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AAT3520/2/4
MicroPower Microprocessor Reset Circuit General Description
The AAT3520 Series of PowerManagerTM products is a member of AATI's Total Power Management ICTM (TPMICTM) 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.
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
Preliminary Information
Applications
* * * * * Notebook Computers Cell Phones Portable Electronics Embedded Systems Intelligent Instruments
Typical Application
VCC
VCC
*
100k (nominal)
VCC
AAT3520 AAT3522 RESET AAT3524 (RESET)
RESET uP INPUT
GND
GND
*AAT3524 Only
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AAT3520/2/4
MicroPower Microprocessor Reset Circuit Pin Descriptions
AAT3520, 3522, 3524 (SOT23-3)
Pin #
1
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)
2 RESET (AAT3522, AAT3524) 3 Vcc
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 (RESET) RESET
1 3 2
VCC
2
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AAT3520/2/4
MicroPower Microprocessor Reset Circuit Absolute Maximum Ratings
Symbol
VCC VRESET IMAX IRESET dVcc/dt TJ TLEAD
(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.
Electrical Characteristics
Symbol
VCC IQ VTH VTH/C tP tRDY
(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 ) Description
Operation Voltage Quiescent Current RESET Threshold (Table 1) RESET Threshold Tempco RESET Propagation Delay RESET Active Timeout Period RESET Low Output Voltage AAT3522, AAT3524 RESET High Output Voltage AAT3522 RESET Low Output Voltage AAT3520
Conditions
TA = 0C to +70C TA = -40C to +85C VCC = 5.5V VCC = 3V TA = 25C TA = -40C to +85C VCC = VTH to (VTH -100mV) -50 option -200 option ISINK =1.6mA, VCC > 2.1V, RESET asserted ISINK =100A, VCC >1.2V, RESET asserted ISOURCE = 800 A ISINK =1.2mA, VCC > 1.2V, RESET not asserted ISINK = 3.2mA, VCC > 4.5V, RESET not asserted ISOURCE = 500A, VCC > 2.1V, RESET asserted ISOURCE = 50A, 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 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 V 0.3 0.4 V
VOL VOH
VCC -1.5
VOL
0.8VCC 0.8VCC 1 V A
VOH IDOFF
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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 (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
Reset Propagation Delay (s)
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 (S)
350 300 250 200 150 100 50 0 1 10 100 1000
Reset Threshold Overdrive, VTH-VCC (mV)
4
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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 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)
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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 100k 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 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.
+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
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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 = 25C
TA = 40 to 85C
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
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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 1
A A1
1
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
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