MAX3322EEUP+ Maxim Integrated Products, MAX3322EEUP+ Datasheet - Page 6

• Manufacturer Part Number: MAX3322EEUP+
• Description: IC TXRX RS232 250KBPS 20TSSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3322EEUP+

• 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 MAX3322E/MAX3323Es’ internal power supply con-
sists of a regulated dual charge pump that provides out-
put voltages of +5.5V (doubling charge pump) and
-5.5V (inverting charge pump), regardless of the input
voltage (V
pumps operate in a discontinuous mode: if the output
voltages are less than 5.5V, the charge pumps are
enabled; if the output voltages exceed 5.5V, the charge
pumps are disabled. Each charge pump requires a fly-
±15kV ESD-Protected, RS-232 Transceivers for
Multidrop Applications
Figure 1. Transmitter Propagation-Delay Timing
Figure 3. Interface Under Control of PMU
LapLink is a trademark of Traveling Software.
6
POWER SUPPLY
INPUT
OUTPUT
_______________________________________________________________________________________
MANAGEMENT
CONTROLLER
CPU
KEYBOARD
t
POWER-
UNIT OR
+3V
PLH
CHIP
Dual Charge-Pump Voltage Converter
I/O
CC
), over a +3.0V to +5.5V range. The charge
SHDN
CHIP
WITH
UART
I/O
V
L
0V
V
L
MAX3322E
SHDN
t
PHL
RS-232
V+
0V
V-
ing capacitor (C1, C2) and reservoir capacitor (C3, C4)
to generate the V+ and V- supplies. Because supply
voltages can vary from +3V up to +5.5V, the selection
of the capacitor values depends on the V
Table 2 shows minimum capacitor values.
The transmitters are inverting level translators that con-
vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The
transmitters are enabled or disabled (three-stated) by
the logic control TXENABLE, which manages transmis-
sion-line sharing in multidrop applications. When
TXENABLE is high, the transmitter is enabled. When
TXENABLE is low, the transmitter is put in a high-
impedance state (see Table 1).
The MAX3322E/MAX3323Es’ transmitters guarantee a
250kbps data rate with worst-case loads of 3kΩ in par-
allel with 1000pF, providing compatibility with PC-to-PC
communication software (such as LapLink™).
Transmitters can be paralleled to drive multiple
receivers or mice. Figure 3 shows a complete system
connection.
MAX3322E/MAX3323E receivers convert RS-232 sig-
nals to CMOS-logic output levels. The unique feature of
the receivers is the switchable input resistance. The
receiver input resistance can be 5kΩ or high imped-
ance. These two conditions are selectable by the logic
control RENABLE. When RENABLE is high, the 5kΩ
resistor is connected across the receiver input and
ground. When RENABLE is low, the receiver input is
high impedance, maintaining receiving capability. This
feature permits the design of multidrop applications,
which observe RS-232 interface standards.
Figure 2. Receiver Propagation-Delay Timing
OUTPUT
INPUT
t
PHL
0V
50%
50%
+3V
RS-232 Transmitters
RS-232 Receivers
50%
50%
GND
CC
t
PLH
V
value.
CC