ics9248-153 Integrated Device Technology, ics9248-153 Datasheet - Page 10
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ics9248-153
Manufacturer Part Number
ics9248-153
Description
Amd-k7 System Clock Chip
Manufacturer
Integrated Device Technology
Datasheet
1.ICS9248-153.pdf
(14 pages)
Third party brands and names are the property of their respective owners.
The I/O pins designated by (input/output) on the ICS9248-
153 serve as dual signal functions to the device. During initial
power-up, they act as input pins. The logic level (voltage)
that is present on these pins at this time is read and stored
into a 5-bit internal data latch. At the end of Power-On reset,
(see AC characteristics for timing values), the device changes
the mode of operations for these pins to an output function.
In this mode the pins produce the specified buffered clocks
to external loads.
To program (load) the internal configuration register for these
pins, a resistor is connected to either the VDD (logic 1) power
supply or the GND (logic 0) voltage potential. A 10 Kilohm
(10K) resistor is used to provide both the solid CMOS
programming voltage needed during the power-up
programming period and to provide an insignificant load on
the output clock during the subsequent operating period.
Shared Pin Operation -
Input/Output Pins
ICS9248-153
Device
Pad
Programming
Header
Via to Gnd
Series Term. Res.
Fig. 1
10
Figure 1 shows a means of implementing this function when
a switch or 2 pin header is used. With no jumper is installed
the pin will be pulled high. With the jumper in place the pin
will be pulled low. If programmability is not necessary, than
only a single resistor is necessary. The programming resistors
should be located close to the series termination resistor to
minimize the current loop area. It is more important to locate
the series termination resistor close to the driver than the
programming resistor.
8.2K
2K
Clock trace to load
Via to
VDD