LM809/LM810 3-Pin Microprocessor Reset Circuits General Description Features The LM809/810 microprocessor supervisory circuits can be used to monitor the power supplies in microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-down and brown-out conditions. The function of the LM809/810 is to monitor the VCC supply voltage, and assert a reset signal whenever this voltage declines below the factory-programmed reset threshold. The reset signal remains asserted for 240ms after VCC rises above the threshold. The LM809 has an active-low RESET output, while the LM810 has an active-high RESET output. Precise monitoring of 3V, 3.3V, and 5V supply voltages Superior upgrade to MAX809/810 Fully specified over temperature 140ms min. Power-On Reset pulse width, 240ms typical Active-low RESET Output (LM809) Active-high RESET Output (LM810) n Guaranteed RESET Output valid for VCC≥1V n Low Supply Current, 15µA typ. n Power supply transient immunity Seven standard reset voltage options are available, suitable for monitoring 5V, 3.3V, and 3V supply voltages. With a low supply current of only 15µA, the LM809/810 are ideal for use in portable equipment. The LM809/LM810 are available in the 3-pin SOT23 package and in the 6-Lead LLP package. Applications n n n n n n n n n n Microprocessor Systems Computers Controllers Intelligent Instruments Portable/Battery-Powered Equipment Automotive Typical Application Circuit 10105701 Connection Diagrams 10105702 ( ) are for LM810 10105715 Top View See NS package Number LDB06A ( ) are for LM810 © 2002 National Semiconductor Corporation DS101057 www.national.com LM809/LM810 3-Pin Microprocessor Reset Circuits September 2002 LM809/LM810 Ordering Information Reset Threshold (V) LM809 Supplied as 1000 units, tape & reel LM809 Supplied as 3000 units, tape & reel Package Top Mark Package Type NSC Package 4.63 LM809M3-4.63 LM809M3X-4.63 S8B 4.38 LM809M3-4.38 LM809M3X-4.38 S7B 4.00 LM809M3-4.00 LM809M3X-4.00 S6B 3.08 LM809M3-3.08 LM809M3X-3.08 S5B SOT23-3 M03B 2.93 LM809M3-2.93 LM809M3X-2.93 S4B 2.63 LM809M3-2.63 LM809M3X-2.63 S3B 2.45 LM809M3-2.45 LM809M3X-2.45 SFB Reset Threshold (V) LM810 Supplied as 1000 units, tape & reel LM810 Supplied as 3000 units, tape & reel Package Top Mark Package Type 4.63 LM810M3-4.63 LM810M3X-4.63 SEB NSC Package 4.38 LM810M3-4.38 LM810M3X-4.38 SDB 4.00 LM810M3-4.00 LM810M3X-4.00 SCB 3.08 LM810M3-3.08 LM810M3X-3.08 SBB SOT23-3 M03B 2.93 LM810M3-2.93 LM810M3X-2.93 SAB 2.63 LM810M3-2.63 LM810M3X-2.63 S9B Reset Threshold (V) LM809 Supplied as 1000 units, tape & reel LM809 Supplied as 4500 units, tape & reel Package Top Mark Package Type 2.63 LM809LD-2.63 LM809LDX-2.63 NSC Package S13 LLP-6 LDB06A Custom voltages and improved accuracies are available, subject to minimum orders. Contact your local National Semiconductor Sales Office for information. Pin Descriptions PIN (LLP) SOT-23 1 1 3 5 www.national.com NAME GND Ground reference RESET (LM809) Active-low output. RESET remains low while VCC is below the reset threshold, and for 240ms after VCC rises above the reset threshold. RESET (LM810) Active-high output. RESET remains high while VCC is below the reset threshold, and for 240ms after VCC rises above the reset threshold. 2 3 FUNCTION VCC Supply Voltage (+5V, +3.3V, or +3.0V) 2 Continuous Power Dissipation (Note 4) (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. θJA: LLP-6 −0.3V to 6.0V VCC RESET, RESET 326˚C/W Ambient Temperature Range 20mA Output Current, RESET, RESET Pin 152˚C/W SOT23-3 −0.3V to (VCC+ 0.3V) Input Current, VCC Pin 320mW −40˚C to +105˚C Maximum Junction Temperature 125˚C Storage Temperature Range 20mA Rate of Rise, VCC Lead Temperature (soldering, 10sec) 100V/µs ESD Rating (Note 2) −65˚C to +160˚C +300˚C 2kV Electrical Characteristics VCC = full range, TA = −40˚C to +105˚C, unless otherwise noted. Typical values are at TA = +25˚C, VCC = 5V for 4.63/4.38/4.00 versions, VCC = 3.3V for 3.08/2.93 versions, and VCC = 3V for 2.63/2.45 version (Note 3). Symbol Parameter VCC Range Conditions Supply Current TA = −40˚C to +105˚C 1.2 5.5 TA = +85˚C to +105˚C LM8_ _ -4.38 LM8_ _ -4.00 Reset Threshold (Note 5) LM8_ _ -3.08 LM8_ _ -2.93 LM8_ _ -2.63 LM8_ _ -2.45 VCC < 5.5V, LM8_ _ -4.63/4.38/4.00 18 60 VCC < 3.6V, LM8_ _ -3.08/2.93/2.63/2.45 15 50 VCC < 5.5V, LM8_ _ -4.63/4.38/4.00 100 VCC < 3.6V, LM8_ _ -3.08/2.93/2.63/2.45 100 TA = +25˚C 4.56 TA = −40˚C to +85˚C 4.50 Reset Active Timeout Period 4.63 4.40 4.31 TA = −40˚C to +85˚C 4.25 4.50 TA = +85˚C to +105˚C 4.16 4.56 TA = +25˚C 3.93 TA = −40˚C to +85˚C 3.89 4.10 TA = +85˚C to +105˚C 3.80 4.20 TA = +25˚C 3.04 TA = −40˚C to +85˚C 3.00 3.15 TA = +85˚C to +105˚C 2.92 3.23 TA = +25˚C 2.89 TA = −40˚C to +85˚C 2.85 TA = +85˚C to +105˚C 2.78 TA = +25˚C 2.59 TA = −40˚C to +85˚C 2.55 TA = +85˚C to +105˚C 2.50 TA = +25˚C 2.41 TA = −40˚C to +85˚C 2.38 2.52 TA = +85˚C to +105˚C 2.33 2.57 TA = −40˚C to +85˚C 140 TA = +85˚C to +105˚C 3 100 V µA 4.75 TA = +25˚C VCC = VTH to (VTH − 100mV) Units 4.70 TA = +85˚C to +105˚C Reset Threshold Temperature Coefficient VCC to Reset Delay (Note 5) Max 5.5 LM8_ _ -4.63 VTH Typ 1.0 TA = −40˚C to +85˚C ICC Min TA = 0˚C to +70˚C 4.86 4.38 4.00 3.08 2.93 4.45 4.06 3.11 V 2.96 3.00 3.08 2.63 2.66 2.70 2.76 2.45 2.49 30 ppm/˚C 20 µs 240 560 840 ms www.national.com LM809/LM810 Absolute Maximum Ratings LM809/LM810 Electrical Characteristics (Continued) VCC = full range, TA = −40˚C to +105˚C, unless otherwise noted. Typical values are at TA = +25˚C, VCC = 5V for 4.63/4.38/4.00 versions, VCC = 3.3V for 3.08/2.93 versions, and VCC = 3V for 2.63/2.45 version (Note 3). Symbol VOL Parameter RESET Output Voltage Low (LM809) Conditions Min RESET Output Voltage High (LM809) VOL RESET Output Voltage Low (LM810) VOH RESET Output Voltage High (LM810) Max 0.3 VCC = VTH min, ISINK = 3.2mA, LM809-4.63/4.38/4.00 0.4 VCC > 1.0V, ISINK = 50µA VOH Typ VCC = VTH min, ISINK = 1.2mA, LM809-2.45/2.63/2.93/3.08 V 0.3 VCC > VTH max, ISOURCE = 500µA, LM809-2.45/2.63/2.93/3.08 0.8VCC VCC > VTH max, ISOURCE = 800µA, LM809-4.63/4.38/4.00 VCC−1.5 V VCC = VTH max, ISINK = 1.2mA, LM810-2.63/2.93/3.08 0.3 VCC = VTH max, ISINK = 3.2mA, LM810-4.63/4.38/4.00 0.4 1.8V < VCC < VTH min, ISOURCE = 150µA Units 0.8VCC V V Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which the device operates correctly. Operating ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics. Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. Note 3: Production testing done at TA = +25˚C, over temperature limits guaranteed by design only. Note 4: At elevated temperatures, devices must be derated based on package thermal resistance. The device in the SOT23-3 package must be derated at 4mW/˚C at ambient temperatures above 70˚C. The device has internal thermal protection. Note 5: RESET Output for LM809, RESET output for LM810. www.national.com 4 Supply Current vs Temperature (No Load, LM8_ _-2.63/2.93/3.08) Power-Down Reset Delay vs Temperature (LM8_ _-4.63/4.38) 10105703 10105706 Supply Current vs Temperature (No Load, LM8_ _-4.63/4.38) Power-Up Reset Timeout vs Temperature 10105707 10105704 Normalized Reset Threshold vs Temperature Power-Down Reset Delay vs Temp (LM8_ _-2.63/2.93/3.08) 10105708 10105705 5 www.national.com LM809/LM810 Typical Performance Characteristics LM809/LM810 Typically, for the 4.63V and 4.38V version of the LM809/810, a VCC transient that goes 100mV below the reset threshold and lasts 20µs or less will not cause a reset pulse. A 0.1 µF bypass capacitor mounted as close as possible to the VCC pin will provide additional transient rejection. Applications Information Benefits of Precision Reset Thresholds A microprocessor supply supervisor must provide a reset output within a predictable range of the supply voltage. A common threshold range is between 5% and 10% below the nominal supply voltage. The 4.63V and 3.08V options of the LM809/810 use highly accurate circuitry to ensure that the reset threshold occurs only within this range (for 5V and 3.3V supplies). The other voltage options have the same tight tolerance to ensure a reset signal for other narrow monitor ranges. See Table 1 for examples of how the standard reset thresholds apply to 3V, 3.3V, and 5V nominal supply voltages. TABLE 1. Reset Thresholds Related to Common Supply Voltages Reset Threshold 3.0V 3.3V 5.0V 4.63 ± 3% 90 - 95% ± ± ± ± ± ± 3% 85 - 90% 3% 78 - 82% 4.38 4.00 3.08 2.93 2.63 2.45 3% 90 - 95% 3% 86 - 90% 3% 85 - 90% 77 - 81% 3% 79 - 84% 72 - 76% 10105709 FIGURE 2. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive Interfacing to µPs with Bidirectional Reset Pins Microprocessors with bidirectional reset pins, such as the Motorola 68HC11 series, can be connected to the LM809 RESET output. To ensure a correct output on the LM809 even when the microprocessor reset pin is in the opposite state, connect a 4.7kΩ resistor between the LM809 RESET output and the µP reset pin, as shown in Figure 3. Buffer the LM809 RESET output to other system components. Ensuring a Valid Reset Output Down to VCC = 0V When VCC falls below 1V, the LM809 RESET output no longer sinks current. A high-impedance CMOS logic input connected to RESET can therefore drift to undetermined voltages. To prevent this situation, a 100kΩ resistor should be connected from the RESET output to ground, as shown in Figure 1. A 100kΩ pull-up resistor to VCC is also recommended for the LM810, if RESET is required to remain valid for VCC < 1V. 10105711 10105710 FIGURE 1. RESET Valid to VCC = Ground Circuit FIGURE 3. Interfacing to Microprocessors with Bidirectional Reset I/O Negative-Going VCC Transients The LM809/810 are relatively immune to short negative-going transients or glitches on VCC. Figure 2 shows the maximum pulse width a negative-going VCC transient can have without causing a reset pulse. In general, as the magnitude of the transient increases, going further below the threshold, the maximum allowable pulse width decreases. LLP Mounting The LLP package requires special mounting techniques which are detailed in National Semiconductor Application Note AN-1187. Referring to the section PCB Design Recommendations, it should be noted that the pad style which should be used with the LLP package is the NSMD (nonsolder mask defined) type. www.national.com 6 LM809/LM810 Physical Dimensions inches (millimeters) unless otherwise noted 3-Lead SOT23-3 For Ordering, refer to Ordering Information table NS Package Number M03B 6-Lead LLP (NLDBB006) For Ordering, refer to Ordering Information table NS Package Number LDB06A 7 www.national.com LM809/LM810 3-Pin Microprocessor Reset Circuits Notes 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. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation Americas Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 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.