XR19L402 Datasheet, PDF (49/50 Pages) Exar Corporation – TWO CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER

REV. 1.0.0
XR19L402
TWO CHANNEL INTEGRATED UART AND RS-485 TRANSCEIVER
TABLE OF CONTENTS
GENERAL DESCRIPTION................................................................................................ 1
APPLICATIONS .............................................................................................................................................. 1
FEATURES .................................................................................................................................................... 1
FIGURE 1. BLOCK DIAGRAM ............................................................................................................................................................. 1
FIGURE 2. PIN OUT OF THE DEVICE.................................................................................................................................................. 2
ORDERING INFORMATION ............................................................................................................................... 2
PIN DESCRIPTIONS ....................................................................................................... 3
1.0 PRODUCT DESCRIPTION ...................................................................................................................... 6
2.0 FUNCTIONAL DESCRIPTIONS .............................................................................................................. 7
2.1 CPU INTERFACE ................................................................................................................................................ 7
FIGURE 3. XR19L402 TYPICAL INTEL/MOTOROLA DATA BUS INTERCONNECTIONS ............................................................................. 7
2.2 5-VOLT TOLERANT INPUTS .............................................................................................................................. 8
2.3 DEVICE HARDWARE RESET............................................................................................................................. 8
2.4 DEVICE IDENTIFICATION AND REVISION ....................................................................................................... 8
2.5 CHANNEL A AND B SELECTION ...................................................................................................................... 8
TABLE 1: CHANNEL A AND B SELECT IN 16 MODE ............................................................................................................................ 8
TABLE 2: CHANNEL A AND B SELECT IN 68 MODE ............................................................................................................................ 8
2.6 CHANNEL A AND B INTERNAL REGISTERS ................................................................................................... 8
2.7 INT (IRQ#) OUTPUT ............................................................................................................................................ 9
TABLE 3: INT (IRQ#) PIN OPERATION FOR TRANSMITTER ................................................................................................................. 9
TABLE 4: INT (IRQ#) PIN OPERATION FOR RECEIVER ...................................................................................................................... 9
2.8 CRYSTAL OR EXTERNAL CLOCK INPUT ........................................................................................................ 9
FIGURE 4. TYPICAL CRYSTAL CONNECTIONS .................................................................................................................................. 10
2.9 PROGRAMMABLE BAUD RATE GENERATOR WITH FRACTIONAL DIVISOR ........................................... 10
FIGURE 5. BAUD RATE GENERATOR ............................................................................................................................................... 11
TABLE 5: TYPICAL DATA RATES WITH A 24 MHZ CRYSTAL OR EXTERNAL CLOCK AT 16X SAMPLING ................................................... 12
2.10 TRANSMITTER................................................................................................................................................ 13
2.10.1 TRANSMIT HOLDING REGISTER (THR) - WRITE ONLY......................................................................................... 13
2.10.2 TRANSMITTER OPERATION IN NON-FIFO MODE .................................................................................................. 13
FIGURE 6. XR19L402 TRANSMITTER AND RECEIVER ...................................................................................................................... 13
FIGURE 7. TRANSMITTER OPERATION IN NON-FIFO MODE .............................................................................................................. 14
2.10.3 TRANSMITTER OPERATION IN FIFO MODE ........................................................................................................... 14
FIGURE 8. TRANSMITTER OPERATION IN FIFO AND FLOW CONTROL MODE ..................................................................................... 14
2.11 RECEIVER ....................................................................................................................................................... 14
2.11.1 RECEIVE HOLDING REGISTER (RHR) - READ-ONLY ............................................................................................ 15
2.11.2 SELECTABLE INPUT TO RX OF CHANNEL B ......................................................................................................... 15
FIGURE 9. RECEIVER OPERATION IN NON-FIFO MODE.................................................................................................................... 15
2.12 AUTO XON/XOFF (SOFTWARE) FLOW CONTROL................................................................................... 15
TABLE 6: AUTO XON/XOFF (SOFTWARE) FLOW CONTROL ............................................................................................................... 16
2.13 SPECIAL CHARACTER DETECT.................................................................................................................. 16
2.14 SLEEP MODE, ACP MODE AND POWER-SAVE FEATURE WITH WAKE-UP INTERRUPT ..................... 17
2.14.1 UART SLEEP MODE (3.3V OR 5V OPERATION) ..................................................................................................... 17
2.14.1.1 RECEIVING DATA IN UART SLEEP MODE.............................................................................................................. 17
2.14.2 UART ACTIVE, CHARGE PUMP OF RS-485 TRANSCEIVER SHUT DOWN (3.3V OPERATION ONLY) .............. 17
2.14.2.1 TRANSMITTING DATA IN ACP MODE .................................................................................................................... 17
2.14.3 UART SLEEP, CHARGE PUMP OF RS-485 TRANSCEIVER SHUT DOWN (3.3V OPERATION ONLY)................ 18
2.14.3.1 RECEIVING DATA IN UART SLEEP MODE.............................................................................................................. 18
2.14.3.2 TRANSMITTING DATA IN ACP MODE..................................................................................................................... 18
2.14.4 POWER-SAVE FEATURE .......................................................................................................................................... 18
2.15 INFRARED MODE (UART CHANNEL B ONLY)............................................................................................. 19
FIGURE 10. INFRARED TRANSMIT DATA ENCODING AND RECEIVE DATA DECODING.......................................................................... 19
2.16 INTERNAL LOOPBACK................................................................................................................................. 20
FIGURE 11. INTERNAL LOOP BACK ................................................................................................................................................. 20
3.0 UART INTERNAL REGISTERS............................................................................................................. 21
TABLE 7: UART INTERNAL REGISTERS .................................................................................................................................... 21
TABLE 8: INTERNAL REGISTERS DESCRIPTION. SHADED BITS ARE ENABLED WHEN EFR BIT-4=1 ......................................... 22
4.0 INTERNAL REGISTER DESCRIPTIONS .............................................................................................. 23
4.1 RECEIVE HOLDING REGISTER (RHR) - READ- ONLY .................................................................................. 23
4.2 TRANSMIT HOLDING REGISTER (THR) - WRITE-ONLY ............................................................................... 23
4.3 INTERRUPT ENABLE REGISTER (IER) - READ/WRITE ................................................................................ 23
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