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MicroPower Microprocessor Reset Circuit General Description The AAT3520 Series of PowerManagerTM products is a member of AnalogicTechTM's Total Power ManagementTM IC (TPM ICsTM) product family. These microprocessor reset circuits are ideal for monitoring voltage supplies in portable systems, where extended battery life is critical. They provide a low cost, reliable solution by eliminating external components. The AAT3520 series operates by monitoring the system power supply voltage. When the input voltage drops below a fixed threshold, the device asserts a reset signal for a fixed time period after VCC has risen back above the fixed threshold; 30ms and 150ms minimum periods are available. The AAT3520 product series is guaranteed to operate down to 1.2V and designed to ignore fast line transients appearing on VCC. The AAT3520 series is available with three output stage versions: AAT3520 push-pull active high output, AAT3522 push-pull active low output and AAT3524 open drain active low output. The quiescent supply current is extremely low, typically 1A, making it ideal for portable battery operated equipment. The AAT3520/2/4 are available in a 3 pin SOT23 package and are specified over -40 to 85C operating temperature range. AAT3520/2/4 Features * * * * * * * * PowerManagerTM * * * 1.2V to 5.5V Input voltage range Operation down to 1.2V Extremely low quiescent current: less than 2A High accuracy detection threshold: 1.5% Monitor Power Supply Voltages Fixed thresholds from 2.2V to 4.6V Reset pulse width options * Minimum 30 ms or 150ms * Fast propagation delay <20s Available output configurations: * Open-drain output * CMOS active high output * CMOS active low output Temp range -40 to 85C 3 pin SOT23 package 4kV ESD rating Applications * * * * * Notebook Computers Cell Phones Portable Electronics Embedded Systems Intelligent Instruments Typical Application VCC VCC VCC 100k (nominal) * AAT3520 AAT3522 RESET AAT3524 (RESET) RESET uP INPUT GND GND *AAT3524 Only 3520.2004.04.1.0 1 MicroPower Microprocessor Reset Circuit Pin Descriptions AAT3520, 3522, 3524 (SOT23-3) Pin # 1 AAT3520/2/4 Symbol GND RESET (AAT3520) Function Ground connection RESET output remains high while VCC is below the reset threshold and remains so for a fixed time period after VCC raises above the reset threshold. RESET output remains low while VCC is below the reset threshold and remains so for a fixed time period after VCC raises above the reset threshold Supply Voltage (+1.2V to +5.5V). Due to extremely low operating current it is recommended to place a 10nF capacitor between VCC and GND. 2 RESET (AAT3522, AAT3524) Vcc 3 Part Number Descriptions SOT23-3 Part Number AAT3520 AAT3522 AAT3524 Part Description Reset Output Push Pull Active High with Delay Reset Output Push Pull Active Low with Delay Reset Output Open Drain Active Low with Delay Pin Configuration SOT-23 (Top View) GND 1 3 VCC (RESET) RESET 2 2 3520.2004.04.1.0 MicroPower Microprocessor Reset Circuit Absolute Maximum Ratings Symbol VCC VRESET IMAX IRESET dVcc/dt TJ TLEAD AAT3520/2/4 (TA=25C unless otherwise noted) Value -0.3 to 5.5 -0.3 to VCC+0.3 -0.3 to 5.5 20 20 100 -40 to 150 300 Description VCC to GND RESET to GND (Push-Pull Output) RESET to GND (Open Drain Output) Maximum Continuous Input Current RESET/RESET Current Rate of rise of Vcc Operating Junction Temperature Range Maximum Soldering Temperature (at Leads) for 10s Units V V mA mA V/s C C Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time. Thermal Information Symbol JA PD Description Maximum Thermal Resistance (SOT23-3)1 Maximum Power Dissipation (SOT23-3)1 Value 200 320 Units C/W mW Note 1: Mounted on an FR4 board. 3520.2004.04.1.0 3 MicroPower Microprocessor Reset Circuit Electrical Characteristics (VIN = 5V, TA = -40 to 85C unless otherwise noted. Typical values are at TA=25C, VCC = 5V for 4.63/4.38V versions, VCC = 3.3V for 3.08/2.93V versions, VCC = 3.0V for 2.63V version and VCC = 2.5V for 2.32/2.2V versions ) Symbol VCC IQ VTH VTH/C tP tRDY AAT3520/2/4 Description Operation Voltage Quiescent Current RESET Threshold (Table 1) RESET Threshold Tempco RESET Propagation Delay RESET Active Timeout Period Conditions TA = 0C to +70C TA = -40C to +85C VCC = 5.5V VCC = 3V TA = 25C TA = -40C to +85C Min 1.0 1.2 Typ Max Units VTH -1.5% VTH -2.5% VOL VOH VOL VOH IDOFF VCC = VTH to (VTH -100mV) -50 option -200 option ISINK =1.2mA, VCC = VTH(min), RESET Low Output Voltage VTH 3.08V, RESET asserted AAT3522, AAT3524 ISINK =3.2mA, VCC = VTH(min), VTH > 3.08V, RESET asserted ISOURCE = 800 A, VTH > 3.08V, RESET High Output Voltage VCC > VTH (max) AAT3522 ISOURCE = 500 A, VTH 3.08V, VCC > VTH (max) ISINK =1.2mA, VCC > VTH (max), RESET Low Output Voltage VTH 3.08V, RESET not asserted AAT3520 ISINK = 3.2mA, VCC > VTH (max), VTH > 3.08V, RESET not asserted ISOURCE = 500A, VCC > 2.1V, RESET High Output Voltage RESET asserted AAT3520 ISOURCE = 50A, VCC > 1.2V, RESET asserted RESET leakage current, VCC > VTH AAT3524 30 150 5.5 V 5.5 1.05 3 A 0.85 2 VTH VTH +1.5% V VTH VTH +2.5% 40 ppm/C 15 s 50 100 ms 250 400 0.3 0.4 V VCC -1.5 0.8 VCC 0.3 0.4 0.8VCC 0.8VCC 1 V V V A 4 3520.2004.04.1.0 MicroPower Microprocessor Reset Circuit Typical Characteristics Supply Current vs. Temperature 1.40 AAT3520/2/4 Normalized Reset Threshold vs. Temperature Normalized Threshold 1.003 1.002 1.001 1.000 0.999 0.998 0.997 -40 -20 0 20 40 60 80 Supply Current (A) 1.20 1.00 0.80 0.60 0.40 0.20 0.00 -40 -20 VCC=5V VCC=3V 0 20 40 60 80 Temperature (C) Temperature (C) Normalized Power-Up Reset Timeout vs. Temperature 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 -40 -20 0 20 40 60 80 100 Power-Down Reset Propagation Delay vs. Temperature Reset Propagation Delay (s) 30 25 20 15 10 5 0 -40 Normalized Power-Up Reset Timeout (ms) VOD=10mV VOD=100mV Temperature (C) -20 0 20 40 60 80 Temperature (C) Maximum Transient Duration vs. Reset Threshold Overdrive 400 Maximum Transient Duration (S) 350 300 250 200 150 100 50 0 1 10 100 1000 Reset Threshold Overdrive, VTH-VCC (mV) 3520.2004.04.1.0 5 MicroPower Microprocessor Reset Circuit Functional Block Diagram AAT3520/2/4 VCC Reset Generator + Timer RESET (RESET) Oscillator VREF GND Functional Description General During start-up, the reset pin on a microprocessor ensures that it is fully reset and starts up in a known condition. The AAT3520 series of microprocessor reset devices monitor the supply voltage to a microprocessor and assert a reset signal whenever the VCC voltage falls below a factory programmed threshold. This threshold is accurate within +/-1.5% at 25C and within +/- 2.5% over the entire operating temperature range. The reset signal remains asserted for a fixed time period (tRDY) after VCC has risen above the threshold as shown in Figure 1. See Ordering Information for available RESET active timeout periods VCC VTH VTH VTH RESET tRDY tRDY Figure 1: Reset Timing Diagram (AAT3522, AAT3524) 6 3520.2004.04.1.0 MicroPower Microprocessor Reset Circuit Applications Information Reset Output Options The AAT3524 has an active low open drain output and the AAT3520/2 have a push-pull output. The AAT3524 may be used in multiple voltage systems, with an external pull-up resistor. This allows the AAT3524 to interface to microprocessors with higher supply voltages up to 5.5V (Figure 3). In the event of a power down or brown-out condition the reset signal remains valid until the VCC drops below 1.2V. To ensure validity down to ground an external 100k resistor should be connected between the RESET output and GND. AAT3520/2/4 Supply Voltage Transient Behavior In some cases fast negative transients of short duration can appear on the VCC power supply. The AAT3520 series devices provide some immunity to line transients which can generate invalid reset pulses. Figure 1 shows typical behavior to short duration pulses verses RESET comparator overdrive. As shown in the Maximum Transient Duration vs. Reset Threshold Overdrive graph, when the transient voltage becomes larger, the time allowed before asserting a reset becomes shorter. e.g. typically a transient of 100mV below the reset threshold would have to present for more than 50s to cause a reset. Immunity can be increased by the addition of a small by-pass capacitor of 0.1F connected as close to the VCC pin as possible. VCC VCC VCC 100k (nominal) * 0.1F AAT3520 AAT3522 RESET AAT3524 (RESET) RESET uP INPUT GND GND *AAT3524 Only Figure 2: Using Recommended Bypass Capacitor +3.3V +5.0V VCC 100k VCC AAT3524 RESET RESET INPUT 5V System GND GND Figure 3: Using AAT3524 Open Drain Output with Multiple Supplies 3520.2004.04.1.0 7 MicroPower Microprocessor Reset Circuit Factory Trimmed Reset Thresholds* and Ordering Information Table 1 Reset Threshold Voltage, VTH (V) Ordering Part Number AAT3522IGY-2.20-200-T1 AAT3520IGY-2.32-200-T1 AAT3522IGY-2.32-200-T1 AAT3524IGY-2.32-200-T1 AAT3522IGY-2.45-200-T1 AAT3520IGY-2.63-200-T1 AAT3522IGY-2.63-200-T1 AAT3524IGY-2.63-200-T1 AAT3520IGY-2.93-200-T1 AAT3522IGY-2.93-50-T1 AAT3522IGY-2.93-200-T1 AAT3524IGY-2.93-200-T1 AAT3520IGY-3.08-50-T1 AAT3520IGY-3.08-200-T1 AAT3522IGY-3.08-50-T1 AAT3522IGY-3.08-200-T1 AAT3524IGY-3.08-200-T1 AAT3520IGY-4.38-200-T1 AAT3522IGY-4.38-200-T1 AAT3524IGY-4.38-200-T1 AAT3520IGY-4.63-200-T1 AAT3522IGY-4.63-200-T1 AAT3524IGY-4.63-200-T1 AAT3520/2/4 Minimum Marking Reset Active (ms) DB DS DT DX GN CA CW CZ FV CC FP EF CN CY CB BG HJ FU IV HK DA DU 150 150 150 150 150 150 150 150 150 30 150 150 30 150 30 150 150 150 150 150 150 150 150 TA = 25C TA = 40 to 85C Min 2.167 2.285 2.413 2.591 Typ 2.200 2.320 2.450 2.630 Max 2.233 2.355 2.487 2.669 Min 2.145 2.262 2.389 2.564 Max 2.255 2.378 2.511 2.696 2.886 2.930 2.974 2.857 3.003 3.034 3.080 3.126 3.003 3.157 4.314 4.380 4.446 4.271 4.490 4.561 4.630 4.699 4.514 4.746 Note: Sample stock is generally held on all part numbers listed in BOLD. *Contact Local Sales Office for custom trimmed options 8 3520.2004.04.1.0 MicroPower Microprocessor Reset Circuit Package Information SOT23-3 2.92 0.12 AAT3520/2/4 1.30 0.10 0.95 BSC 1.90 BSC 2.37 0.27 0.86 0.16 0.075 0.075 0.96 0.21 0.40 0.10 x 3 0.50 0.10 0.54 REF All dimensions in millimeters. 0.14 0.06 4 4 3520.2004.04.1.0 9 MicroPower Microprocessor Reset Circuit AAT3520/2/4 AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech's standard warranty. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 10 3520.2004.04.1.0 |
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