Digilent 410-308P - Manual (Page 13)

JTAG-SMT2-NC Reference Manual
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Page 13 of 14
AC Operating Characteristics
The JTAG-SMT2-NC’s JTAG signals operate according to the timing diagram in Fig. 12. The SMT2-NC supports
JTAG/TCK frequencies from 30 MHz to 8 KHz at integer divisions of 30 MHz from 1 to 3750. Common frequencies
include 30 MHz, 15 MHz, 10 Mhz, 7.5 MHz, and 6 MHz (see Table 2). The JTAG/TCK operating frequency can be set
within the Xilinx tools.
Note: Please refer to Xilinx’s iMPACT documentation for more information.
TMS/TDI
TCK
TDO
T
CKL
T
CKH
T
CK
T
CD
T
SU
T
HD
Mounting to Host PCBs
The JTAG-SMT2-NC module has a moisture sensitivity level (MSL) of 6. Prior to reflow, the JTAG-SMT2-NC module
must be dried by baking it at 125° C for 17 hours. Once this process has been completed, the module has a MSL of
3 and is suitable for reflow for up to 168 hours without additional drying.
The factory finishes the JTAG-SMT2-NC signal pads with the ENIG process using 2u” gold over 150u” electroless
nickel. This makes the SMT2-NC compatible with most mounting and reflow processes (see Fig. 13). The binding
force of the solder is sufficient to hold the SMT2-NC firmly in place so mounting should require no additional
adhesives.
Symbol Parameter Min Max
T
CK
T
CK
period 33ns 2.185ms
T
CKH
, T
CKL
T
CLK
pulse width 20ns 1.1ms
T
CD
T
CLK
to TMS, TDI 0 15ns
T
SU
TDO Setup time 19ns
T
HD
TDO Hold time 0
Figure 12. Timing diagram. Table 2. JTAG frequency support.
Figure 13. JTAG-SMT2-NC reflow temperature over time.