XR19L402_09 Datasheet, PDF (5/49 Pages) Exar Corporation – TWO CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER

REV. 1.0.3
Pin Descriptions
XR19L402
TWO CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER
NAME
48-QFN
PIN#
TYPE
DESCRIPTION
RXBSEL 44
I _{When RXBSEL is HIGH, RXB is the receive data input.}
When RXBSEL is LOW, RXB+ and RXB- are the receive data inputs.
VCC33
22
Pwr _{3.3V power supply. When VCC33 is used, R_EN pin should be connected to GND.}
A 0.1 uF capacitor to GND is recommended on this power supply pin. If VCC33 is not used
as the power supply pin, VCC33 should be left unconnected. See Figure 3 below. All
CMOS/TTL input pins, except XTAL1, are 5V tolerant.
VCC50
39
Pwr _{5.0V power supply. When VCC50 is used, R_EN pin should be connected to VCC.}
A 1uF capacitor to GND is recommended on the VCC50 power supply pin. The 1uF capac-
itor is recommended whether VCC33 or VCC50 is used as the power supply pin. See
Figure 3 below. All CMOS/TTL input pins, except XTAL1, are 5V tolerant.
GND
24, 37 Pwr _{Power supply common, ground.}
-
PAD Pwr _{The center pad on the backside of the 64-QFN package is metallic and is not electrically}
connected to anything inside the device. It must be soldered on to the PCB and may be
optionally connected to GND on the PCB. The thermal pad size on the PCB should be the
approximate size of this center pad and should be solder mask defined. The solder mask
opening should be at least 0.0025" inwards from the edge of the PCB thermal pad.
NC 26, 29, 32, - _{No Connect. Note that in Motorola mode, the IOR# pin also becomes an NC pin.}
35
NOTE: Pin type: I=Input, O=Output, I/O= Input/output, OD=Output Open Drain. For CMOS/TTL Voltage levels, ’LOW’
indicates a voltage in the range 0V to VIL and ’HIGH’ indicates a voltage in the range VIH to VCC.
FIGURE 3. RECOMMENDED 3.3V OR 5V POWER SUPPLY CONNECTIONS
3.3V Power Supply
5V Power Supply
VCC50
1 uF
GND
3.3V
VCC33
0.1 uF
GND
R_EN
GND
5V
1 uF
GND
VCC50
VCC33
R_EN
5