MeiG
Product
Manual
of
SLM750
Module
SLM750
Module
Hardware
Design
Page 42, total 84 pages
In order to enhance the reliability and availability of the USIM card in your application, please
follow the criteria below in the USIM circuit design:
USIM_DATA requires a pull-up resistor of 15k
Ω
to USIM_VCC; the pull-up resistor helps to
increase SIM card's anti-interference ability. When USIM card trace is too long or it is close to
the interference source, it is recommended that you add a pull-up resistor near the card.
In order to suppress stray EMI and enhance ESD protection, it is recommended to connect a
resistance of 22
Ω
on USIM_DATA, USIM_CLK and USIM_RST line.
In order to improve the antistatic ability and offer good ESD protection, it is recommended to
add TVS whose parasitic capacitance should be less than 15pF on USIM_VDD, USIM_DATA,
USIM_CLK and USIM_RST line.
In order to filter GSM900 interference, add a parallel 33pF resistance on USIM_VDD,
USIM_DATA, USIM_CLK and USIM_RST line.
Keep layout of USIM card as close as possible to the module. Assure the length of signal
wiring is less than 200mm.
Keep USIM card signal away from RF and VBAT power line.
To avoid cross-talk between USIM_CLK and USIM_DATA, keep them away from each other
and shield them with surrounded ground.
Complete hot plugging of USIM/SIM card by using the DETECT pin of hot plug card slot and
the 13pin of the module. The default setting does not support hot plug function. Contact us if
you need more information about the function.
Note:
Hot plug of SIM Connectors is not supported. Hot plug to USIM and SIM card can
cause damages to USIM /SIM card or SLM750V USIM /SIM card interfaces.
3.10 USB Interface
SLM750 provides a USB interface which complies with USB 2.0 specification and supports
high-speed (480Mbps) and full-speed (12Mbps) modes. The USB interface is used for AT command
communication, data transmission, software debugging and version upgrade.
