a
Four Channel ECL Delay Line
AD53020
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Four Delay Lines with the Ability to Independently
Adjust All Edges
GND
S0
S1
Pin Compatible and Functionally Equivalent with the
BT624
Reduced Power Dissipation
VWIDTH1
OUT1
AD53020
IN1, IN1
44-Lead PLCC Package with Internal Heat Spreader
OUT1
APPLICATIONS
VDELAY1
VWIDTH2
Automatic Test Equipment
Semiconductor Test Systems
Board Test Systems
OUT2
IN2, IN2
Clocked ECL Circuits
OUT2
DRVMODE
VDELAY2
VWIDTH3
OUT3
IN3, IN3
OUT3
PRODUCT DESCRIPTION
VDELAY3
VWIDTH4
The AD53020 is a four-channel delay line designed for use in
automatic test equipment and digital logic systems. High speed
bipolar transistors and a 44-lead plastic PLCC package with
internal heat spreader provide high frequency performance at a
minimum of space, cost and power dissipation.
OUT4
IN4, IN4
OUT4
VDELAY4
V
EE
Featuring full pin compatibility and functional equivalence to
the BT624, the AD53020 offers independent analog control of
positive and negative edges with five delay ranges. The AD53020
offers attractive performance with optimized power dissipation
and linear delay vs. program voltage control. This device is also
very stable over operating conditions and has very low jitter.
V
COMP1
COMP2
REXT1
REXT2
BB
Digital inputs are ECL compatible. They can either be pro-
vided independently for each channel (IN1, IN1 through IN4,
IN4), or fanned out to all channels from Channel 2 (IN2,
IN2). The choice of these two options is made by setting the
DRVMODE input, with ECL Logic 0 providing four indepen-
dent channels, and ECL Logic 1 enabling a logical OR function
between each channel and the Channel Number 2.
The delay is programmed through the VDELAY and VWIDTH
pins for each channel. The acceptable range is –1.3 V to –0.1 V,
representing the longest and the shortest delays provided by the
device. An 0.01 µF ceramic capacitor to ground is recom-
mended for each input. The bias current for each input is fixed
by an internal current mirror. The value of the bias current is
set by the external resistor at REXT1. A 1.3 kΩ resistor to
ground at this pin establishes 1 mA bias in each input. The
nominal voltage at the REXT1 pin is –1.3 V.
For maximum timing accuracy, differential signals are recom-
mended for use with the digital inputs. However, single-ended
operation is also supported and it is facilitated through the use
of the VBB midpoint level generated on-chip. To make use of
this feature, connect the VBB output to the inverting input of
each channel. It is also advisable, when using the VBB output,
to decouple this signal with a 0.1 µF ceramic capacitor to ground.
The VDELAY affects both the positive and negative edges in all
modes. The VWIDTH is an additional delay adjustment that is
active in Modes 2, 3 and 5. VWIDTH has no effect in Modes 0
and 1. For Modes 2 and 3, the effect of the VWIDTH adjust-
ment is to increase or decrease the delay of the negative edge
relative to the positive edge. In Mode 5, the total delay for both
positive and negative edges is set by the combination of VDELAY
and VWIDTH.
The outputs of the AD53020 are ECL compatible and should
be terminated by 50 Ω to –2.0 V at the inputs of the gates
they drive.
(continued on page 4)
REV. A
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© Analog Devices, Inc., 1999