LTC6268/LTC6269
19
62689f
For more information www.linear.com/LTC6268
APPLICATIONS INFORMATION
ESD
ESD Protection devices can be seen in the simplified sche-
matic. The
+
IN and –IN pins use a sophisticated method
of ESD protection that incorporates a total of 4 reverse-
biased diodes connected as 2 series diodes to each rail.
To maintain extremely low input bias currents, the center
node of each of these series diode chains is driven by a
buffered copy of the input voltage. This maintains the two
diodes connected directly to the input pins at low reverse
bias, minimizing leakage current of these ESD diodes to
the input pins.
The remaining pins have traditional ESD protection, using
reverse-biased ESD diodes connected to each power supply
rail. Care should be taken to make sure that the voltages
on these pins do not exceed the supply voltages by more
than 100mV or these diodes will begin to conduct large
amounts of current.
Shutdown
The LTC6268S6, LTC6268S8, and LTC6269DD have SHDN
pins that can shut down the amplifier to less than 1.2mA
supply current per amplifier. The SHDN pin voltage needs
to be within 0.75V of V
–
for the amplifier to shut down.
During shutdown, the output will be in a high output re-
sistance state
,
so the LTC6268 is suitable for multiplexer
applications. The internal circuitry is kept in a low current
active state for fast recovery. When left floating, the SHDN
pin is internally pulled up to the positive supply and the
amplifier is enabled.
