+/+…when timing is critical
C9819
133 MHz I2C Clock Generator for Mobile Pentium®III / Rambus Systems
Preliminary
Power Management Timing
Tss
Tss
PCI_F
PCI_STP
PCI(0:6)
CPU_STP
CPU
Fig. 4
Tss is the stop clock setup time. All functionality is referenced to the rising edge of PCI_F. If the tss timing is met, with
respect to the next occurring PCI_F low to high transition, then the CPU or PCI clocks that are controlled are guaranteed
to stay low (stopped) or to rise (run) at the next rising edge of PCI_F. See the AC parameters for tss time.
Power Management Function Table
CPU_stp#
PWRDN#
PCI_stp
#
CPU
CPU/2
3V66(0:2)
PCI(0:6)
PCI_F
48M /
REF(0:2)
IOAPIC(0:1)
PLL1
PLL2
x
0
0
1
1
0
1
1
1
1
x
0
1
0
1
0
0
0
run
run
0
0
0
0
run
0
0
0
0
off
off
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
run
Table 2
2-Wire I2C Control Interface
The 2-wire control interface implements a write slave only interface according to Philips I2C specification. (see fig5). The
device cannot be read back. Sub-addressing is not supported, thus all preceding bytes must be sent in order to change
one of the control bytes. The 2-wire control interface allows each clock output to be individually enabled or disabled. 100
Kbits/second (standard mode) data transfer is supported.
During normal data transfer, the SDATA signal only changes when the SCLK signal is low, and is stable when SCLK is
high. There are two exceptions to this. A high to low transition on SDATA while SCLK is high is used to indicate the
start of a data transfer cycle. A low to high transition on SDATA while SCLK is high indicates the end of a data transfer
cycle. Data is always sent as complete 8-bit bytes, after which an acknowledge is generated. The first byte of a transfer
cycle is a 7-bit address with a Read/Write bit (R/W#) as the LSB. R/W# = 1 in read mode .
The device will respond to writes to 10 bytes (max) of data to address D2 by generating the acknowledge (low) signal on
the SDATA wire following reception of each byte.
INTERNATIONAL MICROCIRCUITS, INC 525 LOS COCHES ST.
MILPITAS, CA 95035, USA TEL: 408-263-6300 FAX 408-263-6571
Rev 1.0
11/1/1999
Page 5 of 17
http://www.imicorp.com
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