AD9901
TTL/CMOS MODE FUNCTIONAL PIN DESCRIPTIONS
ECL MODE FUNCTIONAL PIN DESCRIPTIONS
GROUND
Ground connections for AD9901. Connect
all grounds together and to low impedance
ground plane as close to the device as
possible.
–VS
Negative supply connection, nominally
–5.2 V for ECL operation.
BIAS
Connect to –5.2 V for ECL operation.
VCO INPUT
Inverted side of ECL compatible differential
input, normally connected to the VCO output
signal.
+VS
Positive supply connection; nominally +5.0 V
for TTL operation.
BIAS
Connect to +VS (+5 V) for TTL operation.
VCO INPUT
Noninverted side of ECL-compatible
differential input, normally connected to the
VCO output signal.
VCO INPUT
TTL compatible input; normally connected
to the VCO output signal. VCO INPUT and
REFERENCE INPUT are equivalent to one
another.
OUTPUT
GROUND
The noninverted output. In ECL mode, the
output swing is approximately 0 V to –1.8 V.
OUTPUT
The noninverted output. In TTL/CMOS
mode, the output swing is approximately
+3.2 V to +5 V.
Ground connections for AD9901. Connect
all grounds together and to low-impedance
ground plane as close to the device as
possible.
RSET
External RSET connection. The current
through the RSET resistor is equal to the maxi-
mum full-scale output current. RSET should
be connected to ground through an external
RSET
External RSET connection. The current
through the RSET resistor is equal to the maxi-
mum full-scale output current. RSET should
be connected to –VS through an external
resistor in TTL mode. ISET = 0.47 V/RSET
ILOAD (max).
=
resistor in ECL mode. ISET = 0.47 V/RSET
ILOAD (max).
=
OUTPUT
The inverted output. In TTL/CMOS mode,
the output swing is approximately +3.2 V to
+5 V.
OUTPUT
The inverted output. In ECL mode, the out-
put swing is approximately 0 V to –1.8 V.
REFERENCE
INPUT
TTL compatible input, normally connected
to the reference input signal. The VCO
INPUT and the REFERENCE INPUT are
equivalent.
REFERENCE
INPUT
Noninverted side of ECL-compatible
differential input, normally connected to the
reference input signal. The VCO INPUT and
the REFERENCE INPUT are equivalent to
one another.
REFERENCE
INPUT
Inverted side of ECL-compatible differential
input, normally connected to the reference
input signal. The VCO INPUT and the
REFERENCE INPUT are equivalent.
+V
S
–V
S
R1
R2
R1
REFERENCE
OUTPUT +V
R2
REFERENCE
INPUT
REFERENCE
INPUT
R
S
OUTPUT
SET
–V
S
R
SET
OUTPUT
AD9901
AD9901
REG
REG
BIAS
+V
OUTPUT
R3
VCO
INPUT
+V
S
BIAS
OUTPUT
R3
VCO –V
INPUT
VCO
INPUT
S
S
–V
S
+V
S
Figure 1. TTL Mode (Based on DIP Pinouts)
Figure 2. ECL Mode (Based on DIP Pinouts)
–4–
REV. B