MAX13223EEUP+T Maxim Integrated Products, MAX13223EEUP+T Datasheet - Page 9

• Manufacturer Part Number: MAX13223EEUP+T
• Description: IC TXRX RS-232 2TX/2RX 20-TSSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX13223EEUP+T

• Number Of Drivers/receivers: 2/2
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The capacitor type used for C1–C4 is not critical for
proper operation; either polarized or nonpolarized
capacitors may be used. The charge pump requires
0.1µF capacitors for 3.3V operation. For other supply
voltages, see Table 3 for required capacitor values. Do
not use values smaller than those listed in Table 3.
Increasing the capacitor values (e.g., by a factor of 2)
reduces ripple on the transmitter outputs and slightly
reduces power consumption. C2, C3, and C4 can be
increased without changing C1’s value. However, do
not increase C1 without also increasing the values
of C2, C3, and C4 to maintain the proper ratios (C1
to the other capacitors). When using the minimum
required capacitor values, make sure the capacitor
value does not degrade excessively with temperature.
If in doubt, use capacitors with a larger nominal value.
The capacitor’s equivalent series resistance (ESR) usu-
ally rises at low temperatures and influences the
amount of ripple on V+ and V-.
In most circumstances, a 0.1µF V
adequate. In applications that are sensitive to power-sup-
ply noise, decouple V
same value as the charge-pump capacitor C1. Connect
bypass capacitors as close to the IC as possible.
Table 2. AutoShutdown Control
X = Don’t Care.
Table 3. Required Capacitor Values
3.0 to 3.6
4.5 to 5.5
FORCEOFF
V
CC
(V)
0
0
1
1
1
1
C1, C
Applications Information
_______________________________________________________________________________________
BYPASS
FORCEON
0.047
0.1
CC
Power-Supply Decoupling
X
X
0
0
1
1
to ground with a capacitor of the
INPUTS
(µF)
Capacitor Selection
±70V Fault-Protected, 3.0V to 5.5V,
C2, C3 (µF)
CC
VALID RECEIVER INPUT
0.33
bypass capacitor is
0.1
LEVEL
Yes
Yes
Yes
No
No
No
C4 (µF)
2Tx/2Rx RS-232 Transceiver
1
1
Figure 7 shows two transmitter outputs when exiting
shutdown mode. As they become active, the two trans-
mitter outputs are shown going to opposite RS-232 lev-
els. Each transmitter is loaded with 3kΩ in parallel with
2500pF. The transmitter outputs display no ringing or
undesirable transients as they come out of shutdown.
Note that the transmitters are enabled only when the
magnitude of V- exceeds approximately 3V.
Figure 7. Transmitter Outputs when Exiting Shutdown or
Powering Up
OUTPUT
INVALID
0
1
0
1
0
1
5V/div
2V/div
V
C1–C4 = 0.1μF
Shutdown (AutoShutdown)
CC
Shutdown (Forced Off)
Shutdown (Forced Off)
Active (AutoShutdown)
= +3.3V
OPERATION MODE
Active (Forced On)
Active (Forced On)
Transmitter Outputs when
OUTPUTS
40μs/div
Exiting Shutdown
T2OUT
T1OUT
FORCEON =
FORCEOFF
T_OUT
High-Z
High-Z
High-Z
Active
Active
Active
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