XR16L2450 Datasheet, PDF (29/30 Pages) Exar Corporation – 2.25V TO 5.5V DUART

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2.25V TO 5.5V DUART
TABLE OF CONTENTS
XR16L2450
REV. 1.1.0
GENERAL DESCRIPTION................................................................................................. 1
APPLICATIONS ............................................................................................................................................... 1
FEATURES ..................................................................................................................................................... 1
FIGURE 1. XR16L2450 BLOCK DIAGRAM ......................................................................................................................................... 1
FIGURE 2. PIN OUT ASSIGNMENT ..................................................................................................................................................... 2
ORDERING INFORMATION ................................................................................................................................ 2
PACKAGE PIN DESCRIPTIONS ...................................................................................... 3
PIN DESCRIPTIONS ........................................................................................................................................ 3
1.0 PRODUCT DESCRIPTION .................................................................................................................... 6
2.0 FUNCTIONAL DESCRIPTIONS ............................................................................................................ 6
2.1 CPU INTERFACE ............................................................................................................................................. 6
FIGURE 3. XR16L2450 DATA BUS INTERCONNECTIONS.................................................................................................................. 6
2.2 5-VOLT TOLERANT INPUTS ........................................................................................................................... 6
2.3 DEVICE RESET ................................................................................................................................................ 6
2.4 DEVICE IDENTIFICATION AND REVISION .................................................................................................... 7
2.5 CHANNEL A AND B SELECTION ................................................................................................................... 7
TABLE 1: CHANNEL A AND B SELECT ............................................................................................................................................... 7
2.6 CHANNEL A AND B INTERNAL REGISTERS ................................................................................................ 7
2.7 INTA AND INTB OUTPUTS .............................................................................................................................. 7
TABLE 2: INTA AND INTB PINS OPERATION FOR TRANSMITTER ........................................................................................................ 7
2.8 CRYSTAL OSCILLATOR OR EXTERNAL CLOCK INPUT ............................................................................. 7
FIGURE 4. TYPICAL OSCILLATOR CONNECTIONS................................................................................................................................. 8
2.9 PROGRAMMABLE BAUD RATE GENERATOR ............................................................................................. 8
TABLE 3: TYPICAL DATA RATES WITH A 14.7456 MHZ CRYSTAL OR EXTERNAL CLOCK ........................................................................ 9
2.10 TRANSMITTER ............................................................................................................................................... 9
2.10.1 TRANSMIT HOLDING REGISTER (THR) - WRITE ONLY......................................................................................... 9
FIGURE 5. TRANSMITTER OPERATION ............................................................................................................................................... 9
2.11 RECEIVER .................................................................................................................................................... 10
2.11.1 RECEIVE HOLDING REGISTER (RHR) - READ-ONLY .......................................................................................... 10
FIGURE 6. RECEIVER OPERATION................................................................................................................................................... 10
2.12 INTERNAL LOOPBACK ............................................................................................................................... 11
FIGURE 7. INTERNAL LOOP BACK IN CHANNELS A AND B ................................................................................................................ 11
3.0 UART INTERNAL REGISTERS ........................................................................................................... 12
TABLE 4: UART CHANNEL A AND B UART INTERNAL REGISTERS ..................................................................................... 12
TABLE 5: INTERNAL REGISTERS DESCRIPTION ................................................................................................................... 13
4.0 INTERNAL REGISTER DESCRIPTIONS ............................................................................................ 13
4.1 RECEIVE HOLDING REGISTER (RHR) - READ- ONLY ............................................................................... 13
4.2 TRANSMIT HOLDING REGISTER (THR) - WRITE-ONLY ............................................................................ 13
4.3 INTERRUPT ENABLE REGISTER (IER) - READ/WRITE ............................................................................. 13
4.3.1 INTERRUPT MODE OPERATION .............................................................................................................................. 14
4.3.2 POLLED MODE OPERATION .................................................................................................................................... 14
4.4 INTERRUPT STATUS REGISTER (ISR) - READ-ONLY ............................................................................... 14
4.4.1 INTERRUPT GENERATION: ...................................................................................................................................... 15
4.4.2 INTERRUPT CLEARING: ........................................................................................................................................... 15
TABLE 6: INTERRUPT SOURCE AND PRIORITY LEVEL ....................................................................................................................... 15
4.5 LINE CONTROL REGISTER (LCR) - READ/WRITE ..................................................................................... 15
TABLE 7: PARITY SELECTION .......................................................................................................................................................... 16
4.6 MODEM CONTROL REGISTER (MCR) OR GENERAL PURPOSE OUTPUTS CONTROL - READ/WRITE 17
4.7 LINE STATUS REGISTER (LSR) - READ ONLY ........................................................................................... 17
4.8 MODEM STATUS REGISTER (MSR) - READ ONLY .................................................................................... 18
4.9 SCRATCH PAD REGISTER (SPR) - READ/WRITE ...................................................................................... 19
4.10 BAUD RATE GENERATOR REGISTERS (DLL AND DLM) - READ/WRITE .............................................. 19
4.11 DEVICE IDENTIFICATION REGISTER (DVID) - READ ONLY .................................................................... 19
4.12 DEVICE REVISION REGISTER (DREV) - READ ONLY .............................................................................. 19
TABLE 8: UART RESET CONDITIONS FOR CHANNEL A AND B.............................................................................................. 20
ABSOLUTE MAXIMUM RATINGS .................................................................................. 21
TYPICAL PACKAGE THERMAL RESISTANCE DATA (MARGIN OF ERROR: ± 15%) 21
ELECTRICAL CHARACTERISTICS................................................................................ 21
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