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PDF ICS9148-12 Data sheet ( Hoja de datos )
| Número de pieza | ICS9148-12 | |
| Descripción | Pentium/ProTM System Clock Chip | |
| Fabricantes | Integrated Circuit Systems | |
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Integrated
Circuit
Systems, Inc.
ICS9148-12
Pentium/ProTM System Clock Chip
General Description
The ICS9148-12 is a Clock Synthesizer chip for Pentium and
PentiumPro CPU based Desktop/Notebook systems that will
provide all necessary clock timing.
Features include four strong CPU, seven PCI and eight
SDRAM clocks. Two reference outputs are available equal to
the crystal frequency. Stronger drive CPUCLK outputs
typically provide greater than 1 V/ns slew rate into 20pF
loads. This device meets rise and fall requirements with 2
loads per CPU output (ie, one clock to CPU and NB chipset,
one clock to two L2 cache inputs).
PWR_DWN# pin allows low power mode by stopping crystal
OSC and PLL stages. For optional power management,
CPU_STOP# can stop CPU (0:3) clocks and PCI_STOP#
will stop PCICLK (0:5) clocks. CPU and IOAPIC output
buffer strength controlled by CPU 3.3_2.5# pin to match
VDDL voltage.
PCICLK outputs typically provide better than 1V/ns slew rate
into 30pF loads while maintaining 50±5% duty cycle. The REF
clock outputs typically provide better than 0.5V/ns slew rates.
The ICS9148-12 accepts a 14.318MHz reference crystal or
clock as its input and runs on a 3.3V core supply.
Block Diagram
Features
CPU outputs are stronger drive for multiple loads per pin
(ie CPU and NB on one pin)
Generates system clocks for CPU, IOAPIC, SDRAM,
PCI, plus 14.314 MHz REF(0:1), USB, Plus Super I/O
Supports single or dual processor systems
I2C serial configuration interface provides output clock
disabling and other functions
MODE input pin selects optional power management
input control pins
Two fixed outputs separately selectable as 24 or 48MHz
Separate 2.5V and 3.3V supply pins
2.5V or 3.3V outputs: CPU, IOAPIC
3.3V outputs: SDRAM, PCI, REF, 48/24 MHz
CPU 3.3_2.5# logic pin to adjust output strength
No power supply sequence requirements
Uses external 14.318MHz crystal
48 pin 300 mil SSOP and 240 mil TSSOP
Output enable register
for serial port control:
1 = enable
0 = disable
Pin Configuration
Pentium is a trademark on Intel Corporation.
9148-12 Rev F 4/1/99
48-Pin SSOP & TSSOP
Functionality
VDD (1:4) 3.3V±10%, VDDL1, 2 2.5±5% or 3.3±10% 0-70°C
Crystal (X1, X2) = 14.31818 MHz
SEL
CPUCLK, SDRAM PCICLK
(MHz)
(MHz)
0 60
30
1 66.6 33.3
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.
1 page  
Technical Pin Function Descriptions
CPU3.3_2.5#
This Input pin controls the CPU and IOAPIC output buffer
strength for skew matching CPU and SDRAM outputs to
compensate for the external VDDL supply condition. It is
important to use this function when selecting power supply
requirements for VDDL1,2. A logic 0 (ground) will indicate
2.5V operation and a logic 1 will indicate 3.3V operation.
This pin has an internal pullup resistor to VDD.
PWR_DWN#
This is an asynchronous active Low Input pin used to Power
Down the device into a Low Power state by not removing the
power supply. The internal Clocks are disabled and the VCO
and Crystal are stopped. Powered Down will also place all
the Outputs in a low state at the end of their current cycle.
The latency of Power Down will not be greater than 3ms. The
I2C inputs will be Tri-Stated and the device will retain all
programming information. This input pin only valid when
MODE=0 (Power Management Mode)
CPU_STOP#
This is a synchronous active Low Input pin used to stop the
CPUCLK clocks in an active low state. All other Clocks
including SDRAM clocks will continue to run while this
function is enabled. The CPUCLKs will have a turn ON
latency of at least 3 CPU clocks. This input pin only valid
when MODE=0 (Power Management Mode)
PCI_STOP#
This is a synchronous active Low Input pin used to stop the
PCICLK clocks in an active low state. It will not effect
PCICLK_F nor any other outputs. This input pin only valid
when MODE=0 (Power Management Mode)
I2C
The SDATA and SCLOCK Inputs are use to program the
device. The clock generator is a slave-receiver device in the
I2C protocol. It will allow read-back of the registers. See
configuration map for register functions. The I2C
specification in Philips I2C Peripherals Data Handbook
(1996) should be followed.
ICS9148-12
5
5 Page 
ICS9148-12
Notes:
1. All timing is referenced to the Internal CPUCLK (defined as inside the ICS9148 device.)
2. PCI_STOP# is an asynchronous input, and metastable conditions may exist. This signal is required to be synchronized
inside the ICS9148.
3. All other clocks continue to run undisturbed.
4. PD# and CPU_STOP# are shown in a high (true) state.
PD# Timing Diagram
The power down selection is used to put the part into a very low power state without turning off the power to the part. PD# is
an asynchronous active low input. This signal is synchronized internal by the ICS9148-12 prior to its control action of
powering down the clock synthesizer. Internal clocks will not be running after the device is put in power down state. When PD#
is active (low) all clocks are driven to a low state and held prior to turning off the VCOs and the Crystal oscillator. The power
on latency is guaranteed to be less than 3mS. The power down latency is less than three CPUCLK cycles. PCI_STOP# and
CPU_STOP# are dont care signals during the power down operations.
Notes:
1. All timing is referenced to the Internal CPUCLK (defined as inside the ICS9148 device).
2. PD# is an asynchronous input and metastable conditions may exist. This signal is synchronized inside the ICS9148.
3. The shaded sections on the VCO and the Crystal signals indicate an active clock is being generated.
11
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