AD8509/AD8511
Rev. C | Page 8 of 12
APPLICATIONS
The AD8509 and AD8511 are CMOS buffers with A/B inputs
that are used to select between two different reference voltages set
up by an external resistor ladder. Input bias currents are orders
of magnitude less than competitive parts. This allows very large
resistor ladders to be used to save supply current. A guaranteed
value of 50 nA is much higher than actual values and is limited
by leakage in the test system.
Buffer outputs are designed to drive resistive loads. They are
also stable with capacitive loads, so no resistors should be used
in series with these outputs to attain the best display perform-
ance. Outputs have high slew rates and 6 μs settling times. Each
output can deliver a minimum of 120 mA, assuring fast response
to varying loads.
The AD8509 is a 9-channel buffer and is similar to the LMC6009
in functionality. The AD8511 is an 11-channel buffer similar to
the CL-FP6131. However, the control to select either 9- or
11-channel operation, the EN_11 pin of the CL-FP6131, is not
available on the AD8511. If 9-channel operation is desired, use
the AD8509.
Power supply pins on the AD8509 and AD8511 have multiple
ground and V
CC
connections. Because of the high peak currents
that these buffers can deliver, it is strongly recommended to
connect all of the ground and V
CC
pins, and suitably bypass
the V
CC
pins.
