LARA-R2 series - System Integration Manual
UBX-16010573 - R02
Objective Specification
Design-in
Page 84 of 148
2.3.3
Module / host configuration selection
2.3.3.1
Guidelines for HOST_SELECT circuit design
Selection of module / host configuration over
HOST_SELECT
is not supported by “02” product versions.
LARA-R2 series modules include one pin (
HOST_SELECT
) to select the module / host application processor
configuration: the pin is available to select, enable, connect, disconnect and subsequently re-connect the HSIC
(USB High-Speed Inter-Chip) interface.
LARA-R2 series Data Sheet
[1] describes the detailed electrical characteristics of the
HOST_SELECT
pin.
Further guidelines for
HOST_SELECT
pin circuit design will be described in detail in a successive release of
the System Integration Manual.
Do not apply voltage to
HOST_SELECT
pin before the switch-on of its supply source (
V_INT
), to avoid
latch-up of circuits and allow a proper boot of the module. If the external signal 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_SELECT
pin 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_SELECT
pin is not used, they can be left unconnected on the application board.
2.3.3.2
Guidelines for HOST_SELECT layout design
The pin for the selection of the module / host application processor configuration (
HOST_SELECT
) is generally
not critical for layout.
