TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R28
Design-in
Page 85 of 164
2.3.2.2
Guidelines for RESET_N and PERST# layout design
The RESET_N and PERST# circuits require careful layout due to the pin function: ensure that the
voltage level is well defined during operation and no transient noise is coupled on this line, otherwise
the module might detect a spurious reset request. It is recommended to keep the connection line to
RESET_N and PERST# pins as short as possible.
2.3.3
Module configuration selection by host processor
☞
The HOST_SELECT0 and HOST_SELECT1 pins are not available on MPCI-L2 series modules.
2.3.3.1
Guidelines for HOST_SELECTx circuit design
☞
The functionality of HOST_SELECT0 and HOST_SELECT1 pins is not supported by all the TOBY-
L2 series modules product versions: the two input pins should not be driven by the host application
processor or any other external device.
TOBY-L2 series modules include two input pins (HOST_SELECT0 and HOST_SELECT1) for the
selection of the module configuration by the host application processor.
☞
Do not apply voltage to HOST_SELECT0 and HOST_SELECT1 pins before the switch-on of their
supply source (V_INT), to avoid latch-up of circuits and allow a proper boot of the module. If the
external signals connected to the cellular module cannot be tri-stated or set low, insert a multi
channel digital switch (e.g. TI SN74CB3Q16244, TS5A3159, or TS5A63157) between the two-circuit
connections and set to high impedance before V_INT switch-on.
☞
ESD sensitivity rating of the HOST_SELECT0 and HOST_SELECT1 pins is 1 kV (HBM as per
JESD22-A114). Higher protection level could be required if the lines are externally accessible and it
can be achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array)
close to accessible points
☞
If the HOST_SELECT0 and HOST_SELECT1 pins are not used, they can be left unconnected on
the application board.
2.3.3.2
Guidelines for HOST_SELECTx layout design
The input pins for the selection of the module configuration by the host application processor
(HOST_SELECT0 and HOST_SELECT1) are generally not critical for layout.
