Control Signal; Module Start-Up; Start-Up Circuit - Fibocom L850-GL Series Hardware Manual

3.3 Control Signal

The L850 module provides two control signals for power on/off and reset operations. The pin is defined in
the following table:
Pin Pin Name
6 FULL_CARD_POWER_OFF# I
67 RESET#
50 PERST#
Note：
RESET# and PERST# need to be controlled by independent GPIO, and not shared with other
devices on the host. RESET# and PERST# are sensitive signals, so they should keep away from
RF interference and be protected by GND. It should be neither near PCB edge nor route on
surface layer to avoid module abnormal reset caused by ESD.

3.3.1 Module Start-Up

3.3.1.1 Start-up Circuit

The FCPO# (FULL_CARD_POWER_OFF#) pin needs an external 3.3V or 1.8V pull up for booting up. AP
(Application Processor) controls module start-up. The recommended design is using a default PD port to
control FCPO#. It also should reserve a 100K pull down resistor on AP side. The reference design is shown
in Figure3-4:
Reproduction forbidden without Fibocom Wireless Inc. written authorization - All Rights Reserved.
FIBOCOM L850-GL Series Hardware Guide
I/O Reset Value Functions
Module power on/off input,
internal pull up
PU
Power on: High/Floating
Power off: Low
WWAN reset input, internal pull
I
-
up(10KΩ), active low
Asserted to reset module PCIe
interface default. If module went
I PU
into core dump, it will reset whole
module, not only PCIe interface.
Active low, internal pull up(10KΩ)
Type
3.3/1.8V
1.8V
3.3V
Page 25 of 59