Datasheet ADM8699, ADM8698 Datasheet (Analog Devices)

Microprocessor

*

ADM8699 ONLY

+5V

V

CC

WDI

*

GND

ADM8698/

ADM8699

RESET

µP POWER

µP SYSTEM

I/O LINE

µP RESET

a

FEATURES
Superior Up
Guaranteed
Low 70 mA Supply Current
Precision 4.65 V Voltage Monitor
Power OK/Reset Time Delay
Watchdog Timer
Minimum Component Count
Performance Specified over Temperature

APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical mP Power Monitoring

GENERAL DESCRIPTION

The ADM8698/ADM8699 supervisory circuits provide power
supply monitoring and watchdog timing for microprocessor
systems.

The ADM8698 monitors the 5 V V
ates a

RESET pulse during power up, power down and during
low voltage “Brown Out” conditions. The
guaranteed to be functional (logic low) with V

The ADM8699 features an identical monitoring circuit as in the
ADM8698, plus an additional watchdog timer input to monitor
microprocessor activity. The
watchdog input is not toggled within the 1 second watchdog
timeout period.

Both parts are available in 8-pin plastic DIP/SOIC and 16-lead
SOIC packages. The 16-lead SOIC contains additional out­puts

RESET (without inversion) and Watchdog Output WDO

(ADM8699 only).

grade for ADM698/ADM699, MAX698/MAX699

RESET Assertion with VCC = 1 V

power supply and gener-

CC

RESET output is

as low as 1 V.

CC

RESET output is forced low if the

V

CC

WATCHDOG

INPUT

WDI*

Supervisory Circuits

ADM8698/ADM8699

FUNCTIONAL BLOCK DIAGRAM

ADM8698/
ADM8699

RESET

GENERATOR

4.65V

WATCHDOG

TRANSITION DETECTOR

(1 sec)

WDI (ADM8699 ONLY)

*

RESET (SOIC ONLY)
WDO (ADM8699 SOIC ONLY)

TYPICAL APPLICATION CIRCUIT

RESET*

RESET

WATCHDOG
OUTPUT WDO*

REV. 0

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reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
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Fax: [phone] © Analog Devices, Inc., 1997

ADM8698/ADM8699–SPECIFICATIONS

Parameter Min Typ Max Units Test Conditions/Comments

(VCC = +5 V 6 10%, TA = T

MIN

to T

unless otherwise noted)

MAX

VCC Operating Voltage Range 3.0 5.5 V
Supply Current 70 100 µA

Power-Down Reset Assertion 4.5 4.65 4.75 V
Power-Up Reset Deassertion
Reset Threshold Hysteresis 40 mV
Reset Active Time 140 200 280 ms

Watchdog Timeout Period (ADM8699) 1.0 1.6 2.25 s
Minimum WDI Input Pulse Width 50 ns VIL = 0.4, VIH = 0.8 (VCC)

RESET Output Voltage 0.4 V I
RESET Output Voltage (VCC = 1 V) 12 200 mV I

3.5 V I

RESET and

WDO Output Voltage 0.4 V I

3.5 V I

= 3.2 mA, VCC = 4.4 V

SINK

= 100 µA, VCC = 1.0 V

SINK

= 500 µA, VCC = 5 V

SOURCE

= 3.2 mA, VCC = 5 V

SINK

= 1 µA, VCC = 4.4 V

SOURCE

RESET Output Short Circuit Current 45 mA Output Sink Current
WDI Input Threshold (ADM8699)

Logic Low 0.8 V
Logic High 3.5 V

WDI Input Current +1 +10 µA WDI = V

CC

–10 –1 µA WDI = 0 V

Specifications subject to change without notice.

ABSOLUTE MAXIMUM RATINGS*

(TA = +25°C unless otherwise noted)

VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .–0.3 V to +6 V

All Other Inputs . . . . . . . . . . . . . . . . . . . –0.3 V to V

+ 0.3 V

CC

Power Dissipation 8-Pin DIP . . . . . . . . . . . . . . . . . . . .500 mW

θ

, Thermal Impedance . . . . . . . . . . . . . . . . . . . . +120°C/W

JA

Power Dissipation 16-Pin SOIC . . . . . . . . . . . . . . . . .375 mW

θ

, Thermal Impedance . . . . . . . . . . . . . . . . . . . . +110°C/W

JA

Power Dissipation 8-Pin SOIC . . . . . . . . . . . . . . . . . .500 mW

θ

, Thermal Impedance . . . . . . . . . . . . . . . . . . . . +125°C/W

JA

Operating Temperature Range

Industrial (A Version) . . . . . . . . . . . . . . . . .–40°C to +85°C

Storage Temperature Range . . . . . . . . . . . . .–65°C to +150°C

Model Range Options*

ADM8698AN –40°C to +85°C N-8
ADM8698ARW –40°C to +85°C R-16
ADM8698ARN –40°C to +85°C R-8

ADM8699AN –40°C to +85°C N-8
ADM8699ARW –40°C to +85°C R-16
ADM8699ARN –40°C to +85°C R-8

*N = Plastic DIP; R = Small Outline.

ORDERING GUIDE

Temperature Package

Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . +300°C

Vapor Phase (60 secs) . . . . . . . . . . . . . . . . . . . . . . . +215°C

Infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C

ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .>4 kV

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum ratings for
extended periods of time may affect device reliability.

–2–

REV. 0

ADM8698/ADM8699

PIN FUNCTION DESCRIPTIONS

Mnemonic Function

V

CC

+5 V Power Supply Input.
GND 0 V. Ground reference for all signals.
RESET Logic Output. RESET goes low whenever V

CC

falls below the reset voltage threshold (4.65 V

typ).

RESET remains low for a minimum of

140 ms after V

returns to 5 V. RESET also

CC

goes low for a minimum of 140 ms if the watchdog

timer is enabled but not serviced within its time-

out period.
WDI Watchdog Input. WDI is a three level input. If

WDI remains either high or low for longer than

the watchdog timeout period,

and

WDO goes low. The timer resets with each

RESET pulses low

transition on the WDI line. The watchdog timer

may be disabled if WDI is left floating or is driven

to midsupply.
RESET (SOIC packages only) Logic Output. RESET is

an active high output. It is the inverse of

RESET.

WDO (SOIC ADM8699 only) Logic Output. The

Watchdog Output,

WDO, goes low if WDI
remains either high or low for longer than the
watchdog timeout period.

WDO is set high by the
next transition at WDI. If WDI is unconnected or
at midsupply, the watchdog timer is disabled and
WDO remains high.

TYPICAL PERFORMANCE CURVES

A4

3.36 V

100
90

10
0%

1V

1V

Figure 1. RESET Output Voltage vs. V

230

220

210

200

190

RESET DELAY – ms

180

170

–50 90–30 –10 10 30 50 70

TEMPERATURE – °C

500ms

CC

PIN CONFIGURATIONS

8-Lead DIP & SOIC

V
V

GND

GND

1

CC

2

CC

3

4

ADM8698/

ADM8699

O

TOP VIEW

TOP VIEW

(Not to Scale)

(Not to Scale)

*( ) ADM8699 ONLY

NC = NO CONNECT

8

GND

7

RESET

6

NC (WDI)*

5

NC

16-Lead SOIC

1

GND

V

2

CC

ADM8698/

TOP VIEW

V

3

CC

ADM8699

(Not to Scale)

4

GND

TOP VIEW

5

NC

(Not to Scale)

611

NC

710

NC

89

NC

*( ) ADM8699 ONLY

NC = NO CONNECT

16

RESET

O

15

RESET

14

NC (WDO)

13

NC

12

NC
NC (WDI)
NC
GND

Figure 2. RESET Timeout Delay vs. Temperature

4.69

4.67

4.65

4.63

4.61

4.59

RESET VOLTAGE THRESHOLD – V

4.57

4.55
–60 –30 0 30 60 90 120

*

*

Figure 3. RESET Voltage Threshold vs. Temperature

TEMPERATURE – °C

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–3–

ADM8698/ADM8699

CIRCUIT INFORMATION
Power Fail RESET

A precision voltage detector monitors VCC and generates a
RESET output to hold the microprocessor’s Reset line low when
V

falls below the reset threshold 4.65 V (see Figure 4). The

CC

reset voltage threshold is set to accommodate a 5% variation on
V

. The voltage detector has 40 mV hysteresis to ensure that

CC

glitches on V
On power-up, an internal monostable holds

140 ms after V

do not activate the RESET output.

CC

RESET low for

rises above the reset threshold. This allows the

CC

power supply to stabilize on power-up and also prevents repeated
toggling of

RESET even if the 5 V power drops out and recovers
with each power line cycle. In order to prevent mistriggering
due to transient voltage spikes, it is recommended that a 0.1µF
capacitor be connected at the V

RESET output is guaranteed to remain low with V

The

CC

pin.

CC,

as
low as 1 V. This holds the microprocessor in a stable shutdown
condition as the power supply comes up.

On the 16-lead SOIC package, an active high RESET output is
also provided. This is the complement of

RESET and is in-

tended for microprocessors requiring an active high signal.

V

CC

V

2

V

1

V

2

V

1

Watchdog Timer (ADM8699 Only)

The watchdog timer input (WDI) monitors an I/O line from the
µP system. The µP must toggle this input once every 1.6 sec-
onds to verify correct software execution. Failure to toggle the
line indicates that the µP system is not correctly executing its
program and may be tied up in an endless loop. If this happens,
a reset pulse is generated to initialize the processor.

The WDI input is a three level input and will recognize a low­to-high or high-to-low transition on its input. The watchdog
timer is reset by each WDI transition and then begins its timeout
period. If the WDI pin remains either high or low, reset pulses
will be issued every 1.6 seconds typically. If the watchdog timer
is not needed, the WDI input should be left floating.

The Watchdog Output (

WDO) (SOIC package Only) provides
watchdog status information. It is driven low if WDI is not
toggled within the watchdog timeout period. It goes high at the
next WDI transition. It is also set high when V

falls below the

CC

reset threshold.

WDI

WDO

C2926–10–2/97

RESET

t

1

V1 = RESET VOLTAGE THRESHOLD
V

= RESET VOLTAGE THRESHOLD +

2

THRESHOLD HYSTERESIS

t

= RESET TIME

1

t

1

Figure 4. Watchdog Timeout Period vs. Temperature

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Pin Plastic DIP (N-8) 8-Pin SOIC (R-8) 16-Lead SOIC (R-16)

58

0.25

PIN 1

0.18 (4.57)

0.018 (0.46)

14

0.430 (10.92)
MAX

0.1 (2.54)
BSC

0.011
(0.28)

0.3 (7.62)

(6.35)

(7.87)

0.035
(0.89)

0.125
(3.18)
MIN

SEATING
PLANE

0.033 (0.84)

0.18
(4.57)
MAX

0.31

0.2440 (6.20)

0.2284 (5.80)

0.0098 (0.25)

0.0040 (0.10)
SEATING

PLANE

0.0098 (0.25)

0.0075 (0.19)

RESET

t

2

t

1

= RESET TIME

t

1

t

= WATCHDOG TIME OUT PERIOD

2

t

t

2

1

Figure 5. Watchdog Timeout Period and Reset Active Time

0.1968 (5.00)

0.1890 (4.80)

0.299
(7.60)

0.012

0.030
(0.75)

0.013
(0.32)

(0.3)

16

1

0.413 (10.50)

0.05 (1.27)
REF

0.019 (0.49)

85

PIN 1

0.0500
(1.27)

BSC

8°
0°

41

0.102 (2.59)

0.094 (2.39)

0.0192 (0.49)

0.0138 (0.35)

0.0196 (0.50)

0.0099 (0.25)

0.0500 (1.27)

0.0160 (0.41)

0.1574 (4.00)

0.1497 (3.80)

x 45°

9

8

0.042
(1.07)

t

1

0.419

(10.65)

0.104
(2.65)

PRINTED IN U.S.A.

–4–

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