Datasheet AAT3532IAS-T1, AAT3532 Datasheet (Analogic Technologies)

AAT3532

V

MicroPower™ Microprocessor Reset Circuit

General Description

The AAT3532 PowerManager™ product is a mem­ber of AATI’s Total Power Management ICs™
(TPMIC™) 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 condi­tion for a minimum of 250ms while VCCis estab­lished 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 period­ic strobe input from the microprocessor to ensure
correct operation. The AAT3532 has a programma­ble watchdog timer and voltage tolerance level.
The quiescent supply current is extremely low, typ­ically 23µA.

The AAT3532 is available in an 8-pin SOP package
specified over -40° to 85°C temperature range.

PowerManager

Features

• Adjustable 4.5V or 4.75V Voltage Monitor

• 250ms (min) Reset Pulse Width

• Low quiescent current: typically 23µA

• 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 85°C

• Standard 8 pin SOP package

• Pin compatible with MAX1232

Applications

• Computers

• Controllers

• Telecom Equipment

• Embedded Systems

• Intelligent Instrumentation

• Automotive

™

Preliminary Information

Typical Application

PBRST

TD

TOL

DD

V

CC

AAT3532

GND

RST

RST

RESET
INPUT

I/OST

V

DD

µ

P

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AAT3532

MicroPower™ Microprocessor Reset Circuit

Pin Descriptions

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

falls below the reset voltage threshold, or PBRST is forced low, or ST not strobed

CC

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

Pin Programming Selections

TD Pin

Min Typ Max

GND 62.5ms 150ms 250ms
Float 250ms 600ms 1000ms

V

CC

500ms 1200ms 2000ms

Table 1: TD Pin Programming for Watchdog Timeout Selections

TOL Pin Tolerance

V

CC

GND 5%

Table 2: Reset Voltage Threshold Programming Selections

Time-Out

10%

Pin Configuration

SOP-8

(Top View)

PBRST

TD

TOL

GND

1

2

3

4

8

7

6

5

Vcc

ST

RST

RST

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AAT3532

MicroPower™ Microprocessor Reset Circuit

Absolute Maximum Ratings (T

=25°C unless otherwise noted)

A

Symbol Description Value Units

V

CC

V

I/O

T

A

T

S

T

LEAD

V

ESD

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.

Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.

VCCto GND -0.5 to 6 V

Voltage on I/O pins relative to GND -0.5 to (VCC+0.5) V

Operating Temperature Range -40 to 85 °C

Storage Temperature Range -65 to 150 °C

Maximum Soldering Temperature (at Leads) for 10s 300 °C

ESD Rating1—HBM 2000 V

Thermal Characteristics

Symbol Description Value Units

Θ

JA

P

D

Note 2: Mounted on an FR4 board.

Maximum Thermal Resistance

Maximum Power Dissipation

2

2

100 °C/W

1.25 W

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AAT3532

MicroPower™ Microprocessor Reset Circuit

DC Electrical Characteristics (V

= 4.5V to 5.5V, TA= -40 to 85°C unless otherwise noted.

IN

Typical values are at TA=25°C)

Symbol Description Conditions Min Typ Max Units

V

CC

I

Q

V

CCTP

I

IL

I

OH

I

OL

V

IH

V

IL

I

RST

AC Electrical Characteristics (V

Supply Voltage 4.5 5.0 5.5 V

Quiescent Current

1

VCC= 5.5V

CMOS Levels 23 50

TTL Levels 160 500
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
Input Leakage ST, TOL -1.0 1.0 µA
Output Current RST

2

VOH= 2.4V -8.0 mA
Current RST2, RST VOL= 0.4V 10.0 mA
ST and PBRST Input High 2.0 VCC+0.3 V
ST and PBRST Input Low -0.3 0.8 V
RST Output Leakage VOH= V

CC

= 4.5V to 5.5V, TA= -40 to 85°C unless otherwise noted.

IN

1.0 µA

Typical values are at TA=25°C)

Symbol Description Conditions Min Typ Max Units

C

IN

C

OUT

t

PB

t

PBD

t

RST

t

ST

t

TD

t

f

t

r

t

RPD

t

RPU

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

Input Capacitance ST, TOL
Output Capacitance RST, RST
PBRST

4

PBRST Delay Fig 2 1 4 20 ms
Reset Active Time 250 610 1000 ms
ST Pulse Width Fig 3 20 ns

ST Time-out Period TD Pin = Open 250 600 1000 ms

VCCFall Time
VCCRise Time

3

3

VCCDetect to RST High and RST Low VCCFalling 50 µs
VCCDetect to RST Low and RST Open VCCRising 250 610 1000 ms

3

3

TA= 25ºC 5 pF
TA= 25ºC 7 pF
Fig 2 20 ms

TD Pin = 0V 62.5 150 250 ms

TD Pin = V

CC

500 1200 2000 ms

4.75V to 4.25V 10 µs

4.25V to 4.75V 0 5 µs

µA

4 3532.2001.11.0.9

Functional Block Diagram

V

CC

TOL

AAT3532

MicroPower™ Microprocessor Reset Circuit

V

CC

Tolerance

Select

Reset

Generator

V

REF

RST

RST

PBRST

ST

TD

De-Bounce

Circuit

Applications Information

Power Monitor

The reset function monitors the VCCsupply 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 volt­ages down to 1.4V.

The RST and RST pins are asserted whenever V
drops below the reset threshold voltage. This volt-

V

CC

CC

+4.75V (5% Trip Point)

+4.50V (10% Trip Point)

Watchdog

Timer

Detector

GND

+5V

Watchdog

Timer

age can be set by programming the TOL pin.
Connecting TOL to V

sets the 10% tolerance of

CC

the VCCsupply (typically 4.37V for VCC= 5V).
Connecting TOL to GND sets the 5% tolerance of
the VCCsupply (typically 4.62V for VCC= 5V). The
reset pin is guaranteed to remain asserted for a
minimum period of 250ms after VCChas risen
above the reset threshold voltage.

RST output is an open drain output. For correct
operation, a pull-up resistor of 10kΩ should be con-
nected between this output and VCC.

0V

RESET output delay (V

Rising)

CC

RST

RST

t

RPU

RESET output delay (V

t

RPD

Falling)

CC

Figure 1. Reset Output Delay

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AAT3532

MicroPower™ Microprocessor Reset Circuit

Applications Information

Manual Reset

The PBRST pin makes it possible to manually
reset the system by either directly connecting a
mechanical push-button between the PBRST pin

t

PBD

PBRST

RESET

RESET

and GND or connecting to a logic low output.
Internal de-bounce circuitry is provided to reduce
the effect of noise glitches at the input. The signal
should remain low for a minimum of 20ms for cor­rect operation. Once the PBRST signal is released
(or goes to a logic high), RESET (RESET) remains
asserted for a minimum of 250ms.

t

PB

t

RST

Figure 2 Push-button Reset

Watchdog Timer

The watchdog timer monitors the microprocessor
to ensure that the system is functioning correctly.
The ST pin of the AAT3532 can be derived from the
microprocessor data signals, address signals,
and/or I/O signals. The watchdog timer function
forces the RST and RST signals into the active
state when the ST input is not toggled by a pre­determined time. This time period is set by the logic
state of the TD pin as shown in Table 1. The timer

t

ST

ST

t

TD

starts once the RST signals become inactive. If the
watchdog timer does not receive a high-to-low tran­sition within the specified timeout period, then the
RST signals are activated for a minimum 250ms. In
normal operation the timer should receive a transi­tion from the microprocessor within the timeout
period, in which case the timer is reset and normal
operation continues.

The AAT3532 will accept and recognize ST pulses
down to a minimum of 20ns wide.

Figure 3. Watchdog Input

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Ordering Information

AAT3532

MicroPower™ Microprocessor Reset Circuit

Package Marking

8 Pin SOIC AAT3532IAS-B1 AAT3532IAS-T1

Package Information

SOP-8

E

H

D

7 (4x)

A

A2

A1

e

b

y

Θ

Part Number

Bulk Tape and Reel

Dim

Millimeters Inches

Min Max Min Max

A 1.35 1.75 0.053 0.069
A1 0.10 0.25 0.004 0.010
A2 1.45 0.057

B 0.33 0.51 0.013 0.020

C 0.19 0.25 0.007 0.010
D 4.80 5.00 0.189 0.197

E 3.80 4.00 0.150 0.157

e 1.27 0.050

H 5.80 6.20 0.228 0.244

L 0.40 1.27 0.016 0.050

c

L

Y 0.00 0.10 0.000 0.004

θ10° 8° 0° 8°

Note:

1. PACKAGE BODY SIZES EXCLUDE MOLD FLASH
PROTRUSIONS OR GATE BURRS.

2. TOLERANCE± 0.1000mm (4mil) UNLESS OTHER­WISE SPECIFIED

3. COPLANARITY: 0.1000mm

4. DIMENSION L IS MEASURED IN GAGE PLANE.

5. CONTROLLING DIMENSION IS MILLIMETER,
CONVERTED INCH DIMENSIONS ARE NOT NECES­SARILY EXACT.

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AAT3532

MicroPower™ Microprocessor Reset Circuit

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Advanced Analogic Technologies, Inc.

1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone [phone]
Fax [phone]

8 3532.2001.11.0.9