S1K50000 Epson Electronics America, Inc., S1K50000 Datasheet - Page 101

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

Chapter 8: Pin Arrangement and Simultaneous Operation
96
(6) Simultaneous change in outputs
(7) Large-current drivers
a) Restrictions on power-supply enhancement
If multiple pins change state simultaneously, they generate noise, causing the LSI to
operate erratically. If it is necessary to operate a large number of output pins
simultaneously, add power-supply pins to a group of output pins that change state
simultaneously in order to prevent such a noise-induced malfunction. For details on the
number of power-supply pins to add, as well as the placement method for those additional
power-supply pins, see Section 8.2, “Simultaneously Operating Buffers and Added Power
Supply.”
One method of reducing said noise is to insert a cell that causes a delay in front of one
group of output cells. This helps to reduce the number of output pins that change state
simultaneously and therefore the noise generated by a simultaneous change in state
(Figure 8-8).
When using the output of large-current drivers (I
restrictions described below in the placement of these pins.
Because large-current drivers have a large drive capability, the amount of noise generated
by the output buffers when they operate is also large. This noise may cause the LSI to
operate erratically.
When using large-current drivers, place power-supply pins near their pins to secure the
power supply needed for such drivers (Figure 8-9).
Figure 8-7 Example of the Addition of Power-Supply Pins
Figure 8-8 Example of the Addition of a Delay Cell
Simultaneously changing output pins
DL1
XOB3T
XOB3T
A
TA
TS
A
TA
TS
EPSON
OL
= 12 mA, 24 mA, PCI), observe the
OUT1
OUT2
STANDARD CELL S1K50000 SERIES
DESIGN GUIDE