LM8364 Micropower Undervoltage Sensing Circuits General Description Features The LM8364 series are micropower undervoltage sensing circuits that are ideal for use in battery powered microprocessor based systems, where extended battery life is a key requirement. A range of threshold voltages from 2.0V to 4.5V are available with an active low open drain output. These devices feature a very low quiescent current of 0.65µA typical. The LM8364 series features a highly accurate voltage reference, a comparator with precise thresholds and built-in hysterisis to prevent erratic reset operation, and guaranteed Reset operation down to 1.0V with extremely low standby current. n Extremely Low Quiescent Current: 0.65µA, at VIN = 2.87V n High Accuracy Threshold Voltage ( ± 2.5%) n Open Drain Output n Input Voltage Range: 1V to 6V n Surface Mount Package (5-Pin SOT23) n Pin for pin compatible with MC33464 These devices are available in the space saving SOT23 5-pin surface mount package. For other undervoltage thresholds and output options, please contact National Semiconductor. Functional Block Diagram Applications n n n n Low Battery Detection Microprocessor reset Controller Power Fail Indicator Battery Backup Detection Connection Diagram 5-Pin SOT23 20065906 Top View 20065907 © 2003 National Semiconductor Corporation DS200659 www.national.com LM8364 Micropower Undervoltage Sensing Circuits March 2003 LM8364 Pin Description 20065908 Ordering Information Package Part Number LM8364BALMF20 LM8364BALMFX20 5-Pin SOT23 LM8364BALMF30 LM8364BALMFX30 LM8364BALMF45 LM8364BALMFX45 www.national.com Package Marking Threshold Output Type Transport Media F01A 2.0V Open Drain, Active Low 3k Units Tape and Reel F05A 3.0V Open Drain, Active Low 3k Units Tape and Reel F04A 4.5V Open Drain, Active Low 3k Units Tape and Reel 2 NSC Drawing 1k Units Tape and Reel 1k Units Tape and Reel 1k Units Tape and Reel MF05A Junction Temperature (Note 1) 125˚ If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Operating Ratings (Note 1) Supply Voltage −0.3V to 6.5V Temperature Range −0.3V to 6.5V Thermal Resistance to ambient (θJA) RESET Output Voltage RESET Output Current Storage Temperature Range −40˚C to 85˚C 265˚C/W ESD Tolerance 70mA Human Body Model −65˚C to 150˚C 2000V Machine Model Mounting Temp. Lead temp (Soldering, 10 sec) 200V 260˚C Electrical Characteristics Unless otherwise specified, all limits guaranteed for TA = 25˚C. Symbol VDET− VHYS Parameter Detector Threshold Voltage Detector Threshold Hysteresis Conditions Min (Note 3) Typ (Note 2) Max (Note 3) Units 20 Suffix 1.950 2.0 2.050 V 30 Suffix 2.925 3.0 3.075 45 Suffix 4.388 4.5 4.613 20 Suffix 0.060 0.100 0.140 30 Suffix 0.090 0.150 0.210 45 Suffix 0.135 0.225 0.315 High to Low State Output (VIN Decreasing) VIN Increasing ∆Vdet/∆T Detector Threshold Voltage Temperature Coefficient VOL RESET Output Voltage Low State (Open Drain Output: ISINK = 1mA) IOL RESET Output Sink Current VIN = 1.5V, VOL = 0.5V VIN Operating Input Voltage Range IIN Quiescent Input Current ± 100 0.25 1.0 PPM/˚C 0.5 2.5 1.0 V V mA 6.0 V 20 Suffix VIN = 1.9V 0.55 0.8 VIN = 4.0V 0.70 1.3 VIN = 2.87V 0.65 0.9 VIN = 5.0V 0.77 1.3 VIN = 4.34V 0.70 1.0 VIN = 6.0 0.85 1.4 60 300 30 Suffix µA 45 Suffix tp Propagation Delay Time Figure 1 µs 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 specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. Note 2: Typical values represent the most likely parametric norm Note 3: All limits are guaranteed by testing or statistical analysis. 3 www.national.com LM8364 Absolute Maximum Ratings LM8364 Typical Performance Characteristics Input Current vs. Input Voltage LM8364BALMF45 Reset Output Voltage vs. Input Voltage LM8364BALMF45 20065901 20065902 Reset Output Sink Current vs. Output Voltage LM8364BALMF45 Reset Output Sink Current vs. Input Voltage LM8364BALMF45 20065903 20065904 Detector Threshold Voltage vs. Temperature LM8364BALMF45 20065905 www.national.com 4 The propagation delay time for the LM8364 is measured using a 470kΩ pull-up resistor connected to from the RESET output pin to 5V in addition to a 10pF capacitive load con- 20065909 FIGURE 1. Propagation Delay Timing Diagrams VHYS. This point is also known as VDET+ as indicated earlier. This built-in hysteresis has been added to the design to help prevent erratic reset operation when the input voltage crosses the threshold. The LM8364 ultra-low current voltage detector was designed to monitor voltages and to provide an indication when the monitored voltage, VIN, dropped below a precisely trimmed threshold voltage. This characteristic is displayed in the typical operating timing diagram below. VIN is the voltage that is being monitored and a pull up resistor is connected from the RESET output pin to VIN. VIN is at some value above VDET+ and then begins to decrease. Since this is an Active Low device the RESET output is pulled High through the pull-up resistor and tracks VIN until VIN crosses the trimmed threshold VDET−. At this point the LM8364 recognizes that VIN is now in a fault condition and the output immediately changes to the Logic Low State. The RESET output will remain in this low state until VIN increases above the threshold VDET− + The LM8364 has a wide variety of applications that can take advantage of its precision and low current consumption to monitor Input voltages even though it was designed as a reset controller in portable microprocessor based systems. It is a very cost effective and space saving device that will protect your more expensive investments of microprocessors and other devices that need a guaranteed supply voltage for proper operation. 20065910 FIGURE 2. Timing Waveforms 5 www.national.com LM8364 nected from the same pin to GND. Figure 1 shows the timing diagram for the measurement for the propagation delay. VDET+ is equal to the sum of the detector threshold, VDET−, and the built in hysteresis, VHYS. Application Notes LM8364 Typical Applications 20065911 Microprocessor Reset Circuit 20065912 Dual Power Supply Undervoltage Supervision www.national.com 6 LM8364 Typical Applications (Continued) 20065913 Microcontroller System Load Sensing 20065914 LED Bar Graph Voltage Monitor 7 www.national.com LM8364 Micropower Undervoltage Sensing Circuits Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23 NSC Package Number MF05A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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