ADR121

Precision, Micropower LDO Voltage References in TSOT ADR121/ADR125/ADR127 FEATURES Initial accuracy A grade: ±0.24% B grade: ±0.12% Maximum tempco A grade: 25 ppm/°C B grade: 9 ppm/°C Low dropout: 300 mV for ADR121, ADR125 High output current: +5 mA/−2 mA Low typical operating current: 85 μA Input range: 2.7 V to 18 V Temperature range: −40°C to +125°C Tiny TSOT (UJ-6) package PIN CONFIGURATION NC1 1 6 NC1 GND 2 5 NC1 TOP VIEW (Not to Scale) VIN 3 4 VOUT ADR12x NC = NO CONNECT 1 MUST BE LEFT FLOATING Figure 1. APPLICATIONS Battery-powered instrumentation Portable medical equipment Data acquisition systems Automotive GENERAL DESCRIPTION The ADR121/ADR125/ADR127 are a family of micropower, high precision, series mode, band gap references with sink and source capability. The parts feature high accuracy and low power consumption in a tiny package. The ADR12x design includes a patented temperature drift curvature correction technique that minimizes the nonlinearities in the output voltage vs. temperature characteristics. The ADR12x is a low dropout voltage reference, requiring only 300 mV for ADR121/ADR125 and 1.45 V for ADR127 above the nominal output voltage on the input to provide a stable output voltage. This low dropout performance coupled with the low 85 μA operating current makes the ADR12x ideal for battery-powered applications. Available in an extended industrial temperature range of −40°C to +125°C, the ADR12x is housed in the tiny TSOT (UJ-6) package. 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 ©2006 Analog Devices, Inc. All rights reserved. 05725-001 ADR121/ADR125/ADR127 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configuration............................................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 ADR121 Electrical Characteristics............................................. 3 ADR125 Electrical Characteristics............................................. 4 ADR127 Electrical Characteristics............................................. 5 Absolute Maximum Ratings............................................................ 6 Thermal Resistance ...................................................................... 6 ESD Caution.................................................................................. 6 Terminology .......................................................................................7 Typical Performance Characteristics ..............................................8 Theory of Operation ...................................................................... 16 Power Dissipation Considerations........................................... 16 Notes ............................................................................................ 16 Applications..................................................................................... 17 Basic Voltage Reference Connection ....................................... 17 Stacking Reference ICs for Arbitrary Outputs ....................... 17 Negative Precision Reference Without Precision Resistors.. 17 General-Purpose Current Source ............................................ 17 Outline Dimensions ....................................................................... 18 Ordering Guide .......................................................................... 18 REVISION HISTORY 6/06—Revision 0: Initial Version Rev. 0 | Page 2 of 20 ADR121/ADR125/ADR127 SPECIFICATIONS ADR121 ELECTRICAL CHARACTERISTICS @ TA = 25°C, VIN = 2.8 V to 18 V, IOUT = 0 mA, unless otherwise noted. Table 1. Parameter OUTPUT VOLTAGE B Grade A Grade INITIAL ACCURACY ERROR B Grade A Grade TEMPERATURE COEFFICIENT B Grade A Grade DROPOUT (VOUT − VIN) LOAD REGULATION Symbol VO Conditions/Comments @ 25°C Min 2.497 2.494 VOERR @ 25°C −0.12 −0.24 TCVO −40°C < TA < +125°C 3 15 VDO IOUT = 0 mA −40°C < TA < +125°C; VIN = 3.0 V, 0 mA < IOUT < 5 mA −40°C < TA < +125°C; VIN = 3.0 V, −2 mA < IOUT < 0 mA 2.8 V to 18 V IOUT = 0 mA f = 1 Khz f = 60 Hz −40°C < TA < +125°C, no load VIN = 18 V VIN = 2.8 V VIN = 2.8 V VIN = 18 V @ 25°C f = 10 KHz 0.1 Hz to 10 Hz To 0.1%, CL = 0.2 μF 1000 hours @ 25°C See the Terminology section 300 80 50 −50 +3 −90 60 95 80 18 40 500 10 100 150 300 300 300 +50 9 25 ppm/°C ppm/°C mV ppm/mA ppm/mA ppm/V dB dB μA μA mA mA nV/√Hz μV p-p μs ppm/1000 hrs ppm +0.12 +0.24 % % Typ 2.5 2.5 Max 2.503 2.506 Unit V V LINE REGULATION PSRR RIPPLE REJECTION QUIESCENT CURRENT ΔVOUT/ΔVIN IQ 125 95 SHORT-CIRCUIT CURRENT TO GROUND VOLTAGE NOISE TURN-ON SETTLING TIME LONG-TERM STABILITY OUTPUT VOLTAGE HYSTERESIS Rev. 0 | Page 3 of 20 ADR121/ADR125/ADR127 ADR125 ELECTRICAL CHARACTERISTICS @ TA = 25°C, VIN = 5.3 V to 18 V, IOUT = 0 mA, unless otherwise noted. Table 2. Parameter OUTPUT VOLTAGE B Grade A Grade INITIAL ACCURACY ERROR B Grade A Grade TEMPERATURE COEFFICIENT B Grade A Grade DROPOUT (VOUT − VIN) LOAD REGULATION Symbol VO Condition @ 25°C 2.497 @ 25°C Min 4.994 4.988 −0.12 −0.24 TCVO −40°C < TA < +125°C 3 15 VDO IOUT = 5 mA −40°C < TA < +125°C; VIN = 3.0 V, 0 mA < IOUT < 5 mA −40°C < TA < +125°C; VIN = 3.0 V, −2 mA < IOUT < 0 mA 5.3 V < VIN < 18 V IOUT = 0 mA f = 60 Hz f = 60 Hz −40°C < TA < +125°C, no load VIN = 18 V VIN = 3.0 V VIN = 5.3 V VIN = 18 V @ 25°C f = 10 Khz 0.1 Hz to 10 Hz To 0.1%, CL = 0.2 μF 1000 hours @ 25°C See the Terminology section 300 35 35 200 200 30 −90 60 95 80 25 40 900 20 100 150 300 125 95 9 25 ppm/°C ppm/°C mV ppm/mA ppm/mA ppm/V dB dB μA μA mA mA nV/√Hz μV p-p μs ppm/1000 hrs ppm Typ 5.0 5.0 Max 5.006 5.012 +0.12 +0.24 Unit V V % % VOERR LINE REGULATION PSRR RIPPLE REJECTION QUIESCENT CURRENT ΔVOUT/ΔVIN IQ SHORT-CIRCUIT CURRENT TO GROUND VOLTAGE NOISE TURN-ON SETTLING TIME LONG-TERM STABILITY OUTPUT VOLTAGE HYSTERESIS Rev. 0 | Page 4 of 20 ADR121/ADR125/ADR127 ADR127 ELECTRICAL CHARACTERISTICS @ TA = 25°C, 2.7 V to 18 V, IOUT = 0 mA, unless otherwise noted. Table 3. Parameter OUTPUT VOLTAGE B Grade A Grade INITIAL ACCURACY ERROR B Grade A Grade TEMPERATURE COEFFICIENT B Grade A Grade DROPOUT (VOUT − VIN) LOAD REGULATION Symbol VO Condition @ 25°C Min 1.2485 1.2470 VOERR @ 25°C −0.12 −0.24 TCVO −40°C < TA < +125°C 3 15 VDO IOUT = 0 mA −40°C < TA < +125°C; VIN = 3.0 V, 0 mA < IOUT < 5 mA −40°C < TA < +125°C; VIN = 3.0 V, −2 mA < IOUT < 0 mA 2.7 V to 18 V IOUT = 0 mA F = 60 Hz f = 60 Hz −40°C < TA < +125°C, no load VIN = 18 V VIN = 2.7 V VIN = 2.7 V VIN = 18 V @ 25°C f = 10 kHz 0.1 Hz to 10 Hz To 0.1%, CL = 0.2 μF 1000 hours @ 25°C See the Terminology section 1.45 85 65 30 −90 60 95 80 15 30 300 5 80 150 300 125 95 400 400 90 9 25 ppm/°C ppm/°C V ppm/mA ppm/mA ppm/V dB dB μA μA mA mA nV/√Hz μV p-p μs ppm/1000 hrs ppm +0.12 +0.24 % % Typ 1.25 1.25 Max 1.2515 1.2530 Unit V V LINE REGULATION PSRR RIPPLE REJECTION QUIENSCENT CURRENT ΔVOUT/ΔVIN IQ SHORT-CIRCUIT CURRENT TO GROUND VOLTAGE NOISE Noise Density TURN-ON SETTLING TIME LONG-TERM STABILITY OUTPUT VOLTAGE HYSTERESIS Rev. 0 | Page 5 of 20 ADR121/ADR125/ADR127 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter VIN to GND Internal Power Dissipation TSOT (UJ-6) Storage Temperature Range Specified Temperature Range Lead Temperature, Soldering Vapor Phase (60 sec) Infrared (15 sec) Ratings 20 V 40 mW −65°C to +150°C −40°C to +125°C 215°C 220°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. THERMAL RESISTANCE θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 5. Thermal Resistance Package Type TSOT (UJ-6) θJA 230 θJC 146 Unit °C/W 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 6 of 20 ADR121/ADR125/ADR127 TERMINOLOGY Temperature Coefficient The change of output voltage with respect to operating temperature change normalized by the output voltage at 25°C. This parameter is expressed in ppm/°C and can be determined by Long-Term Stability Typical shift of output voltage at 25°C on a sample of parts subjected to a test of 1000 hours at 25°C. ΔVO = VO (t O ) − VO (t1 ) ΔVO [ppm ] = VO (t O ) − VO (t1 ) VO (t O ) TCVO [ppm/°C ] = where: VO (25°C ) × (T2 − T1 ) VO (T2 ) − VO (T1 ) × 10 6 × 10 6 where: VO(t0) = VO at 25°C at Time 0. VO(t1) = VO at 25°C after 1000 hours operating at 25°C. Thermal Hysteresis The change of output voltage after the device is cycled through temperatures from +25°C to −40°C to +125°C and back to +25°C. This is a typical value from a sample of parts put through such a cycle. where: VO (25°C) = VO at 25°C. VOTC = VO at 25°C after temperature cycle at +25°C to −40°C to +125°C and back to +25°C. VO(25°C) = VO at 25°C. VO(T1) = VO at Temperature 1. VO(T2) = VO at Temperature 2. Line Regulation The change in the output due to a specified change in input voltage. This parameter accounts for the effects of self-heating. Line regulation is expressed in either percent per volt, partsper-million per volt, or microvolts per voltage changes in input voltage. Load Regulation The change in output voltage due to a specified change in load current. This parameter accounts for the effects of self-heating. Load regulation is expressed in either microvolts per milliampere, parts-per-million per milliampere, or ohms of dc output resistance. Rev. 0 | Page 7 of 20 ADR121/ADR125/ADR127 TYPICAL PERFORMANCE CHARACTERISTICS 1.256 5 1.254 4 1.252 VOUT (V) NUMBER OF PARTS 05725-006 3 1.250 2 1.248 1.246 1 –25 –10 5 20 35 50 65 80 95 110 125 –40 –30 –20 –10 0 10 20 30 40 50 TEMPERATURE (°C) TEMPERATURE COEFFICIENT (ppm/°C) Figure 2. ADR127 VOUT vs. Temperature 2.510 2.508 2.506 Figure 5. ADR127 Temperature Coefficient 5 4 VOUT (V) 2.502 2.500 2.498 2.496 2.494 2.492 05725-007 NUMBER OF PARTS 2.504 3 2 1 –25 –10 5 20 35 50 65 80 95 110 125 –40 –30 –20 –10 0 10 20 30 40 50 TEMPERATURE (°C) TEMPERATURE COEFFICIENT (ppm/°C) Figure 3. ADR121 VOUT vs. Temperature 5.020 5.015 5.010 5.005 4 5 Figure 6. ADR125 Temperature Coefficient NUMBER OF PARTS VOUT (V) 3 5.000 4.995 4.990 2 1 4.985 4.980 –40 0 –50 –40 –30 –20 –10 0 10 20 30 40 50 TEMPERATURE (°C) TEMPERATURE COEFFICIENT (ppm/°C) Figure 4. ADR125 VOUT vs. Temperature Figure 7. ADR121 Temperature Coefficient Rev. 0 | Page 8 of 20 05725-011 –25 –10 5 20 35 50 65 80 95 110 125 05725-008 05725-010 2.490 –40 0 –50 05725-009 1.244 –40 0 –50 ADR121/ADR125/ADR127 3.0 120 2.8 100 SUPPLY CURRENT (µA) –40°C 80 +25°C +125°C VIN_MIN (V) 2.6 +25°C 2.4 60 –40°C 40 2.2 +125°C 20 05725-012 –1 0 1 2 3 4 5 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 LOAD CURRENT (mA) INPUT VOLTAGE (V) Figure 8. ADR127 Minimum Input Voltage vs. Load Current 3.5 3.4 3.3 Figure 11. ADR127 Supply Current vs. Input Voltage 120 100 +125°C +25°C 3.2 SUPPLY CURRENT (µA) +125°C +25°C –40°C 80 VIN_MIN (V) 3.1 3.0 2.9 2.8 2.7 2.6 60 –40°C 40 20 05725-013 –1 0 1 2 3 4 5 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 LOAD CURRENT (mA) INPUT VOLTAGE (V) Figure 9. ADR121 Minimum Input Voltage vs. Load Current 6.2 Figure 12. ADR121 Supply Current vs. Input Voltage 120 6.0 +125°C 5.8 100 SUPPLY CURRENT (µA) 80 +25°C +125°C VIN_MIN (V) +25°C 5.6 –40°C 60 –40°C 5.4 40 5.2 20 05725-014 –1 0 1 2 3 4 5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 LOAD CURRENT (mA) INPUT VOLTAGE (V) Figure 10. ADR125 Minimum Input Voltage vs. Load Current Figure 13. ADR125 Supply Current vs. Input Voltage Rev. 0 | Page 9 of 20 05725-017 5.0 –2 0 05725-016 2.5 –2 0 05725-015 2.0 –2 0 ADR121/ADR125/ADR127 6 — +125°C — +25°C — –40°C 0 5 4 LINE REGULATION (ppm/V) –10 SUPPLY CURRENT (mA) –20 VIN = 2.7V TO 18V –30 3 2 1 –40 05725-018 –1 0 1 2 3 4 5 -25 -10 5 20 35 50 65 80 95 110 125 LOAD CURRENT (mA) TEMPERATURE (°C) Figure 14. ADR127 Supply Current vs. Load Current 6 — +125°C — +25°C — –40°C 3 Figure 17. ADR127 Line Regulation vs. Temperature 5 2 4 LINE REGULATION (ppm/V) SUPPLY CURRENT (mA) 1 3 0 VIN = 2.8V TO 18V 2 –1 1 –2 –25 –10 5 20 35 50 65 80 95 110 125 LOAD CURRENT (mA) TEMPERATURE (°C) Figure 15. ADR121 Supply Current vs. Load Current 6 — +125°C — +25°C — –40°C 6 Figure 18. ADR121 Line Regulation vs. Temperature 5 4 4 LINE REGULATION (ppm/V) SUPPLY CURRENT (mA) 2 VIN = 5.3V TO 18V 3 0 2 –2 1 –4 –25 –10 5 20 35 50 65 80 95 110 125 LOAD CURRENT (mA) TEMPERATURE (°C) Figure 16. ADR125 Supply Current vs. Load Current Figure 19. ADR125 Line Regulation vs. Temperature Rev. 0 | Page 10 of 20 05725-023 –1 0 1 2 3 4 5 05725-020 0 –2 –6 –40 05725-022 –1 0 1 2 3 4 5 05725-019 0 –2 –3 –40 05725-021 0 –2 –50 –40 ADR121/ADR125/ADR127 200 150 CIN = COUT = 0.1µF 2mA SINKING, VIN = 3V LOAD REGULATION (ppm/mA) 100 50 0 –50 –100 –150 CH1 p-p 5.76µV 1 CH1 rms 0.862µV 5mA SOURCING, VIN = 3V 2µV/DIV –25 –10 5 20 35 50 65 80 95 110 125 05725-024 TIME (1s/DIV) 05725-027 –200 –40 TEMPERATURE (°C) Figure 20. ADR127 Load Regulation vs. Temperature 100 80 Figure 23. ADR127 0.1 Hz to 10 Hz Noise LOAD REGULATION (ppm/mA) 60 40 20 0 –20 –40 –60 –80 –25 –10 5 20 35 50 65 80 95 110 125 05725-025 CIN = COUT = 0.1µF 2mA SINKING, VIN = 5V CH1 p-p 10.8µV 5mA SOURCING, VIN = 5V 1 CH1 rms 1.75µV 5µV/DIV TIME (1s/DIV) 05725-028 –100 –40 TEMPERATURE (°C) Figure 21. ADR121 Load Regulation vs. Temperature 50 40 Figure 24. ADR121 0.1 Hz to 10 Hz Noise LOAD REGULATION (ppm/mA) 30 20 10 0 –10 –20 –30 –40 –25 –10 5 20 35 50 65 80 95 110 125 05725-026 CIN = COUT = 0.1µF 2mA SINKING, VIN = 6V CH1 p-p 20.6µV 1 5mA SOURCING, VIN = 6V CH1 rms 3.34µV 10µV/DIV TIME (1s/DIV) 05725-029 –50 –40 TEMPERATURE (°C) Figure 22. ADR125 Load Regulation vs. Temperature Figure 25. ADR125 0.1 Hz to 10 Hz Noise Rev. 0 | Page 11 of 20 ADR121/ADR125/ADR127 CIN = COUT = 0.1µF VIN 1V/DIV CIN = COUT = 0.1µF CH1 p-p 287µV 1 CH1 rms 38.8µV 1 05725-030 50µV/DIV TIME (1s/DIV) TIME (200µs/DIV) Figure 26. ADR127 10 Hz to 10 KHz Noise CIN = COUT = 0.1µF Figure 29. ADR127 Turn-On Response VIN 1V/DIV CIN = COUT = 0.1µF CH1 p-p 450µV 1 CH1 rms 58.1µV 1 VOUT 500mV/DIV 100µV/DIV TIME (1s/DIV) 05725-031 TIME (40µs/DIV) 05725-034 2 Figure 27. ADR121 10 Hz to 10 KHz Noise CIN = COUT = 0.1µF Figure 30. ADR127 Turn-On Response VIN 1V/DIV CIN = COUT = 0.1µF CH1 p-p 788µV 1 CH1 rms 115µV 1 200µV/DIV TIME (1s/DIV) 05725-032 VOUT 500mV/DIV TIME (100µs/DIV) Figure 28. ADR125 10 Hz to 10 KHz Noise Figure 31. ADR127 Turn-Off Response Rev. 0 | Page 12 of 20 05725-035 2 05725-033 2 VOUT 500mV/DIV ADR121/ADR125/ADR127 CIN = COUT = 0.1µF VIN 1V/DIV CIN = COUT = 0.1µF VIN 2V/DIV 1 1 VOUT 1V/DIV VOUT 2V/DIV 05725-036 TIME (100µs/DIV) Figure 32. ADR121 Turn-On Response Figure 35. ADR125 Turn-On Response CIN = COUT = 0.1µF VIN 1V/DIV CIN = COUT = 0.1µF VIN 2V/DIV 1 1 VOUT 1V/DIV 2 TIME (40µs/DIV) 05725-037 VOUT 2V/DIV 2 TIME (20µs/DIV) 05725-040 Figure 33. ADR121 Turn-On Response Figure 36. ADR125 Turn-On Response CIN = COUT = 0.1µF VIN 1V/DIV VIN 2V/DIV 1 1 VOUT 1V/DIV VOUT 2V/DIV 05725-038 TIME (20µs/DIV) Figure 34. ADR121 Turn-Off Response Figure 37. ADR125 Turn-Off Response Rev. 0 | Page 13 of 20 05725-041 2 TIME (200µs/DIV) 2 05725-039 2 TIME (100µs/DIV) 2 ADR121/ADR125/ADR127 CIN = COUT = 0.1µF 2.50V 1 VIN 1V/DIV LINE INTERRUPTION VIN 500mV/DIV CIN = COUT = 0.1µF 625Ω LOAD 2mA SINKING 1.25V 2 2 1 05725-042 Figure 38. ADR127 Line Transient Response CIN = COUT = 0.1µF LINE INTERRUPTION 1V/DIV Figure 41. ADR127 Load Transient Response (Sinking) 1 VIN 500mV/DIV CIN = COUT = 0.1µF 250Ω LOAD 5mA SOURCING 1 TIME (400µs/DIV) 2 2 05725-043 TIME (40µs/DIV) Figure 39. ADR121 Line Transient Response CIN = COUT = 0.1µF VIN 1V/DIV Figure 42. ADR127 Load Transient Response (Sourcing) 1 VIN 1V/DIV CIN = COUT = 0.1µF 1250 Ω LOAD 2mA SINKING 1 2 2 05725-044 TIME (400µs/DIV) Figure 40. ADR125 Line Transient Response Figure 43. ADR121 Load Transient Response (Sinking) Rev. 0 | Page 14 of 20 05725-047 VOUT 500mV/DIV VOUT 10mV/DIV TIME (40µs/DIV) 05725-046 VOUT 500mV/DIV VOUT 100mV/DIV 05725-045 VOUT 500mV/DIV TIME (200µs/DIV) VOUT 20mV/DIV TIME (40µs/DIV) 1.25V 0V 5V 2.5V ADR121/ADR125/ADR127 0 2.5V VIN 1V/DIV CIN = COUT = 0.1µF 500 Ω LOAD 5mA SOURCING –20 –40 –60 1 0V (dB) –80 1 –100 –120 –140 2 –160 05725-048 TIME (40µs/DIV) –200 10 100 1k 10k 100k 1M 10M 100M Figure 44. ADR121 Load Transient Response (Sourcing) 50 Figure 47. ADR121/ADR125/ADR127 PSRR 10V OUTPUT IMPEDANCE (Ω) 45 40 35 30 25 20 15 10 ADR125 ADR121 ADR127 VIN 2V/DIV CIN = COUT = 0.1µF 2.5kΩ LOAD 2mA SINKING 5V 1 2 10 100 1k FREQUENCY (Hz) 10k 100k Figure 45. ADR125 Load Transient Response (Sinking) Figure 48. ADR121/ADR125/ADR127 Output Impedance vs. Frequency 5V VIN 2V/DIV CIN = COUT = 0.1µF 1kΩ LOAD 5mA SOURCING 1 0V 2 TIME (40µs/DIV) Figure 46. ADR125 Load Transient Response (Sourcing) 05725-050 VOUT 100mV/DIV Rev. 0 | Page 15 of 20 05725-054 TIME (40µs/DIV) 05725-049 VOUT 20mV/DIV 5 0 1 05725-051 VOUT 100mV/DIV –180 ADR121/ADR125/ADR127 THEORY OF OPERATION The ADR12x band gap references are the high performance solution for low supply voltage and low power applications. The uniqueness of these products lies in their architecture. NOTES Input Capacitor Input capacitors are not required on the ADR12x. There is no limit for the value of the capacitor used on the input, but a 1 μF to 10 μF capacitor on the input improved transient response in the applications where there is a sudden supply change. An additional 0.1 μF capacitor in parallel also helps reduce noise from the supply. Output Capacitor The ADR12x requires a small 0.1 μF capacitor for stability. Additional 0.1 μF to 10 μF capacitance in parallel can improve load transient response. This acts as a source of stored energy for a sudden increase in load current. The only parameter affected with the additional capacitance is turn-on time. POWER DISSIPATION CONSIDERATIONS The ADR12x family is capable of delivering load currents to 5 mA with an input range from 3.0 V to 18 V. When this device is used in applications with large input voltages, care must be taken to avoid exceeding the specified maximum power dissipation or junction temperature, because this could result in premature device failure. Use the following formula to calculate a device’s maximum junction temperature or dissipation: PD = TJ − TA θ JA where: TJ is the junction temperature. TA is the ambient temperature. PD is the device power dissipation. θJA is the device package thermal resistance. Rev. 0 | Page 16 of 20 ADR121/ADR125/ADR127 APPLICATIONS BASIC VOLTAGE REFERENCE CONNECTION The circuit in Figure 4 illustrates the basic configuration for the ADR12x family voltage reference. 1 Table 6. Required Outputs U1/U2 ADR127/ADR121 ADR127/ADR125 ADR121/ADR125 VOUT2 1.25 V 1.25 V 2.5 V VOUT1 3.75 V 6.25 V 7.5 V NC NC 6 ADR12x 2 GND VIN NC 5 VOUT 4 + OUTPUT NEGATIVE PRECISION REFERENCE WITHOUT PRECISION RESISTORS 0.1µF INPUT + 3 Figure 49. Basic Configuration for the ADR12x Family STACKING REFERENCE ICs FOR ARBITRARY OUTPUTS Some applications may require two reference voltage sources that are a combined sum of the standard outputs. Figure 50 shows how this stacked output reference can be implemented. 05725-002 0.1µF A negative reference is easily generated by adding an op amp, A1, and is configured as shown in Figure 51. VOUT1 is at virtual ground and, therefore, the negative reference can be taken directly from the output of the op amp. The op amp must be dual-supply, low offset, and rail-to-rail if the negative supply voltage is close to the reference output. 1 NC NC 6 ADR127 2 GND NC 5 VOUT 4 +VDD 1 NC 3 VIN NC 6 0.1µF V+ – 2 1kΩ ADR12x 2 GND NC 5 VOUT 4 + OUTPUT1 –VREF 3 VIN AD8603 05725-055 V– + 3 –VDD + 0.1µF 0.1µF Figure 51. Negative Reference INPUT 1 NC NC 6 OUTPUT2 ADR12x 2 GND GENERAL-PURPOSE CURRENT SOURCE In low power applications, the need can arise for a precision current source that can operate on low supply voltages. The ADR12x can be configured as a precision current source (see Figure 52). The circuit configuration shown is a floating current source with a grounded load. The reference’s output voltage is bootstrapped across RSET, which sets the output current into the load. With this configuration, circuit precision is maintained for load currents ranging from the reference’s supply current, typically 85 μA, to approximately 5 mA. 1 NC NC 5 VOUT 4 + 3 VIN + Figure 50. Stacking References with ADR12x Two reference ICs are used and fed from an unregulated input, VIN. The outputs of the individual ICs are connected in series, which provide two output voltages, VOUT1 and VOUT2. VOUT1 is the terminal voltage of U1, while VOUT2 is the sum of this voltage and the terminal of U2. U1 and U2 are chosen for the two voltages that supply the required outputs (see Table 6). For example, if U1 and U2 are ADR127 and VIN ≥ 3.95 V, VOUT1 is 1.25 V and VOUT2 is 2.5 V. 05725-003 0.1µF 0.1µF NC 6 ADR12x 2 GND NC 5 VOUT 4 R1 ISET +VDD 3 VIN ISY P1 RL Figure 52. ADR12x Trim Configuration Rev. 0 | Page 17 of 20 05725-005 ADR121/ADR125/ADR127 OUTLINE DIMENSIONS 2.90 BSC 6 5 4 1.60 BSC 1 2 3 2.80 BSC PIN 1 INDICATOR 0.95 BSC *0.90 0.87 0.84 1.90 BSC *1.00 MAX 0.20 0.08 8° 4° 0° 0.60 0.45 0.30 0.10 MAX 0.50 0.30 SEATING PLANE *COMPLIANT TO JEDEC STANDARDS MO-193-AA WITH THE EXCEPTION OF PACKAGE HEIGHT AND THICKNESS. Figure 53. 6-Lead Thin Small Outline Transistor Package [TSOT] (UJ-6) Dimensions shown in millimeters ORDERING GUIDE Model ADR121AUJZREEL7 1 ADR121AUJZR21 ADR121BUJZREEL71 ADR125AUJZREEL71 ADR125AUJZR21 ADR125BUJZREEL71 ADR127AUJZREEL71 ADR127AUJZR21 ADR127BUJZREEL71 1 Output Voltage (VO) 2.5 2.5 2.5 5.0 5.0 5.0 1.25 1.25 1.25 Initial Accuracy (mV/%) 2.5 2.5 2.5 5.0 5.0 5.0 3 3 1.5 0.24 0.24 0.12 0.24 0.24 0.12 0.24 0.24 0.12 Temperature Coefficient (ppm/°C) 25 25 9 25 25 9 25 25 9 Package Description 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT 6-Lead TSOT Package Option UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 UJ-6 Temperature Range (°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 −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C Ordering Quantity 3000 250 3000 3000 250 3000 3000 250 3000 Branding R0N R0N R0P R0Q R0Q R0R R0S R0S R0T Z = Pb-free part. Rev. 0 | Page 18 of 20 ADR121/ADR125/ADR127 NOTES Rev. 0 | Page 19 of 20 ADR121/ADR125/ADR127 NOTES ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05725-0-6/06(0) Rev. 0 | Page 20 of 20