT1999F added to Figure 1 (Simplified Block Diagram) 13 LT1999F added to Figure 2 (Test Circuit) 14 Additional test condition (VCM = 80) added to table 1 and table 2 19 Note added regarding the use of FMEA information 19 1999fd 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. For more information www.linear.com/LT1999 25 LT1999-10/LT1999-20/ LT1999-50 Typical Application Battery Charge Current and Load Current Monitor VOUT = 0.25V/A, Maximum Measured Current ±9.5A 0.025Ω CHARGER BAT 42V V+ LT1999-10 LOAD V+ 5V 2µA 1 V+IN SHDN + – 4k 2 + V 0.8k 8 VSHDN 7 VOUT 3 4k 0.8k V+ 5V – + 160k 0.1µF + +IN VOUT 6 VREF 160k 10µF – VCC VREF LTC2433-1 –IN CS SCK SDO 0.1µF 5 4 0.1µF 0.1µF 40k V+ V–IN 5V 1999 TA02 Related Parts PART NUMBER DESCRIPTION COMMENTS LT1787/ LT1787HV Precision, Bidirectional High Side Current Sense Amplifier 2.7V to 60V Operation, 75μV Offset, 60μA Current Draw LT6100 Gain-Selectable High Side Current Sense Amplifier 4.1V to 48V Operation, Pin-Selectable Gain: 10V/V, 12.5V/V, 20V/V, 25V/V, 40V/V, 50V/V LTC6101/ LTC6101HV High Voltage High Side Current Sense Amplifier 4V to 60V/5V to 100V Operation, External Resistor Set Gain, SOT23 LTC6102/ LTC6102HV Zero Drift High Side Current Sense Amplifier 4V to 60V/5V to 100V Operation, ±10μV Offset, 1μs Step Response, MSOP8/DFN Packages LTC6103 Dual High Side Precision Current Sense Amplifier 4V to 60V, Gain Configurable, 8-Pin MSOP Package LTC6104 Bidirectional, High Side Current Sense 4V to 60V, Gain Configurable, 8-Pin MSOP Package LT6106 Low Cost, High Side Precision Current Sense Amplifier 2.7V to 36V, Gain Configurable, SOT23 Package LT6105 Precision, Extended Input Range Current Sense Amplifier –0.3 to 44V, Gain Configurable, 8-Pin MSOP Package LTC4150 Coulomb Counter/Battery Gas Gauge Indicates Charge Quantity and Polarity LT1990 Precision, 100μA Gain Selectable Amplifier 2.7V to 36V Operation, CMRR > 70dB, Input Voltage = ±250V LT1991 ±250V Input Range Difference Amplifier 2.7V to 36V Operation, 50μV Offset, CMRR > 75B, Input Voltage = ±60V LT1637/LT1638 1.1/1.2MHz, 0.4V/μs Over-The-Top, Rail-to-Rail Input and Output Amplifier 26 Linear Technology Corporation 0.4V/μs Slew Rate, 230μA per Amplifier 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LT1999 FAX: (408) (408)434-0507 434-0507 ●lwww.linear.com/LT1999 www.linear.com (408) 432-1900 ●l FAX: 1999fd LT 0615 REV D • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2010