Telit Wireless Solutions LE910C1-AP - Page 43

LE910Cx mPCIe Hardware Design Guide
1VV0301510 Rev. 13 Page 43 of 73 2021-07-07
Not Subject to NDA
The easiest way to translate the levels and invert the signal is by using a single chip-level
translator. There are a multitude of them, differing in the number of drivers and receivers
and in the levels (make sure to get a true RS232 level translator, not a RS485 or other
standards).
By convention, the driver is the level translator from the 0-1.8V UART to the RS232 level.
The receiver is the translator from the RS232 level to 0-1.8V UART.
To translate the whole set of control lines of the UART, the following is required:
• 1 driver
• 1 receiver
Note:
The digital input lines operating at 1.8V CMOS therefore, the
level translator IC must not be powered by the +3.8V supply of the
module. Instead, it must be powered from a dedicated +1.8V power
supply.
RS232 Level Adaption Circuitry Example:
Figure 12: RS232 Level Adaption Circuitry Example
Note:
In this case, the length of the lines on the application must be
taken into account to avoid problems in the case of High-speed rates
on RS232