MAX3243EWI+ Maxim Integrated Products, MAX3243EWI+ Datasheet - Page 6

• Manufacturer Part Number: MAX3243EWI+
• Description: IC TXRX RS-232 W/SHTDWN 28-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3243EWI+

• Number Of Drivers/receivers: 3/5
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
Figure 1. Interface Under Control of PMU
The MAX3221/MAX3223/MAX3243’s receivers convert
RS-232 signals to CMOS-logic output levels. All
receivers have one inverting three-state output. In shut-
down (FORCEOFF = low) or in AutoShutdown, the
MAX3221/MAX3223’s receivers are active (Table 1).
Driving EN high places the receiver(s) in a high-imped-
ance state. The MAX3243’s receivers are high imped-
ance when the part is shut down.
The MAX3243 has an always-active complementary
output (R2OUTB). R2OUTB is an extra output that mon-
itors receiver activity while the other receivers are high
impedance. This allows Ring Indicator to be monitored
without forward biasing other devices connected to the
receiver outputs. This is ideal for systems where V
set to 0V in shutdown to accommodate peripherals,
such as UARTs (Figure 2).
6
POWER
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER
_______________________________________________________________________________________
CPU
WITH
UART
CHIP
INVALID
FORCEOFF
FORCEON
I/O
RS-232 Receivers
MAX3243
RS-232
CC
is
Figure 2. The MAX3243 detects RS-232 activity when the
UART and interface are shut down.
(b)
(a)
OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE
RECEIVER OUTPUT IN SHUTDOWN.
NEW MAX3243: IN SHUTDOWN, R2OUTB IS USED TO MONITOR EXTERNAL
DEVICES AND R2OUT IS THREE STATED, ELIMINATING A CURRENT PATH
THROUGH THE UART'S PROTECTION DIODE.
V
V
CC
CC
UART
GND
GND
UART
TO
µP
PROTECTION
DIODE
PROTECTION
DIODE
Rx
Rx
Tx
Tx
TRANSITION
DETECTOR
LOGIC
SHDN = GND
FORCEOFF = GND
THREE-STATED
V
CC
I
V
R2OUTB
CC
R2OUT
T1IN
I
PREVIOUS
MAX3243
RS-232
5kΩ
5kΩ
R2IN
T1OUT