AAT3520

AAT3520/2/4 MicroPower™ Microprocessor Reset Circuit General Description The AAT3520 series of PowerManager products is part of AnalogicTech's Total Power Management IC™ (TPMIC™) 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 the need for 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 is 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 1µA, making it ideal for portable battery-operated equipment. The AAT3520/2/4 are available in a Pb-free, 3-pin SOT23 package and are specified over the -40°C to +85°C operating temperature range. Features • • • • • • • PowerManager™ • • • • Input Voltage Range: 1.2V to 5.5V Operation Down to 1.2V Extremely Low Quiescent Current: 3.08V, RESET High Output Voltage VCC > VTH (max) AAT3522 ISOURCE = 500µA, 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 = 500µA, VCC > 2.1V, RESET High Output Voltage RESET Asserted AAT3520 ISOURCE = 50µA, VCC > 1.2V, RESET Asserted RESET Leakage Current VCC > VTH AAT3524 30 150 15 50 250 100 400 0.3 ms V 0.4 VCC -1.5 V 0.8 VCC 0.3 V 0.4 0.8VCC V 0.8VCC 1 µA 4 3520.2006.03.1.2 AAT3520/2/4 MicroPower™ Microprocessor Reset Circuit Typical Characteristics Supply Current vs. Temperature 1.40 Normalized Reset Threshold vs. Temperature 1.003 Supply Current (µA) 1.00 0.80 0.60 0.40 0.20 0.00 -40 -20 0 20 40 60 80 Normalized Threshold 1.20 VCC = 5V 1.002 1.001 1.000 0.999 0.998 0.997 -40 -20 0 20 40 60 80 VCC = 3V 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 Power-Down Reset Propagation Delay vs. Temperature Reset Propagation Delay (µs) 30 25 20 15 10 5 0 -40 Normalized Power-Up Reset Timeout (ms) VOD = 10mV VOD = 100mV -40 -20 0 20 40 60 80 100 Temperature (°C) -20 0 20 40 60 80 Temperature (°C) Maximum Transient Duration vs. Reset Threshold Overdrive 400 Maximum Transient Duration (µs) 350 300 250 200 150 100 50 0 1 10 100 1000 Reset Threshold Overdrive, VTH - VCC (mV) 3520.2006.03.1.2 5 AAT3520/2/4 MicroPower™ Microprocessor Reset Circuit Functional Block Diagram 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 25ºC 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 3520.2006.03.1.2 AAT3520/2/4 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 100kΩ resistor should be connected between the RESET output and GND. 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 versus 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 (i.e., typically a transient of 100mV below the reset threshold would have to present for more than 50µs to cause a reset). Immunity can be increased by the addition of a small bypass capacitor of 0.1µF connected as closely to the VCC pin as possible. VCC VCC * 100kΩ (nominal) VCC 0.1µF AAT3520 AAT3522 RESET AAT3524 (RESET) RESET µP INPUT GND GND *AAT3524 Only Figure 2: Using Recommended Bypass Capacitor. +3.3V +5.0V VCC 100kΩ VCC AAT3524 RESET RESET INPUT 5V System GND GND Figure 3: Using AAT3524 Open Drain Output with Multiple Supplies. 3520.2006.03.1.2 7 AAT3520/2/4 MicroPower™ Microprocessor Reset Circuit Factory Trimmed Reset Thresholds1 and Ordering Information Reset Threshold Voltage, VTH (V) Ordering Part Number2 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 TA = 25°C TA = -40°C to +85°C Marking3 DBXYY DTXYY DXXYY GNXYY CAXYY CWXYY CZXYY FVXYY CCXYY FPXYY EFXYY CNXYY CYXYY CBXYY BGXYY FUXYY IVXYY HKXYY DAXYY DUXYY Minimum Reset Active (ms) 150 150 150 150 150 150 150 150 150 30 150 150 30 150 30 150 150 150 150 150 150 150 150 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 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree. 1. Contact Local Sales Office for custom trimmed options. 2. Sample stock is generally held on part numbers listed in BOLD. 3. XYY = assembly and date code. 8 3520.2006.03.1.2 AAT3520/2/4 MicroPower™ Microprocessor Reset Circuit Package Information SOT23-3 2.92 ± 0.12 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 × 3 0.50 ± 0.10 0.54 REF All dimensions in millimeters. © Advanced Analogic Technologies, Inc. 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. Customers are advised 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 3520.2006.03.1.2 0.14 ± 0.06 4° ± 4° 9