Timing Diagram For Sed Operation; Sed Run Time - Lattice Semiconductor MachXO2 Series Usage Manual

Timing Diagram for SED Operation

Figure 5. Timing Diagram for SED Operation
SEDENABLE
t
EN_MIN
SEDSTART
SEDINPROG
SEDFRCERR
SEDERR
SEDDONE
Where:

SED Run Time

The amount of time needed to perform an SED check depends on the density of the device and the frequency of
the SED Clock Driver signal. There will also be some overhead time for calculation, but it is fairly short in compari-
son. An approximation of the time required can be found by using the following formula:
(Maxbits / 8) / SED Clock Driver Frequency = Time (ms)
Maxbits is in kbits and depends on the density of the PLD (see Table 4). The SED Clock Driver signal frequency is
shown in MHz. Time is in milliseconds. The SED checking in the MachXO2 device reads 8 bits (1 byte) on each
SED clock cycle.
For example, for a design using a MachXO2 with 4,000 look-up tables and an SED Clock Driver frequency of 7
MHz:
(972 kbits / 8) / 7.0 MHz = 17.4 ms
In this example, SED checking will take approximately 17.4 ms.
Note that the internal oscillator is used to generate the SED Clock Driver signal and its frequency can vary by
±5.5%.
t
IPDEL
t
FEHOLD_MIN
Parameter
t
EN_MIN
t
IPDEL
t
FEHOLD_MIN
t
FESETUP_MIN
t
FE_MIN
t
ERROUT
t
ST_HMIN
t
ST_LMIN
t
OUT_CLR
t
DONE_SET
t
INPROG_TYP
t
FESETUP_MIN
t
FE_MIN
Value Units
0 SEDCLK
2 SEDCLK
92 SEDCLK
5 SEDCLK
2 SEDCLK
1 SEDCLK
0 SEDCLK
1 SEDCLK
2 SEDCLK
0 SEDCLK
7
MachXO2 SED Usage Guide
t t
ST_HMIN ST_LMIN
t t
ERROUT OUT_CLR
t
DONE_SET