Datasheet

MAX3212
not the absolute voltages. Increasing the size of C1 and
C2 increases the time V+ and V- take to reach their final
value. Bypass V
CC
to GND with at least 0.33 µF close to
the MAX3212. Increase this to 4.7µF if there are no other
V
CC
supply bypass components less than 6 inches
(15cm) away from the MAX3212.
Component suppliers are listed in Table 1.
RS-232 Drivers
All three drivers are identical and deliver EIA/TIA-232E
and EIA/TIA-562 output voltage levels when V
CC
is be-
tween 2.7V and 3.6V. When FORCEOFF is driven low or
when the AutoShutdown circuitry senses invalid voltage
levels at all receiver inputs, the drivers are disabled
and the outputs are forced into a high-impedance
state.
RS-232 Receivers
The MAX3212 receivers convert RS-232 signals to
CMOS-logic output levels. All receivers have one in -
verting three-state output. Receiver 5 also has a com-
plementary (noninverting) output. In shutdown, all five
inverting receivers can be either active or inactive
under logic control.
The complementary output (R5OUTB) is always active,
regardless of the state of EN or the part’s shutdown sta-
tus. R5OUTB can monitor RS-232 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 the UART’s V
CC
is set to 0V in shut-
down. (See Figure 2.)
Enable Control
The EN input has two functions: It allows enabling/dis-
abling of the receivers, and it is used to reset the transi-
tion detector.
Driving EN low places five inverting receiver outputs
(R_OUT) into a high-impedance state. R5OUTB is
always active, regardless of the state of EN or the part’s
shutdown status (Table 2). EN has no effect on T_OUT.
EN also resets the transition detector. Drive EN high and
then low to reset the TRAN output low. TRAN goes high
when a transition occurs on any receiver input.
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
6 _______________________________________________________________________________________
Table 1. Suggested Component Suppliers
Table 2. AutoShutdown Logic
MANUFACTURER PART NUMBER PHONE FAX
Motorola MMBD6050LT1 USA [phone] USA [phone]
Murata-Erie LQH4N150K-TA
USA [phone]
Japan [phone]
USA [phone]
Japan [phone]
Sumida CD43150
USA [phone]
Japan [phone]
USA [phone]
Japan [phone]
TDK NLC453232T-150K
USA [phone]
Japan [phone]
USA [phone]
Japan [phone]
Allegro TMPD6050LT USA [phone] USA [phone]
Philips PMBD6050 USA [phone] USA [phone]
RS-232 SIGNAL
PRESENT AT
RECEIVER INPUT
FORCEOFF INPUT
FORCEON
INPUT
INVALID OUTPUT TRANSCEIVER STATUS
Yes H X H Normal Operation
No H H L Normal Operation (Forced On)
No H L L Shutdown (AutoShutdown)
Yes L X H Shutdown (Forced Off)
No L X L Shutdown (Forced Off)
Diodes
Inductors