LMP7312

LMP7312 Precision SPI-Programmable AFE with Differential/Single-Ended Input/Output June 18, 2010 LMP7312 Precision SPI-Programmable AFE with Differential/SingleEnded Input/Output General Description The LMP7312 is a digitally programmable variable gain amplifier/attenuator. Its wide input voltage range and superior precision make it a prime choice for applications requiring high accuracy such as data acquisition systems for IO modules in programmable logic control (PLC). The LMP7312 provides a differential output to maximize dynamic range and signal to noise ratio, thereby reducing the overall system error. It can also be configured to handle single ended input data converters by means of the VOCM pin (see application section for details). The inputs of LMP7312 can be configured in attenuation mode to handle large input signals of up to +/- 15V, as well as in amplification mode to handle current loops of 0-20mA and 4-20mA.The LMP7312 is equipped with a null switch to evaluate the offset of the internal amplifier. A guaranteed 0.035% maximum gain error (for all gains) and a maximum gain drift of 5ppm over the extended industrial temperature range (-40° to 125°C) make the LMP7312 very attractive for high precision systems even under harsh conditions. A low input offset voltage of 100µV and low voltage noise of 3µVpp give the LMP7312 a superior performance. The LMP7312 is fully specified from -40° to 125°C and is available in SOIC-14 package. Features Typical Values, TA = 25°C, V+=5V, V-=0V. 1 MHz ■ Gain bandwidth -15V to +15V ■ Input voltage range (G= 0.096 V/V) 100 µV (max) ■ Core op-amp input offset voltage 2 mA (max) ■ Supply current 0.096 V/V, 0.192 V/V ■ Gain (Attenuation Mode) 0.384 V/V, 0.768 V/V 1 V/V, 2 V/V ■ Gain (AmplificationMode) 0.035% (max) ■ Gain Error 90 dB (min) ■ Core op-amp PSRR 80 dB (min) ■ CMRR 1V to 4V ■ Adjustable output common mode −40 to 125°C ■ Temperature range 14-Pin SOIC ■ Package Applications ■ Signal conditioning AFE ■ ■ ■ ■ ■ ±10V; ±5V; 0-5V; 0-10V; 0-20mA; 4-20mA Data Acquisition systems Motor control Instrument and process control Remote sensing Programmable automation control Typical Application 30075513 LMP™ is a trademark of National Semiconductor Corporation. © 2010 National Semiconductor Corporation 300755 www.national.com LMP7312 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Rating (Note 2) Human Body Model Machine Body Model Charge device Model Analog Supply Voltage (VS = V+ - V-) DigitaI Supply Voltage (VDIO=VIO-V-) Attenuation pins -VIN, +VIN referred to VAmplification pins -IN, +IN referred to VVoltage at all other pins referred to VStorage Temperature Range 2000V 150V 1000V 6V 6V ±17.5V ±10V 6V -65°C to 150°C (Note 4) For soldering specification:  see product folder at www.national.com and  www.national.com/ms/MS/MS-SOLDERING.pdf Junction Temperature 150°C Operating Ratings V+ (Note 1) 4.5V to 5.5V 2.7V to 5.5V -15V to 15V -2.35V to 7.35V −40°C to 125°C 145°C/W Analog Supply Voltage (VS = – V-), V=0V Digital Supply Voltage (VDIO = VIO– V-), V-=0V Attenuation pins -VIN, +VIN referred to VAmplification pins -IN, +IN referred to VTemperature Range (Note 3) Package Thermal Resistance (Note 3) SOIC-14 5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TA = 25°C, V+ = 5V, VIO = 5V, V− = 0V, G = 0.192 V/V, VCM_ATT=(+VIN+(-VIN))/2, VCM_AMP=(+IN+(-IN))/2. Differential output configuration. SE = Single Ended Output, DE = Differential Output. Boldface limits apply at the temperature extremes. Symbol VOS Parameter Core op-amp Input Offset Voltage Conditions Nulling Switch Mode, DE, VOCM = 1V; Nulling switch Mode, SE, -VOUT/VR = 1V Nulling Switch Mode, DE, VOCM = 4V; Nulling Switch Mode, SE, -VOUT/VR = 4V TCVOS Core op-amp Input Offset Voltage (Note 7) Nulling Switch Mode, DE, VOCM = 1V; Nulling Switch Mode, SE, -VOUT/VR = 1V Nulling Switch Mode, DE, VOCM = 4V; Nulling Switch Mode, SE, -VOUT/VR = 4V All gains, RL = 10 kΩ, CL = 50pF, SE / DE SE / DE Min (Note 6) –100 –250 –100 –250 -3 -3 –0.035 –0.045 -5 ±1 7.25 3 2 120 62.08 40 248.3 160 kΩ ±1.5 ±1.5 Typ (Note 5) Max (Note 6) 100 250 100 250 3 3 0.035 0.045 5 µV/°C µV Units Av en Gain Error Gain Drift % ppm/°C nV/ µVPP mA μA kΩ Core op-amp Voltage RTI, Nulling Switch Mode, f = 10 kHz Noise Density Core op-amp Peak to RTI, Nulling Switch Mode, f= 0.1Hz to 10Hz Peak Voltage Noise IVA IVIO RIN_CM RIN_DIFF Analog Supply Current +VIN = −VIN = VOCM Digital Supply Current Without any load connected to SDO pin CM Input Resistance Differential Input Resistance G= 0.192 V/V G= 1 V/V G= 0.192 V/V G= 1 V/V G= 0.096V/V, -15V < VCM_ATT < 15V, SE / DE G= 0.192V/V, -11.4V < VCM_ATT < 15V, SE / DE DC Common Mode Rejection Ratio G= 0.384V/V, -6V < VCM_ATT < 11V, SE / DE G= 0.768V/V, -3V < VCM_ATT < 8V, SE / DE G= 1V/V, -2.3V < VCM_AMP < 7.3V, SE / DE G= 2V/V, -1.15V < VCM_AMP < 6.15V, SE / DE. 80 77 CMRR dB PSRR Core op-amp DC Power Supply Rejection Ratio Nulling Switch Mode, 4.5V