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| a FEATURES Initial Accuracy: 5 mV Max, 0.27% Max Low Temperature Coefficient: 25 ppm/ C Max 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 Max Shutdown to Less than 3 A Max Output Current: 5 mA Wide Temperature Range: 0 C to 70 C Tiny 5-Lead SOT-23 Package APPLICATIONS Battery Powered Instrumentation Portable Medical Instruments Data Acquisition Systems Industrial Process Control Systems Fault Protection Critical Systems Precision Low Drift SOT-23 Voltage Reference with Shutdown ADR318* PIN CONFIGURATION 5-Lead SOT-23 SHDN 1 VIN 2 ADR318 VOUT (SENSE) 3 4 -VOUT (FORCE) 5 GND 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. The ADR318 is a low dropout voltage (LDV) device that provides a stable output voltage from supplies as low as 600 mV above the output voltage. This device is specified over the industrial operating range of 0C to 70C, and is available in the 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. Details are provided in the Applications section. *Protected by U.S. Patent No. 5,969,657; other patents pending. 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. 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 companies. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 (c) 2003 Analog Devices, Inc. All rights reserved. ADR318-SPECIFICATIONS ELECTRICAL CHARACTERISTICS (T = T A MIN to TMAX,1 VIN = 5 V, unless otherwise noted.) Conditions Min 1.795 -0.27 0C to 70C 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 10 25 100 100 5 20 50 40 85 25 30 3 500 0.8 2.4 120 140 Typ 1.8 5 Max 1.802 +0.27 25 Unit V % ppm/C mV ppm/V ppm/mA A A V p-p s ppm/1,000 hrs ppm dB mA mA A nA V V Parameter Initial Accuracy Initial Accuracy Error Temperature Coefficient Minimum Supply Voltage Headroom Line Regulation Load Regulation Quiescent Current Voltage Noise Turn-On Settling Time Long Term Stability2 Output Voltage Hysteresis Ripple Rejection Ratio Short Circuit to Ground Shutdown Supply Current Shutdown Logic Input Current Shutdown Logic Low Shutdown Logic High Symbol VO VOERR TCVO VIN - VOUT VOUT/VIN VOUT/ILOAD ISY eN tR VOUT VO_HYS RRR ISC ISHDN ILOGIC VINL VINH fIN = 60 Hz VIN = 5.0 V VIN = 15.0 V NOTES 1 TMIN = 0C, TMAX = 70C 2 The long-term stability specification is noncumulative. The drift in subsequent 1,000 hour periods is significantly lower than in the first 1,000 hour period. Specifications subject to change without notice. -2- REV. 0 ADR318 ABSOLUTE MAXIMUM RATINGS 1, 2 Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V Output Short-Circuit Duration to GND . . . . . . . . . . . . . . . . . . . . . Observe Derating Curves Storage Temperature Range RJ Package . . . . . . . . . . . . . . . . . . . . . . . . . -65C to +125C Operating Temperature Range . . . . . . . . . . . . . . . 0C to 70C Junction Temperature Range RJ Package . . . . . . . . . . . . . . . . . . . . . . . . . -65C to +150C Lead Temperature Range Soldering, 60 sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300C NOTES 1 Absolute maximum ratings apply at 25C, unless otherwise noted. 2 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 listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package Type 5-Lead SOT-23 (RJ) JA JC Unit C/W 230 146 ORDERING GUIDE Model ADR318ARJ-REEL7 Temperature Range 0C to 70C Package Description 5-Lead SOT-23 Package Option RJ-5 Branding Information R0A Output Voltage 1.800 V Devices per Reel 3,000 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 the ADR318 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 -3- ADR318-Typical Performance Characteristics 1.802 110 70 C A -30 LOAD REGULATION - ppm/mA -40 10V 1.801 100 25 C 90 0C SUPPLY CURRENT - VOUT - V -50 1.800 -60 2.5V -70 1.799 80 1.798 0 10 20 30 40 50 TEMPERATURE - C 60 70 70 2.5 5.0 7.5 10.0 12.5 INPUT VOLTAGE - V 15.0 -80 0 10 20 30 40 50 TEMPERATURE - C 60 70 TPC 1. Typical Output Voltage vs. Temperature TPC 2. Supply Current vs. Input Voltage TPC 3. Load Regulation vs. Temperature 0 2.5 LINE REGULATION - ppm/mV -5 VOLTAGE - 2mV/DIV 5 2.3 VIN_MIN - V -10 0C 2.1 25 C -15 -20 1.9 70 C -25 0 10 20 30 40 50 TEMPERATURE - C 60 70 1.7 0 1 2 3 4 LOAD CURRENT - mA TIME - 400ms/DIV TPC 4. Line Regulation vs. Temperature TPC 5. Minimum Input Voltage vs. Load Current TPC 6. Typical Output Voltage Noise 0.1 Hz to 10 Hz VOLTAGE - 10mV/DIV VOLTAGE - 50mV/DIV TIME - 10ms/DIV TIME - 40 s/DIV VOLTAGE - 50mV/DIV TIME - 40 s/DIV TPC 7. Typical Output Voltage Noise 10 Hz to 10 kHz TPC 8. Line Transient Response, CBYPASS = 0 F TPC 9. Line Transient Response, CBYPASS = 0.1 F -4- REV. 0 ADR318 VOLTAGE - 200mV/DIV VOLTAGE - 200mV/DIV VOLTAGE - 200mV/DIV LOAD OFF LOAD ON LOAD OFF LOAD ON LOAD OFF LOAD ON TIME - 200 s/DIV TIME - 200 s/DIV TIME - 200 s/DIV TPC 10. Load Transient Response, CL = 0 nF TPC 11. Load Transient Response, CL = 1 nF TPC 12. Load Transient Response, CL = 100 nF VIN VIN VOUT VOLTAGE - 50mV/DIV VOLTAGE - 2V/DIV VOLTAGE - 1V/DIV VOUT VOUT SHUTDOWN PIN TIME - 40 s/DIV TIME - 100 s/DIV TIME - 4 s/DIV TPC 13. Turn On/Turn Off Response at 5 V, RLOAD = 1.8 k TPC 14. Turn On/Turn Off Response at 5 V, RLOAD = 1.8 k, CBYPASS = 0.1 F TPC 15. Shutdown Pin Response REV. 0 -5- ADR318 PARAMETER DEFINITIONS Temperature Coefficient THEORY OF OPERATION 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 6 TCVO = V (25C ) x (T - T ) x 10 C 2 1 O (1) where: VO(25C) = VO at 25C VO(T1) = VO at temperature 1 VO(T2) = VO at temperature 2 Long Term Stability 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 product lies in its architecture. By observing Figure 1, the ideal zero TC band gap voltage is referenced to the output, not to ground. Therefore, if noise exists on the ground line, it will be greatly attenuated on VOUT. The band gap cell consists of the PNP pair Q51 and Q52, running at unequal current densities. The difference in VBE results in a voltage with a positive TC that is amplified by the ratio of 2 R58/R54. This PTAT voltage, combined with the VBEs of Q51 and 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 Long term stability is the typical shift of output voltage at 25C on a sample of parts subjected to a test of 1,000 hours at 25C: VO = VO (t0 ) -VO (t1) VO [ ppm ] = where: VO(t0) = VO at 25C at time 0 VO(t1) = VO at 25C after 1,000 hours operation at 25C Thermal Hysteresis VO (t0 ) -VO (t1) VO (t0 ) Q1 VOUT(FORCE) VOUT(SENSE) x 106 (2) R59 R44 R58 R49 R54 R53 Q51 SHDN Q52 Thermal hystereses is defined as 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 _ HYS [ ppm ] = where: VO(25C) = VO at 25C VO_TC = VO at 25C after temperature cycle at +25C to -40C to +125C and back to +25C VO (25C ) -VO _ TC VO (25C ) R48 R60 R61 GND x 106 (3) Figure 1. Simplified Schematic Device Power Dissipation Considerations 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 that could result in premature device failure. The following formula should be used to calculate the device's maximum junction temperature or dissipation: PD = TJ - TA JA (4) In Equation 4, TJ and TA are, respectively, the junction and ambient temperatures, PD is the device power dissipation, and JA is the device package thermal resistance. Shutdown Mode Operation 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). -6- REV. 0 ADR318 APPLICATIONS Basic Voltage Reference Connection General-Purpose Current Source The circuit in Figure 2 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. SHUTDOWN INPUT CI 0.1 F SHDN VIN VOUT(S) GND ADR318 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 4, the ADR318 can be configured as a precision current source. The circuit configuration illustrated is a floating current source with a grounded load. The reference's output voltage is bootstrapped across R1, which sets the output current into the load. With this configuration, circuit precision is maintained for load currents in the range from the reference's supply current, typically 90 mA to approximately 5 mA. The supply current is a function of ISET and will increase slightly at a given ISET. +VDD VOUT(F) U1 OUTPUT CO 0.1 F SHDN VIN ADR318 VOUT(F) Figure 2. Voltage Reference Connection Precision Negative Voltage Reference without Precision Resistors VOUT(S) GND 0.1 F ISY (ISET) ISY ADJ R1 ISET A negative reference can be easily generated by combining the ADR318 with an op amp. Figure 3 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. +VDD RL IOUT = ISET + ISV (ISET) Figure 4. General-Purpose Current Source ADR318 VIN VOUT(F) SHDN VOUT(S) GND -VREF OP1177 -VSS Figure 3. Negative Reference REV. 0 -7- ADR318 High Power Performance with Current Limit 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 on the data sheet with no load. However, the output voltage changes with load current. The circuit in Figure 5 provides high current without compromising the accuracy of the ADR318. The power BJT Q1 provides the required current, up to a 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. 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. VIN A similar circuit function can also be achieved using the Darlington transistor configuration, as shown in Figure 6. VIN ADR318 R1 4.7k SHDN VOUT(S) GND VOUT(F) Q1 Q2 RS RL ADR318 R1 4.7k VIN SHDN Figure 6. High Output Current with Darlington Drive Configuration GND VOUT(S) VOUT(F) Q2 RS Q1 RL Figure 5. High Power Performance with Current Limit OUTLINE DIMENSIONS 5-Lead Plastic Surface-Mount Package [SOT-23] (RJ-5) Dimensions shown in millimeters 2.90 BSC 5 4 1.60 BSC 1 2 3 2.80 BSC PIN 1 0.95 BSC 1.30 1.15 0.90 1.90 BSC 1.45 MAX 10 0 0.15 MAX 0.50 0.30 SEATING PLANE 0.22 0.08 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178AA -8- REV. 0 PRINTED IN U.S.A. C03431-0-1/03(0) VIN |
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