AAT3532
MicroPowerTM Microprocessor Reset Circuit
Preliminary
Information
3532.2001.11.0.9
1
PowerManager
TM
General Description
The AAT3532 PowerManagerTM product is a mem-
ber of AATI's Total Power Management ICsTM
(TPMICTM) product family. It is a fully integrated
device for monitoring microprocessor activity,
external reset, and power supply conditions. The
device holds the microprocessor in a reset condi-
tion for a minimum of 250ms while V
CC
is estab-
lished to ensure correct system start-up. A manual
reset can be initiated via a de-bounced input pin.
As an additional level of protection, the AAT3532
includes a watchdog timer which requires a period-
ic strobe input from the microprocessor to ensure
correct operation. The AAT3532 has a programma-
ble watchdog timer and voltage tolerance level.
The quiescent supply current is extremely low, typ-
ically 23A.
The AAT3532 is available in an 8-pin SOP package
specified over -40 to 85C temperature range.
Features
Adjustable 4.5V or 4.75V Voltage Monitor
250ms (min) Reset Pulse Width
Low quiescent current: typically 23A
Adjustable Watchdog Timer (150ms, 600ms,
or 1200ms)
De-bounced Manual Reset Input
Operates down to 20ns strobe input pulse
width
No external components
Temp range -40 to 85C
Standard 8 pin SOP package
Pin compatible with MAX1232
Applications
Computers
Controllers
Telecom Equipment
Embedded Systems
Intelligent Instrumentation
Automotive
Typical Application
AAT3532
V
CC
RST
GND
RST
RESET
INPUT
P
V
DD
V
DD
I/O
ST
PBRST
TD
TOL
Pin Descriptions
Pin Programming Selections
Table 1: TD Pin Programming for Watchdog Timeout Selections
Table 2: Reset Voltage Threshold Programming Selections
Pin Configuration
SOP-8
(Top View)
PBRST
TD
TOL
ST
RST
Vcc
GND
RST
1
2
3
4
8
7
6
5
TOL Pin
Tolerance
V
CC
10%
GND
5%
TD Pin
Time-Out
Min
Typ
Max
GND
62.5ms
150ms
250ms
Float
250ms
600ms
1000ms
V
CC
500ms
1200ms
2000ms
Pin #
Symbol
Function
1
PBRST
Pushbutton reset input. A de-bounced active low input for manual reset. Guaranteed
to recognize inputs 20ms or greater.
2
TD
Watchdog time delay set input. See Table 1 for watchdog timeout selections.
3
TOL
Tolerance set. Input selects 5% or 10% threshold detection
4
GND
IC ground connection
5
RST
Reset Output (active high). Activated when either:
V
CC
falls below the reset voltage threshold, or PBRST is forced low, or ST not strobed
within the minimum timeout period, or during power-up.
6
RST
Reset Output (active low, open drain). Inverse of RST.
7
ST
Strobe input to watchdog timer. A pulse is required within watchdog timeout period to
prevent RST and RST entering active state
8
Vcc
5V Supply
AAT3532
MicroPowerTM Microprocessor Reset Circuit
2
3532.2001.11.0.9
AAT3532
MicroPowerTM Microprocessor Reset Circuit
3532.2001.11.0.9
3
Absolute Maximum Ratings
(T
A
=25C unless otherwise noted)
Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-
ditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time.
Note 1: Human body model is a 100pF capacitor discharged through a 1.5k
resistor into each pin.
Thermal Characteristics
Note 2: Mounted on an FR4 board.
Symbol
Description
Value
Units
JA
Maximum Thermal Resistance
2
100
C/W
P
D
Maximum Power Dissipation
2
1.25
W
Symbol
Description
Value
Units
V
CC
V
CC
to GND
-0.5 to 6
V
V
I/O
Voltage on I/O pins relative to GND
-0.5 to (V
CC
+0.5)
V
T
A
Operating Temperature Range
-40 to 85
C
T
S
Storage Temperature Range
-65 to 150
C
T
LEAD
Maximum Soldering Temperature (at Leads) for 10s
300
C
V
ESD
ESD Rating
1
--HBM
2000
V
AAT3532
MicroPowerTM Microprocessor Reset Circuit
4
3532.2001.11.0.9
DC Electrical Characteristics
(V
IN
= 4.5V to 5.5V, T
A
= -40 to 85C unless otherwise noted.
Typical values are at T
A
=25C)
AC Electrical Characteristics
(V
IN
= 4.5V to 5.5V, T
A
= -40 to 85C unless otherwise noted.
Typical values are at T
A
=25C)
Notes:
1. Measured with outputs open and ST toggling at 100kHz, 50% duty cycle
2. RST is an open drain output
3. Guaranteed by design and not subject to production testing.
4. PBRST must remain low for greater than 20ms to guarantee a reset
Symbol
Description
Conditions
Min
Typ
Max
Units
C
IN
Input Capacitance ST, TOL
3
T
A
= 25C
5
pF
C
OUT
Output Capacitance RST, RST
3
T
A
= 25C
7
pF
t
PB
PBRST
4
Fig 2
20
ms
t
PBD
PBRST Delay
Fig 2
1
4
20
ms
t
RST
Reset Active Time
250
610
1000
ms
t
ST
ST Pulse Width
Fig 3
20
ns
TD Pin = 0V
62.5
150
250
ms
t
TD
ST Time-out Period
TD Pin = Open
250
600
1000
ms
TD Pin = V
CC
500
1200
2000
ms
t
f
V
CC
Fall Time
3
4.75V to 4.25V
10
s
t
r
V
CC
Rise Time
3
4.25V to 4.75V
0
5
s
t
RPD
V
CC
Detect to RST High and RST Low
V
CC
Falling
50
s
t
RPU
V
CC
Detect to RST Low and RST Open
V
CC
Rising
250
610
1000
ms
Symbol
Description
Conditions
Min
Typ
Max
Units
V
CC
Supply Voltage
4.5
5.0
5.5
V
CMOS Levels
23
50
I
Q
Quiescent Current
1
V
CC
= 5.5V
TTL Levels
160
500
A
V
CCTP
Reset Threshold 5%
TOL = GND
4.50
4.62
4.74
V
Reset Threshold 10%
TOL = V
CC
4.25
4.37
4.49
V
I
IL
Input Leakage ST, TOL
-1.0
1.0
A
I
OH
Output Current RST
2
V
OH
= 2.4V
-8.0
mA
I
OL
Current RST
2
, RST
V
OL
= 0.4V
10.0
mA
V
IH
ST and PBRST Input High
2.0
V
CC
+0.3
V
V
IL
ST and PBRST Input Low
-0.3
0.8
V
I
RST
RST Output Leakage
V
OH
= V
CC
1.0
A
AAT3532
MicroPowerTM Microprocessor Reset Circuit
3532.2001.11.0.9
5
Applications Information
Power Monitor
The reset function monitors the V
CC
supply to ensure
a microprocessor is correctly reset and is powered
up into a known condition following a power supply
failure. RST and RST will remain valid for Vcc volt-
ages down to 1.4V.
The RST and RST pins are asserted whenever V
CC
drops below the reset threshold voltage. This volt-
age can be set by programming the TOL pin.
Connecting TOL to V
CC
sets the 10% tolerance of
the V
CC
supply (typically 4.37V for V
CC
= 5V).
Connecting TOL to GND sets the 5% tolerance of
the V
CC
supply (typically 4.62V for V
CC
= 5V). The
reset pin is guaranteed to remain asserted for a
minimum period of 250ms after V
CC
has risen
above the reset threshold voltage.
RST output is an open drain output. For correct
operation, a pull-up resistor of 10k
should be con-
nected between this output and V
CC
.
Functional Block Diagram
Watchdog
Timer
Detector
De-Bounce
Circuit
Watchdog
Timer
Reset
Generator
V
CC
Tolerance
Select
V
CC
TOL
TD
ST
PBRST
GND
RST
RST
V
REF
Figure 1. Reset Output Delay
V
CC
t
RPU
t
RPD
RST
RST
+5V
+4.75V (5% Trip Point)
+4.50V (10% Trip Point)
RESET output delay (V
CC
Falling)
RESET output delay (V
CC
Rising)
0V
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