ANALOG DEVICES ADM8616, ADM8617 Service Manual

www.BDTIC.com/ADI

Low Voltage Supervisory Circuits

FEATURES

Precision 1.8 V to 5 V power supply monitoring

RESET

9

4

3 watchdog timeout options

RESET

Low power consumption (5 μA) Guaranteed reset output valid to V Power supply glitch immunity Specified over −40°C t 4-lead SC70 package

APPLICATIONS

Microprocessor systems Computers Controllers Intelligent instruments Portable equipment

threshold options

1.58 V to 4.63 V RESET

timeout options

1 ms, 20 ms, 140 ms, 1120 ms

6.3 ms, 102 ms, 1.6 sec

output stages Push-pull active-low (ADM8616) Open-drain active-low (ADM8617)

o +85°C temperature range

= 1 V

CC

with Watchdog in 4-Lead SC70

ADM8616/ADM8617

FUNCTIONAL BLOCK DIAGRAM

V

CC

ADM8616

V

REF

RESET

GENERATOR

WATCHDOG

DETECT OR

GND WDI

Figure 1.

V

CC

RESET

4795-001

GENERAL DESCRIPTION

The ADM8616/ADM8617 are supervisory circuits that monitor power supply voltage levels and code execution integrity in microprocessor-based systems. A power-on reset signal is generated when the supply voltage rises to a preset threshold level. The ADM8616/ADM8617 have an on-chip watchdog timer that can reset the microprocessor if it fails to strobe within a preset timeout period.

Each part is available in the following nine reset threshold

ptions: 1.58 V, 1.67 V, 2.19 V, 2.32 V, 2.63 V, 2.93 V, 3.08 V,

o

4.38 V, and 4.63 V. There are four reset timeout options: 1 ms, 20 ms, 140 ms, and 1120 ms. There are also three possible watchdog timeouts available: 6.3 ms, 102 ms, and 1.6 sec.

Rev. B

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

The parts differ in terms of reset output configuration. The AD

M8616 is active-low with a push-pull output, while the

ADM8617 is active-low with an open-drain output.

The ADM8616/ADM8617 are available in 4-lead SC70 packages

nd typically consume only 5 μA, making them suitable for use

a in low power, portable applications.

ADM8616/ADM8617

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REVISION HISTORY

1/07—Rev. A to Rev. B

Changes to Functional Block Diagram.......................................... 1

11/06—Rev. 0 to Rev. A

Changes to Ordering Guide.......................................................... 10

6/05—Revision 0: Initial Version

Circuit Description............................................................................8

RESET Output ...............................................................................8

Watchdog Input.............................................................................8

Application Information...................................................................9

Watchdog Input Current ..............................................................9

Negative-Going V

Ensuring RESET Valid to V

Watchdog Software Considerations............................................9

Outline Dimensions....................................................................... 10

Ordering Guide .......................................................................... 10

Transients...................................................9

CC

= 0 V...........................................9

CC

Rev. B | Page 2 of 12

ADM8616/ADM8617

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SPECIFICATIONS

VCC = full operating range, TA = −40oC to +85oC, unless otherwise noted.

Table 1.

Parameter Min Typ Max Unit Test Conditions/Comments

SUPPLY

VCC Operating Voltage Range 1 5.5 V Supply Current 10 20 μA VCC = 5.5 V 5 12 μA VCC = 3.6 V

RESET THRESHOLD VOLTAGE

ADM861xL ADM861xM ADM861xT ADM861xS ADM861xR ADM861xZ ADM861xY ADM861xW

ADM861xV RESET THRESHOLD TEMPERATURE COEFFICIENT

RESET THRESHOLD HYSTERESIS

RESET TIMEOUT PERIOD

ADM861xxA 1 1.4 2 ms

ADM861xxB 20 28 40 ms

ADM861xxC 140 200 280 ms

ADM861xxD 1120 1600 2240 ms VCC TO RESET DELAY

RESET OUTPUT VOLTAGE

VOL (Open-Drain and Push-Pull) 0.3 V VCC ≥ 1.0 V, I

0.3 V VCC ≥ 1.2 V, I

0.3 V VCC ≥ 2.7 V, I

0.4 V VCC ≥ 4.5 V, I

VOH (Push-Pull Only) 0.8 × VCC V VCC ≥ 2.7 V, I

RESET Rise Time

Open-Drain RESET Output Leakage Current

WATCHDOG INPUT

Watchdog Timeout Period

ADM861xxxW 4.3 6.3 9.3 ms ADM861xxxX 71 102 153 ms

ADM861xxxY 1.12 1.6 2.4 sec WDI Pulse Width 50 ns VIL = 0.3 × VCC, V WDI Input Threshold V

VIL 0.3 × VCC

VIH 0.7 × VCC V WDI Input Current 120 160 μA V

4.50 4.63 4.75 V

4.25 4.38 4.50 V

3.00 3.08 3.15 V

2.85 2.93 3.00 V

2.55 2.63 2.70 V

2.25 2.32 2.38 V

2.12 2.19 2.25 V

1.62 1.67 1.71 V

1.52 1.58 1.62 V 40 ppm/°C

2 × V

mV

TH

40 μs V

falling at 1 mV/μs

CC

= 50 μA

SINK

= 100 μA

SINK

= 1.2 mA

SINK

= 3.2 mA

SINK

= 500 μA

SOURCE

VCC − 1.5

V VCC ≥ 4.5 V, I

5 25 ns From 10% to 90% V

SOURCE

= 800 μA

, CL = 5 pF, VCC = 3.3 V

CC

1 μA

= 0.7 × VCC

IH

= VCC

WDI

−20 −15

μA V

WDI

= 0

Rev. B | Page 3 of 12

ADM8616/ADM8617

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ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted.

Table 2.

Parameter Rating VCC

RESET

Output Current (RESET) Operating Temperature Range

Storage Temperature Range θJA Thermal Impedance, SC70 146°C/W

Soldering Temperature

Sn/Pb 240°C, 30 sec Pb-Free 260°C, 40 sec

−0.3 V to +6 V

20 mA

−40°C to +85°C

−65°C to +150°C

Stresses above those listed under Absolute Maximum Ratings ma

y cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

ESD CAUTION

Rev. B | Page 4 of 12

ADM8616/ADM8617

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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

GND

1

2

RESET

Figure 2. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Description

1 GND Ground. 2

RESET

Active-Low RESET Output. Asserted whenever VCC is below the reset threshold (VTH). Push-Pull Output Stage for ADM8616.

Open-Drain Output Stage for ADM8617.

3 WDI

Watchdog Input. Generates a RESET

if the logic level on the pin remains low or high for the duration of the watchdog timeout. The timer is cleared if a logic transition occurs on this pin, or if a reset is generated. Leave floating to disable the watchdog timer.

4 VCC Power Supply Voltage Being Monitored.

ADM8616/ ADM8617

TOP VIEW

(Not to Scale)

V

4

CC

WDI

3

04795-002

Rev. B | Page 5 of 12

ADM8616/ADM8617

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TYPICAL PERFORMANCE CHARACTERISTICS

10.0

9.5

9.0

8.5

8.0

7.5

7.0

(µA)

6.5

CC

I

6.0

5.5

5.0

4.5

4.0

3.5

1.20

1.15

1.10

1.05

1.00

0.95

0.90

NORMALIZE D RESET TI MEOUT

0.85

0.80

Figure 4. Normalized

100

90

80

70

60

50

40

30

TO RESET DELAY (µs)

CC

V

20

10

0

VCC = 5V

VCC = 3.3V

VCC = 1.5V

TEMPERATURE ( °C)

Figure 3. Supply Current vs. Temperature

TEMPERATURE ( °C)

RESET

Timeout Period vs. Temperature

TEMPERATURE ( °C)

RESET

to

Figure 5. V

CC

Output Delay vs. Temperature

120–40 –20 0 20 40 60 80 100

04795-003

120–40 0–20 4020 1008060

04795-004

120–40 0–20 4020 1008060

04795-005

1.20

1.15

1.10

1.05

1.00

0.95

NORMALIZE D WATCHDOG T IMEOUT

0.90

TEMPERATURE ( °C)

Figure 6. Normalized Watchdog Timeout Period vs. Temperature

1.05

1.04

1.03

1.02

1.01

1.00

0.99

0.98

0.97

NORMALIZE D RESET THRES HOLD

0.96

0.95

TEMPERATURE ( °C)

RESET

Figure 7. Normalized

160

140

120

100

80

60

40

MINIMUM PUL SE WIDTH (µs)

20

VCC = 2.93V

0

Figure 8. Maximum V

RESET THRESHO LD OVERDRI VE (mV)

Transient Duration vs.

CC

Threshold vs. Temperature

VCC = 4.63V

RESET

Threshold Overdrive

120–40 0–20 4020 1008060

04795-006

120–40 0–20 4020 1008060

04795-007

100010 100

04795-008

Rev. B | Page 6 of 12

ADM8616/ADM8617

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0.20

VCC = 2.9V

2.92

VCC = 2.9V

0.15

(V)

0.10

OUT

V

0.05

0

I

(mA)

SINK

Figure 9. Voltage Output Low vs. I

SINK

75603412

04795-009

2.90

2.88

(V)

OUT

V

2.86

2.84

2.82

I

(mA)

SOURCE

Figure 10. Voltage Output High vs. I

8

SOURCE

1.000.60.0.2 0.4

04795-010

Rev. B | Page 7 of 12

ADM8616/ADM8617

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CIRCUIT DESCRIPTION

The ADM8616/ADM8617 provide microprocessor supply voltage supervision by controlling the microprocessors

RESET input. Code execution errors are avoided during power-up, power-down, and brownout conditions by asserting a

RESET

signal when the supply voltage is below a preset threshold and by allowing supply voltage stabilization with a fixed timeout RESET

after the supply voltage rises above the threshold. In addition, problems with microprocessor code execution can be monitored and corrected with a watchdog timer. By including watchdog strobe instructions in microprocessor code, a watchdog timer can detect if the microprocessor code breaks down or becomes stuck in an infinite loop. If this happens, the watchdog timer asserts a

RESET

pulse that restarts the microprocessor in

a known state.

RESET OUTPUT

The ADM8616 features an active-low, push-pull while the ADM8617 features an active-low, open-drain output. The logic high, respectively, for V

The threshold (V watchdog timeout period (t duration of the above the

RESET

signal is guaranteed to be logic low and

down to 1 V.

CC

RESET

output is asserted when VCC is below the

), or when WDI is not serviced within the

TH

RESET

).

WD

RESET

active timeout period (tRP) after VCC rises

RESET

threshold or after the watchdog timer times

remains asserted for the

out. Figure 11 illustrates the behavior of the

V

RESET

CC

1V 0V

V

CC

0V

V

TH

Figure 11.

t

RP

RESET

Timing Diagram

RESET

V

TH

output,

RESET

outputs.

t

RD

04795-011

WATCHDOG INPUT

The ADM8616/ADM8617 feature a watchdog timer that monitors microprocessor activity. A timer circuit is cleared with every low-to-high or high-to-low logic transition on the watchdog input pin (WDI), which detects pulses as short as 50 ns. If the timer counts through the preset watchdog timeout period

RESET

(t

),

WD

toggle the WDI pin to avoid being reset. Failure of the microprocessor to toggle WDI within the timeout period, therefore, indicates a code execution error, and the restarts the microprocessor in a known state.

In addition to logic transitions on WDI, the watchdog timer

lso cleared by a

is a condition on V is cleared and does not begin counting again until serts. The watchdog timer can be disabled by leaving WDI

floating or by three-stating the WDI driver.

V

RESET

WDI

is asserted. The microprocessor is required to

RESET

assertion due to an undervoltage

RESET

. When

CC

V

CC

1V 0V

V

CC

0V

V

CC

0V

V

TH

t

RP

Figure 12. Watchdog Timing Diagram

is asserted, the watchdog timer

t

WD

pulse generated

RESET

deas-

t

RD

04795-012

Rev. B | Page 8 of 12

ADM8616/ADM8617

V

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APPLICATION INFORMATION

WATCHDOG INPUT CURRENT

To minimize watchdog input current (and minimize overall power consumption), leave WDI low for the majority of the watchdog timeout period. When driven high, WDI can draw as much as 160 μA. Pulsing WDI low-high-low at a low duty cycle reduces the effect of the large input current. When WDI is unconnected, a window comparator disconnects the watchdog timer from the

RESET

output circuitry so that

RESET

is not asserted when the watchdog timer times out.

NEGATIVE-GOING VCC TRANSIENTS

To avoid unnecessary resets caused by fast power supply transients, the ADM8616/ADM8617 are equipped with glitch rejection circuitry. The typical performance characteristic in Figure 8 plots V

transient duration vs. transient magnitude.

CC

The curve shows combinations of transient magnitude and duration for which a

RESET

is not generated for 4.63 V and

2.93 V reset threshold parts. For example, with the 2.93 V threshold, a transient that goes 100 mV below the threshold and lasts 8 μs typically does not cause a transient is any bigger in magnitude or duration, a

RESET

, but if the

RESET

is generated. An optional 0.1 μF bypass capacitor mounted close to V

provides additional glitch rejection.

CC

ENSURING RESET VALID TO VCC = 0 V

The active-low

as low as 1 V. However, by using an external resistor,

V

CC

valid outputs for V connected between when it is unable to sink current. A large resistance, such as 100 kΩ, should be used so that it does not overload the output when V

RESET

output is guaranteed to be valid for

as low as 0 V are possible. The resistor,

CC

RESET

and ground, pulls the output low

is above 1 V.

CC

RESET

WATCHDOG SOFTWARE CONSIDERATIONS

In implementing the microprocessors watchdog strobe code, quickly switching WDI low to high and then high to low (minimizing WDI high time) is desirable for current consumption reasons. However, a more effective way of using the watchdog function can be considered.

A low-high-low WDI pulse within a given subroutine prevents

he watchdog from timing out. However, if the subroutine

t becomes stuck in an infinite loop, the watchdog does not detect this because the subroutine continues to toggle WDI. A more effective coding scheme for detecting this error involves using a slightly longer watchdog timeout. In the program that calls the subroutine, WDI is set high. The subroutine sets WDI low when it is called. If the program executes without error, WDI is toggled high and low with every loop of the program. If the subroutine enters an infinite loop, WDI is kept low, the watchdog times out, and the microprocessor is reset.

START

SET WDI

HIGH

PROGRAM

CODE

SUBROUTINE

SET WDI

LOW

RETURN

Figure 14. Watchdog Flow Diagram

CC

RESET

INFINITE LOOP:

WATCHDOG

TIMES OUT

04795-014

ADM8616/

ADM8617

Figure 13. Ensuring

RESET

Valid to VCC = 0 V

100kΩ

4795-013

Rev. B | Page 9 of 12

RESET RESET

ADM8616/ ADM8617

WDI I/O

Figure 15. Typical Application Circuit

µP

04795-015

ADM8616/ADM8617

7

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OUTLINE DIMENSIONS

2.20

1.35

1.15

PIN 1

0.65 BSC

1.00

0.80

1.80

4

1

3

2

0.50 BSC

2.40

1.80

1.10

0.80

0.40

0.10

12°

8°

0.30

0.10

0.10 MAX

0.30

0.15

0.10 COPLANARITY

*

PACKAGE OUTLINE CORRESPONDS IN FULL TO EIAJ SC82 EXCEPT FOR WIDTH OF PIN 2 AS SHOWN.

*

0.70

0.50

SEATING PLANE

0.18

0.10

Figure 16. 4-Lead Thin Shrink Small Outline Transistor Package [SC70]

(K

S-4)

Dimensions shown in millimeters

RESET THRESHO LD

L: 4.63V

M: 4.38V

T: 3.08V S: 2.93V R: 2.63V Z: 2.32V Y: 2.19V

W: 1.67V

V: 1.58V

ADM861 KS -RL

GENERIC NUMBER

RESET TIMEOUT PERIOD

D: 1120ms (MIN)

Figure 17. Ordering Code Structure

xxxxx x

(6/7)

A: 1ms (MIN)

B: 20ms (MIN)

C: 140ms (MIN)

ORDERING QUANT ITY RL7: 3,000 PIE CE REEL

Z: LEAD FREE

PACKAGE CODE KS: 4-LEAD SC70

TEMPERATURE RANG E A: –40°C TO + 85°C

WATCHDOG TIMEOUT PERIOD W: 6.3ms (TYP) X: 102ms (TYP) Y: 1.6s (T YP)

04795-016

ORDERING GUIDE

1

Model

ADM8616LCYAKSZ-RL7

ADM8616MCYAKSZ-RL724.38

ADM8616TCYAKSZ-RL7

ADM8616SCYAKSZ-RL7

ADM8616RCYAKSZ-RL7

ADM8616ZCYAKSZ-RL7

ADM8616YCYAKSZ-RL7

ADM8616WCYAKSZ-RL721.67

ADM8616VCYAKSZ-RL7

ADM8617SAYAKSZ-RL7

ADM8617RCYAKSZ-RL7

1

If ordering nonstandard models, complete the ordering code shown in Figure 17 by inserting reset threshold, reset timeout, and watchdog timeout suffixes. Contact

Sales for availability of nonstandard models.

2

Z = Pb-free part.

Reset Threshold (V) Temperature Range Quantity

2

4.63

−40°C to +85°C

2

3.08

2

2.93

2

2.63

2

2.32

2

2.19

−40°C to +85°C

2

1.58

2

2.93

2

2.63

−40°C to +85°C

3,000 4-Lead SC70 KS-4 N0F

3,000 4-Lead SC70 KS-4 M4X

Package Description Package Option Branding

Rev. B | Page 10 of 12

ADM8616/ADM8617

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NOTES

Rev. B | Page 11 of 12

ADM8616/ADM8617

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NOTES

Rev. B | Page 12 of 12

ANALOG DEVICES ADM8616, ADM8617 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

FUNCTIONAL BLOCK DIAGRAM

GENERAL DESCRIPTION

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TYPICAL PERFORMANCE CHARACTERISTICS

CIRCUIT DESCRIPTION

RESET OUTPUT

WATCHDOG INPUT

APPLICATION INFORMATION

WATCHDOG INPUT CURRENT

NEGATIVE-GOING VCC TRANSIENTS

ENSURING RESET VALID TO VCC = 0 V

WATCHDOG SOFTWARE CONSIDERATIONS

OUTLINE DIMENSIONS

ORDERING GUIDE