19-4770; Rev 2; 12/05
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
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 ESD-
protected 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 con-
trolled 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.
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
Ordering Information
PART
MAX6816EUS-T
TEMP RANGE
-40°C to +85°C
SOT
PIN-
PACKAGE TOP MARK
4 SOT143
KABA
Applications
µP Switch Interfacing
Industrial Instruments
PC-Based Instruments
Portable Instruments
Automotive Applications
Membrane Keypads
MAX6817EUT-T
-40°C to +85°C 6 SOT23-6
AAAU
MAX6818EAP
—
-40°C to +85°C 20 SSOP
Note:
There is a minimum order increment of 2500 pieces for
SOT packages.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Typical Operating Circuit
TOP VIEW
V
CC
GND
MECHANICAL
SWITCH
1
Pin Configurations
4
V
CC
MAX6816
0.1
µ
F
µ
P
MAX6816
IN
GND
OUT
DEBOUNCED
OUTPUT
RESET
IN
2
3
OUT
SOT143
Pin Configurations continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
MAX6816/MAX6817/MAX6818
ABSOLUTE MAXIMUM RATINGS
Voltage (with respect to GND)
V
CC
.......................................................................-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, 10s) .................................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
CC
= +2.7V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
CC
= +5V, T
A
= +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
Supply Current
Debounce Duration
SYMBOL
V
CC
I
CC
t
DP
V
IL
Input Threshold
Input Hysteresis
Input Pull-Up Resistance
IN Input Current
Input Voltage Range
Undervoltage-Lockout Threshold
OUT_,
CH
Output Voltage
EN
Pulse Width
EN
Threshold
EN
Input Current
EN
Low to Out Active
Propagation Delay
EN
High to Out Three-State
Propagation Delay
EN
Low to
CH
Out High
Propagation Delay
OUT_ Three-State Leakage Current
ESD CHARACTERISTICS
IEC1000-4-2 Air Discharge
ESD Protection
IN_
IEC1000-4-2 Contact Discharge
Human Body Model
±15
±8
±15
kV
I
IL
t
PE
t
PD
t
PC
R
L
= 10kΩ, C
L
= 100pF
R
L
= 1kΩ, C
L
= 15pF
R
L
= 10kΩ, C
L
= 50pF
V
OUT
= 0 or V
CC
V
OL
V
OH
t
EN
V
CC
= 5V
V
CC
= 2.7V
I
SINK
= 1.6mA
I
SOURCE
= 0.4mA
V
CC
- 1.0
200
0.8
0.8
1.7
1.1
2.4
2.0
±1
100
100
100
±10
I
IN
V
IN
V
IN
= ±15V
-25
1.9
32
V
IH
V
CC
= 5V
V
CC
= 2.7V
2.4
2.0
300
63
100
±1
+25
2.6
0.4
V
CC
= 5V, I
OUT
= 0, IN_ = V
CC
MAX6818
MAX6816/MAX6817
20
20
CONDITIONS
MIN
2.7
6
40
50
TYP
MAX
5.5
20
60
80
0.8
UNITS
V
µA
ms
V
V
mV
kΩ
mA
V
V
V
ns
V
µA
ns
ns
ns
µA
Note 1:
MAX6816 and MAX6817 production testing is done at T
A
= +25°C; over-temperature limits are guaranteed by design.
2
_______________________________________________________________________________________
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
MAX6816/MAX6817/MAX6818
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
V
CC
= 5V
6
SUPPLY CURRENT (µA)
5
4
3
2
1
0
-50
-25
0
25
50
75
100
V
CC
= 3V
MAX6816 TOC01
DEBOUNCE OF CLOSING SWITCH
MAX6816 TOC02
DEBOUNCE OF OPENING SWITCH
MAX6816 TOC03
7
IN (5V/div)
-5V
4V
OUT (2V/div)
IN (5V/div)
V
CC
= 5V
10ms/div
5V
5V
-5V
4V
OUT (2V/div)
0
0
V
CC
= 5V
10ms/div
TEMPERATURE (°C)
OUTPUT LOGIC LEVEL
vs. SUPPLY VOLTAGE
V
OH
, I
SOURCE
= 0.4mA
5
OUTPUT LOGIC LEVEL (V)
4
3
2
1
V
OL
, I
SINK
= 1.6mA
0
2
3
4
SUPPLY VOLTAGE (V)
5
6
0
MAX6816 toc04
MAX6818 EN INPUT LOGIC THRESHOLD
vs. SUPPLY VOLTAGE
MAX6816 toc05
6
5
4
LOGIC THRESHOLD (V)
3
2
1
2
3
4
SUPPLY VOLTAGE (V)
5
6
DEBOUNCE DELAY PERIOD
vs. TEMPERATURE
MAX6816 toc06
V
CC
UNDERVOLTAGE LOCKOUT
vs. TEMPERATURE
MAX6816 toc07
50
DEBOUNCE DELAY PERIOD (ms)
5
V
CC
UNDERVOLTAGE LOCKOUT (V)
4
45
V
CC
= 3V
40
V
CC
= 5V
35
3
2
1
30
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
0
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
_______________________________________________________________________________________
3
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
MAX6816/MAX6817/MAX6818
Pin Description
PIN
MAX6816
1
2
—
—
3
—
—
4
—
—
MAX6817
2
—
1, 3
—
—
4, 6
—
5
—
—
MAX6818
10
—
—
2–9
—
—
12–19
20
1
11
NAME
GND
IN
IN1, IN2
IN1–IN8
OUT
OUT2, OUT1
OUT8–OUT1
V
CC
EN
CH
Ground
Switch Input
Switch Inputs
Switch Inputs
CMOS Debounced Output
CMOS Debounced Outputs
CMOS Debounced Outputs
+2.7V to +5.5V Supply Voltage
Active-Low, Three-State Enable Input for outputs. Resets
CH.
Tie to GND to “always enable” outputs.
Change-of-State Output. Goes low on switch input change of
state. Resets on
EN.
Leave unconnected if not used.
FUNCTION
V
CC
V
CC
V
CC
R
PU
IN
ESD
PROTECTION
OSC.
D
R
COUNTER
Q
D
Q
OUT
LOAD
UNDER-
VOLTAGE
LOCKOUT
MAX6816
MAX6817
MAX6818
Figure 1. Block Diagram
_______________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 func-
tional blocks consisting of an on-chip oscillator,
counter, exclusive-NOR gate, and D flip-flop. When the
4
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 out-
puts are at the correct state on power-up. While the sup-
ply voltage is below the undervoltage threshold
(typically 1.9V), the debounce circuitry remains trans-
parent. Switch states are present at the logic outputs
without delay.
_______________________________________________________________________________________
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
MAX6816/MAX6817/MAX6818
t
DP
IN1
EN
1/2
V
CC
t
EN
1/2
V
CC
OUT1–OUT8
OUT1
t
PE
OUT NORMALLY
1/2
V
CC
LOW
t
PE
t
PD
V
OL
+ 0.5V
IN2
OUT1–OUT8
t
PC
1/2
V
CC
OUT NORMALLY
HIGH
V
OH
- 0.5V
t
PD
OUT2
CH
1/2
V
CC
Figure 4. MAX6818 µP-Interface Timing Diagram
CH
+V
CC
MAX6818 ONLY
0.1
µ
F
+V
CC
Figure 2. Input Characteristics
SW1
IN1
20V
IN
(20V/div)
0
-20V
IN8
SW8
4V
OUT
(2V/div)
0
OUT8
EN
CH
I/O
IRQ
µ
P
MAX6818
OUT1
D0
D7
Figure 5. MAX6818 Typical µP Interfacing Circuit
20ms/div
Figure 3. Switch Input ±25V Fault Tolerance
Robust Switch Inputs
The switch inputs on the MAX6816/MAX6817/MAX6818
have overvoltage clamping diodes to protect against
damaging fault conditions. Switch input voltages
can safely swing ±25V to ground (Figure 3). Proprietary
ESD-protection structures protect against high
ESD encountered in harsh industrial environments,
membrane keypads, and portable applications.
They are designed to withstand ±15kV per the
IEC1000-4-2 Air Gap Discharge Test and ±8kV per the
IEC1000-4-2 Contact Discharge Test.
Since there are 63kΩ (typical) pull-up resistors con-
nected to each input, driving an input to -25V will draw
approximately 0.5mA (up to 4mA for eight inputs) from
the V
CC
supply. Driving an input to +25V will cause
approximately 0.32mA of current (up to 2.6mA for eight
inputs) to flow back into the V
CC
supply. If the total sys-
tem V
CC
supply current is less than the current flowing
back into the V
CC
supply, V
CC
will rise above normal
levels. In some low-current systems, a zener diode on
V
CC
may be required.
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro-
static discharges encountered during handling and
assembly. The MAX6816/MAX6817/MAX6818 have
extra protection against static electricity. Maxim's engi-
neers have developed state-of-the-art structures to pro-
tect against ESD of ±15kV at the switch inputs without
5
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