LM3711

LM3710/LM3711 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output, Manual Reset and Watchdog Timer June 2002 LM3710/LM3711 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output, Manual Reset and Watchdog Timer General Description The LM3710/LM3711 series of microprocessor supervisory circuits provide the maximum flexibility for monitoring power supplies and battery controlled functions in systems without backup batteries. The LM3710/LM3711 series are available in MSOP-10 and 9-bump micro SMD packages. Built-in features include the following: Reset: Reset is asserted during power-up, power-down, and brownout conditions. RESET is guaranteed down to VCC of 1.0V. Manual Reset Input: An input that asserts reset when pulled low. Power-Fail Input: A 1.225V threshold detector for power fail warning, or to monitor a power supply other than VCC. Low Line Output: This early power failure warning indicator goes low when the supply voltage drops to a value which is 2% higher than the reset threshold voltage. Watchdog Timer: The WDI (Watchdog Input) monitors one of the µP’s output lines for activity. If no output transition occurs during the watchdog timeout period, reset is activated. Features n Standard Reset Threshold voltage: 3.08V n Custom Reset Threshold voltages: For other voltages between 2.2V and 5.0V in 10mV increments, contact National Semiconductor Corp. n No external components required n Manual-Reset input n RESET (LM3710) or RESET (LM3711) outputs n Precision supply voltage monitor n Factory programmable Reset and Watchdog Timeout Delays n Separate Power Fail comparator n Available in micro SMD package for minimum footprint n ± 0.5% Reset threshold accuracy at room temperature n ± 2% Reset threshold accuracy over temperature extremes n Reset assertion down to 1V VCC (RESET option only) n 28 µA VCC supply current Applications n n n n Embedded Controllers and Processors Intelligent Instruments Automotive Systems Critical µP Power Monitoring Typical Application 20011803 © 2002 National Semiconductor Corporation DS200118 www.national.com LM3710/LM3711 Connection Diagram Top View (looking from the coating side) micro SMD 9 Bump Package BPA09 MSOP-10 20011802 20011801 Pin Descriptions Pin No. micro SMD A1 B1 C1 MSOP 2 1 10 Name MR VCC RESET Function Manual-Reset input. When MR is less than VMRT (Manual Reset Threshold) RESET/RESET is engaged. Power Supply input. Reset Logic Output. Pulses low for tRP (Reset Timeout Period) when triggered, and stays low whenever VCC is below the reset threshold or when MR is below VMRT. It remains low for tRP after either VCC rises above the reset threshold, or after MR input rises above VMRT (LM3710 only). Reset Logic Output. RESET is the inverse of RESET (LM3711 only). Power-Fail Logic Output. When PFI is below VPFT, PFO goes low; otherwise, PFO remains high. Low-Line Logic Output. Early Power-Fail warning output. Low when VCC falls below VLLOT (Low-Line Output Threshold). This output can be used to generate an NMI (Non-Maskable Interrupt) to provide an early warning of imminent power-failure. Ground reference for all signals. Watchdog Input Transition Monitor: If no transition activity occurs for a period exceeding tWD (Watchdog Timeout Period), reset is engaged. Power-Fail Comparator Input. When PFI is less than VPFT (Power-Fail Reset Threshold), the PFO goes low; otherwise, PFO remains high. No Connect. Test input used at factory only. Leave floating. RESET C2 C3 8 7 PFO LLO B3 A3 A2 B2 5 4 3 6, 9 GND WDI PFI NC www.national.com 2 LM3710/LM3711 Block Diagram 20011805 3 www.national.com LM3710/LM3711 Ordering Information 20011804 *For other voltages between 2.2V and 5.0V, please contact National Semiconductor sales office. LM3710/LM3711 Part Number LM3710XQBP-308 LM3710XQBPX-308 LM3710XQMM-308 LM3710XQMMX-308 LM3711XQBP-308 LM3711XQBPX-308 LM3711XQMM-308 LM3711XQMMX-308 Output totem-pole totem-pole totem-pole totem-pole totem-pole totem-pole totem-pole totem-pole Reset Timeout Period 200ms 200ms 200ms 200ms 200ms 200ms 200ms 200ms Watchdog Timeout Period 1600ms 1600ms 1600ms 1600ms 1600ms 1600ms 1600ms 1600ms x x x x x x Package MSOP micro SMD x x Package Marking %%IA %%IA R37B R37B %%IB %%IB R38B R38B %% is the datecode and will vary with time. Table Of Functions Part Number LM3710 LM3711 Active Low Reset x x Active High Reset Output (X = totem-pole) (Y = open-drain) X, Y* X Reset Timeout Period Customized Customized Watchdog Timeout Period Customized Customized Manual Reset x x Power Fail Comparator x x Low Line Output x x * = available upon request. Contact National www.national.com 4 LM3710/LM3711 Absolute Maximum Ratings (Note 1) Power Dissipation (Note 3) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (VCC) All Other Inputs ESD Ratings (Note 2) Human Body Model Machine Model −0.3V to 6.0V −0.3V to VCC + 0.3V 1.5kV 150V Operating Ratings (Note 1) Temperature Range −40˚C ≤ TJ ≤ 85˚C LM3710/LM3711 Series Electrical Characteristics Limits in the standard typeface are for TJ = 25˚C and limits in boldface type apply over full operating range. Unless otherwise specified: VCC = +2.2V to 5.5V. Symbol VCC ICC Parameter Operating Voltage Range: VCC VCC Supply Current Reset Threshold LM3710 LM3711 All inputs = VCC; all outputs floating Conditions Min 1.0 1.2 28 Typ Max 5.5 5.5 50 Units POWER SUPPLY V µA RESET THRESHOLD VRST VCC falling VCC falling: TA = 0˚C to 70˚C VRSTH tRP Reset Threshold Hysteresis Reset Timeout Period Reset Reset Reset Reset Timeout Timeout Timeout Timeout Period Period Period Period = = = = E, J, N, S F, K, P, T G, L, Q, U H, M, R, V 1 20 140 1120 −0.5 −2 −1.5 0.0032 • VRST 1.4 28 200 1600 20 2 40 280 2240 VRST +0.5 +2 +1.5 mV % ms tRD VCCto Reset Delay RESET VCCfalling at 1mV/µs µs RESET (LM3711) VOL VCC > 2.25V, ISINK = 900µA VCC VCC VOH RESET VCC VCC VCC VCC VCC ILKG Output Leakage Current RESET 0.3 0.3 0.4 0.8 VCC 0.8 VCC 0.8 VCC 0.8 VCC VCC − 1.5V 1.0 µA V V > > > > > > > 2.7V, ISINK = 1.2mA 4.5V, ISINK = 3.2mA 1.2V, ISOURCE = 50µA 1.8V, ISOURCE = 150µA 2.25V, ISOURCE = 300µA 2.7V, ISOURCE = 500µA 4.5V, ISOURCE = 800µA VRESET = 5.5V RESET (LM3710) VOL VCC > 1.0V, ISINK = 50µA VCC VCC VCC VCC VOH RESET VCC VCC VCC 0.3 0.3 0.3 0.3 0.4 0.8 VCC 0.8 VCC VCC − 1.5V V > > > > > > > 1.2V, ISINK = 100µA 2.25V, ISINK = 900µA 2.7V, ISINK = 1.2mA 4.5V, ISINK = 3.2mA 2.25V, ISOURCE = 300µA 2.7V, ISOURCE = 500µA 4.5V, ISOURCE = 800µA 5 www.national.com LM3710/LM3711 LM3710/LM3711 Series Electrical Characteristics Symbol WDI WDI WDIT tWD Watchdog Input Current Watchdog Input Threshold Watchdog Timeout Period Watchdog Watchdog Watchdog Watchdog Timeout Timeout Timeout Timeout Period Period Period Period = = = = E, F, G, H J, K, L, M N, P, Q, R S, T, U, V Parameter Conditions (Continued) Limits in the standard typeface are for TJ = 25˚C and limits in boldface type apply over full operating range. Unless otherwise specified: VCC = +2.2V to 5.5V. Min −1 Typ Max +1 Units µA 0.2 • VCC 4.3 71 1120 17900 1.200 MR, Low MR, High PFI/MR falling: VCC = VRST MAX 1.225 6.2 102 1600 25600 1.225 0.8 • VCC 9.3 153 2400 38400 1.250 0.8 V ms PFI/MR VPFT VMRT VPFTH/ VMRTH IPFI RMR tMD tMR PFO, LLO VOL PFO, LLO Output Voltage VCC > 2.25V, ISINK = 900µA VCC > 2.7V, ISINK = 1.2mA VCC > 4.5V, ISINK = 3.2mA VOH VCC > 2.25V, ISOURCE = 300µA VCC > 2.7V, ISOURCE = 500µA VCC > 4.5V, ISOURCE = 800µA LLO OUTPUT VLLOT LLO Output Threshold (VLLO − VRST, VCC falling) Low-Line Comparator Hysteresis Low-Line Comparator Delay VCC falling at 1mV/µs 1.01 • VRST 1.02 • VRST 1.03 • VRST V 0.8 VCC 0.8 VCC VCC − 1.5V 0.3 0.3 0.4 V PFI Input Threshold MR Input Threshold PFI/MR Threshold Hysteresis Input Current (PFI only) MR Pull-up Resistance MR to Reset Delay MR Pulse Width 25 V 2.0 to 5.5V −75 35 56 12 0.0032 • VRST 75 75 V mV nA kΩ µS µS VLLOTH 0.0032 • VRST mV tCD 20 µs www.national.com 6 LM3710/LM3711 LM3710/LM3711 Series Electrical Characteristics (Continued) 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. Some performance characteristics may degrade when the device is not operated under the listed conditions. Note 2: The Human Body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200pF capacitor discharged directly into each pin. Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, θJ-A, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperture is calculated using: Where the value of θJ-A for the MSOP-10 package is 195˚C/W in a typical PC board mounting and the micro SMD package is 220˚C/W. 7 www.national.com LM3710/LM3711 Typical Performance Characteristics Supply Current vs Supply Voltage 3.3V Supply Current vs Temperature 20011811 20011815 Normalized Reset Threshold Voltage vs Temperature Reset Timeout Period vs VCC 20011812 20011832 Reset Timeout Period vs Temperature Max. Transient Duration vs Reset Comparator Overdrive (VCC = 3.3V) 20011810 20011816 www.national.com 8 LM3710/LM3711 Typical Performance Characteristics Watchdog Timeout Period vs Temperature (tWD programmed as 6.2ms) (Continued) Low-Line Comparator Propagation Delay vs Temperature 20011814 20011813 Circuit Information Reset Output The Reset input of a µP initializes the device into a known state. The LM3710/LM3711 microprocessor supervisory circuits assert a forced reset output to prevent code execution errors during power-up, power-down, and brownout conditions. RESET is guaranteed valid for VCC > 1V. Once VCC exceeds the reset threshold, an internal timer maintains the output for the reset timeout period. After this interval, reset goes high. The LM3710 offers an active-low RESET; The LM3711 offers an active-high RESET. Any time VCC drops below the reset threshold (such as during a brownout), the reset activates. When VCC again rises above the reset threshold, the internal timer starts. Reset holds until VCC exceeds the reset threshold for longer than the reset timeout period. After this time, reset releases. The Manual Reset input (MR) will initiate a forced reset also. See the Manual Reset Input section. Reset Threshold The LM3710/LM3711 family is available with a reset voltage of 3.08V. Other reset thresholds in the 2.20V to 5.0V range, in steps of 10 mV, are available; contact National Semiconductor for details. Manual Reset Input (MR) Many µP-based products require a manual reset capability, allowing the operator to initiate a reset. The MR input is fully debounced and provides an internal 56 kΩ pull-up. When the MR input is pulled below VMRT (1.225V) for more than 25 µs, reset is asserted after a typical delay of 12 µs. Reset remains active as long as MR is held low, and releases after the reset timeout period expires after MR rises above VMRT. Use MR with digital logic to assert or to daisy chain supervisory circuits. It may be used as another low-line comparator by adding a buffer. Power-Fail Comparator (PFI/PFO) The PFI is compared to a 1.225V internal reference, VPFT. If PFI is less than VPFT, the Power Fail Output PFO drops low. The power-fail comparator signals a falling power supply, and is driven typically by an external voltage divider that senses either the unregulated supply or another system supply voltage. The voltage divider generally is chosen so the voltage at PFI drops below VPFT several milliseconds before the main supply voltage drops below the reset threshold, providing advanced warning of a brownout. The voltage threshold is set by R1 and R2 and is calculated as follows: Note this comparator is completely separate from the rest of the circuitry, and may be employed for other functions as needed. Low-Line Output (LLO) The low-line output comparator is typically used to provide a non-maskable interrupt to a µP when VCC begins falling. LLO monitors VCC and goes low when VCC falls below VLLOT (typically 1.02 • VRST) with hysteresis of 0.0032 • VRST. Watchdog Timer Input (WDI) The watchdog timer input monitors one of the microprocessor’s output lines for activity. Each time a transition occurs on this monitored line, the watchdog counter is reset. However, if no transition occurs and the timeout period is reached, the LM3710/LM3711 assumes that the microprocessor has locked up and the reset output is activated. WDI is a high impedance input. Special Precautions for the micro SMD Package As with most integrated circuits, the LM3710 and LM3711 are sensitive to exposure from visible and infrared (IR) light radiation. Unlike a plastic encapsulated IC, the micro SMD package has very limited shielding from light, and some sensitivity to light reflected from the surface of the PC board or long wavelength IR entering the die from the side may be 9 www.national.com LM3710/LM3711 Circuit Information (Continued) experienced. This light could have an unpredictable affect on the electrical performance of the IC. Care should be taken to shield the device from direct exposure to bright visible or IR light during operation. Micro SMD Mounting The micro SMD package requires specific mounting techniques which are detailed in National Semiconductor Application Note AN-1112. Referring to the section Surface Mount Technology (SMT) Assembly Considerations, it should be noted that the pad style which must be used with the 9-pin package is the NSMD (non-solder mask defined) type. For best results during assembly, alignment ordinals on the PC board may be used to facilitate placement of the micro SMD device. www.national.com 10 LM3710/LM3711 Timing Diagrams 20011828 FIGURE 1. LM3710/LM3711 Reset Time with MR and WDI 20011829 FIGURE 2. LLO Output 20011830 FIGURE 3. PFI Comparator Timing Diagram 11 www.national.com LM3710/LM3711 Typical Application Circuits 20011818 FIGURE 4. Monitoring Two Critical Supplies And Dataline 20011819 FIGURE 5. Monitoring Two Supplies plus Manual Reset And Dataline www.national.com 12 LM3710/LM3711 Typical Application Circuits (Continued) 20011820 FIGURE 6. Monitoring Dual Supplies plus External Fault Input And Dataline 20011821 Note: MR input with its 1.225V nominal threshold, may monitor an additional supply voltage. An internal 56 kΩ pull-up resistor is included on this input. FIGURE 7. Microprocessor Supervisor with Early Warning Detector 13 www.national.com LM3710/LM3711 Typical Application Circuits (Continued) 20011840 FIGURE 8. LM3710 Long Period oscillator www.national.com 14 LM3710/LM3711 Physical Dimensions unless otherwise noted inches (millimeters) 10 Lead MSOP Package NS Package Number MUB10A 15 www.national.com LM3710/LM3711 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output, Manual Reset and Watchdog Timer Physical Dimensions inches (millimeters) unless otherwise noted (Continued) NOTES: UNLESS OTHERWISE SPECIFIED 1. EPOXY COATING 2. 63Sn/37Pb EUTECTIC BUMP 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN 1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED COUNTER CLOCKWISE. 5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE HEIGHT. 6.NO JEDEC REGISTRATION AS OF AUG.1999. 9 bump micro SMD Package NS Package Number BPA09FFB The dimensions of X1, X2 and X3 are given below X1 = 1.412mm X2 = 1.412mm X3 = 0.850mm 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: support@nsc.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com 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: ap.support@nsc.com National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 www.national.com 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.