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| Ultralow Power, 3-Lead, SOT-23 Microprocessor Reset Circuits ADM6326/ADM6328/ADM6346/ADM6348 FEATURES Ultralow supply current of 1 A maximum (ADM6326/ADM6328) Accurate monitoring of 2.5 V, 3 V, 3.3 V, and 5 V rails Reset thresholds available in increments from 2.2 V to 4.63 V Glitch immunity from negative-going VCC transients 2 reset output options Push-pull RESET (ADM6326/ADM6346) Open-drain RESET (ADM6328/ADM6348) Minimum reset timeout of 100 ms Operating temperature range of -40C to +85C 3-lead SOT-23 package FUNCTIONAL BLOCK DIAGRAMS ADM6326/ADM6346 VCC VREF RESET GENERATOR (100ms) RESET GND Figure 1. ADM6328/ADM6348 VCC VREF RESET GENERATOR (100ms) RESET APPLICATIONS Telecommunications Microprocessor systems Desktop and notebook computers Portable equipment GND Figure 2. GENERAL DESCRIPTION The ADM6326/ADM6328/ADM6346/ADM6348 devices provide low cost solutions for protecting sensitive circuitry, such as microprocessor and telecommunications circuitry. With built-in glitch immunity, ultralow supply currents, and 24 reset threshold voltage options, the ADM6326/ADM6328/ ADM6346/ADM6348 not only ensure that systems are immune to fast transients on VCC, but also that the devices are suitable for monitoring a variety of supply voltages in low power, portable equipment. These devices provide a reset output during power-up, powerdown, and brownout conditions. On power-up, an internal timer holds RESET asserted for at least 100 ms. This holds the microprocessor in a reset state until conditions have stabilized. The reset output remains operational with VCC as low as 1 V. The ADM6326 and ADM6346 have an active low push-pull reset output. The ADM6328 and ADM6348 have an active low opendrain reset output, which requires an external pull-up resistor. The ADM6326 and ADM6328 offer a choice of ten reset thresholds in increments between 2.2 V and 3.08 V, whereas the ADM6346 and ADM6348 offer a choice of 14 reset thresholds between 3.3 V and 4.63 V. These devices are available in a 3-lead SOT-23 package and operate over the extended temperature range of -40C to +85C. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2009 Analog Devices, Inc. All rights reserved. 08052-002 08052-001 ADM6326/ADM6328/ADM6346/ADM6348 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagrams ............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 Thermal Resistance ...................................................................... 4 ESD Caution .................................................................................. 4 Pin Configuration and Function Descriptions..............................5 Typical Performance Characteristics ..............................................6 Theory of Operation .........................................................................7 Reset Output ..................................................................................7 Interfacing to Other Devices .......................................................7 Transient Immunity ......................................................................7 Outline Dimensions ..........................................................................8 Ordering Guide .............................................................................9 REVISION HISTORY 9/09--Revision 0: Initial Version Rev. 0 | Page 2 of 12 ADM6326/ADM6328/ADM6346/ADM6348 SPECIFICATIONS TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C and VCC = 3 V. Overtemperature limits are guaranteed by design. Table 1. Parameter OPERATING VOLTAGE RANGE, VCC INPUT CURRENT, ICC Min 1.0 Typ 0.5 1.0 RESET THRESHOLD Threshold Voltage, VTH (See Table 2) Temperature Coefficient Hysteresis ADM6326/ADM6328 ADM6346/ADM6348 TIMING CHARACTERISTICS VCC to Reset Delay (tRD) Reset Active Timeout Period (tRP) RESET OUTPUT VOLTAGE LOW, VOL RESET OUTPUT VOLTAGE HIGH, VOH VTH - 2.5% VTH - 1.5% VTH VTH 40 6.3 9.5 20 185 Max 5.5 1.0 1.75 VTH + 2.5% VTH + 1.5% Unit V A A V V ppm/C mV mV s ms V V V V V 0.1 A VCC = VTH to (VTH - 100 mV) VCC > 2.1 V, ISINK = 1.6 mA, reset asserted VCC 1.2 V, ISINK = 100 A, reset asserted ADM6326 only, VCC = 3.2 V, ISOURCE = 500 A ADM6326/ADM6346 only, VCC = 4.5 V, ISOURCE = 800 A, VTH 4.38 V ADM6326/ADM6346 only, VCC = VTH(MAX), ISOURCE = 800 A, VTH 4.5 V Test Conditions/Comments ADM6326/ADM6328 only, VCC = 3.0 V for VTH 2.93 V, VCC = 3.2 V for VTH > 2.93 V, no load VCC = 5.5 V, no load TA = 25C 100 280 0.3 0.4 0.8 x VCC 0.8 x VCC 0.8 x VCC OPEN-DRAIN RESET OUTPUT LEAKAGE CURRENT Table 2. Reset Threshold Voltage TA = 25C Parameter RESET THRESHOLD VOLTAGE (VTH) ADM632x-22 ADM632x-23 ADM632x-24 ADM632x-25 ADM632x-26 ADM632x-27 ADM632x-28 ADM632x-29 ADM632x-30 ADM632x-31 ADM634x-33 ADM634x-34 ADM634x-35 ADM634x-36 ADM634x-37 ADM634x-38 ADM634x-39 ADM634x-40 ADM634x-41 ADM634x-42 ADM634x-43 ADM634x-44 ADM634x-45 ADM634x-46 Min 2.167 2.285 2.364 2.462 2.591 2.66 2.758 2.886 2.955 3.034 3.25 3.349 3.447 3.546 3.644 3.743 3.841 3.94 4.038 4.137 4.235 4.314 4.432 4.56 Typ 2.2 2.32 2.4 2.5 2.63 2.7 2.8 2.93 3.00 3.08 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.38 4.5 4.63 Max 2.233 2.355 2.436 2.537 2.669 2.741 2.842 2.974 3.045 3.126 3.35 3.451 3.552 3.654 3.755 3.857 3.958 4.06 4.161 4.263 4.364 4.446 4.567 4.699 TA = -40C to +85C Min 2.145 2.262 2.34 2.437 2.564 2.633 2.73 2.857 2.925 3.003 3.217 3.315 3.412 3.51 3.607 3.705 3.802 3.9 3.997 4.095 4.192 4.27 4.387 4.514 Max 2.25 2.375 2.46 2.562 2.696 2.768 2.87 3.0 3.075 3.15 3.383 3.485 3.587 3.69 3.792 3.895 3.997 4.1 4.202 4.305 4.407 4.489 4.612 4.746 Unit V V V V V V V V V V V V V V V V V V V V V V V V Rev. 0 | Page 3 of 12 ADM6326/ADM6328/ADM6346/ADM6348 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter Supply Voltage, VCC Input Current, ICC Output Voltage Push-Pull RESET Open-Drain RESET Output Current (RESET) Rate of Rise of VCC Temperature Storage Operating Soldering (10 sec) Rating -0.3 V to +6 V 20 mA -0.3 V to (VCC + 0.3 V) -0.3 V to +6 V 20 mA 100 V/s -65C to +155C -40C to +85C 300C THERMAL RESISTANCE JA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 4. Thermal Resistance Package Type 3-Lead SOT-23 JA 270 Unit C/W ESD CAUTION Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. 0 | Page 4 of 12 ADM6326/ADM6328/ADM6346/ADM6348 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS GND 1 ADM6326/ ADM6328/ ADM6346/ ADM6348 TOP VIEW (Not to Scale) 3 VCC 08052-003 RESET 2 Figure 3. ADM6326/ADM6328/ADM6346/ADM6348 Pin Configuration Table 5. Pin Function Descriptions Pin No. 1 2 3 Mnemonic GND RESET VCC Description Ground Reference for All Signals; 0 V. Active Low Logic Output. This pin is low when VCC is less than the reset threshold; it remains low for 185 ms (typical) after VCC becomes greater than the reset threshold. Supply Voltage Being Monitored. Rev. 0 | Page 5 of 12 ADM6326/ADM6328/ADM6346/ADM6348 TYPICAL PERFORMANCE CHARACTERISTICS 1.0 0.9 0.8 VCC = 5V VCC = 3.3V 280 260 POWER-UP RESET TIMEOUT (ms) 240 220 200 180 160 140 120 08052-007 SUPPLY CURRENT (A) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 08052-004 VCC = 1.4V 0 -40 -20 0 20 40 60 80 100 -40 -20 0 20 40 60 80 TEMPERATURE (C) TEMPERATURE (C) Figure 4. Supply Current vs. Temperature Figure 6. Power-Up Reset Timeout vs. Temperature 800 250 MAXIMUM TRANSIENT DURATION (s) 700 POWER-DOWN RESET DELAY (s) 200 600 500 400 300 200 100 0 08052-006 150 100 VOD = 10mV 50 VOD = 20mV VOD = 200mV 0 -40 VOD = 100mV -20 0 20 40 60 80 RESET THRESHOLD OVERDRIVE, VTH - VCC (mV) TEMPERATURE (C) Figure 5. Maximum Transient Duration vs. Reset Threshold Overdrive Figure 7. Power-Down Reset Delay vs. Temperature Rev. 0 | Page 6 of 12 08052-005 1 10 100 1000 ADM6326/ADM6328/ADM6346/ADM6348 THEORY OF OPERATION The ADM6326/ADM6328/ADM6346/ADM6348 are designed to protect the integrity of a system's operation by ensuring the proper operation of the system during power-up, power-down, and brownout conditions. Ultralow supply currents make these devices particularly suitable for use in low power, portable equipment. INTERFACING TO OTHER DEVICES The active low, open-drain reset output of the ADM6328 and ADM6348 makes these devices ideal for integration with devices such as microprocessors with bidirectional reset pins. Simply connect the RESET output of the ADM6328 or ADM6348 to the RESET input of the microprocessor using a single pull-up resistor to allow either device to initiate a system reset (see Figure 8). VCC VCC VCC RESET OUTPUT The ADM6326 and ADM6346 have an active low, push-pull reset output, whereas the ADM6328 and ADM6348 have an active low, open-drain reset output, which requires an external pull-up resistor. The RESET signal is guaranteed to be valid for VCC down to 1 V. When the ADM6326/ADM6328/ADM6346/ADM6348 are powered up, the RESET output remains low for a period typically equal to the RESET active timeout period of 185 ms. This feature allows adequate time for the system to power up correctly and for the power supply to stabilize before any devices are brought out of reset and are allowed to begin executing instructions. Initializing a system in this way provides a more reliable startup for microprocessor systems. When the monitored voltage falls below its associated threshold (VTH), RESET is asserted within 20 s (typical). Asserting RESET this quickly means that the entire system can be reset at once before any part of the system's voltage falls below its recommended operating voltage. This system reset can avoid dangerous and/or erroneous operation of a microprocessor based system. RPULL-UP ADM6328/ADM6348 RESET GND MICROPROCESSOR SYSTEM RESET INPUT 08052-008 GND Figure 8. Interfacing to a Microprocessor with a Bidirectional Reset Pin TRANSIENT IMMUNITY To avoid unnecessary resets caused by fast power supply transients, the ADM6326/ADM6328/ADM6346/ADM6348 provide glitch immunity from negative-going VCC transients. Figure 5 shows the RESET comparator overdrive (that is, the maximum magnitude of negative-going pulses with respect to the typical threshold) vs. the pulse duration without a reset. VCC VCC 1V 0V VCC VTH VTH 0V Figure 9. RESET Timing Rev. 0 | Page 7 of 12 08052-009 RESET tRP tRD ADM6326/ADM6328/ADM6346/ADM6348 OUTLINE DIMENSIONS 3.04 2.90 2.80 1.40 1.30 1.20 1 3 2.64 2.10 2 0.60 0.45 1.02 0.95 0.88 0.100 0.013 SEATING PLANE 2.05 1.78 1.03 0.89 1.12 0.89 GAUGE PLANE 0.54 REF 0.180 0.085 0.51 0.37 0.25 0.60 MAX 0.30 MIN 011909-C COMPLIANT TO JEDEC STANDARDS TO-236-AB Figure 10. 3-Lead Small Outline Transistor Package [SOT-23-3] (RT-3) Dimensions shown in millimeters Rev. 0 | Page 8 of 12 ADM6326/ADM6328/ADM6346/ADM6348 ORDERING GUIDE Model 1 ADM6326-22ARTZ-R7 2, 3 ADM6326-23ARTZ-R72 ADM6326-24ARTZ-R72 ADM6326-25ARTZ-R72 ADM6326-26ARTZ-R72 ADM6326-27ARTZ-R72 ADM6326-28ARTZ-R72 ADM6326-29ARTZ-R72 ADM6326-30ARTZ-R72 ADM6326-31ARTZ-R72 ADM6328-22ARTZ-R72 ADM6328-23ARTZ-R72 ADM6328-24ARTZ-R72 ADM6328-25ARTZ-R72 ADM6328-26ARTZ-R72 ADM6328-27ARTZ-R72 ADM6328-28ARTZ-R72, 3 ADM6328-29ARTZ-R72 ADM6328-30ARTZ-R72 ADM6328-31ARTZ-R72 ADM6346-33ARTZ-R72, 3 ADM6346-34ARTZ-R72 ADM6346-35ARTZ-R72 ADM6346-36ARTZ-R72 ADM6346-37ARTZ-R72 ADM6346-38ARTZ-R72 ADM6346-39ARTZ-R72 ADM6346-40ARTZ-R72 ADM6346-41ARTZ-R72 ADM6346-42ARTZ-R72 ADM6346-43ARTZ-R72 ADM6346-44ARTZ-R72 ADM6346-45ARTZ-R72 ADM6346-46ARTZ-R72 ADM6348-33ARTZ-R72 ADM6348-34ARTZ-R72 ADM6348-35ARTZ-R72 ADM6348-36ARTZ-R72 ADM6348-37ARTZ-R72 ADM6348-38ARTZ-R72 ADM6348-39ARTZ-R72 ADM6348-40ARTZ-R72 ADM6348-41ARTZ-R72 ADM6348-42ARTZ-R72 ADM6348-43ARTZ-R72 ADM6348-44ARTZ-R72 ADM6348-45ARTZ-R72 ADM6348-46ARTZ-R72, 3 1 2 Typical Threshold Voltage (TA = 25C) 2.2 V 2.32 V 2.4 V 2.5 V 2.63 V 2.7 V 2.8 V 2.93 V 3.0 V 3.08 V 2.2 V 2.32 V 2.4 V 2.5 V 2.63 V 2.7 V 2.8 V 2.93 V 3.0 V 3.08 V 3.3 V 3.4 V 3.5 V 3.6 V 3.7 V 3.8 V 3.9 V 3.0 V 4.1 V 4.2 V 4.3 V 4.38 V 4.5 V 4.63 V 3.3 V 3.4 V 3.5 V 3.6 V 3.7 V 3.8 V 3.9 V 3.0 V 4.1 V 4.2 V 4.3 V 4.38 V 4.5 V 4.63 V RESET Output Structure Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Push-Pull Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Open-Drain Package Description 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 3-Lead SOT-23 Package Option RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 RT-3 Branding LAQ LAR LAS LAT LAU LAV LAW LAX LAY LAZ LB0 LB1 LB2 LB3 LB4 LB5 LB6 LB7 LB8 LB9 LBA LBC LBD LBE LBF LBG LBH LCN LCP LCQ LCR LCS LCT LCU LCV LCW LCX LCY LCZ LD0 LD1 LD2 LD3 LD4 LD5 LD6 LD7 LD8 Contact sales for the availability of nonstandard models. Z = RoHS Compliant Part. 3 Standard model. Rev. 0 | Page 9 of 12 ADM6326/ADM6328/ADM6346/ADM6348 NOTES Rev. 0 | Page 10 of 12 ADM6326/ADM6328/ADM6346/ADM6348 NOTES Rev. 0 | Page 11 of 12 ADM6326/ADM6328/ADM6346/ADM6348 NOTES (c)2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08052-0-9/09(0) Rev. 0 | Page 12 of 12 |
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