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MC100E196FN View Datasheet(PDF) - Motorola => Freescale

Part Name
Description
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MC100E196FN
Motorola
Motorola => Freescale Motorola
MC100E196FN Datasheet PDF : 7 Pages
1 2 3 4 5 6 7
MC10E196 MC100E196
USING THE FTUNE ANALOG INPUT
The analog FTUNE pin on the E196 device is intended to
enhance the 20 ps resolution capabilities of the fully digital
E195. The level of resolution obtained is dependent on the
number of increments applied to the appropriate range on the
FTUNE pin.
To provide another level of resolution the FTUNE pin must
be capable of adjusting the delay by greater than the 20 ps
digital resolution. From the provided graphs one sees that this
requirement is easily achieved as over the entire FTUNE
voltage range a 100 ps delay can be achieved. This extra
analog range ensures that the FTUNE pin will be capable even
under worst case conditions of covering the digital
resolution.Typically the analog input will be driven by an
external DAC to provide a digital control with very fine analog
output steps. The final resolution of the device will be
dependent on the width of the DAC chosen.
To determine the voltage range necessary for the FTUNE
input, the graphs provided should be used. As an example if a
range of 40 ps is selected to cover worst case conditions and
ensure coverage of the digital range, from the 100E196 graph
a voltage range of –3.25 V to –4.0 V would be necessary on the
FTUNE pin. Obviously there are numerous voltage ranges
which can be used to cover a given delay range, users are
given the flexibility to determine which one best fits their
designs.
Cascading Multiple E196’s
To increase the programmable range of the E195 internal
cascade circuitry has been included. This circuitry allows for
the cascading of multiple E195’s without the need for any
external gating. Furthermore this capability requires only one
more address line per added E195. Obviously cascading
multiple PDC’s will result in a larger programmable range,
however, this increase is at the expense of a longer minimum
delay.
Figure 1 illustrates the interconnect scheme for cascading
two E195’s. As can be seen, this scheme can easily be
expanded for larger E195 chains. The D7 input of the E195 is
the cascade control pin. With the interconnect scheme of
Figure 1 when D7 is asserted it signals the need for a larger
programmable range than is achievable with a single device.
An expansion of the latch section of the block diagram is
pictured below. Use of this diagram will simplify the
explanation of how the cascade circuitry works. When D7 of
chip #1 above is low the cascade output will also be low while
the cascade bar output will be a logical high. In this condition
the SET MIN pin of chip #2 will be asserted and thus all of the
latches of chip #2 will be reset and the device will be set at its
minimum delay. Since the RESET and SET inputs of the
latches are overriding any changes on the A0–A6 address bus
will not affect the operation of chip #2.
Chip #1 on the other hand will have both SET MIN and SET
MAX de-asserted so that its delay will be controlled entirely by
the address bus A0–A6. If the delay needed is greater than
can be achieved with 31.75 gate delays (1111111 on the
A0–A6 address bus) D7 will be asserted to signal the need to
cascade the delay to the next E195 device. When D7 is
asserted the SET MIN pin of chip #2 will be de-asserted and
the delay will be controlled by the A0–A6 address bus. Chip #1
on the other hand will have its SET MAX pin asserted
resulting in the device delay to be independent of the A0–A6
address bus.
When the SET MAX pin of chip #1 is asserted the D0 and D1
latches will be reset while the rest of the latches will be set. In
addition, to maintain monotonicity an additional gate delay is
selected in the cascade circuitry. As a result when D7 of chip
#1 is asserted the delay increases from 31.75 gates to 32
gates. A 32 gate delay is the maximum delay setting for
the E195.
When cascading multiple PDC’s it will prove more cost
effective to use a single E196 for the MSB of the chain while
using E195 for the lower order bits. This is due to the fact that
only one fine tune input is needed to further reduce the delay
step resolution.
A7
INPUT
ADDRESS BUS (A0–A6)
LINEAR
INPUT
D1
FTUNE
D0
E196
LEN
Chip #1
VCC
VEE
VCC0
IN
Q
IN
Q
VBB
VCC0
D1
FTUNE
D0
E196
LEN
Chip #2
VCC
VEE
VCC0
IN
Q
IN
OUTPUT
Q
VBB
VCC0
MOTOROLA
Figure 1. Cascading Interconnect Architecture
2–4
ECLinPS and ECLinPS Lite
DL140 — Rev 4
 

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