Datasheet
Robust Switch Inputs
The switch inputs on the MAX6816/MAX6817/MAX6818
have overvoltage clamping diodes to protect against
damaging fault conditions. Switch input voltage scan
safely swing ±25V to ground (Figure 3). Proprietary
ESD-protection structures protect against high ESD
encountered in harsh industrial enviroments, membrane
keypads, and portable applications. They are designed to
withstand ±15kV per the IEC 1000-4-2 Air Gap Discharge
Test and ±8kV per the IEC 1000-4-2 Contact Discharge
Test.
Since there are 63kW (typical) pullup resistors
connected to each input, driving an input to -25V draws
approximately 0.5mA (up to 4mA for eight inputs) from the
V
CC
supply. Driving an input to +25V will cause approx-
imately 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 struc-
tures are incorporated on all pins to protect against
electrostatic discharges encountered during handling
and assembly. The MAX6816/MAX6817/MAX6818
have extra protection against static electricity. Maxim’s
engineers have developed state-of-the-art structures to
protect against ESD of ±15kV at the switch inputs without
damage. The ESD structures withstand high ESD in all
states: normal operation, shutdown, and powered
Figure 5. MAX6818 Typical μP Interfacing Circuit
Figure 4. MAX6818 μP-Interface Timing Diagram
Figure 3. Switch Input ±25V Fault Tolerance
Figure 2. Input Characteristics
IN1
SW1
SW8
IN8
+V
CC
+V
CC
µP
0.1µF
OUT1
OUT8
EN I/O
IRQ
D0
D7
CH
MAX6818
t
EN
OUT NORMALLY
LOW
OUT NORMALLY
HIGH
OUT1–OUT8
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
OUT1–OUT8
CH
20ms/div
20V
0V
-20V
4V
OUT
(2V/div)
IN
(20V/div)
0V
t
DP
IN1
OUT1
IN2
OUT2
CH
MAX6818 ONLY
www.maximintegrated.com
Maxim Integrated
│
5
MAX6816/MAX6817/
MAX6818
±15kV ESD-Protected, Single/Dual/Octal,
CMOS Switch Debouncers