High Common-Mode Voltage, Programmable Gain Difference Amplifier AD628

Transcription

1 High Common-Mode Voltage, Programmable Gain Difference Amplifier AD628 FEATURES FUNCTIONAL BLOCK DIAGRAM High common-mode input voltage range ±20 V at VS = ±5 V Gain range 0. to 00 Operating temperature range: 40 C to +85 C Supply voltage range Dual supply: ±2.25 V to ±8 V Single supply: 4.5 V to 36 V Excellent ac and dc performance Offset temperature stability RTI: 0 μv/ C maximum Offset: ±.5 V mv maximum CMRR RTI: 75 db minimum, dc to 500 Hz, G = + IN +IN 8 +V S 7 00kΩ 0kΩ G = +0. IN 0kΩ A +IN 00kΩ 0kΩ R EXT2 R EXT R G 6 IN A2 +IN AD628 OUT 5 APPLICATIONS High voltage current shunt sensing Programmable logic controllers Analog input front end signal conditioning +5 V, +0 V, ±5 V, ±0 V, and 4 to 20 ma Isolation Sensor signal conditioning Power supply monitoring Electrohydraulic controls Motor controls GENERAL DESCRIPTION The AD628 is a precision difference amplifier that combines excellent dc performance with high common-mode rejection over a wide range of frequencies. When used to scale high voltages, it allows simple conversion of standard control voltages or currents for use with single-supply ADCs. A wideband feedback loop minimizes distortion effects due to capacitor charging of Σ-Δ ADCs. A reference pin (VREF) provides a dc offset for converting bipolar to single-sided signals. The AD628 converts +5 V, +0 V, ±5 V, ±0 V, and 4 to 20 ma input signals to a single-ended output within the input range of single-supply ADCs. The AD628 has an input common mode and differential mode operating range of ±20 V. The high common mode, input impedance makes the device well suited for high voltage measurements across a shunt resistor. The inverting input of the buffer amplifier is available for making a remote Kelvin connection. CMRR (db) V S V REF C FILT Figure. V S = ±5V k 0k 00k FREQUENCY (Hz) V S = ±2.5V Figure 2. CMRR vs. Frequency of the AD628 A precision 0 kω resistor connected to an external pin is provided for either a low-pass filter or to attenuate large differential input signals. A single capacitor implements a lowpass filter. The AD628 operates from single and dual supplies and is available in an 8-lead SOIC_N or an 8-lead MSOP. It operates over the standard industrial temperature range of 40 C to +85 C Rev. G Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

2 SPECIFICATIONS TA = 25 C, VS = ±5 V, RL = 2 kω, REXT = 0 kω, REXT2 =, VREF = 0 V, unless otherwise noted. Table. M DIFFERENTIAL AND OUTPUT AMPLIFIER Gain Equation G = +0. ( + REXT/REXT2) V/V Gain Range See Figure V/V Offset Voltage VCM = 0 V; RTI of input pins 2 ; mv output amplifier G = + vs. Temperature μv/ C CMRR 3 RTI of input pins; db G = +0. to +00 vs. Temperature 4 4 (μv/v)/ C PSRR (RTI) VS = ±0 V to ±8 V db Input Voltage Range Common Mode V Differential V Dynamic Response Small Signal Bandwidth 3 db G = khz Full Power Bandwidth 5 5 khz Settling Time G = +0., to 0.0%, 00 V step μs Slew Rate V/μs Noise (RTI) Spectral Density khz nv/ Hz 0. Hz to 0 Hz 5 5 μv p-p DIFFERENTIAL AMPLIFIER Gain V/V Error % vs. Temperature 5 5 ppm/ C Nonlinearity 5 5 ppm vs. Temperature ppm Offset Voltage RTI of input pins mv vs. Temperature 8 8 μv/ C Input Impedance Differential kω Common Mode kω CMRR 4 RTI of input pins; db G = +0. to +00 vs. Temperature 4 4 (μv/v)/ C Output Resistance 0 0 kω Error % Rev. G Page 3 of 20

3 M OUTPUT AMPLIFIER Gain Equation G = ( + REXT/REXT2) V/V Nonlinearity G = +, VOUT = ±0 V ppm Offset Voltage RTI of output amp mv vs. Temperature μv/ C Output Voltage Swing RL = 0 kω V RL = 2 kω V Bias Current na Offset Current na CMRR VCM = ±3 V db Open-Loop Gain VOUT = ±3 V db POWER SUPPLY Operating Range ±2.25 ±8 ±2.25 ±8 V Quiescent Current.6.6 ma TEMPERATURE RANGE C To use a lower gain, see the Ga in Adjustment section. 2 The addition of the difference amplifier and output amplifier offset voltage does not exceed this specification. 3 (0.)( V ) Error due to common mode as seen at the output: CM V OUT = [ Output AmplifierGain] (0.)( V Error due to common mode as seen at the output of A: = CM ) V OUT A Rev. G Page 4 of 20

4 TA = 25 C, VS = 5 V, RL = 2 kω, REXT = 0 kω, REXT2 =, VREF = 2.5 V, unless otherwise noted. Table 2. M DIFFERENTIAL AND OUTPUT AMPLIFIER Gain Equation G = +0.(+ REXT/REXT2) V/V Gain Range See Figure V/V Offset Voltage VCM = 2.25 V; RTI of input pins 2 ; mv output amplifier G = + vs. Temperature μv/ C CMRR 3 RTI of input pins; G = +0. to db vs. Temperature 4 4 (μv/v)/ C PSRR (RTI) VS = 4.5 V to 0 V db Input Voltage Range Common Mode V Differential V Dynamic Response Small Signal Bandwidth 3 db G = khz Full Power Bandwidth khz Settling Time G = +0.; to 0.0%, 30 V step 5 5 μs Slew Rate V/μs Noise (RTI) Spectral Density khz nv/ Hz 0. Hz to 0 Hz 5 5 μv p-p DIFFERENTIAL AMPLIFIER Gain V/V Error % Nonlinearity 3 3 ppm vs. Temperature ppm Offset Voltage RTI of input pins mv vs. Temperature 0 0 μv/ C Input Impedance Differential kω Common Mode kω CMRR 5 RTI of input pins; G = +0. to db vs. Temperature 4 4 (μv/v)/ C Output Resistance 0 0 kω Error % OUTPUT AMPLIFIER Gain Equation G = ( + REXT/REXT2) V/V Nonlinearity G = +, VOUT = V to 4 V ppm Output Offset Voltage RTI of output amplifier mv vs. Temperature μv/ C Output Voltage Swing RL = 0 kω V RL = 2 kω 4 4 V Bias Current na Offset Current na CMRR VCM = V to 4 V db Open-Loop Gain VOUT = V to 4 V db Rev. G Page 5 of 20

5 M POWER SUPPLY Operating Range ± ± V Quiescent Current.6.6 ma TEMPERATURE RANGE C To use a lower gain, see the Gain Adjustment section. 2 The addition of the difference amplifier and output amplifier offset voltage does not exceed this specification. 3 (0.)( V ) Error due to common mode as seen at the output: CM V OUT = [ Output AmplifierGain] Greater values of voltage are possible with greater or lesser values of VREF. 5 (0.)( V Error due to common mode as seen at the output of A: = CM ) V OUT A Rev. G Page 6 of 20

6 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter Rating Supply Voltage ±8 V Internal Power Dissipation See Figure 3 Input Voltage (Common Mode) ±20 V Differential Input Voltage ±20 V Output Short-Circuit Duration Indefinite Storage Temperature Range 65 C to +25 C Operating Temperature Range 40 C to +85 C Lead Temperature (Soldering, 0 sec) 300 C When using ±2 V supplies or higher, see the Input Voltage Range section. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. THERMAL CHARACTERISTICS.6.4 T J = 50 C POWER DISSIPATION (W) LEAD SOIC PACKAGE 8-LEAD MSOP PACKAGE MSOP θ JA (JEDEC; 4-LAYER BOARD) = C/W SOIC θ JA (JEDEC; 4-LAYER BOARD) = 54 C/W AMBIENT TEMPERATURE ( C) Figure 3. Maximum Power Dissipation vs. Temperature ESD CAUTION Rev. G Page 7 of 20

7 OUTLINE DIMENSIONS PIN 0.65 BSC COPLANARITY MAX SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-87-AA Figure Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters 5.00 (0.968) 4.80 (0.890) 4.00 (0.574) 3.80 (0.497) (0.244) 5.80 (0.2284) 0.25 (0.0098) 0.0 (0.0040) COPLANARITY 0.0 SEATING PLANE.27 (0.0500) BSC.75 (0.0688).35 (0.0532) 0.5 (0.020) 0.3 (0.022) 0.25 (0.0098) 0.7 (0.0067) 0.50 (0.096) 0.25 (0.0099).27 (0.0500) 0.40 (0.057) COMPLIANT TO JEDEC STANDARDS MS-02-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model Temperature Range Description Package Option Branding 40 C to +85 C 8-Lead SOIC_N R-8 -REEL 40 C to +85 C 8-Lead SOIC_N 3" Reel R-8 -REEL7 40 C to +85 C 8-Lead SOIC_N 7" Reel R-8 Z 40 C to +85 C 8-Lead SOIC_N R-8 Z-RL 40 C to +85 C 8-Lead SOIC_N 3" Reel R-8 Z-R7 40 C to +85 C 8-Lead SOIC_N 7" Reel R-8 M 40 C to +85 C 8-Lead MSOP RM-8 JGA M-REEL 40 C to +85 C 8-Lead MSOP 3" Reel RM-8 JGA M-REEL7 40 C to +85 C 8-Lead MSOP 7" Reel RM-8 JGA MZ 40 C to +85 C 8-Lead MSOP RM-8 JGZ MZ-RL 40 C to +85 C 8-Lead MSOP 3" Reel RM-8 JGZ MZ-R7 40 C to +85 C 8-Lead MSOP 7" Reel RM-8 JGZ AD628-EVAL Evaluation Board Z = RoHS Compliant Part Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C /07(G) A Rev. G Page 20 of 20