SEMICONDUCTOR TECHNICAL DATA
4–1
REV 2
Motorola, Inc. 1996
3/96
÷
÷
The MC100LVEL39 is a low skew ÷2/4, ÷4/6 clock generation chip
designed explicitly for low skew clock generation applications. The
MC100EL39 is pin and functionally equivalent to the MC100LVEL39 but
is specified for operation at the standard 100K ECL voltage supply. The
internal dividers are synchronous to each other, therefore, the common
output edges are all precisely aligned. The device can be driven by either
a differential or single-ended LVECL or, if positive power supplies are
used, LVPECL input signal. In addition, by using the VBB output, a
sinusoidal source can be AC coupled into the device (see Interfacing
section of the ECLinPS Data Book DL140/D). If a single-ended input is
to be used, the VBB output should be connected to the CLK
input and
bypassed to ground via a 0.01µF capacitor. The VBB output is designed to
act as the switching reference for the input of the LVEL39 under
single-ended input conditions, as a result, this pin can only source/sink up
to 0.5mA of current.
The common enable (EN) is synchronous so that the internal dividers
will only be enabled/disabled when the internal clock is already in the
LOW state. This avoids any chance of generating a runt clock pulse on
the internal clock when the device is enabled/disabled as can happen
with an asynchronous control. An internal runt pulse could lead to losing
synchronization between the internal divider stages. The internal enable
flip-flop is clocked on the falling edge of the input clock, therefore, all
associated specification limits are referenced to the negative edge of the
clock input.
Upon startup, the internal flip-flops will attain a random state; therefore,
for systems which utilize multiple LVEL39s, the master reset (MR) input
must be asserted to ensure synchronization. For systems which only use
one LVEL39, the MR pin need not be exercised as the internal divider
design ensures synchronization between the ÷2/4 and the ÷4/6 outputs of
a single device.
• 50ps Output-to-Output Skew
• Synchronous Enable/Disable
• Master Reset for Synchronization
• 75kΩ Internal Input Pulldown Resistors
• >2000V ESD Protection
• Low Voltage V
EE
Range of –3.0 to –3.8V
CLK
Pinout: 20-Lead SOIC (Top View)
CLK MR V
CC
1718 16 15 14 13 12
43
5 6 7 8 9
Q0
11
10
Q1 Q1 Q2 Q2 Q3 Q3 V
EE
EN
1920
21
VCCQ0
DIVSELb V
BB
V
CC
NC DIVSELa
DW SUFFIX
PLASTIC SOIC PACKAGE
CASE 751D-04
1
20
PIN FUNCTION
CLK Diff Clock Inputs
EN
Sync Enable
MR Master Reset
V
BB
Reference Output
Q0, Q
1
Diff ÷2/4 Outputs
Q2, Q
3
Diff ÷4/6 Outputs
DIVSEL Frequency Select Input
PIN DESCRIPTION
CLK
Z
ZZ
X
EN
L
H
X
MR
L
L
H
FUNCTION
Divide
Hold Q
0–3
Reset Q
0–3
FUNCTION TABLE
Z = Low-to-High Transition
ZZ = High-to-Low Transition
DIVSELa Q0, Q1 OUTPUTS
0 Divide by 2
1 Divide by 4
DIVSELb Q2, Q3 OUTPUTS
0 Divide by 4
1 Divide by 6