Neoway N720 OpenLinux - Usim; Figure 3-15 Reference Design of USIM Card Interface

N720 OpenLinux
Hardware User Guide
Copyright © Neoway Technology Co., Ltd
26

Pull USB_ID low before supplying power for USB_VBUS.
PCB Design Guidelines

Place filer capacitors on the USB_VBUS line as close to the pin of the module as possible and
the ESD component as close to the USB connector as possible.

Place the ESD triodes on USB_DP and USB_DM lines as close to the USB connector as
possible.

USB_DM and USB_DP traces should be routed in differential mode, and the differential
impedance of the transmission line is 90Ω.

Isolate USB traces from traces of other signals by connecting their grounds to main ground.
3.3.3 USIM
Signal
Pin
I/O
Function
Remarks
USIM1_VCC
35
PO
USIM1 power output
Compatible with 1.8V/3V UIM card
USIM1_DATA
36
B
USIM data IO
A 10 kΩ resistor is required between
USIM1_VCC and USIM1_DATA.
USIM1_CLK
37
DO
USIM1 clock output
USIM1_RESET
38
DO
USIM1 reset
USIM1_DET
39
DI
USIM1 detect
A pull-up resistor is recommended
N720 OpenLinux provides one USIM1 interface by default. USIM2 interface is a multiplex function of
Ethernet interface and compatible with 1.8V/2.85V USIM card. For details, see Section 3.7 MUX
Interfaces. Figure 3-15 shows the reference design of the USIM card interface.
Figure 3-15 Reference design of USIM card interface
1uF
CLK
RST
VCC
VPP
GND
USIM card
DATA
GND
USIM-DET
20Ω
47kΩ
VDD_1P8
USIM_DATA
USIM_CLK
USIM_RESET
USIM_VCC
USIM_DET
N720 module
20Ω
20Ω
20Ω
10kΩ
R1
R2
R3
R4
R5
R6
C1
ESD1 ESD2
ESD3 ESD4 ESD5