MAX3140 Maxim, MAX3140 Datasheet - Page 11

• 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
DUPLEX
FULL
10
11
12
13
14
15
16
17
18
19
20
—
—
—
—
1
2
3
4
5
6
7
8
9
PIN
DUPLEX
HALF
10
11
12
13
14
15
16
17
18
19
20
—
—
—
—
1
2
3
4
5
6
7
8
9
______________________________________________________________________________________
True Fail-Safe RS-485/RS-422 Transceivers
NAME
GND
N.C.
N.C.
CTS
RTS
SRL
TXP
H/F
RO
RX
RE
DE
X2
X1
TX
DI
B
B
A
A
Y
Y
Z
Z
UART Crystal Connection. Leave X2 unconnected for external clock. See the Crystals,
Oscillators, and Ceramic Resonators section.
UART Crystal Connection. X1 also serves as an external clock input. See the Crystals,
Oscillators, and Ceramic Resonators section.
UART Clear-to-Send Active-Low Input. Read via the CTS bit.
UART Request-to-Send Active-Low Output. Controlled by the RTS bit. Use to control the dri-
ver enable in RS-485 networks.
UART Asynchronous Serial-Data (receiver) Input. The serial information received from the modem
or RS-232/RS-485 receiver. A transition on RX while in shutdown generates an interrupt (Table 1).
UART Asynchronous Serial-Data (transmitter) Output
RS-485 Half/Full-Duplex Selector Pin. Connect H/F to V
to GND or leave it unconnected for full-duplex mode.
Ground
RS-485 Receiver Output. When RE is low and if A - B ≥ -50mV, RO will be high; if A - B ≤
-200mV, RO will be low.
RS-485 Receiver Output Enable. Drive RE low to enable RO; RO is high impedance when RE
is high. Drive RE high and DE low to enter low-power shutdown mode.
RS-485 Driver Output Enable. Drive DE high to enable driver outputs. These outputs are high
impedance when DE is low. Drive RE high and DE low to enter low-power shutdown mode.
RS-485 Driver Input. With DE high, a low on DI forces noninverting output low and inverting
output high. Similarly, a high on DI forces noninverting output high and inverting output low.
RS-485 Transceiver Slew-Rate-Limit Selector Pin. Connect SRL to GND for a 10Mbps com-
munication rate, connect SRL to V
115kbps rate.
No Connection. Not internally connected.
RS-485 Transmitter Phase. Connect TXP to GND or leave it floating for normal transmitter
phase/polarity. Connect TXP to V
RS-485 Noninverting Driver Output
RS-485 Noninverting Receiver Input and RS-485 Noninverting Driver Output*
No Connection. Not internally connected.
RS-485 Inverting Driver Output
RS-485 Inverting Receiver Input and RS-485 Inverting Driver Output*
RS-485 Inverting Receiver Input
RS-485 Receiver Input Resistors*
RS-485 Noninverting Receiver Input
RS-485 Receiver Input Resistors*
CC
CC
to invert the transmitter phase/polarity.
for a 500kbps rate, or leave SRL unconnected for a
FUNCTION
CC
for half-duplex mode; connect H/F
Pin Description
11