XR21B1424_17 Datasheet, PDF (9/64 Pages) Exar Corporation – Enhanced 4-Ch Full-Speed USB UART

Functional Block Diagram
VBUS_SENSE
USBD+
USBD-
RESET#
VCC
VCC_REG
GND
Internal
Oscillator
(48MHz)
USB Slave Interface
USB
Descriptors
OTP
Fractional
BRG
512-byte
TX FIFO
512-byte
RX FIFO
Internal
Status and
Control
Registers
GPIOs/
Modem IO
LDO
UART Ch A
3V3
UART Ch B
(same as Ch A)
UART Ch C
(same as Ch A)
UART Ch D
(same as Ch A)
XR21B1424
VIO
TXA
RXA
GPIOA9/RXTA
GPIOA8/TXTA
GPIOA7/RS485A
GPIOA6/CLKA
GPIOA5/RTSA#/RS485A
GPIOA4/CTSA#
GPIOA3/DTRA#
GPIOA2/DSRA#
GPIOA1/CDA#
GPIOA0/RIA#/RWKA#
TXB
RXB
GPIOB[9-0]
TXC
RXC
GPIOC[9-0]
TXD
RXD
GPIOD[9-0]
USB_STAT1
USB_STAT2
9 / 64
exar.com/XR21B1424
Rev 1C