Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 Design-In Page 127 of 182
typically accessed by the end user, it can be subjected to ESD discharges: add adequate ESD
protection to protect module SIM pins near the SIM connector
 Digital Audio (I2S_CLK, I2S_RX, I2S_TX, I2S_WA and I2S1_CLK, I2S1_RXD, I2S1_TXD, I2S1_WA):
the I
2
S interface requires the same consideration regarding electro-magnetic interference as the
SIM card. Keep the traces short and avoid coupling with RF line or sensitive analog inputs
 DDC (SCL, SDA): the DDC interface requires the same consideration regarding electro-magnetic
interference as the SIM card. Keep the traces short and avoid coupling with RF line or sensitive
analog inputs
 UART (TXD, RXD, CTS, RTS, DSR, RI, DCD, DTR): the serial interface requires the same
consideration regarding electro-magnetic interference as the SIM card. Keep the traces short and
avoid coupling with RF line or sensitive analog inputs
 General Purpose I/O (GPIOx): the general purpose input/output pins are generally not critical for
layout
 Reserved pins: these pins are reserved for future use. Leave them unconnected on the baseboard
 USB detection (VUSB_DET): this input will generate an interrupt to the baseband processor for
USB detection. The USB supply (5.0 V typ.) must be provided to VUSB_DET by the connected USB
host to enable the USB interface of the module
 Interfaces Supply (V_INT): this supply output is generated by an integrated switching step down
converter, used internally to supply the digital interfaces. Because of this, it can be a source of
noise: avoid coupling with sensitive signals