Precision Low Drift SOT-23 Voltage Reference with Shutdown ADR318 Initial accuracy: 5 mV maximum, 0.27% maximum Low temperature coefficient: 25 ppm/C maximum Load regulation: 100 ppm/mA Line regulation: 25 ppm/V Low supply headroom: 0.6 V Wide operating range: (VOUT + 0.6 V) to 15 V Low power: 120 A maximum Shutdown to less than 3 A maximum Output current: 5 mA Wide temperature range: 0C to 70C Tiny 5-lead SOT-23 package PIN CONFIGURATION SHDN 1 VIN 2 VOUT(SENSE) 3 5 GND 4 VOUT(FORCE) ADR318 TOP VIEW (Not to Scale) 03431-001 FEATURES Figure 1. 5-Lead SOT-23 APPLICATIONS Battery-powered instrumentation Portable medical instruments Data acquisition systems Industrial process control systems Fault protection critical systems GENERAL DESCRIPTION The ADR318 is a precision 1.8 V band gap voltage reference featuring high accuracy, high stability, and low power consumption in a tiny footprint. Patented temperature drift curvature correction techniques minimize nonlinearity of the voltage change with temperature. The wide operating range and low power consumption with additional shutdown capability make the part ideal for battery-powered applications. The VOUT (SENSE) pin enables greater accuracy by supporting full Kelvin operation in PCBs employing thin or long traces. above the output voltage. This device is specified over the industrial operating range of 0C to 70C, and is available in a tiny 5-lead SOT-23 package. The combination of VOUT (SENSE) and shutdown functions also enables a number of unique applications, combining precision reference/regulation with fault decision and overcurrent protection. See the Applications section for details. The ADR318 is a low dropout voltage (LDV) device that provides a stable output voltage from supplies as low as 600 mV Rev. A 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 (c)2006 Analog Devices, Inc. All rights reserved. ADR318 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation .........................................................................9 Applications....................................................................................... 1 Device Power Dissipation Considerations.................................9 Pin Configuration............................................................................. 1 Shutdown Mode Operation .........................................................9 General Description ......................................................................... 1 Applications..................................................................................... 10 Revision History ............................................................................... 2 Basic Voltage Reference Connection ....................................... 10 Specifications..................................................................................... 3 Electrical Characteristics............................................................. 3 Precision Negative Voltage Reference Without Precision Resistors....................................................................................... 10 Absolute Maximum Ratings............................................................ 4 General-Purpose Current Source ............................................ 10 Thermal Resistance ...................................................................... 4 High Power Performance with Current Limit ........................... 10 ESD Caution.................................................................................. 4 Outline Dimensions ....................................................................... 12 Typical Performance Characteristics ............................................. 5 Ordering Guide .......................................................................... 12 Terminology ...................................................................................... 8 REVISION HISTORY 10/06--Rev. 0 to Rev. A Updated Format..................................................................Universal Changes to Ordering Guide .......................................................... 12 Updated Outline Dimensions ....................................................... 12 1/03--Revision 0: Initial Version Rev. A | Page 2 of 12 ADR318 SPECIFICATIONS ELECTRICAL CHARACTERISTICS TA = TMIN to TMAX, VIN = 5 V, unless otherwise noted 1 . Table 1. Parameter Initial Accuracy Initial Accuracy Error Temperature Coefficient Minimum Supply Voltage Headroom Line Regulation Symbol VO VOERR TCVO VIN - VOUT VOUT/VIN Load Regulation VOUT/ILOAD Quiescent Current ISY Voltage Noise Turn-On Settling Time Long-Term Stability 2 Output Voltage Hysteresis Ripple Rejection Ratio Short Circuit to Ground eN tR VOUT VO_HYS RRR ISC Shutdown Supply Current Shutdown Logic Input Current Shutdown Logic Low Shutdown Logic High ISHDN ILOGIC VINL VINH 1 2 Conditions Min 1.795 -0.27 0C to 70C Typ 1.8 5 Max 1.802 +0.27 25 10 25 Unit V % ppm/C mV ppm/V 100 ppm/mA 120 140 A A V p-p s ppm/1000 hours ppm dB mA mA A nA V V 600 VIN = 2.5 V to 15 V, 0C < TA < 70C VIN = 3 V, ILOAD = 0 mA to 5 mA, 0C < TA < 70C No load 0C < TA < 70C 0.1 Hz to 10 Hz 100 5 20 50 40 85 25 30 fIN = 60 Hz VIN = 5.0 V VIN = 15.0 V 3 500 0.8 2.4 TMIN = 0C, TMAX = 70C. The long-term stability specification is noncumulative. The drift in subsequent 1000-hour periods is significantly lower than in the first 1000-hour period. Rev. A | Page 3 of 12 ADR318 ABSOLUTE MAXIMUM RATINGS At 25C, unless otherwise noted. Table 2. Parameter Supply Voltage Output Short-Circuit Duration to GND Storage Temperature Range: RJ-5 Package Operating Temperature Range Junction Temperature Range: RJ-5 Package Lead Temperature Range (Soldering, 60 sec) Rating 18 V Observe derating curves -65C to +125C 0C to 70C -65C to +150C 300C 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 RESISTANCE JA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 3. Thermal Resistance Package Type 5-Lead SOT-23 (RJ-5) ESD CAUTION Rev. A | Page 4 of 12 JA 230 JC 146 Unit C/W ADR318 TYPICAL PERFORMANCE CHARACTERISTICS 1.802 0 1.801 1.800 MEAN 1.799 1.798 MEAN - STANDARD DEVIATION 0 10 20 30 40 50 60 70 TEMPERATURE (C) -10 -15 -20 -25 03431-002 VOUT (V) MEAN + STANDARD DEVIATION -5 0 10 20 30 40 50 60 70 TEMPERATURE (C) Figure 2. Typical Output Voltage vs. Temperature 03431-005 LINE REGULATION (ppm/mV) VIN = 2.5V TO 15V Figure 5. Line Regulation vs. Temperature 110 2.5 2.3 0C VIN_MIN (V) 25C 90 0C 25C 2.1 70C 70 2.5 5.0 7.5 10.0 15.0 12.5 INPUT VOLTAGE (V) 1.7 0 1 2 3 4 5 LOAD CURRENT (mA) Figure 3. Supply Current vs. Input Voltage Figure 6. Minimum Input Voltage vs. Load Current VOLTAGE (2mV/DIV) -40 10V -50 -60 2.5V -80 0 10 20 30 40 50 TEMPERATURE (C) 60 70 Figure 4. Load Regulation vs. Temperature TIME (400ms/DIV) Figure 7. Typical Output Voltage Noise 0.1 Hz to 10 Hz Rev. A | Page 5 of 12 03431-007 -70 03431-004 LOAD REGULATION (ppm/mA) -30 03431-006 1.9 80 03431-003 SUPPLY CURRENT (A) 70C 100 ADR318 VL LOAD ON IL = 5mA IL = 0mA 03431-011 TIME (10ms/DIV) LOAD OFF 03431-008 VOLTAGE (10mV/DIV) VOLTAGE (200mV/DIV) VOUT TIME (200s/DIV) Figure 8. Typical Output Voltage Noise 10 Hz to 10 kHz Figure 11. Load Transient Response, CL = 0 nF VIN TIME (40s/DIV) LOAD OFF VL LOAD ON IL = 5mA IL = 0mA 03431-012 VOLTAGE (200mV/DIV) VOUT 03431-009 VOLTAGE (50mV/DIV) VOUT TIME (200s/DIV) Figure 9. Line Transient Response, CBYPASS = 0 F Figure 12. Load Transient Response, CL = 1 nF VIN TIME (40s/DIV) LOAD OFF VL LOAD ON IL = 5mA IL = 0mA TIME (200s/DIV) Figure 10. Line Transient Response, CBYPASS = 0.1 F Figure 13. Load Transient Response, CL = 100 nF Rev. A | Page 6 of 12 03431-013 VOLTAGE (200mV/DIV) VOUT 03431-010 VOLTAGE (50mV/DIV) VOUT ADR318 VOUT TIME (40s/DIV) TIME (4s/DIV) Figure 14. Turn-On/Turn-Off Response at 5 V, RLOAD = 1.8 k Figure 16. Shutdown Pin Response VOUT 03431-015 VOLTAGE (2V/DIV) VIN TIME (100s/DIV) SHUTDOWN PIN Figure 15. Turn-On/Turn-Off Response at 5 V, RLOAD = 1.8 k, CBYPASS = 0.1 F Rev. A | Page 7 of 12 03431-016 VOLTAGE (1V/DIV) VOUT 03431-014 VOLTAGE (50mV/DIV) VIN ADR318 TERMINOLOGY Temperature Coefficient Temperature coefficient is the change of output voltage with respect to operating temperature changes, normalized by the output voltage at 25C. This parameter is expressed in ppm/C, and can be determined with the following equation: VO (T2 ) - VO (T1 ) ppm = x 10 6 TCVO C VO (25C ) x (T2 - T1 ) (1) where: where: VO(t0) = VO at 25C at Time 0. VO(t1) = VO at 25C after 1000 hours of operation at 25C. Thermal Hysteresis Thermal hysteresis is the change of output voltage after the device is cycled through temperature from +25C to -40C to +125C and back to +25C. This is a typical value from a sample of parts put through such a cycle. VO_HYS = VO(25C) - VO_TC VO(25C) = VO at 25C. VO _ HYS [ppm ] = VO(T1) = VO at Temperature 1. VO (25C ) - VO _ TC VO(T2) = VO at Temperature 2. Long-Term Stability Long-term stability is the typical shift of output voltage at 25C on a sample of parts subjected to a test of 1000 hours at 25C. VO = VO(t0) - VO(t1) VO [ppm ] = VO (t 0 ) - VO (t1 ) VO (t 0 ) x 106 VO (25C ) x 10 6 (3) where: VO(25C) = VO at 25C. VO_TC = VO at 25C after temperature cycle at +25C to -40C to +125C and back to +25C. (2) Rev. A | Page 8 of 12 ADR318 THEORY OF OPERATION Band gap references are the high performance solution for low supply voltage and low power voltage reference applications, and the ADR318 is no exception. The uniqueness of this lies in its architecture. By observing Figure 17, the ideal zero temperature coefficient (TC) band gap voltage is referenced to the output, not to ground. Therefore, if noise exists on the ground line, it is greatly attenuated on VOUT. The band gap cell consists of the PNP pair, Q51 and Q52, running at unequal current densities. The difference in voltage base emitter (VBE) results in a voltage with a positive TC that is amplified by the ratio of 2 x (R58/R54). This proportional-to-absolute temperature (PTAT) voltage, combined with VBE Q51 and VBE Q52, produces the stable band gap voltage. Reduction in band gap curvature is performed by the ratio of the resistors R44 and R59, one of which is linearly temperature dependent. Precision laser-trimming and other patented circuit techniques are used to further enhance the drift performance. VIN Q1 Q51 R49 R53 TA = the ambient temperatures. PD = the device power dissipation. 03431-017 GND (4) TJ = the junction temperature. Q52 R61 JA where: R48 R60 T J - TA The ADR318 includes a shutdown feature that is TTL/CMOS compatible. A logic low or a 0 V condition on the SHDN pin is required to turn the device off. During shutdown, the output of the reference becomes a high impedance state where its potential would then be determined by external circuitry. If the shutdown feature is not used, the SHDN pin should be connected to VIN (Pin 2). R44 R54 SHDN PD = SHUTDOWN MODE OPERATION VOUT(FORCE) R58 The ADR318 is capable of delivering load currents up to 5 mA with an input voltage that ranges from 2.4 V to 15 V. When this device is used in applications with high input voltages, care should be taken to avoid exceeding the specified maximum power dissipation or junction temperature. Doing so results in premature device failure. The following formula should be used to calculate the device's maximum junction temperature or dissipation: JA = the device package thermal resistance. VOUT(SENSE) R59 DEVICE POWER DISSIPATION CONSIDERATIONS Figure 17. Simplified Schematic Rev. A | Page 9 of 12 ADR318 APPLICATIONS BASIC VOLTAGE REFERENCE CONNECTION GENERAL-PURPOSE CURRENT SOURCE The circuit in Figure 18 illustrates the basic configuration for the ADR318. Decoupling capacitors are not required for circuit stability. The ADR318 is capable of driving capacitative loads from 0 F to 10 F. However, a 0.1 F ceramic output capacitor is recommended to absorb and deliver the charge as is required by a dynamic load. Many times in low power applications, the need arises for a precision current source that can operate on low supply voltages. As shown in Figure 20, the ADR318 can be configured as a precision current source. The illustrated circuit configuration is a floating current source with a grounded load. The reference output voltage is bootstrapped across R1 that sets the output current into the load. With this configuration, circuit precision is maintained for load currents in the range of the reference supply current, typically 90 mA, to approximately 5 mA. The supply current is a function of ISET and increases slightly at a given ISET. ADR318 GND SHDN SHUTDOWN INPUT VIN CI 0.1F VOUT(S) VOUT(F) +VDD OUTPUT VIN 03431-018 U1 ADR318 Figure 18. Voltage Reference Connection SHDN VOUT(F) VOUT(S) PRECISION NEGATIVE VOLTAGE REFERENCE WITHOUT PRECISION RESISTORS GND R1 0.1F A negative reference can be easily generated by combining the ADR318 with an op amp. Figure 19 shows this simple negative reference configuration. VOUT(F) and VOUT(S) are at virtual ground and therefore the negative reference can be taken directly from the output of the op amp. The op amp should be a dual-supply, low offset, rail-to-rail amplifier, such as the OP1177. ISY (ISET ) RL ISET ISY ADJ IOUT = ISET + ISV (ISET) 03431-020 CO 0.1F Figure 20. General-Purpose Current Source +VDD HIGH POWER PERFORMANCE WITH CURRENT LIMIT VIN In some cases, the user may want higher output current delivered to a load and still achieve better than 0.5% accuracy out of the ADR318. The accuracy for a reference is normally specified with no load (see the Specifications section). However, the output voltage changes with the load current. ADR318 VOUT(F) SHDN VOUT(S) GND -VSS 03431-019 -VREF OP1177 The circuit in Figure 21 provides high current without compromising the accuracy of the ADR318. The power bipolar junction transistor (BJT) Q1 provides the required current, up to 1 A. The ADR318 delivers the base drive to Q1 through the force pin. The sense pin of the ADR318 is a regulated output and is connected to the load. Figure 19. Negative Reference Rev. A | Page 10 of 12 ADR318 The transistor Q2 protects Q1 during short-circuit limit faults by robbing its base drive. The maximum current is IL, MAX = 0.6 V/RS. A similar circuit function can also be achieved using the Darlington transistor configuration, as shown in Figure 22. VIN VIN R1 4.7k VIN ADR318 SHDN VIN ADR318 SHDN GND GND VOUT(S) VOUT(F) VOUT(S) VOUT(F) Q1 Q1 Q2 RS Q2 RS RL 03431-021 RL 03431-022 R1 4.7k Figure 22. High Output Current with Darlington Drive Configuration Figure 21. High Power Performance with Current Limit Rev. A | Page 11 of 12 ADR318 OUTLINE DIMENSIONS 2.90 BSC 5 4 2.80 BSC 1.60 BSC 1 2 3 PIN 1 0.95 BSC 1.90 BSC 1.30 1.15 0.90 1.45 MAX 0.15 MAX 0.50 0.30 0.22 0.08 SEATING PLANE 10 5 0 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178-AA Figure 23. 5-Lead Small Outline Transistor Package [SOT-23] (RJ-5) Dimensions shown in millimeters ORDERING GUIDE Model ADR318ARJ-R2 ADR318ARJ-REEL ADR318ARJ-REEL7 ADR318ARJZ-REEL71 1 Temperature Range 0C to 70C 0C to 70C 0C to 70C 0C to 70C Package Description 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 Package Option RJ-5 RJ-5 RJ-5 RJ-5 Z = Pb-free part. (c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03431-0-10/06(A) Rev. A | Page 12 of 12 Branding REA REA REA L28 Output Voltage 1.800 V 1.800 V 1.800 V 1.800 V Ordering Quantity 250 10,000 3,000 3,000