S1K50000 Epson Electronics America, Inc., S1K50000 Datasheet - Page 100

• Manufacturer Part Number: S1K50000
• Description: Design Guide S1k50000 Series
• Manufacturer: Epson Electronics America, Inc.

STANDARD CELL S1K50000 SERIES
DESIGN GUIDE
(5) Pull-up/pull-down resistor inputs
a) Place the pull-up/pull-down resistors as far from the fast input-signal pins (e.g., clock input
b) Place the pull-up/pull-down resistors so that they are separated from the output-signal pins
Pull-up/pull-down resistors have rather large resistance values ranging from several 10
kohms to several 100 kohms and, due to their structure, they are dependent on the power-
supply voltage.
If these resistors are used, for example, as test pins while being left open, they tend to be
affected easily by power-supply noise and the like to become a cause of malfunction.
Therefore, observe the following precautions when placing these resistors:
pin) as possible (Figure 8-5).
(particularly large-current output pins) (Figure 8-6).
In addition to the above pin-placement precautions, also take the following into account:
• Apply pull-up/pull-down processing to the board (PCB) as much as possible.
• Choose pull-up/pull-down resistors with resistance values as small as possible.
Figure 8-5 Example of the Placement of Pull-Up/Pull-Down Pins – 1
Figure 8-6 Example of the Placement of Pull-Up/Pull-Down Pins – 2
Figure 8-4 Example of the Placement of Critical Signal Pins – 2
PULL DOWN
CLK
OSCOUT
OSCIN
V
V
V
DD
SS
SS
EPSON
output
Chapter 8: Pin Arrangement and Simultaneous Operation
PULL UP
High drive
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