MB2100-01A-E Single Port Embedded Emulator Debugger SPEED-BOX Operation Guide, Doc. # 002-05542 Rev. *A
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User System Board Design Guidelines
Table 4-1 shows all of the rules.
If a scheme other than as recommended is used for the connection specifications, the signal quality
will degrade slightly. Care is needed because this also has an effect on noise immunity.
Table 4-1. User system circuit board design rules
Item
Applies to
Description
Importance
1
CN selection 1
Cypress recommended coaxial connector
Recommended
2
CN selection 2
■
Connector for signal applications as suitable for a 50MHz
logic signal interface, current capacity of 25mA or more
■
When using a multi-pin composite connector, arrange
the MDI (or DEBUG I/F) pin and GND pin next to each
other, and locate the MDI (or DEBUG I/F) pin as far away
from other high-speed or high current signal pins as pos-
sible.
Mandatory
3
R0 selection
■
The resistance value specified in the MCU ratings (the
output impedance becomes 50
when the MCU is out-
putting L).
■
Pw (permissible power dissipation) = 0.1W or more. Typ-
ically,
R0 = 43
± 5%
Mandatory
4
R1 selection
10k
± 5%, Pw = 0.1W or more
Mandatory
5
Dz selection and
placement
■
ESD protection Zener diode for high-speed signal lines
with capacitance of 5pF or less and Zener voltage of
0.1V + MDI bus maximum voltage or more.
■
Locate next to the CN.
Recommended
6
R0, Dz wiring
Keep as short as possible.
Mandatory
7
GND wiring
■
Keep the impedance between the MCU and CN as small
as possible.
■
Connect directly to the GND layer on multi-layer PCBs
that have a GND layer.
Mandatory
8
L1 wiring length
Make as short as possible, and keep less than 5cm.
Mandatory
9
L2 wiring length
■
When item 1 is applicable, less than 15cm
■
When item 1 is not applicable, the total combined dis-
tance from R0 to the coaxial cable impedance change
point is 15cm or less
Mandatory
10
L2 characteristic
impedance
50
Recommended
11
L1 and L2 via
holes
Two locations or less in each wiring path (excluding ends)
Mandatory
12
L1 and L2 noise
protection 1
Surround both ends of the signal line with GND pattern.
Recommended
13
L1 and L2 noise
protection 2
Avoid running parallel with other signal lines as much as possible.
In areas that run parallel, create as large a gap as possible to fully
reduce cross-talk from the parallel signal.
Mandatory
