21154BC Intel, 21154BC Datasheet - Page 18

• Manufacturer Part Number: 21154BC
• Manufacturer: Intel

Specifications of 21154BC

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 70C
• Package Type: BGA
• Rad Hardened: No
• Lead Free Status / Rohs Status: Not Compliant

Errata
Figure 1.
18Intel Confidential
S_Clock Multiplexer Workaround Circuit for Errata 6.
2. In the second recommendation, to guarantee the proper initialization of the s_clk circuits, the
addition of an external circuit that provides a minimum of two transitions on the s_clk input
during the power-up ramp is necessary. This can be done using a solution that drives an
external clock onto the s_clk input while 3.3V Vcc is ramping during power up.
Figure 2
The Vcc ramp rate and R1,C1 time constant determine the duration and amplitude of the
pulses generated during power up. The R2-R3 values are chosen based on applicable board
etch impedance-matching requirements.
Note:The NC7SB3157 2:1 Multiplexer / Demultiplexer Bus Switch used in this example has a
.02 uF
maximum propagation delay of 800ps that should be taken into consideration when
matching trace lengths of the clock lines to avoid introducing excessive skew in the
clocks. All S_Clock etch lengths must be matched to within 2ns @ 33Mhx or 1ns
@66Mhz. The addition of this circuit requires that the etch length for the S_clock_in
signal be reduced to compensate for the 800ps delay.
illustrates the use of a tristable buffer to provide multiple pulses to the s_clk input.
C1
R1
47K
R3
68K
B0
B1
S
A
S_Clk_in
NC7SB3157
21154 PCI-to-PCI Bridge Specification Update
21154
33
R2
S_Clk_out
A9661-01