LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode General Description The LM185-1.2/LM285-1.2/LM385-1.2 are micropower 2-terminal band-gap voltage regulator diodes. Operating over a 10µA to 20mA current range, they feature exceptionally low dynamic impedance and good temperature stability. On-chip trimming is used to provide tight voltage tolerance. Since the LM185-1.2 band-gap reference uses only transistors and resistors, low noise and good long term stability result. Careful design of the LM185-1.2 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 LM185-1.2 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. The LM185-1.2 is rated for operation over a −55˚C to 125˚C temperature range while the LM285-1.2 is rated −40˚C to 85˚C and the LM385-1.2 0˚C to 70˚C. The LM185-1.2/ LM285-1.2 are available in a hermetic TO-46 package and the LM285-1.2/LM385-1.2 are also available in a low-cost TO-92 molded package, as well as SO and SOT-23. The LM185-1.2 is also available in a hermetic leadless chip carrier package. Features n n n n n n n ± 1% and 2% initial tolerance Operating current of 10µA to 20mA 1Ω dynamic impedance Low temperature coefficient Low voltage reference — 1.235V 2.5V device and adjustable device also available LM185-2.5 series and LM185 series, respectively Connection Diagrams T0-92 Plastic Package (Z) SOT23 00551833 00551810 Bottom View Order Number LM285Z-1.2, LM285BXZ-1.2, LM285BYZ-1.2 LM385Z-1.2, LM385BZ-1.2 LM385BXZ-1.2 or LM385BYZ-1.2 See NS Package Number Z03A © 2004 National Semiconductor Corporation DS005518 * Pin 3 is attached to the Die Attach Pad (DAP) and should be connected to Pin 2 or left floating. Order Number LM385M3-1.2 See NS Package Number MF03A www.national.com LM185-1.2/LM285-1.2/LM385-1.2 Micropower Voltage Reference Diode May 2003 LM185-1.2/LM285-1.2/LM385-1.2 Connection Diagrams (Continued) TO-46 Metal Can Package (H) SO Package 00551806 Bottom View Order Number LM185H-1.2, LM185H-1.2/883, LM185BXH-1.2, LM185BYH-1.2 LM285H-1.2 or LM285BXH-1.2 See NS Package Number H02A 00551809 Order Number LM285M-1.2, LM285BXM-1.2, LM285BYM-1.2 LM385M-1.2, LM385BM-1.2 LM385BXM-1.2 or LM385BYM-1.2 See NS Package Number M08A www.national.com 2 Storage Temperature If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Soldering Information (Note 2) −55˚C to +150˚C TO-92 package: 10 sec. 260˚C TO-46 package:10 sec. 300˚C SO and SOT Pkg. Reverse Current 30mA Vapor phase (60 sec.) 215˚C Forward Current 10mA Infrared (15 sec.) 220˚C Operating Temperature Range (Note 3) LM185-1.2 −55˚C to +125˚C LM285-1.2 −40˚C to +85˚C LM385-1.2 0˚C to 70˚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) LM185-1.2 Parameter Conditions Typ LM185BX-1.2 LM385B-1.2 LM185BY-1.2 LM385BX-1.2 LM285-1.2 LM385BY-1.2 LM385-1.2 Units LM285BX-1.2 (Limit) LM285BY-1.2 Reverse Breakdown TA = 25˚C, Voltage 10µA ≤ IR ≤ 20mA Minimum Operating 1.235 8 Current LM385M3-1.2 Reverse Breakdown 10µA ≤ IR ≤ 1mA Tested Design Tested Design Tested Design Limit Limit Limit Limit Limit Limit (Notes 5, 8) (Note 6) (Note 5) (Note 6) (Note 5) (Note 6) 1.223 1.223 1.205 V(Min) 1.247 1.247 1.260 V(Max) 10 20 1 1.5 15 1 20 1.5 15 20 µA 10 15 (Max) 1 1.5 Voltage Change with Current mV (Max) 1mA ≤ IR ≤ 20mA 10 20 20 25 20 25 mV (Max) Reverse Dynamic IR = 100µA, f = 20Hz 1 Ω 60 µV 20 ppm Impedance Wideband Noise IR = 100µA, (rms) 10Hz ≤ f ≤ 10kHz Long Term Stability IR = 100µA, T = 1000 Hr, Average Temperature IR = 100µA Coefficient (Note 7) X Suffix 30 Y Suffix 50 TA = 25˚C ± 0.1˚C 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-1.2 for military specifications. Note 3: For elevated temperature operation, Tj max is: LM185 150˚C LM285 125˚C LM385 100˚C 3 www.national.com LM185-1.2/LM285-1.2/LM385-1.2 Absolute Maximum Ratings (Note 1) LM185-1.2/LM285-1.2/LM385-1.2 Thermal Resistance θJA (junction to ambient) TO-92 TO-46 SO-8 SOT23 180˚C/W (0.4" leads) 440˚C/W 165˚C/W 283˚C/W 80˚C/W N/A N/A 170˚C/W (0.125" leads) θJC (junction to case) N/A Note 4: Parameters identified with boldface type apply at temperature extremes. All other numbers apply at TA = TJ = 25˚C. 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 is available on request. Typical Performance Characteristics Reverse Characteristics Reverse Characteristics 00551813 00551814 Temperature Drift of 3 Representative Units Forward Characteristics 00551816 00551815 Reverse Dynamic Impedance Reverse Dynamic Impedance 00551818 00551817 www.national.com 4 LM185-1.2/LM285-1.2/LM385-1.2 Typical Performance Characteristics (Continued) Noise Voltage Filtered Output Noise 00551820 00551819 Response Time 00551821 Typical Applications Reference from 1.5V Battery Wide Input Range Reference 00551823 00551808 Micropower Reference from 9V Battery 00551822 5 www.national.com LM185-1.2/LM285-1.2/LM385-1.2 Typical Applications (Continued) Precision 1µA to 1mA Current Sources Micropower* 5V Regulator 00551826 00551824 *IQ . 30µA Micropower* 10V Reference 00551827 00551825 *IQ .20µA standby current www.national.com 6 (Continued) METER THERMOMETERS Micropower Thermocouple Cold Junction Compensator 0˚C−100˚C Thermometer 00551828 Calibration 1. Short LM385-1.2, adjust R3 for IOUT= temp at 1µA/˚K 2. Remove short, adjust R2 for correct reading in centigrade 00551831 †IQ at 1.3V.500µA Adjustment Procedure IQ at 1.6V.2.4mA 1. Adjust TC ADJ pot until voltage across R1 equals Kelvin temperature multiplied by the thermocouple Seebeck coefficient. Lower Power Thermometer 2. Adjust zero ADJ pot until voltage across R2 equals the thermocouple Seebeck coefficient multiplied by 273.2. Thermocouple Type R1 R2 Voltage Voltage Coefficient (Ω) (Ω) Seebeck Across R1 Across R2 @ 25˚C (mV) (µV/˚C) (mV) J 52.3 5231.24k 15.60 14.32 T 42.8 432 1k 12.77 11.78 *2N3638 or 2N2907 select for inverse HFE . 5 K 40.8 412953Ω 12.17 11.17 †Select for operation at 1.3V S 6.4 63.4150Ω 1.908 1.766 00551829 ‡ IQ . 600µA to 900µA 0˚F−50˚F Thermometer 00551830 Calibration 1. Short LM385-1.2, adjust R3 for IOUT= temp at 1.8µA/˚K 2. Remove short, adjust R2 for correct reading in ˚F Typical supply current 50µA 7 www.national.com LM185-1.2/LM285-1.2/LM385-1.2 Typical Applications LM185-1.2/LM285-1.2/LM385-1.2 Typical Applications (Continued) Centigrade Thermometer 00551801 Calibration 1. Adjust R1 so that V1 = temp at 1mV/˚K 2. Adjust V2 to 273.2mV †IQ for 1.3V to 1.6V battery volt- age = 50µA to 150µA Schematic Diagram 00551807 www.national.com 8 LM185-1.2/LM285-1.2/LM385-1.2 Physical Dimensions inches (millimeters) unless otherwise noted TO-46 Metal Can Package (H) Order Number LM185H-1.2, LM185H-1.2/883, LM185BXH-1.2, LM185BYH-1.2, LM285H-1.2, or LM285BXH-1.2 NS Package Number H02A SOT-23 Package (M3) Order Number LM385M3-1.2 NS Package Number MF03A 9 www.national.com LM185-1.2/LM285-1.2/LM385-1.2 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Small Outline (SO-8) Package Order Number LM285M-1.2, LM285BXM-1.2, LM285BYM-1.2 LM385M-1.2, LM385BM-1.2, LM385BXM-1.2, LM385BYM-1.2 NS Package Number M08A TO-92 Plastic Package (Z) Order Number LM285Z-1.2, LM285BXZ-1.2 LM285BYZ-1.2, LM385Z-1.2, LM385BZ-1.2 LM385BXZ-1.2 or LM385BYZ-1.2 NS Package Number Z03A www.national.com 10 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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