Telit Wireless Solutions SE868SY-D, Руководство по конструкции аппаратуры, Страница: 21 / 44

SE868SY-D Hardware Design Guide
1VV0301705 Rev. 5 Page 21 of 44 2021-12-15
Not Subject to NDA
Digital I/O
5.3.1. nRESET
The module will generate an internal reset as appropriate by means of a POR (Power on
Reset) section. Therefore, no external signal is required for the module to operate
properly, and this pin may be left unconnected. However, it is recommended to connect
it for debug purposes. The external nRESET signal will not reset the RTC section.
5.3.2. LNA Enable
LNA_EN is an output signal, mapped on pin 26 and can be used to enable external LNA.
The SE868SY-D embeds an internal LNA with a 17 dB gain for both the L1 and L5 bands.
If higher gain is required, an external LNA can be added to the RF path. For improved EMI
performance, a maximum external gain of 8 dB is recommended; however a gain up to
33 dB can be accepted as shown in the table below.
Gain Internal Gain (*) External Gain Range (*)
SE868SY-D 17 dB 0 to 33 dB (0 to 8 dB for better EMI performance)
Table 17: LNA Internal Gain and Allowed External Gain Range(*) Estimated Values
5.3.3. 1PPS
The GNSS receiver generates a one-pulse-per-second signal for synchronization. It is
mapped on PIN 28 on SE868SY-D.
5.3.4. System ON
SYS_ON is an output signal, mapped on pin 5 and is available only on SE868SY-D Low
Power part number. The signal is High when the module is in Exec state (acquisition or
tracking) or in Idle state, while it is Low when the module is in deep sleep. Thus, the signal
can be used to monitor the module state and MUST be used to enable the 0.8 V Voltage
regulator allowing the module to enter a deep sleep state.