LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode General Description The LM185-2.5/LM285-2.5/LM385-2.5 are micropower 2-terminal band-gap voltage regulator diodes. Operating over a 20 µA to 20 mA current range, they feature exceptionally low dynamic impedance and good temperature stability. On-chip trimming is used to provide tight voltage tolerance. Since the LM-185-2.5 band-gap reference uses only transistors and resistors, low noise and good long term stability result. Careful design of the LM185-2.5 has made the device exceptionally tolerant of capacitive loading, making it easy to use in almost any reference application. The wide dynamic operating range allows its use with widely varying supplies with excellent regulation. The extremely low power drain of the LM185-2.5 makes it useful for micropower circuitry. This voltage reference can be used to make portable meters, regulators or general purpose analog circuitry with battery life approaching shelf life. Further, the wide operating current allows it to replace older references with a tighter tolerance part. For applications requiring 1.2V see LM185-1.2. The LM185-2.5 is rated for operation over a −55˚C to 125˚C temperature range while the LM285-2.5 is rated −40˚C to 85˚C and the LM385-2.5 0˚C to 70˚C. The LM185-2.5/ LM285-2.5 are available in a hermetic TO-46 package and the LM285-2.5/LM385-2.5 are also available in a low-cost TO-92 molded package, as well as S.O. and SOT-23. The LM185-2.5 is also available in a hermetic leadless chip carrier package. Features n n n n n n ± 20 mV ( ± 0.8%) max. initial tolerance (A grade) Operating current of 20 µA to 20 mA 0.6Ω dynamic impedance (A grade) Low temperature coefficient Low voltage reference — 2.5V 1.2V device and adjustable device also available — LM185-1.2 series and LM185 series, respectively Connection Diagrams TO-92 Plastic Package SO Package 00551908 Bottom View Order Number LM285Z-2.5, LM285BXZ-2.5, LM285BYZ-2.5 LM385Z-2.5, LM385AXZ-2.5 LM385AYZ-2.5, LM385BZ-2.5, LM385BXZ-2.5 or LM385BYZ-2.5 See NS Package Number Z03A 00551911 Order Number LM285M-2.5, LM285BXM-2.5, LM285BYM-2.5 LM385M-2.5, LM385BM-2.5 LM385BXM-2.5 or LM385BYM-2.5 See NS Package Number M08A SOT-23 00551929 * Pin 3 is attached to the Die Attach Pad (DAP) and should be connected to Pin 2 or left floating. Order Number LM385M3-2.5 See NS Package Number MA03B © 2005 National Semiconductor Corporation DS005519 www.national.com LM185-2.5/LM285-2.5/LM385-2.5 Micropower Voltage Reference Diode February 2005 LM185-2.5/LM285-2.5/LM385-2.5 Connection Diagrams (Continued) LCC Leadless Chip Carrier TO-46 Metal Can Package 00551913 Bottom View Order Number LM185H-2.5, LM185H-2.5/883, LM185BXH-2.5, LM185BXH-2.5/883, LM185BYH-2.5, LM185BYH2.5/883, LM285H-2.5, or LM285BYH-2.5 See NS Package Number H02A 00551914 Order Number LM185E-2.5/883 See NS Package Number E20A www.national.com 2 LM385-2.5 (Notes 1, 0˚C to 70˚C 2) Storage Temperature If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Soldering Information Reverse Current 30 mA Forward Current 10 mA −55˚C to + 125˚C LM285-2.5 −40˚C to + 85˚C TO-92 Package (10 sec.) 260˚C TO-46 Package (10 sec.) 300˚C SO and SOT Package Operating Temperature Range (Note 3) LM185-2.5 −55˚C to + 150˚C Vapor Phase (60 sec.) 215˚C Infrared (15 sec.) 220˚C See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” for other methods of soldering surface mount devices. Electrical Characteristics (Note 4) LM385A-2.5 LM385AX-2.5 Parameter Reverse Breakdown Conditions Typ IR = 100 µA 2.500 Voltage LM385AY-2.5 Tested Design Limit Limit (Note 5) (Note 6) 2.480 V(Min) 2.520 2.500 Minimum Operating 12 18 V(Max) 2.470 V(Min) 2.530 V(Max) 20 Current Reverse Breakdown µA (Max) IMIN ≤ IR ≤ 1mA 1 1.5 1 mA ≤ IR ≤ 20 mA 10 20 Voltage Change with Current Units (Limits) mV (Max) mV (Max) Reverse Dynamic IR = 100 µA, Impedance f = 20 Hz Wideband Noise (rms) IR = 100 µA 0.2 0.6 Ω 1.5 120 µV 20 ppm 10 Hz ≤ f ≤ 10 kHz Long Term Stability IR = 100 µA, T = 1000 Hr, TA = 25˚C ± 0.1˚C Average Temperature IMIN ≤ IR ≤ 20 mA Coefficient (Note 7) X Suffix 30 Y Suffix 50 All Others ppm/˚C (Max) 150 3 www.national.com LM185-2.5/LM285-2.5/LM385-2.5 Absolute Maximum Ratings LM185-2.5/LM285-2.5/LM385-2.5 Electrical Characteristics LM185-2.5 Parameter Conditions Typ LM185BX-2.5 LM385B-2.5 LM185BY-2.5 LM385BX-2.5 LM285-2.5 LM385BY-2.5 LM385-2.5 Units (Limit) LM285BX-2.5 LM285BY-2.5 Tested Reverse Breakdown TA = 25˚C, Voltage 20 µA ≤ IR ≤ 20 mA Minimum Operating Current 2.5 13 Design Tested Design Tested Design Limit Limit Limit Limit Limit Limit (Note 5) (Note 8) (Note 6) (Note 5) (Note 6) (Note 5) (Note 6) 2.462 2.462 2.425 V(Min) 2.538 2.538 2.575 V(Max) 20 30 20 30 LM385M3-2.5 Reverse Breakdown Voltage Change with Current 20 30 15 20 µA (Max) 20 µA ≤ IR ≤ 1 mA 1 1.5 2.0 2.5 2.0 2.5 mV (Max) 1 mA ≤ IR ≤ 20 mA 10 20 20 25 20 25 mV (Max) Reverse Dynamic IR = 100 µA, Impedance f = 20 Hz Wideband Noise (rms) IR = 100 µA, 1 Ω 120 µV 20 ppm 10 Hz ≤ f ≤ 10 kHz IR = 100 µA, Long Term Stability T = 1000 Hr, TA = 25˚C ± 0.1˚C Average Temperature IR = 100 µA Coefficient (Note 7) X Suffix 30 Y Suffix 50 30 ppm/˚C 50 All Others 150 ppm/˚C 150 150 ppm/˚C (Max) Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Note 2: Refer to RETS185H-2.5 for military specifications. Note 3: For elevated temperature operation, TJ MAX is: LM185 150˚C LM285 125˚C LM385 100˚C Thermal Resistance θja (Junction to Ambient) TO-92 180˚C/W (0.4" Leads) TO-46 SO-8 SOT-23 440˚C/W 165˚C/W 283˚C/W 170˚C/W (0.125" Leads) θjc (Junction to Case) www.national.com N/A 80˚C/W 4 N/A N/A Note 5: Guaranteed and 100% production tested. Note 6: Guaranteed, but not 100% production tested. These limits are not used to calculate average outgoing quality levels. Note 7: The average temperature coefficient is defined as the maximum deviation of reference voltage at all measured temperatures between the operating TMAX and TMIN, divided by TMAX–TMIN. The measured temperatures are −55˚C, −40˚C, 0˚C, 25˚C, 70˚C, 85˚C, 125˚C. Note 8: A military RETS electrical specification available on request. Typical Performance Characteristics Reverse Characteristics Reverse Characteristics 00551916 00551915 Forward Characteristics Temperature Drift 00551917 00551918 Reverse Dynamic Impedance Reverse Dynamic Impedance 00551919 00551920 5 www.national.com LM185-2.5/LM285-2.5/LM385-2.5 Note 4: Parameters identified with boldface type apply at temperature extremes. All other numbers apply at TA = TJ = 25˚C. LM185-2.5/LM285-2.5/LM385-2.5 Typical Performance Characteristics (Continued) Noise Voltage Filtered Output Noise 00551922 00551921 Response Time 00551923 Applications LM385-2.5 Applications Wide Input Range Reference Micropower 5V Reference (Note 9) 00551912 Micropower Reference from 9V Battery 00551909 Note 9: IQ . 40 µA 00551902 www.national.com 6 LM185-2.5/LM285-2.5/LM385-2.5 LM385-2.5 Applications (Continued) Micropower 10V Reference (Note 10) 00551910 Note 10: IQ . 30 µA standby current Precision 1 µA to 1 mA Current Sources 00551925 00551924 7 www.national.com LM185-2.5/LM285-2.5/LM385-2.5 LM385-2.5 Applications (Continued) METER THERMOMETERS 0˚C–100˚C Thermomemter Micropower Thermocouple Cold Junction Compensator 00551926 Calibration 1. Short LM385-2.5, adjust R3 for IOUT=temp at 1µA/˚K 2. Remove short, adjust R2 for correct reading in centigrade 00551906 Adjustment Procedure 1. Adjust TC ADJ pot until voltage across R1 equals Kelvin temperature multiplied by the thermocouple Seebeck coefficient. 0˚F–50˚F Thermomemter 2. Adjust zero ADJ pot until voltage across R2 equals the thermocouple Seebeck coefficient multiplied by 273.2. 00551927 Calibration 1. Short LM385-2.5, adjust R3 for IOUT=temp at 1.8 µA/˚K 2. Remove short, adjust R2 for correct reading in ˚F Voltage Voltage Thermocouple Seebeck Co- R1 R2 Across R1 Across R2 Type efficient (Ω) (Ω) @ 25˚C (mV) (µV/˚C) (mV) J 52.3 523 1.24k 1k 14.32 T 42.8 432 12.77 11.78 K 40.8 412 953Ω 12.17 11.17 S 6.4 63.4 150Ω 1.908 1.766 Typical supply current 50 µA www.national.com 15.60 8 LM185-2.5/LM285-2.5/LM385-2.5 LM385-2.5 Applications (Continued) Improving Regulation of Adjstable Regulators 00551907 Schematic Diagram 00551901 9 www.national.com LM185-2.5/LM285-2.5/LM385-2.5 Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM185E-2.5/883 NS Package Number E20A TO-46 Metal Can Package (H) Order Number LM185H-2.5, LM185H-2.5/883, LM185BXH-2.5, LM185BXH-2.5/883, LM185BYH-2.5, LM185BYH-2.5/883, LM285H-2.5, or LM285BYH-2.5 NS Package Number H02A www.national.com 10 LM185-2.5/LM285-2.5/LM385-2.5 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) SOT-23 Package (M3) Order Number LM385M3-2.5 NS Package Number MA03B 11 www.national.com LM185-2.5/LM285-2.5/LM385-2.5 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Small Outline (SO-8) Package (M) Order Number LM285M-2.5, LM285BXM-2.5, LM285BYM-2.5, LM385M-2.5, LM385BM-2.5, LM385BXM-2.5 or LM385BYM-2.5 NS Package Number M08A www.national.com 12 inches (millimeters) unless otherwise noted (Continued) TO-92 Plastic Package (Z) Order Number LM285Z-2.5, LM285BXZ-2.5, LM285BYZ-2.5, LM385Z-2.5, LM385AXZ-2.5, LM385AYZ-2.5, LM385BZ-2.5, LM385BXZ-2.5 or LM385BYZ-2.5 NS Package Number Z03A National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. 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