LTC6403-1
9
64031fa
PIN FUNCTIONS
V
OCM
(Pin 4): Output Common Mode Reference Voltage.
The voltage on V
OCM
sets the output common mode voltage
level (which is defi ned as the average of the voltages on
the +OUT and –OUT pins). The V
OCM
pin is the midpoint
of an internal resistive voltage divider between V
+
and
V
–
that develops a (default) mid-supply voltage potential
to maximize output signal swing. The V
OCM
pin can be
overdriven by an external voltage reference capable of
driving the input impedance presented by the V
OCM
pin.
On the LTC6403-1, the V
OCM
pin has an input resistance
of approximately 23k to a mid-supply potential. The V
OCM
pin should be bypassed with a high quality ceramic bypass
capacitor of at least 0.01μF, (unless you are using split
supplies, then connect directly to a low impedance, low
noise ground plane) to minimize common mode noise
from being converted to differential noise by impedance
mismatches both external and internal to the IC.
NC (Pins 5, 16): No Connection. These pins are not con-
nected internally.
+OUT, –OUT (Pins 7, 14): Unfi ltered Output Pins. Each
amplifi er output is designed to drive a load capacitance of
10pF. This means the amplifi er can drive 10pF from each
output to ground or 5pF differentially. Larger capacitive
loads should be decoupled with at least 25Ω resistors
from each output.
+OUTF, –OUTF (Pins 8, 13): Filtered Output Pins. These
pins have a series 100Ω resistor connected between the
fi ltered and unfi ltered outputs and three 12pF capacitors.
Both +OUTF, and –OUTF have 12pF to V
–
, plus an additional
12pF differentially between +OUTF and –OUTF. This fi lter
creates a differential lowpass pole with a –3dB bandwidth
of 44.2MHz.
+IN, –IN (Pins 15, 6): Noninverting and Inverting Input
pins of the amplifi er, respectively. For best performance,
it is highly recommended that stray capacitance be kept
to an absolute minimum by keeping printed circuit con-
nections as short as possible and stripping back nearby
surrounding ground plane away from these pins.
Exposed Pad (Pin 17): Tie the pad to V
–
(Pins 3, 9, and 12).
If split supplies are used, do not tie the pad to ground.
BLOCK DIAGRAM
–
+
1
5
NC
6
–IN
7
+OUT
8
+OUTF
16
NC
15
+IN
14
–OUT
13
–OUTF
2
V
+
3
V
–
V
+
V
+
V
+
V
+
V
+
V
–
V
–
V
+
V
+
100Ω
12pF
12pF
12pF
66k
V
–
4
V
OCM
V
OCM
12
V
–
64031 BD
11
V
+
10
V
+
9
V
–
100Ω
46k
V
–
V
–
V
+
V
–
V
+
V
–
V
+
V
–
V
+
V
–
V
+
V
–
V
–
V
–
46k
SHDN
