AAT3528

AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset General Description The AAT3526/7/8 PowerManager™ products are members 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 AAT3526/7/8 products operate by monitoring the system power supply voltage. When the input voltage drops below a fixed threshold, the device asserts a reset signal for a minimum of 150ms after VCC has risen back above the fixed threshold. They are guaranteed to operate down to 1.2V and designed to ignore fast line transients appearing on VCC. The AAT3526/7/8 series is available with three output stage versions: AAT3526 push-pull active low output, AAT3527 push-pull active high output and AAT3528 open drain active low output. The quiescent supply current is extremely low, typically 1µA, making this device ideal for portable battery operated equipment. The AAT3526/7/8 are available in a 4 pin SOT143 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 Minimum 150ms reset pulse width with fast delay time 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 20 VCC -1.5 0.3 0.4 0.8VCC 0.8VCC 1 V VOL V VOH IDOFF RESET High Output Voltage AAT3527 RESET leakage current, AAT3528 V µA 4 3526.2002.1.0.62 AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset 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) Power-Up Reset Timeout vs. Temperature Reset Propagation Delay (µs) 320 300 30 25 20 15 10 5 0 -40 Power-Down Reset Propagation Delay vs. Temperature Power-Up Reset Timeout (ms) VOD=10mV 280 260 240 220 200 180 160 -40 -20 0 20 40 60 80 100 VOD=100mV -20 0 20 40 60 80 Temperature (°C) 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) 3526.2002.1.0.62 5 AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset Functional Block Diagram MR 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 AAT3526/7/8 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 minimum of 150ms after VCC has risen above the threshold as shown in Figure 1. VTH VCC VTH VTH tRDY tRDY Figure 1: Reset Timing Diagram 6 3526.2002.1.0.62 AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset Applications Information Reset Output Options The AAT3528 has an active low open drain output and the AAT3526/7 have a push-pull output. The AAT3528 may be used in multiple voltage systems, with an external pull-up resistor. This allows the AAT3528 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. input is internally debounced which allows use of a mechanical switch. It should be a normally-open momentary switch connected from MR to GND. Additionally, the MR pin can be driven from TTL, CMOS, or open drain logic outputs. Supply Voltage Transient Behavior In some cases fast negative transients of short duration can appear on the VCC power supply. The AAT3526/7/8 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. Manual Reset Input A logic low signal on MR asserts a reset condition. Reset continues to be asserted as long as MR is low and for a minimum of 150ms after MR returns high. This input is internally pulled up to VCC via a 20kΩ resistor, so leaving the pin unconnected is acceptable if manual reset function is not needed. The MR +3.3V +5.0V VCC 100k VCC AAT3528 MR RESET RESET INPUT 5V System GND GND Figure 2: Using AAT3528 Open Drain Output with Multiple Supplies 3526.2002.1.0.62 7 AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset Factory Trimmed Reset Thresholds* and Ordering Information Table 1 Ordering Part Number AAT3526ICX-2.32-200-T1 AAT3527ICX-2.32-200-T1 AAT3528ICX-2.32-200-T1 AAT3526ICX-2.63-200-T1 AAT3527ICX-2.63-200-T1 AAT3528ICX-2.63-200-T1 AAT3526ICX-2.93-200-T1 AAT3527ICX-2.93-200-T1 AAT3528ICX-2.93-200-T1 AAT3526ICX-3.08-200-T1 AAT3527ICX-3.08-200-T1 AAT3528ICX-3.08-200-T1 AAT3526ICX-4.38-200-T1 AAT3527ICX-4.38-200-T1 AAT3528ICX-4.38-200-T1 AAT3526ICX-4.63-200-T1 AAT3527ICX-4.63-200-T1 AAT3528ICX-4.63-200-T1 *Contact Local Sales Office for custom trimmed options Marking Reset Threshold Voltage, VTH (V) TA = 40 to 85ºC TA = 25ºC Min Typ Max Min Max 2.285 2.320 2.355 2.262 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 8 3526.2002.1.0.62 AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset Package Information SOT143 B e1 CL CL E H PIN 1 S Dim A A1 B B1 C D E E1 E2 H I S Θ C CL I e2 B1 D A CL θ Millimeters Min Max 0.787 1.194 0.025 1.027 0.356 0.559 0.762 0.965 0.086 0.152 2.667 3.048 1.194 1.397 1.803 2.007 0.200 BSC 2.083 2.489 0.102 0.305 0.450 0.600 0° 8° Inches Min Max 0.031 0.047 0.001 0.005 0.014 0.022 0.030 0.038 0.0034 0.006 0.105 0.120 0.047 0.055 0.071 0.079 0.008 BSC 0.082 0.098 0.004 0.012 0.018 0.024 0° 8° A1 3526.2002.1.0.62 9 AAT3526/7/8 MicroPower Supervisory Circuit with Manual Reset This page intentionally left blank. Advanced Analogic Technologies, Inc. 1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086 Phone (408) 524-9684 Fax (408) 524-9689 10 3526.2002.1.0.62