MAX3140 Maxim, MAX3140 Datasheet - Page 14

• Manufacturer Part Number: MAX3140
• Description: SPI/MICROWIRE-Compatible UART with Integrated True Fail-Safe RS-485/RS-422 Transceivers
• Manufacturer: Maxim

SPI/MICROWIRE-Compatible UART with Integrated
True Fail-Safe RS-485/RS-422 Transceivers
Figure 7. Receiver Propagation Delays
The MAX3140 combines an SPI/QSPI/MICROWIRE-
compatible UART (MAX3100) and an RS-485/RS-422
transceiver (MAX3089) in one package. The UART sup-
ports data rates up to 230k baud for both standard
UART bit streams as well as IrDA, and includes an
8-word receive FIFO. Also included is a parity-bit inter-
rupt useful in 9-bit address recognition.
The RS-485/RS-422 transceiver has a true fail-safe
receiver and allows up to 256 transceivers on the bus.
Other features include pin-selectable full/half-duplex
operation and a phase control to correct for twisted-
14
_______________Detailed Description
-1V
RO
1V
V
V
______________________________________________________________________________________
OH
OL
A
B
1.5V
t
PHL
INPUT
Figure 9. Receiver Propagation Delay Test Circuit
OUTPUT
t
PLH
ATE
1.5V
V
ID
pair reversal. The slew rate of the RS-485/RS-422 trans-
ceiver is selectable, limiting the maximum data rate to
115kbps, 500kbps, or 10Mbps. The RS-485/RS-422 dri-
vers are output short-circuit current limited, and thermal
shutdown circuitry protects the RS-485/RS-422 drivers
against excessive power dissipation.
The UART and RS-485/RS422 functions can be used
together or independently since the two functions only
share supply and ground connections. This part oper-
ates from a single +5V supply.
Figure 8. Receiver Enable and Disable Times
RO
RO
RE
V
3V
CC
0
0
B
A
R
R
1.5V
RECEIVER
OUTPUT
1.5V
1.5V
t
t
ZL(SHDN)
ZH(SHDN)
OUTPUT NORMALLY HIGH
OUTPUT NORMALLY LOW
, t
, t
ZL
ZH
t
t
HZ
LZ
1.5V
V
V
OL
OH
+ 0.5V
- 0.5V