
NE866B1_Hardware_Design_Guide
1VV0301354 Rev. 6
Page
41
of
70
2018-02-28
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.
In order to translate the whole set of control lines of the UART you will need:
•
5 drivers
•
3 receivers
An example of RS232 level adaptation circuitry could be done using a MAXIM transceiver
(MAX218).
In this case the chipset is capable to translate directly from 1.8V to the RS232 levels
(Example done on 4 signals only).
NOTE
:
The digital input lines operating at 1.8V CMOS have an absolute
maximum input voltage of 2.2V. The level translator IC outputs on the
module side (i.e. module inputs) will cause damage to the module
inputs if the level translator is powered by a +3.8V supply. So the
level translator IC must be powered from a ded1.8V power
supply to match the module I/O level.
The RS232 serial port lines are usually connected to a DB9 connector with the following
layout: