LT6600-20
6
66002fb
PIN FUNCTIONS
IN
–
and IN
+
(Pins 1, 8): Input Pins. Signals can be ap-
plied to either or both input pins through identical external
resistors, R
IN
. The DC gain from differential inputs to the
differential outputs is 402Ω/R
IN
.
V
OCM
(Pin 2): Is the DC Common Mode Reference Voltage-
for the 2nd Filter Stage. Its value programs the common
mode voltage of the differential output of the fi lter. Pin 2 is a
high impedance input, which can be driven from an external
voltage reference, or Pin 2 can be tied to Pin 7 on the PC
board. Pin 2 should be bypassed with a 0.01µF ceramic
capacitor unless it is connected to a ground plane.
V
+
and V
–
(Pins 3, 6): Power Supply Pins. For a single
3.3V or 5V supply (Pin 6 grounded) a quality 0.1µF ceramic
bypass capacitor is required from the positive supply pin
(Pin 3) to the negative supply pin (Pin 6). The bypass
should be as close as possible to the IC. For dual supply
applications, bypass Pin 3 to ground and Pin 6 to ground
with a quality 0.1µF ceramic capacitor.
OUT
+
and OUT
–
(Pins 4, 5): Output Pins. Pins 4 and 5 are
the fi lter differential outputs. Each pin can drive a 100Ω
and/or 50pF load.
V
MID
(Pin 7): The V
MID
pin is internally biased at mid-
supply, see block diagram. For single supply operation,
the V
MID
pin should be bypassed with a quality 0.01µF
ceramic capacitor to Pin 6. For dual supply operation,
Pin 7 can be bypassed or connected to a high quality DC
ground. A ground plane should be used. A poor ground
will increase noise and distortion. Pin 7 sets the output
common mode voltage of the 1st stage of the fi lter. It has
a 5.5kΩ impedance, and it can be overridden with an
external low impedance voltage source.
BLOCK DIAGRAM
–
+
–
+
V
OCM
–
–
+
+
V
OCM
402Ω
402Ω
200Ω
200Ω
200Ω
200Ω
1 2 3 4
V
+
V
–
11k
11k
8 7 6 5
OP AMP
PROPRIETARY
LOWPASS
FILTER STAGE
V
IN
–
V
IN
+
R
IN
R
IN
66002 BD
IN
+
V
OCM V
+
OUT
+
OUT
–
V
–
V
MID
IN
–
