Low Power, Precision Auto-Zero Op Amp AD8538 Low offset voltage: 13 μV maximum Input offset drift: 0.03 μV/°C Single-supply operation: 2.7 V to 5.5 V High gain, CMRR, and PSRR Low input bias current: 25 pA Low supply current: 180 μA PIN CONFIGURATION DIAGRAMS OUT 1 5 V+ 4 –IN AD8538 V– 2 +IN 3 TOP VIEW (Not to Scale) 05624-002 FEATURES Figure 1. 5-Lead TSOT-23 (UJ-5) APPLICATIONS NC 1 −IN 2 AD8538 8 NC 7 V+ +IN 3 V− 6 OUT TOP VIEW 4 (Not to Scale) 5 NC NC = NO CONNECT 05624-001 Mobile communications Portable instrumentation Battery-powered devices Sensor interfaces Temperature measurement Electronic scales Figure 2. 8-Lead SOIC_N (R-8) GENERAL DESCRIPTION The AD8538 is a very high precision amplifier featuring extremely low offset voltage, low input bias current, and low power consumption. The supply current is less than 180 μA at 5.0 V. Operation is fully specified from 2.7 V to 5.0 V single supply (±1.35 V to ±2.5 V dual supply). The AD8538 operates using very low power making this amplifier ideal for battery-powered devices and portable equipment. The AD8538 is specified over the extended industrial temperature range (−40°C to +125°C). The AD8538 amplifier is available in 5-lead TSOT-23, and 8-lead, narrow body SOIC packages. Rev. 0 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. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved. AD8538 TABLE OF CONTENTS Features .............................................................................................. 1 Absolute Maximum Ratings ............................................................5 Applications....................................................................................... 1 Thermal Resistance .......................................................................5 Pin Configuration Diagrams........................................................... 1 ESD Caution...................................................................................5 General Description ......................................................................... 1 Typical Performance Characteristics ..............................................6 Revision History ............................................................................... 2 Outline Dimensions ....................................................................... 12 Specifications..................................................................................... 3 Ordering Guide .......................................................................... 12 Electrical Specifications............................................................... 3 REVISION HISTORY 10/05—Revision 0: Initial Version Rev. 0 | Page 2 of 12 AD8538 SPECIFICATIONS ELECTRICAL SPECIFICATIONS @VS = 5.0 V, VCM = 2.5 V, VO = 2.5 V, TA = 25°C, unless otherwise specified. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol Conditions Min VOS Typ Max Unit 5 13 30 25 100 1.0 50 150 5 μV μV pA pA nA pA pA V dB dB dB dB μV/°C −40°C ≤ TA ≤ +125°C Input Bias Current IB 15 35 0.7 20 −40°C ≤ TA ≤ +85°C −40°C ≤ TA ≤ +125°C Input Offset Current IOS −40°C ≤ TA ≤ +125°C Input Voltage Range Common-Mode Rejection Ratio CMRR Large Signal Voltage Gain AVO Offset Voltage Drift ΔVOS/ΔT OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Short-Circuit Limit POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time 0.01% Overload Recovery Time Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density VOH VOL VCM = 0 V to 5 V −40°C ≤ TA ≤ +125°C; VCM = 0.2 V to 4.8 V RL = 10 kΩ, VO = 0.1 V to 4.9 V −40°C ≤ TA ≤ +125°C −40°C ≤ TA ≤ +125°C 0 115 100 115 110 RL = 100 kΩ to ground −40°C ≤ TA ≤ +125°C RL = 10 kΩ to ground −40°C ≤ TA ≤ +125°C RL = 100 kΩ to V+ −40°C ≤ TA ≤ +125°C RL = 10 kΩ to V+ −40°C ≤ TA ≤ +125°C 4.99 4.98 4.95 4.94 VS = 2.7 V to 5.0 V −40°C ≤ TA ≤ +125°C IO = 0 −40°C ≤ TA ≤ +125°C 105 100 ISY SR tS RL =10 kΩ G = ±1, 2 V step, CL = 20 pF, RL = 1 kΩ GBP ØO en p-p en 0.1 4.998 4.970 1.9 2.8 17 20 ±25 ISC PSRR 150 135 141 135 0.03 125 125 150 190 5 7 20 30 180 215 V V V V mV mV mV mV mA dB dB μA μA RL = 10 kΩ, RL = 100 kΩ, CL = 20 pF 0.4 10 0.05 600 65 V/μs μs ms kHz Degrees f = 0.1 Hz to 10 Hz f = 1 kHz 2.0 50 μV p-p nV/√Hz Rev. 0 | Page 3 of 12 AD8538 @ VS = 2.7 V, VCM = 1.35 V, VO = 1.35 V, TA = 25°C, unless otherwise specified. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol Conditions Min VOS Typ Max Unit 5 13 30 25 100 1.0 50 150 2.7 μV μV pA pA nA pA pA V dB dB dB dB μV/°C −40°C ≤ TA ≤ +125°C Input Bias Current IB 15 35 0.7 20 −40°C ≤ TA ≤ +85°C −40°C ≤ TA ≤ +125°C Input Offset Current IOS −40°C ≤ TA ≤ +125°C Input Voltage Range Common-Mode Rejection Ratio CMRR Large Signal Voltage Gain AVO Offset Voltage Drift ΔVOS/ΔT OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Short-Circuit Limit POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time 0.01% Overload Recovery Time Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density VOH VOL VCM = 0 V to 2.5 V −40°C ≤ TA ≤ +125°C RL = 10 kΩ, VO = 0.1 V to 1.7 V −40°C ≤ TA ≤ +125°C −40°C ≤ TA ≤ +125°C 0 110 100 110 105 RL = 100 kΩ to ground −40°C ≤ TA ≤ +125°C RL = 10 kΩ to ground −40°C ≤ TA ≤ +125°C RL = 100 kΩ to V+ −40°C ≤ TA ≤ +125°C RL = 10 kΩ to V+ −40°C ≤ TA ≤ +125°C 2.68 2.68 2.67 2.66 VS = 2.7 V to 5.5 V −40°C ≤ TA ≤ +125°C IO = 0 −40°C ≤ TA ≤ +125°C 105 100 ISY SR tS RL = 10 kΩ G = ±1, 1 V step, CL = 20 pF, RL = 1 kΩ GBP ØO en p-p en 0.1 2.698 2.68 1.7 2.4 14 20 ±8 ISC PSRR 140 135 140 135 0.03 125 125 150 190 5 5 20 25 180 215 V V V V mV mV mV mV mA dB dB μA μA RL = 10 kΩ, RL = 100 kΩ, CL = 20 pF 0.4 5 0.05 600 65 V/μs μs ms kHz Degrees f = 0.1 Hz to 10 Hz f = 1 kHz 2.0 50 μV p-p nV/√Hz Rev. 0 | Page 4 of 12 AD8538 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration to GND Storage Temperature Range Lead Temperature (Soldering, 60 sec) Operating Temperature Range Junction Temperature Range Rating +6 V VSS − 0.3 V to VDD + 0.3 V ±6 V Observe derating curve –65°C to +150°C 300°C –40°C to +125°C −65°C to +150°C 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. Absolute maximum ratings apply at 25°C, unless otherwise noted. THERMAL RESISTANCE θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 4. Thermal Characteristics Package Type 5-Lead TSOT-23 (UJ-5) 8-Lead SOIC_N (R-8) θJA 207 158 ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. 0 | Page 5 of 12 θJC 61 43 Unit °C/W °C/W AD8538 TYPICAL PERFORMANCE CHARACTERISTICS VSY = 5 V or ±2.5 V, unless otherwise noted. 400 VSY = 5V AND 2.7V 600 350 INPUT BIAS CURRENT (pA) NUMBER OF AMPLIFIERS 700 VSY = 5V 0V < VCM < 5V TA = 25°C 300 250 200 150 100 0 –10.0 –8.4 –6.8 –5.2 –3.6 –2.0 –0.4 1.2 2.8 4.4 6.0 7.6 9.2 400 300 200 100 05624-003 50 500 05624-006 450 0 25 45 65 TA = 25°C 140 SUPPLY CURRENT (µA) 8 6 4 0.012 0.024 0.036 0.048 0.060 0.072 0.084 100 80 60 40 0 0.096 05624-007 20 05624-004 2 120 0 5 4 VSY = 5V SUPPLY CURRENT (µA) 6 4 2 0 –2 –4 150 VSY = 2.7V 100 50 –6 05624-005 INPUT OFFSET VOLTAGE (µV) 3 200 VSY = 5V TA = 25°C 8 2 Figure 7. Supply Current vs. Supply Voltage Figure 4. Input Offset Voltage Drift Distribution 10 1 SUPPLY VOLTAGE (V) TCVOS (µV/°C) –8 –10 0 1 2 3 4 0 –40 5 05624-008 NUMBER OF AMPLIFIERS 10 0 125 160 VSY = 5V –40°C < TA < +125°C 12 0 105 Figure 6. Input Bias Current vs. Temperature Figure 3. Input Offset Voltage Distribution 14 85 TEMPERATURE (°C) INPUT OFFSET VOLTAGE (µV) 10 60 TEMPERATURE (°C) INPUT COMMON-MODE VOLTAGE (V) Figure 8. Supply Current vs. Temperature Figure 5. Input Offset Voltage vs. Input Common-Mode Voltage Rev. 0 | Page 6 of 12 110 AD8538 70 50 OPEN-LOOP GAIN (dB) VSY – VOH 100 VOL 10 SOURCE 1 30 0.01 0.001 45 20 ФM 10 0 0 SINK 0.1 90 40 0.01 0.1 1 –10 –20 1k 10 VSY = ±2.5V AND ±1.35V RL = 100kΩ CL = 20pF 10k LOAD CURRENT (mA) FREQUENCY (Hz) Figure 9. Output Saturation Voltage vs. Load Current Figure 12. Open-Loop Gain and Phase vs. Frequency 120 VSY = 5V RL = 10kΩ 30 VSY = 5V AND 2.7V TA = 25°C 100 VSY – VOH 25 CMRR (dB) 80 20 VOL 15 60 40 10 0 –40 –25 –10 5 20 35 50 65 80 95 110 0 100 125 05624-013 20 5 05624-010 OUTPUT SATURATION VOLTAGE (mV) 35 1k 10k +PSRR AV = 10 60 –PSRR 40 AV = 1 –20 1k 20 10k 100k 0 100 1M 05624-014 0 VSY = ±2.5V AND ±1.35V TA = 25°C 80 AV = 100 PSRR (dB) 20 100 VSY = 5V AND 2.7V CL = 20pF RL = 2kΩ 05624-011 40 1M Figure 13. CMRR vs. Frequency Figure 10. Output Saturation Voltage vs. Temperature 60 100k FREQUENCY (Hz) TEMPERATURE (°C) CLOSED-LOOP GAIN (dB) –45 1M 100k 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) Figure 11. Closed-Loop Gain vs. Frequency Figure 14. PSRR vs. Frequency Rev. 0 | Page 7 of 12 1M OPEN-LOOP PHASE SHIFT (Degrees) 135 60 1000 05624-012 VSY = 5V TA = 25°C 05624-009 OUTPUT SATURATION VOLTAGE (mV) 10000 AD8538 1000 VOLTAGE (1V/DIV) AV = 100 100 OUTPUT IMPEDANCE (Ω) VSY = 5V AV = 1 CL = 300pF RL = 10kΩ VSY = 5V AND 2.7V AV = 10 10 AV = 1 1 05624-022 05624-017 0.1 0.01 100 1k 10k 100k 1M TIME (4µs/DIV) FREQUENCY (Hz) Figure 18. Large Signal Transient Response Figure 15. Closed-Loop Output Impedance vs. Frequency VSY = 5V TA = 25°C RL = 2kΩ VSY = 5V AV = –50 VIN (mV) 50 100 40 0 30 OS+ 0 10 1 100 05624-018 OS– 10 0 VOUT (V) 20 05624-015 SMALL SIGNAL OVERSHOOT (%) 60 –2.5 1000 TIME (10µs/DIV) LOAD CAPACITANCE (pF) Figure 16. Small Signal Overshoot vs. Load Capacitance Figure 19. Positive Overload Recovery VSY = 5V AND 2.7V AV = 1 CL = 300pF RL = 2kΩ VSY = 5V AV = –50 VOLTAGE (50mV/DIV) VIN (mV) 0 –100 VOUT (V) 2.5 05624-019 05624-016 0 TIME (10µs/DIV) TIME (4µs/DIV) Figure 17. Small Signal Transient Response Figure 20. Negative Overload Recovery Rev. 0 | Page 8 of 12 AD8538 VSY = 5V TA = 25°C VOLTAGE (1V/DIV) VIN 100 100 1k 10k 05624-023 10 10 VOUT VSY = 5V AV = 1 VIN = 6V p-p RL = 10kΩ 05624-021 VOLTAGE NOISE DENSITY (nV/√Hz) 1000 TIME (200µs/DIV) FREQUENCY (Hz) Figure 23. No Phase Reversal Figure 21. Voltage Noise Density 05624-020 VOLTAGE (500nV/DIV) VSY = 5V AND 2.7V TIME (1s/DIV) Figure 22. 0.1 Hz to 10 Hz Input Voltage Noise Rev. 0 | Page 9 of 12 AD8538 VS = 2.7 V or ±1.35 V. 10000 120 100 80 60 40 05624-024 20 0 –10.0 –8.4 –6.8 –5.2 –3.6 –2.0 –0.4 1.2 2.8 4.4 6.0 7.6 9.2 1000 100 10 SOURCE SINK 1 0.1 0.001 0.01 INPUT OFFSET VOLTAGE (µV) Figure 24. Input Offset Voltage Distribution Figure 27. Output Saturation Voltage vs. Load Current 30 NUMBER OF AMPLIFIERS 25 20 15 10 0 05624-025 5 0 VSY = 2.7V RL = 10kΩ 25 VSY = VOH 20 15 VOL 10 5 0 –40 0.012 0.024 0.036 0.048 0.060 0.072 0.084 0.096 05624-028 VSY = 2.7V –40°C < TA < +125°C OUTPUT SATURATION VOLTAGE (mV) 35 30 –25 –10 5 20 Figure 25. Input Offset Voltage Drift Distribution 65 80 95 110 125 80 SMALL SIGNAL OVERSHOOT (%) VSY = 2.7V 8 TA = 25°C 6 4 2 0 –2 –4 –6 05624-026 INPUT OFFSET VOLTAGE (µV) 50 Figure 28. Output Saturation Voltage vs. Temperature 10 –8 0 35 TEMPERATURE (°C) TCVOS (µV/°C) –10 1 0.1 LOAD CURRENT (mA) 0.5 1.0 1.5 2.0 2.5 VSY = 2.7V TA = 25°C 70 RL = 2kΩ 60 50 40 30 20 OS+ 10 0 OS– 1 10 100 LOAD CAPACITANCE (pF) INPUT COMMON-MODE VOLTAGE (V) Figure 26. Input Offset Voltage vs. Input Common-Mode Voltage Rev. 0 | Page 10 of 12 Figure 29. Small Signal Overshoot vs. Load Capacitance 05624-029 NUMBER OF AMPLIFIERS 140 VSY = 2.7V TA = 25°C 05624-027 VSY = 2.7V 0V < VCM < 2.7V 160 T = 25°C A OUTPUT SATURATION VOLTAGE (mV) 180 1000 AD8538 1000 TIME (4µs/DIV) VSY = 2.7V TA = 25°C 100 10 10 05624-032 05624-030 VOLTAGE (500mV/DIV) VOLTAGE NOISE DENSITY (nV/√Hz) VSY = 2.7V AV = 1 CL = 100pF RL = 10kΩ 100 1k 10k FREQUENCY (Hz) Figure 30. Large Signal Transient Response Figure 31. Voltage Noise Density Rev. 0 | Page 11 of 12 100k AD8538 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 2.90 BSC 5 8 4 4.00 (0.1574) 3.80 (0.1497) 1 2.80 BSC 1.60 BSC 1 2 1.27 (0.0500) BSC 0.95 BSC 0.25 (0.0098) 0.10 (0.0040) 1.90 BSC *1.00 MAX 0.10 MAX 6.20 (0.2440) 4 5.80 (0.2284) 3 PIN 1 *0.90 0.87 0.84 5 0.50 0.30 SEATING PLANE 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 0.20 0.08 8° 4° 0° 0.60 0.45 0.30 0.50 (0.0196) × 45° 0.25 (0.0099) 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012-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. *COMPLIANT TO JEDEC STANDARDS MO-193-AB WITH THE EXCEPTION OF PACKAGE HEIGHT AND THICKNESS. Figure 32. 5-Lead Thin Small Outline Transistor Package [TSOT_23] (UJ-5) Dimensions shown in millimeters Figure 33. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model AD8538AUJZ-R2 1 AD8538AUJZ-REEL1 AD8538AUJZ-REEL71 AD8538ARZ1 AD8538ARZ-REEL1 AD8538ARZ-REEL71 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 5-Lead TSOT-23 5-Lead TSOT-23 5-Lead TSOT-23 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N Package Option UJ-5 UJ-5 UJ-5 R-8 R-8 R-8 Branding AOC AOC AOC Z = Pb-free part. © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05624-0-10/05(0) T T Rev. 0 | Page 12 of 12