AAT3524

AAT3520/2/4 MicroPower Microprocessor Reset Circuit General Description The AAT3520 Series of PowerManager™ products is a member of AATI'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 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 1µA, 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 85°C operating temperature range. Features • • • • • • • PowerManager™ • • • 1.2V to 5.5V Input voltage range Operation down to 1.2V Extremely low quiescent current: less than 2µA 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 2.1V, RESET asserted ISINK =100µA, VCC >1.2V, RESET asserted ISOURCE = 800 µA ISINK =1.2mA, VCC > 1.2V, RESET not asserted ISINK = 3.2mA, VCC > 4.5V, RESET not asserted ISOURCE = 500µA, VCC > 2.1V, RESET asserted ISOURCE = 50µA, VCC > 1.2V, RESET asserted VCC > VTH Min 1.0 1.2 Typ Max Units VTH -1.5% VTH -2.5% 30 150 5.5 V 5.5 1.05 3 µA 0.85 2 VTH VTH +1.5% V VTH VTH +2.5% 40 ppm/°C 15 µs 50 100 ms 250 400 0.3 0.4 V V 0.3 0.4 V VOL VOH VCC -1.5 VOL 0.8VCC 0.8VCC 1 V µA VOH IDOFF 3520.2002.2.0.9 RESET High Output Voltage AAT3520 RESET leakage current, AAT3524 3 AAT3520/2/4 MicroPower Microprocessor Reset Circuit Typical Characteristics Supply Current vs. Temperature 1.40 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 (µA) 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 Reset Propagation Delay (µs) 30 25 20 15 10 5 0 -40 Power-Down Reset Propagation Delay vs. Temperature Normalized Power-Up Reset Timeout (ms) 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 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 (µS) 350 300 250 200 150 100 50 0 1 10 100 1000 Reset Threshold Overdrive, VTH-VCC (mV) 4 3520.2002.2.0.9 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) 3520.2002.2.0.9 5 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 2). 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 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 50µs to cause a reset. Immunity can be increased by the addition of a small by-pass capacitor of 0.1µF connected as close to the VCC pin as possible. +3.3V +5.0V VCC 100k RESET INPUT VCC AAT3524 RESET 5V System GND GND Figure 2: Using AAT3524 Open Drain Output with Multiple Supplies 6 3520.2002.2.0.9 AAT3520/2/4 MicroPower Microprocessor Reset Circuit Factory Trimmed Reset Thresholds* and Ordering Information Table 1 Reset Threshold Voltage, VTH (V) Ordering Part Number AAT3520IGY-2.32-200-T1 AAT3522IGY-2.32-200-T1 AAT3524IGY-2.32-200-T1 AAT3520IGY-2.63-200-T1 AAT3522IGY-2.63-200-T1 AAT3524IGY-2.63-200-T1 AAT3520IGY-2.93-200-T1 AAT3522IGY-2.93-200-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 *Contact Local Sales Office for custom trimmed options Minimum Marking Reset Active (ms) 150 150 150 150 150 150 150 150 150 30 150 30 150 150 150 150 150 150 150 150 TA = 25ºC TA = 40 to 85ºC Min 2.285 Typ 2.320 Max 2.355 Min 2.262 Max 2.378 2.591 2.630 2.669 2.564 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 3520.2002.2.0.9 7 AAT3520/2/4 MicroPower Microprocessor Reset Circuit Package Information SOT23-3 D S1 Dim A A1 A2 b C D E e H L S S1 θ1 A A1 Θ1 E H S e Millimeters Min Max .887 1.02 .013 0.10 0.37 0.51 0.085 0.180 2.80 3.04 1.20 1.40 1.78 2.05 2.10 2.64 0.69 0.45 0.60 0.89 1.03 0° 8° Inches Min Max 0.034 .040 0.0005 .004 0.015 0.020 0.003 0.007 0.110 0.120 0.047 0.055 0.070 0.080 0.083 0.104 0.027 0.018 0.024 0.035 0.040 0° 8° A2 b C L Note: 1. PACKAGE BODY SIZE EXCLUDE MOLD FLASH PROTRUSIONS OR GATE BURRS. 2. TOLERANCE ±0.1000 mm (4mi) UNLESS OTHERWISE SPECIFIED 3. COPLANARITY: 0.1000 4. DIMENSION L IS MEASURED IN GAGE PLANE Advanced Analogic Technologies, Inc. 1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086 Phone (408) 524-9684 Fax (408) 524-9689 8 3520.2002.2.0.9