UG-043
Evaluation Board User Guide
Rev. 0 | Page 4 of 8
In addition, the ground and power planes can be capacitively
linked via C15 to C18 at the user’s option. This can provide plane-
to-plane noise bypassing through several paths to reduce radiated
emissions from the
ADuM5000
power supply.
There are two large screw holes along the top edge of the PCB
that provide connection to the upstream ground plane and the
downstream ground plane. These are provided to allow grounding
of the PCB to the system in multiple configurations. The floating
planes are designed with 0.4 mm of setback to all vias and other
board planes. The PCB should not be used for high voltage testing
if the floating structures are employed for noise reduction. If this
type of structure is required in a final design, it should be built
on an inner layer of the PCB to avoid creepage and clearance issues.
SPEED SELECTION
The
ADuM4160
works at a fixed USB transmission speed, either
low speed or full speed. The speed is set by the SPU and SPD
pins on the upstream and downstream sides of the part and must
be set by jumpers on the evaluation board. Both speed jumpers
must be set to the same speed setting for proper operation.
Table 3. Speed Selection Jumpers
SPU (JP4)
SPD (JP5)
Speed
Short SPU-Full
Short SPD-Full
Full (12 Mbps)
Short SPU-Low
Short SPD-Low
Low (1.5 Mbps)
PULL-UP CONTROL
The PIN pin is provided to allow the control of enumeration and
disconnect by the peripheral. When PIN is logic high, the pull-up
on the upstream side of the ADuM4160 is applied to the data
line appropriate for the USB speed mode. This allows enumeration
and data transmission. When PIN is logic low, the upstream
pull-up is disconnected, making the upstream port behave as
though the port was not present.
This function is provided to allow the peripheral to delay
communication with the host by delaying application of the
upstream pull-up resistor until it is ready to be enumerated on
the bus. If this functionality is not required, then PIN can be
tied to V
DD2
, and the pull-up is applied to the upstream side
when power is applied to both the downstream power supplies.
Control of PIN is provided through Jumper JP6. The PIN input
is pulled high by a 10 kΩ resistor. When a shunt is placed across
JP6, it is pulled low. This provides a default state of high to PIN,
allowing immediate enumeration.
Table 4. PIN Pull-Up Control
PIN (JP5)
Upstream Pull-Up State
Short Disconnected
Open Connected
SERIES RESISTORS
The two USB speeds supported by the ADuM4160 require
different series resistance values at the transceiver terminals.
For full speed operation, Resistor R1 to Resistor R4 should be
populated with 24 Ω, 1% resistors. These are installed in the
base configuration of the evaluation board, and if the board is
operated at full speed, no changes are required.
For low speed operation, R1 to R4 should be replaced by 0 Ω
shunts. If the board is operated at a low speed, it must be modified
from the as-received configuration. The shunt can be an 805-
size SMT device or a simple wire shorting the pads. The resistors
do not significantly affect the low speed performance and may
be left in place for both speed modes, if impedance is not
critical to the evaluation.
TEST POINTS
Positions for eight test points are included on the evaluation board.
No headers are provided in the default configuration. Mounting
holes for a ground signal pair are provided. The holes fit a standard
square-pin spaced at 100 mil or 200 mil on center. This configuration
was chosen to match the dimensions of the Tektronix high frequency
active probes or standard headers. An appropriate scope header
can be obtained by using 3-pin SIP wire wrap header and removing
the center pin. The signal pin can be trimmed to match the spacing
of the probe. If another type of connection is required, wires
can be inserted into the holes provided for these connections.
OPTIONAL COMPONENTS
Options for installing common-mode chokes and external ESD
protection on the DD+/DD− and UD+/UD− data lines are also
available. Positions for TDK ACM3225 chokes are provided at
Position FL1 and Position FL2. Positions for ESD diode packs,
NUP2202 from ON Semiconductor, are provided at Position D1
and Position D2. In addition, pads for surface-mount ferrite
inductors are provided at Position R6 to Position R10. All of
these component positions are either unpopulated or filled
with 0 Ω resistors from Analog Devices. They are on the PCB
as a convenience to the end user.
