DOC#: SP-AP-0065 (Rev. AA) Page 3 of 22
PC EProClock
®
Programmable Technology
PC EProClock
®
is the world’s first non-volatile programmable
PC clock. The PC EProClock
®
technology allows board
designer to promptly achieve optimum compliance and clock
signal integrity; historically, attainable typically through device
and/or board redesigns.
PC EProClock
®
technology can be configured through SMBus
or hard coded.
Features:
- > 4000 bits of configurations
- Can be configured through SMBus or hard coded
- Custom frequency sets
- Differential skew control on true or compliment or both
- Differential duty cycle control on true or compliment or both
- Differential amplitude control
- Differential and single-ended slew rate control
- Program Internal or External series resistor on single-ended
clocks
- Program different spread profiles
- Program different spread modulation rate
Frequency Select Pin FS
Apply the appropriate logic levels to FS inputs before
CKPWRGD assertion to achieve host clock frequency
selection. When the clock chip sampled HIGH on CKPWRGD
and indicates that VTT voltage is stable then FS input values
are sampled. This process employs a one-shot functionality
and once the CKPWRGD sampled a valid HIGH, all other FS,
and CKPWRGD transitions are ignored except in test mode.
Serial Data Interface
To enhance the flexibility and function of the clock synthesizer,
a two-signal serial interface is provided. Through the Serial
Data Interface, various device functions, such as individual
clock output buffers are individually enabled or disabled. The
registers associated with the Serial Data Interface initialize to
their default setting at power-up. The use of this interface is
optional. Clock device register changes are normally made at
system initialization, if any are required. The interface cannot
be used during system operation for power management
functions.
Data Protocol
The clock driver serial protocol accepts byte write, byte read,
block write, and block read operations from the controller. For
block write/read operation, access the bytes in sequential
order from lowest to highest (most significant bit first) with the
ability to stop after any complete byte is transferred. For byte
write and byte read operations, the system controller can
access individually indexed bytes. The offset of the indexed
byte is encoded in the command code described in Table 1.
The block write and block read protocol is outlined in Table 2
while Table 3 outlines byte write and byte read protocol. The
slave receiver address is 11010010 (D2h).
.
Frequency Select Pin (FS)
FS CPU Power On SRC SATA DOT96 USB_48 27MHz REF
0 133MHz Default
100MHz 100MHz 96MHz 48MHz 27MHz 14.318MHz
1 100MHz
Table 1. Command Code Definition
Bit Description
7 0 = Block read or block write operation, 1 = Byte read or byte write operation
(6:0) Byte offset for byte read or byte write operation. For block read or block write operations, these bits should be '0000000'
Table 2. Block Read and Block Write Protocol
Block Write Protocol Block Read Protocol
Bit Description Bit Description
1Start 1Start
8:2 Slave address–7 bits 8:2 Slave address–7 bits
9 Write 9 Write
10 Acknowledge from slave 10 Acknowledge from slave
18:11 Command Code–8 bits 18:11 Command Code–8 bits
19 Acknowledge from slave 19 Acknowledge from slave
27:20 Byte Count–8 bits 20 Repeat start
28 Acknowledge from slave 27:21 Slave address–7 bits
