Maxim MAX6817EUT-T, MAX6818EAP, MAX6816EUS-T Datasheet

General Description

The MAX6816/MAX6817/MAX6818 are single, dual, and
octal switch debouncers that provide clean interfacing
of mechanical switches to digital systems. They accept
one or more bouncing inputs from a mechanical switch
and produce a clean digital output after a short, preset
qualification delay. Both the switch opening bounce
and the switch closing bounce are removed. Robust
switch inputs handle ±25V levels and are ±15kV ESD­protected for use in harsh industrial environments. They
feature single-supply operation from +2.7V to +5.5V.
Undervoltage lockout circuitry ensures the output is in
the correct state upon power-up.

The single MAX6816 and dual MAX6817 are offered in
SOT packages and require no external components.
Their low supply current makes them ideal for use in
portable equipment.

The MAX6818 octal switch debouncer is designed for
data-bus interfacing. The MAX6818 monitors switches
and provides a switch change-of-state output (CH),
simplifying microprocessor (µP) polling and interrupts.
Additionally, the MAX6818 has three-state outputs con­trolled by an enable (EN) pin, and is pin-compatible
with the ‘LS573 octal latch (except for the CH pin),
allowing easy interfacing to a digital data bus.

Applications

µP Switch Interfacing
Industrial Instruments
PC-Based Instruments
Portable Instruments
Automotive Applications
Membrane Keypads

Features

♦ Robust Inputs can Exceed Power Supplies

up to ±25V

♦ ESD Protection for Input Pins

±15kV—Human Body Model
±8kV—IEC 1000-4-2, Contact Discharge
±15kV—IEC 1000-4-2, Air-Gap Discharge

♦ Small SOT Packages (4 and 6 pins)
♦ Single-Supply Operation from +2.7V to +5.5V
♦ Single (MAX6816), Dual (MAX6817), and Octal

(MAX6818) Versions Available

♦ No External Components Required
♦ 6µA Supply Current
♦ Three-State Outputs for Directly Interfacing

Switches to µP Data Bus (MAX6818)

♦ Switch Change-of-State Output Simplifies

Polling and Interrupts (MAX6818)

♦ Pin-Compatible with ’LS573 (MAX6818)

MAX6816/MAX6817/MAX6818

±15kV ESD-Protected, Single/Dual/Octal,

CMOS Switch Debouncers

________________________________________________________________

Maxim Integrated Products

1

1

2

4

3

V

CC

OUTIN

GND

MAX6816

SOT143

TOP VIEW

IN

MECHANICAL

SWITCH

RESET

GND

DEBOUNCED

OUTPUT

V

CC

µP

0.1µF

OUT

MAX6816

Typical Operating Circuit

19-4770; Rev 1; 1/99

PART

MAX6816EUS-T
MAX6817EUT-T
MAX6818EAP

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE

PIN­PACKAGE

4 SOT143
6 SOT23-6
20 SSOP

Note:

There is a minimum order increment of 2500 pieces for

SOT packages.

Pin Configurations

Ordering Information

SOT

TOP MARK

KABA
AAAU

—

Pin Configurations continued at end of data sheet.

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone].
For small orders, phone [phone].

MAX6816/MAX6817/MAX6818

±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at V

CC

= +5V, TA= +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

Voltage (with respect to GND)

VCC.......................................................................-0.3V to +6V

IN_ (Switch Inputs)..............................................-30V to +30V

EN.........................................................................-0.3V to +6V

OUT_, CH ...............................................-0.3V to (V

CC

+ 0.3V)
OUT Short-Circuit Duration

(One or Two Outputs to GND)....................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

4-Pin SOT143 (derate 4.0mW/°C above +70°C)..........320mW

6-Pin SOT23 (derate 8.7mW/°C above +70°C)............691mW

20-Pin SSOP (derate 8.0mW/°C above +70°C) ...........640mW

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range.............................-65°C to +160°C

Lead Temperature (soldering, 10sec).............................+300°C

MAX6818

RL= 10kΩ, CL= 50pF

VCC= 5V, I

OUT

= 0, IN_ = V

CC

RL= 1kΩ, CL = 15pF

RL= 10kΩ, CL= 100pF

VCC= 2.7V

I

SINK

= 1.6mA

VCC= 5V

V

IN

= ±15V

V

CC

= 5V

VCC= 2.7V

I

SOURCE

= 0.4mA

CONDITIONS

ns100t

PC

EN Low to CH Out High
Propagation Delay

ns100t

PD

EN High to Out Three-State
Propagation Delay

ns100t

PE

EN Low to Out Active
Propagation Delay

µA±1I

IL

EN Input Current

0.8 1.1 2.0

0.8 1.7 2.4

ns200t

EN

EN Pulse Width

V

CC

- 1.0V

OH

ms

20 50 80

t

DP

Debounce Duration

µA620I

CC

V2.7 5.5V

CC

Operating Voltage Range
Supply Current

V

0.4V

OL

OUT_, CH Output Voltage

V-25 25V

IN

Input Voltage Range

mA±1I

IN

IN Input Current

kΩ32 63 100Input Pull-Up Resistance

V0.8V

IL

V

2.4

V

IH

2.0
mV300Input Hysteresis

UNITSMIN TYP MAXSYMBOLPARAMETER

Input Threshold

V1.9 2.6Undervoltage-Lockout Threshold

V

OUT

= 0 or V

CC

µA±10

OUT_ Three-State Leakage Current

kV

±15

±8

IN_

±15

ESD Protection

V

EN Threshold

IEC1000-4-2 Air Discharge
IEC1000-4-2 Contact Discharge
Human Body Model

MAX6816/MAX6817

20 40 60

Note 1: MAX6816 and MAX6817 production testing is done at TA = +25°C; over-temperature limits are guaranteed by design.

ESD CHARACTERISTICS

MAX6816/MAX6817/MAX6818

±15kV ESD-Protected, Single/Dual/Octal,

CMOS Switch Debouncers

_______________________________________________________________________________________

3

0

2

1

4

3

6

5

7

-50 0 25-25 50 75 100

SUPPLY CURRENT vs. TEMPERATURE

MAX6816 TOC01

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

VCC = 5V

VCC = 3V

IN (5V/div)OUT (2V/div)

4V

0

-5V

5V

10ms/div

DEBOUNCE OF CLOSING SWITCH

MAX6816 TOC02

VCC = 5V

4V

0

-5V

5V

10ms/div

DEBOUNCE OF OPENING SWITCH

MAX6816 TOC03

VCC = 5V

IN (5V/div)OUT (2V/div)

0

2

1

4

3

5

6

24356

OUTPUT LOGIC LEVEL
vs. SUPPLY VOLTAGE

MAX6816 toc04

SUPPLY VOLTAGE (V)

OUTPUT LOGIC LEVEL (V)

VOH, I

SOURCE

= 0.4mA

VOL, I

SINK

= 1.6mA

30

40

35

45

50

-50 25-25 0 7550

100

DEBOUNCE DELAY PERIOD

vs. TEMPERATURE

MAX6816 toc06

TEMPERATURE (°C)

DEBOUNCE DELAY PERIOD (ms)

VCC = 5V

VCC = 3V

0

2

1

4

3

5

24356

MAX6818 EN INPUT LOGIC THRESHOLD

vs. SUPPLY VOLTAGE

MAX6816 toc05

SUPPLY VOLTAGE (V)

LOGIC THRESHOLD (V)

0

3

1

2

4

5

-50 25 50-25 0 75 100

VCC UNDERVOLTAGE LOCKOUT

vs. TEMPERATURE

MAX6816 toc07

TEMPERATURE (°C)

V

CC

UNDERVOLTAGE LOCKOUT (V)

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

_______________Detailed Description

Theory of Operation

The MAX6816/MAX6817/MAX6818 are designed to
eliminate the extraneous level changes that result from
interfacing with mechanical switches (switch bounce).
Virtually all mechanical switches bounce upon opening
or closing. These switch debouncers remove bounce
when a switch opens or closes by requiring that
sequentially clocked inputs remain in the same state for
a number of sampling periods. The output does not
change until the input is stable for a duration of 40ms.

The circuit block diagram (Figure 1) shows the func­tional blocks consisting of an on-chip oscillator,
counter, exclusive-NOR gate, and D flip-flop. When the

input does not equal the output, the XNOR gate issues
a counter reset. When the switch input state is stable
for the full qualification period, the counter clocks the
flip-flop, updating the output. Figure 2 shows the typical
opening and closing switch debounce operation. On
the MAX6818, the change output (CH) is updated
simultaneously with the switch outputs.

Undervoltage Lockout

The undervoltage lockout circuitry ensures that the out­puts are at the correct state on power-up. While the sup­ply voltage is below the undervoltage threshold
(typically 1.9V), the debounce circuitry remains trans­parent. Switch states are present at the logic outputs
without delay.

MAX6816/MAX6817/MAX6818

±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers

4 _______________________________________________________________________________________

PIN

2 — —

— 1, 3 —

— — 12–19

— 4, 6 —

3 — —

— — 2–9

— — 11

— — 1

4 5 20

Pin Description

FUNCTION

Switch Input
Switch Inputs

CMOS Debounced Outputs

CMOS Debounced Outputs

CMOS Debounced Output

Switch Inputs

Change-of-State Output. Goes low on switch input change of
state. Resets on EN. Leave unconnected if not used.

Active-Low, Three-State Enable Input for outputs. Resets CH.
Tie to GND to “always enable” outputs.

+2.7V to +5.5V Supply Voltage

NAME

IN

IN1, IN2

OUT8–OUT1

OUT2, OUT1

OUT

IN1–IN8

CH

EN

V

CC

Figure 1. Block Diagram

1 2 10 GroundGND

MAX6816 MAX6817 MAX6818

V

CC

V

CC

IN

PROTECTION

ESD

R

PU

V

CC

OSC.

COUNTER

R

DQ

QD

UNDER­VOLTAGE
LOCKOUT

LOAD

MAX6816
MAX6817
MAX6818

OUT