Usb Interface; Can Critical Components; Oem628 Can Transceiver Implementation Schematic - Novatel OEM6 Series User Manual

Figure 65: OEM628 CAN Transceiver Implementation Schematic
OEM628_CAN1RX
P1502, pin 10
OEM628_CAN1TX
P1502, pin 11
R101
22.1K-1%
Only use a 120 Ω termination resistor when the CAN device is used at one end of the CAN bus. Multiple
terminations along the length of the CAN bus will degrade performance for all CAN devices on that bus.
The slew rate adjustment resistor (R101) value in Figure 65 on page 133 sets the slew rate for
applications for SAE J1939 agricultural applications. Other applications may require a different slew rate.
Refer to the transceiver data sheet for more information.
Designator
FB100, FB101
U100
U101
C101, C102
C.1.4

USB Interface

The OEM628 includes one USB 2.0 full speed (12 Mbps) / low speed (1.5 Mbps) interface.
For signal integrity and EMI reasons, route differential data traces as a 90 Ω differential pair. A small
value common mode choke (as shown in the figure below) may improve the radiated emissions
performance. Small ferrite beads are shown on VBUS and UID lines as a contingency against radiated
emissions.
As long as the 90 Ω impedance is maintained while routing the USB D+/D- signals, no matching resistors
are required. The pull resistors for mode selection are part of the USB PHY on the receiver card (no
external pull resistors are required on the data lines to set host or device modes).
There is an ESD protection device on the receiver card for the USB differential pair. An additional device
may be added near the USB connector but care should be taken not to cause a mismatch on the
differential pair—stubs or large capacitance ESD protection should be avoided.
The OEM628_VBUS trace should be capable of handling at least 100 mA. The traces for VBUS and UID
should be routed away from any high current switching nets and high frequency signals. The common
mode choke, ferrite beads and bypass capacitor should be placed as close as possible to the USB
connector.
When the USB interface is used as a device, the UID (pin 14) may be omitted (left as a no connect) and
a standard USB Type-B connector used.
OEM6 Family Installation and Operation User Manual Rev 7
3V3
U100
R100
5.1K-1%
1 3
D VCC
4 5
R VREF
8 7
RS CANH
2 6
GND CANL
TI SN65HVD231
C100
0.1µF
D
D D
Table 26: CAN Critical Components
Manufacturer
TDK
Texas Instruments
Semtech
Bourns
OnSemi
various
FB100
U101
PLC03-6
C101 1
IO1 IO4
22pF
2
GND1 GND4
3
GND2 GND3
D
D 4
IO2 IO3
FB101
C102
22pF
D
Manufacturer Part Number
MMZ1005B800C
SN74LVC1G86DCK
LC03-6.TBT
CDNBS08-PLC03-6
LC03-6R2G
(22 pF 5% 50V COG 0603)
CAN1+
8
120 ohm termination only
required if unit is on the
7 R102
end of the CAN bus
120
6
(not all CAN devices
5
require termination)
D
CAN1-
133