MAX3140EEI Maxim Integrated Products, MAX3140EEI Datasheet - Page 22
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MAX3140EEI
Manufacturer Part Number
MAX3140EEI
Description
IC UART SPI RS485/422 28-QSOP
Manufacturer
Maxim Integrated Products
Datasheet
1.MAX3140CEIT.pdf
(36 pages)
Specifications of MAX3140EEI
Features
Transceiver
Fifo's
8 Byte
Protocol
RS232, RS485
Voltage - Supply
4.75 V ~ 5.25 V
With Irda Encoder/decoder
Yes
With False Start Bit Detection
Yes
With Cmos
Yes
Mounting Type
Surface Mount
Package / Case
28-QSOP
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
MAX3140EEI
Manufacturer:
MAXIM/美信
Quantity:
20 000
Notes:
bit 15, 14: DIN
0, 0 = Read Data
bit 13–0: DIN
Zeros
bit 15: DOUT
R = 1, Data is available to be read from the receive register or
FIFO.
R = 0, Receive register and FIFO are empty.
bit 14: DOUT
T = 1, Transmit buffer is empty.
T = 0, Transmit buffer is full.
The baud-rate generator determines the rate at which
the transmitter and receiver operate. Bits B3–B0 in the
WRITE CONFIGURATION register determine the baud-
rate divisor (BRD), which divides the X1 oscillator
frequency. The on-board oscillator operates with either
a 1.8432MHz or a 3.6864MHz crystal, or is driven at X1
with a 45% to 55% duty-cycle square wave. Table 6
shows baud-rate divisors for given input codes, as well
as the baud rate for 1.8432MHz and 3.6864MHz crys-
tals. The generator’s clock is 16 times the baud rate.
Using the READ DATA or WRITE DATA register clears
the interrupt IRQ, assuming the conditions that initiated
the interrupt no longer exist. Table 7 gives the details
for each interrupt source. Figure 15 shows the function-
al diagram for the interrupt sources and mask blocks.
Two examples of setting up an IRQ for the MAX3140
are shown below.
Example 1: Setting up only the transmit buffer-empty
interrupt.
Send the 16-bit word below into DIN of the MAX3140
using the WRITE CONFIGURATION register. This 16-bit
word configures the MAX3140 for 9600bps, 8-bit words,
no parity, and one stop bit with a 1.8432MHz crystal.
binary 1100100000001010
HEX
SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers
Table 5. READ DATA Register Bit Assignment (D15, D14 = 0, 0)
22
DOUT
DIN
BIT
______________________________________________________________________________________
C80A
15
R
0
14
0
T
13
0
0
Interrupt Sources and Masks
12
0
0
Baud-Rate Generator
11
0
0
RA/FE
10
0
CTS
9
0
Pr
8
0
bit 13–11: DOUT
Zeros
bit 10: DOUT
RA/FE = Receive-activity (UART shutdown)/Framing-error
(normal operation) bit
bit 9: DOUT
CTS = CTS input state. If CTS = 0, then CTS = 1 and vice versa.
bit 8: DOUT
Pr = Received parity bit. This is only valid if PE = 1.
bit 7–0: DOUT
D7t–D0t = Received Data bits. D7r = 0 for L = 1.
Table 6. Baud-Rate Selection Table*
*Standard baud rates shown in bold
**Default baud rate
B3 B2 B1 B0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
D7r
7
0
BAUD
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
D6r
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
6
0
0**
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
D5r
5
0
DIVISION
RATIO
128
192
384
16
32
64
12
24
48
96
1
2
4
8
3
6
D4r
4
0
D3r
1.8432MHz)
3
0
115.2k**
(f
BAUD
RATE
57.6k
38.4k
19.2k
28.8k
14.4k
7200
3600
1800
9600
4800
2400
1200
OSC
900
600
300
D2r
=
2
0
3.6864MHz)
D1r
1
0
230.4k**
(f
115.2k
BAUD
RATE
57.6k
38.4k
19.2k
28.8k
14.4k
76.8k
7200
3600
1800
9600
4800
2400
1200
OSC
600
D0r
=
0
0