ADM6348 (Analog Devices) - (ADM6326 - ADM6348) SOT-23 Microprocessor Reset Circuits (ADM6348.pdf)

Analog Devices

Description
Ultralow Power, 3-Lead, SOT-23 Microprocessor Reset Circuits ADM6326/ADM6328/ADM6346/ADM6348 FEATURES Ultralow supply current of 1 μA 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 −40°C to +85°C 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, www.DataSheet4U.com 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 −40°C to +85°C. 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 ©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 www.DataSheet4U.com Rev. 0 | Page 2 of 12 ADM6326/ADM6328/ADM6346/ADM6348 SPECIFICATIONS TA = −40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C 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 μA μA V V ppm/°C mV mV μs ms V V V V V 0.1 μA VCC = VTH to (VTH − 100 mV) VCC > 2.1 V, ISINK = 1.6 mA, reset asserted VCC ≥ 1.2 V, ISINK = 100 μA, reset asserted ADM6326 only, VCC = 3.2 V, ISOURCE = 500 μA ADM6326/ADM6346 only, VCC = 4.5 V, ISOURCE = 800 μA, VTH ≤ 4.38 V ADM6326/ADM6346 only, VCC = VTH(MAX), ISOURCE = 800 μA, 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 = 25°C 100 280 0.3 0.4 0.8 × VCC 0.8 × VCC 0.8 × VCC OPEN-DRAIN RESET OUTPUT LEAKAGE CURRENT Table 2. Reset Threshold Voltage TA = 25°C Parameter RESET THRESHOLD VOLTAGE (VTH) ADM632x-22 ADM632x-23 www.DataSheet4U.com 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 = −40°C to +85°C 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/μs −65°C to +155°C −40°C to +85°C 300°C THERMAL RESISTANCE θJA 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 θJA 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. www.DataSheet4U.com 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. www.DataSheet4U.com 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 (µA) 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 (µs) 700 POWER-DOWN RESET DELAY (µs) 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 www.DataSheet4U.com Figure 5. Maximum Transient Duration vs. Reset Threshold Overdrive RESET THRESHOLD OVERDRIVE, VTH – VCC (mV) TEMPERATURE (°C) 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 an

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