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.
Applications
µP Switch Interfacing
Industrial Instruments
PC-Based Instruments
Portable Instruments
Automotive Applications
Membrane Keypads
Features
o
Robust Inputs can Exceed Power Supplies
up to ±25V
o
ESD Protection for Input Pins
±15kV--Human Body Model
±8kV--IEC 1000-4-2, Contact Discharge
±15kV--IEC 1000-4-2, Air-Gap Discharge
o
Small SOT Packages (4 and 6 pins)
o
Single-Supply Operation from +2.7V to +5.5V
o
Single (MAX6816), Dual (MAX6817), and Octal
(MAX6818) Versions Available
o
No External Components Required
o
6µA Supply Current
o
Three-State Outputs for Directly Interfacing
Switches to µP Data Bus (MAX6818)
o
Switch Change-of-State Output Simplifies
Polling and Interrupts (MAX6818)
o
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
OUT
IN
GND
MAX6816
SOT143
TOP VIEW
IN
MECHANICAL
SWITCH
RESET
GND
DEBOUNCED
OUTPUT
V
CC
µ
P
0.1
µ
F
OUT
MAX6816
Typical Operating Circuit
19-4770; Rev 1; 1/99
PART
MAX6816
EUS-T
MAX6817
EUT-T
MAX6818
EAP
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE
PIN-
PACKAGE
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 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX6816/MAX6817/MAX6818
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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)
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)
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, 10sec) .............................+300°C
MAX6818
R
L
= 10k
, C
L
= 50pF
V
CC
= 5V, I
OUT
= 0, IN_ = V
CC
R
L
= 1k
, C
L
= 15pF
R
L
= 10k
, C
L
= 100pF
V
CC
= 2.7V
I
SINK
= 1.6mA
V
CC
= 5V
V
IN
= ±15V
V
CC
= 5V
V
CC
= 2.7V
I
SOURCE
= 0.4mA
CONDITIONS
ns
100
t
PC
EN Low to CH Out High
Propagation Delay
ns
100
t
PD
EN High to Out Three-State
Propagation Delay
ns
100
t
PE
EN Low to Out Active
Propagation Delay
µA
±1
I
IL
EN Input Current
0.8
1.1
2.0
0.8
1.7
2.4
ns
200
t
EN
EN Pulse Width
V
CC
- 1.0
V
OH
ms
20
50
80
t
DP
Debounce Duration
µA
6
20
I
CC
V
2.7
5.5
V
CC
Operating Voltage Range
Supply Current
V
0.4
V
OL
OUT_, CH Output Voltage
V
-25
25
V
IN
Input Voltage Range
mA
±1
I
IN
IN Input Current
k
32
63
100
Input Pull-Up Resistance
V
0.8
V
IL
V
2.4
V
IH
2.0
mV
300
Input Hysteresis
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
Input Threshold
V
1.9
2.6
Undervoltage-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 T
A
= +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 (
µ
A)
V
CC
= 5V
V
CC
= 3V
IN (5V/div)
OUT (2V/div)
4V
0
-5V
5V
10ms/div
DEBOUNCE OF CLOSING SWITCH
MAX6816 TOC02
V
CC
= 5V
4V
0
-5V
5V
10ms/div
DEBOUNCE OF OPENING SWITCH
MAX6816 TOC03
V
CC
= 5V
IN (5V/div)
OUT (2V/div)
0
2
1
4
3
5
6
2
4
3
5
6
OUTPUT LOGIC LEVEL
vs. SUPPLY VOLTAGE
MAX6816 toc04
SUPPLY VOLTAGE (V)
OUTPUT LOGIC LEVEL (V)
V
OH
, I
SOURCE
= 0.4mA
V
OL
, I
SINK
= 1.6mA
30
40
35
45
50
-50
25
-25
0
75
50
100
DEBOUNCE DELAY PERIOD
vs. TEMPERATURE
MAX6816 toc06
TEMPERATURE (°C)
DEBOUNCE DELAY PERIOD (ms)
V
CC
= 5V
V
CC
= 3V
0
2
1
4
3
5
2
4
3
5
6
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
V
CC
UNDERVOLTAGE LOCKOUT
vs. TEMPERATURE
MAX6816 toc07
TEMPERATURE (°C)
V
CC
UNDERVOLTAGE LOCKOUT (V)
Typical Operating Characteristics
(T
A
= +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 func-
tional 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 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.
MAX6816/MAX6817/MAX6818
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
4
_______________________________________________________________________________________
PIN
2
--
--
--
1, 3
--
--
--
1219
--
4, 6
--
3
--
--
--
--
29
--
--
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
OUT8OUT1
OUT2, OUT1
OUT
IN1IN8
CH
EN
V
CC
V
CC
V
CC
V
CC
R
PU
D
Q
R
Q
D
COUNTER
LOAD
OUT
IN
ESD
PROTECTION
UNDER-
VOLTAGE
LOCKOUT
OSC.
MAX6816
MAX6817
MAX6818
Figure 1. Block Diagram
1
2
10
Ground
GND
MAX6816
MAX6817
MAX6818
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 63k
(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
MAX6816/MAX6817/MAX6818
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers
_______________________________________________________________________________________
5
t
DP
IN1
OUT1
IN2
OUT2
CH
MAX6818 ONLY
20ms/div
20V
0
-20V
4V
OUT
(2V/div)
IN
(20V/div)
0
t
EN
OUT NORMALLY
LOW
OUT NORMALLY
HIGH
OUT1OUT8
1/2
V
CC
1/2
V
CC
1/2
V
CC
1/2
V
CC
1/2
V
CC
EN
t
PE
t
PD
t
PD
V
OL
+ 0.5V
V
OH
- 0.5V
t
PE
t
PC
OUT1OUT8
CH
Figure 2. Input Characteristics
Figure 3. Switch Input ±25V Fault Tolerance
Figure 4. MAX6818 µP-Interface Timing Diagram
IN1
SW1
SW8
IN8
+V
CC
+V
CC
µ
P
0.1
µ
F
OUT1
OUT8
EN
I/O
IRQ
D0
D7
CH
MAX6818
Figure 5. MAX6818 Typical µP Interfacing Circuit
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