XR19L212 Datasheet, PDF (5/52 Pages) Exar Corporation – TWO CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER

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Pin Descriptions
XR19L212
TWO CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER
NAME
48-QFN
PIN#
TYPE
DESCRIPTION
I/M#
23
I _{Intel or Motorola Bus Select.}
When I/M# pin is HIGH, 16 or Intel Mode, the device will operate in the Intel bus type of
interface.
When I/M# pin is LOW, 68 or Motorola mode, the device will operate in the Motorola bus
type of interface.
RESET
35
(RESET#)
I _{When I/M# pin is HIGH for Intel bus interface, this input becomes RESET (active high).}
When I/M# pin is LOW for Motorola bus interface, this input becomes RESET# (active low).
A 40 ns minimum active pulse on this pin will reset the internal registers and all outputs of
the UART. The UART transmitter output will be held HIGH, the receiver input will be ignored
and outputs are reset during reset period (see Table 16).
C2P
C2N
36
- _{Charge pump capacitors. As shown in Figure 1, a 0.1 uF capacitor should be placed}
34
between these 2 pins.
C1P
C1N
39
- _{Charge pump capacitors. As shown in Figure 1, a 0.1 uF capacitor should be placed}
38
between these 2 pins.
VREFP
40
Pwr _{+5.0V generated by the charge pump.}
VREFN
21
Pwr _{-5.0V generated by the charge pump.}
R_EN
19
I _{When the supply voltage is < 3.6V, connect R_EN to GND.}
When the supply voltage is > 3.6V, connect R_EN to VCC.
C3
42
I _{When the supply voltage is 3.3 V, C3A and C3B should be connected to VCC.}
When the supply voltage is 5 V, C3A should be connected to C3B with a 1 uF capacitor to
GND.
RXBSEL
7
I _{When RXBSEL is HIGH, RXB is the input to the receiver of the UART.}
When RXBSEL is LOW, RXDB is the input to the receiver of the UART.
FAST
15
I _{When FAST is HIGH, the maximum serial data rate is 1 Mbps.}
When FAST is LOW, the maximum serial data rate is 250 Kbps.
VCC
37, 41 Pwr _{3.3V to 5.5V power supply. All CMOS/TTL input pins, except XTAL1, are 5V tolerant.}
GND 1, 17, 26 Pwr _{Power supply common, ground.}
-
PAD Pwr _{The center pad on the backside of the 48-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.
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. For RS-232
Voltage levels, ’LOW’ is any voltage < 1.5V and ’HIGH’ is any voltage > 3V.
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