XR19L212 Datasheet, PDF (51/52 Pages) Exar Corporation – TWO CHANNEL INTEGRATED UART AND RS-232 TRANSCEIVER

REV. 1.0.0
XR19L212
TWO CHANNEL INTEGRATED UART AND RS-232 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. XR19L212 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 DMA MODE ......................................................................................................................................................... 9
2.8 INT (IRQ#) OUTPUT ............................................................................................................................................ 9
TABLE 3: INT (IRQ#) PIN OPERATION FOR TRANSMITTER ................................................................................................................. 9
TABLE 4: INT (IRQ#) PIN OPERATION FOR RECEIVER ...................................................................................................................... 9
2.9 CRYSTAL OR EXTERNAL CLOCK INPUT ........................................................................................................ 9
FIGURE 4. TYPICAL CRYSTAL CONNECTIONS .................................................................................................................................. 10
2.10 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
2.11 TRANSMITTER................................................................................................................................................ 13
2.11.1 TRANSMIT HOLDING REGISTER (THR) - WRITE ONLY......................................................................................... 13
2.11.2 TRANSMITTER OPERATION IN NON-FIFO MODE .................................................................................................. 13
FIGURE 6. XR19L212 TRANSMITTER AND RECEIVER ...................................................................................................................... 13
FIGURE 7. TRANSMITTER OPERATION IN NON-FIFO MODE .............................................................................................................. 14
2.11.3 TRANSMITTER OPERATION IN FIFO MODE ........................................................................................................... 14
FIGURE 8. TRANSMITTER OPERATION IN FIFO AND FLOW CONTROL MODE ..................................................................................... 14
2.12 RECEIVER ....................................................................................................................................................... 14
2.12.1 RECEIVE HOLDING REGISTER (RHR) - READ-ONLY ............................................................................................ 15
2.12.2 SELECTABLE INPUT TO RX OF CHANNEL B ......................................................................................................... 15
FIGURE 9. RECEIVER OPERATION IN NON-FIFO MODE.................................................................................................................... 15
FIGURE 10. RECEIVER OPERATION IN FIFO AND AUTO RTS FLOW CONTROL MODE ....................................................................... 16
2.13 AUTO RTS (HARDWARE) FLOW CONTROL ............................................................................................... 16
2.14 AUTO RTS HYSTERESIS .............................................................................................................................. 16
2.15 AUTO CTS FLOW CONTROL........................................................................................................................ 17
FIGURE 11. AUTO RTS AND CTS FLOW CONTROL OPERATION....................................................................................................... 17
2.16 AUTO XON/XOFF (SOFTWARE) FLOW CONTROL..................................................................................... 18
TABLE 6: AUTO XON/XOFF (SOFTWARE) FLOW CONTROL ............................................................................................................... 18
2.17 SPECIAL CHARACTER DETECT.................................................................................................................. 18
2.18 SLEEP MODES AND POWER-SAVE FEATURE WITH WAKE-UP INTERRUPT ........................................ 19
2.18.1 PARTIAL SLEEP MODE............................................................................................................................................. 19
2.18.1.1 UART IN SLEEP MODE, RS-232 TRANSCEIVER ACTIVE......................................................................................... 19
2.18.1.2 UART ACTIVE, CHARGE PUMP OF RS-232 TRANSCEIVER SHUT DOWN.................................................................. 20
2.18.2 FULL SLEEP MODE ................................................................................................................................................... 20
2.18.3 POWER-SAVE FEATURE .......................................................................................................................................... 20
2.19 INFRARED MODE (UART CHANNEL B ONLY)............................................................................................. 21
FIGURE 12. INTERNAL LOOP BACK ................................................................................................................................................. 21
3.0 UART INTERNAL REGISTERS............................................................................................................. 22
TABLE 7: UART INTERNAL REGISTERS .................................................................................................................................... 22
TABLE 8: INTERNAL REGISTERS DESCRIPTION. SHADED BITS ARE ENABLED WHEN EFR BIT-4=1 ......................................... 23
4.0 INTERNAL REGISTER DESCRIPTIONS .............................................................................................. 24
4.1 RECEIVE HOLDING REGISTER (RHR) - READ- ONLY .................................................................................. 24
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