Intel IXP2800 and IXP2850 Network Processors
Electrical Specifications
118
Datasheet
Table 59. Slowport Write AC Parameters 1
1. These timing parameters are specified for a 1.4 GHz core frequency and from the rising edge of SP_CLK. Guaranteed by
functional test.
External Signals
tco l
max2/min (ns)
2. The default output timing is controlled by the TXE register. Refer to the Intel IXP2400 and IXP2800 Programmer’s Reference
Manual for further details. By default, this register is set to a value of 0x1. For each increment to this register, a PCLK period
delay is added to both the maximum and minimum specified values. For example, for a PCLK frequency of 700 MHz, a period
delay is ~ 1.4 ns; using a TXE register value of 0x5, the maximum and minimum delay values would be calculated as follows:
Max = 9.0 + (5- 1) * 1.4 = 14.6 ns.
Min = 1.5 + (5 - 1) * 1.4 = 7.1 ns.
Note: this delay should not exceed the cycle time of SP_CLK.
th3 (ns) min
3. The sampling of the SP_ACK_L signal is controlled by the RXE register. Refer to the Intel IXP2400 and IXP2800 Program-
mer’s Reference Manual for further details. By default, this register is set to a value of 0x1. For each increment to this register,
a PCLK period delay is added to the setup and is subtracted from the hold specified values. For example, for a PCLK frequen-
cy of 700 MHz, a period delay is ~ 1.4 ns; using an RXE register value of 0x5, the setup and hold delay values would be cal-
culated as follows:
Setup = 12.2 + (5-1) * 1.4 = 17.8 ns.
Hold = 1.0 - (5-1) * 1.4 = - 4.6 ns.
Note: this delay should not exceed the cycle time of SP_CLK.
min
tpw (ns)
Loading
(pF)
SP_ALE
9.0/1.5
50
SP_CS[0]
9.0/1.5
50
SP_CS[1]
9.0/1.5
50
SP_WR
9.0/1.5
50
SP_ACK
1
12.2
SP_AD[1:0]
9.0/1.5
50
SP_AD[7:0]
output to external device
9.0/1.5
Figure 21. Read Transaction for Self-Timing Device
B2866-02
SP_ALE_L
SP_WR_L
SP_RD_L
SP_A[1:0]
02
46
8
10
12
14
16
18
20
SP_CLK
9:2
17:
10
24:
18
SP_CS_L
[1:0]
SP_AD[7:0]
SP_ACK_L
tdoz
tco
9:2
D[7:0]
17:
10
24:
18
tsu
th
tdzo
tco
th
tco
th
tco
tsu