ICST ICS9169CM-231, ICS9169CF-231, ICS9169CF-232 Datasheet

Integrated
Circuit

ICS9169C-231

Systems, Inc.

Frequency Generator for Pentium™ Based Systems

General Description Features

The ICS9169C-231 is a low-cost frequency generator
designed specifically for Pentium and Pentium-Pro based
chip set systems. The integrated buffer minimizes skew
and provides all the clocks required. A 14.318 MHz XTAL
oscillator provides the reference clock to generate standard
Pentium frequencies. The CPU clock makes gradual
frequency transitions without violating the PLL timing of
internal microprocessor clock multipliers. A raised
frequency setting of 68.5 MHz is available for Turbo-mode
of the 66.8 MHz CPU. The ICS9169C-231 contains 8 CPU
clocks, 6 PCI clocks, 1 REF at 48MHz and 1 at 24MHz.

Either synchronous (CPU/2) or asynchronous (32 MHz)
PCI bus operation can be selected by latching data on
BSEL input.

• Eight selectable CPU clocks operate up to 83.3 MHz

• Frequency selections include Turbo-mode speed of

68.5 MHz

• Maximum CPU jitter of ±200ps

• Six BUS clocks support sync or async bus operation

• 250ps skew window for CPU outputs, 500ps skew
window for BUS outputs

• CPU clocks to BUS clocks skew 1-4 ns (CPU early)

• 48 MHz clock for USB support & 24 MHz clock for FD.

• Logic inputs latched at Power-On for frequency
selection saving pins as Input/Output

• Integrated buffer outputs drive up to 30pF loads

• 3.0V - 3.7V supply range, CPU (1:8) outputs 2.5V
(2.375 - 2.6V) VDD option

• 28-pin SOIC or SSOP package

Block Diagram

VDD Groups:

VDD1 = X1, X2, REF/BSEL
VDD2 = CPU1-6
VDD3 = CPU7-8 & PLL Core
VDD4 = BUS1-6
VDD5 = 48/24 MHz

Latched Inputs:

L1 = BSEL
L2 = FS0
L3 = FS1
L4 = FS2

Pin Configuration

28-Pin SOIC or SSOP

Functionality

3.3V±10%, 0-70°C
Crystal (X1, X2) = 14.31818 MHz

ADDRESS

SELECT

FS2 FS1 FS0 BSEL=1 BSEL=0

0005025324824REF
0016030324824REF
0 1 0 66. 8 33. 4 32 4 8 24 RE F
01 1 75.9 32 32 48 24REF
10 0 55 27.5 32 48 24REF
1 0 1 75. 9 37. 5 32 4 8 24 RE F
1 1 0 83. 3 41. 7 32 4 8 24 RE F
1 1 1 68.5 34.25 32 48 24 REF

CPU(1:8)

(MHz)

BUS (1:6)MHz

48MHz 24MHz REF

Pentium is a trademark of Intel Corporation.

9169C-231RevB040697P

ICS reserves the right to make changes in the device data identified in this publication
without further notice. ICS advises its customers to obtain the latest version of all
device data to verify that any information being relied upon by the customer is current
and accurate.

ICS169C-231

Pin Descriptions

PIN NUMBER PIN NAME TYPE DESCRIPTION

1 VDD1 PWR

2X1 IN

3 X2 OUT

4,11,16,22 GND PWR Ground for control logic.

6,7,9,10,15 CPU(2,3,4,5,8) OUT

5,12,13

5,12,13 FS (0:2) IN

8 VDD2 PWR

14 VDD3 PWR

17,18,20,21,23, 24 BUS(1:6) OUT

19 VDD4 PWR Power for BUS clock buffers BUS (1:6)
25 VDD5 PWR Power for fixed clock buffer (48 MHz, 24 MHz)
26 24 MHz OUT Fixed 24 MHz clock (assuming a 14.31818 MHz REF frequency).
27 48 MHz OUT Fixed 48 MHz clock (assuming a 14.31818 MHz REF frequency).

28

CPU1, CPU6,
CPU7

REF OUT Fixed 14.31818 MHz clock (assuming a 14.31818 MHz REF frequency).

BSEL IN

OUT

Power for control logic and crystal oscillator circuit and

14.318 MHz output
XTAL or external reference frequency input. This input includes XTAL

load capacitance and feedback bias for a 12-16MHz crystal, nominally

14.31818mhz. External crystal load of 30pF to GND recommended for
VDD power on faster than 2.0ms.

XTAL output drive from device. XTAL output which includes XTAL load
capacitance. External crystal load of 10pF to GND recommended for VDD
power on faster than 2.0ms.

Processor clock outputs which are a multiple of the input reference clock
as shown in the preceding table.

Processor clock outputs which are a multiple of the input reference clock
as shown in the preceding table.

Frequency multiplier select pins. See shared pin programming description
later in this data sheet for further explanation. 350K* internal pull up.

Power for CPU (1:6) clock buffers only. This VDD supply can be reduced
to 2.5V for CPU (1:6) outputs.

Power for CPU (7:8) clock buffers and internal PLL and Core logic. Must
be nominal 3.3V (3.0 to 3.7V)

BUS clock outputs which are a multiple of the input reference clock as
shown in the preceding table.

Selection for synchronous or asynchronous bus clock operation. 350K*
internal pull up.

* The internal pull up will vary from 350K to 500K based on temperature

2

ICS169C-231

Shared Pin Operation ­Input/Output Pins

Shared Pin Operation - Input/Output, Pins 5, 28, 12 and
13 on the ICS9169C-231 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 4-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.

Figs. 1 and 2 show the recommended means of
implementing this function. In Fig. 1 either one of the
resistors is loaded onto the board (selective stuffing) to
configure the de vice’s internal logic. Figs. 2a and b provide
a single resistor loading option where either solder spot
tabs or a physical jumper header may be used.

Test Mode Operation

The ICS9169C-231 includes a production test verification
mode of operation. This requires that the FS0 and FS1 pins
be programmed to a logic high and the FS2 pin be
programmed to a logic low(see Shared Pin Operation
section). In this mode the device will output the following
frequencies.

Pin Frequency

REF REF
48MHz REF/2
24MHz REF/4

CPU (1:8) REF2

BUS (1:6)

Note: REF is the frequency of either the crystal connected
between the devices X1and X2 or, in the case of a device
being driven by an external reference clock, the frequency
of the reference (or test) clock on the device’s X1 pin.

BSEL=1 REF/4
BESEL = 0 REF/3

These figures illustrate the optimal PCB physical layout
options. These configuration resistors are of such a large
ohmic value that they do not effect the low impedance
clock signals. The layouts have been optimized to provide
as little impedance transition to the clock signal as possible,
as it passes through the programming resistor pad(s).

Fig. 1

3