MAX3243EWI+ Maxim Integrated Products, MAX3243EWI+ Datasheet - Page 5

• 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

The MAX3221/MAX3223/MAX3243’s internal power
supply consists of a regulated dual charge pump that
provides output voltages of +5.5V (doubling charge
pump) and -5.5V (inverting charge pump), regardless
of the input voltage (V
range. The charge 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 flying capacitor (C1, C2) and
a reservoir capacitor (C3, C4) to generate the V+ and
V- supplies.
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______________________________________________________________Pin Description
_______________Detailed Description
MAX3221
13
11
10
16
12
14
15
—
1
5
6
7
8
9
4
3
2
Dual Charge-Pump Voltage Converter
MAX3223
12, 13
10, 15
9, 16
8, 17
PIN
11
20
14
18
19
—
1
5
6
7
4
3
2
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________
1µA Supply-Current, True +3V to +5.5V
CC
MAX3243
12, 13, 14
9, 10, 11
15–19
4–8
) over the +3.0V to +5.5V
20
21
22
23
24
25
26
27
28
—
1
2
3
FORCEOFF
FORCEON
R2OUTB
INVALID
T_OUT
R_OUT
NAME
R_IN
GND
T_IN
C2+
C1+
V
C2-
C1-
EN
V+
V-
CC
Receiver Enable Control. Drive low for normal operation. Drive high to force
the receiver outputs into a high-Z state.
Positive terminal of inverting charge-pump capacitor
Negative terminal of inverting charge-pump capacitor
-5.5V generated by the charge pump
RS-232 Receiver Inputs
RS-232 Transmitter Outputs
TTL/CMOS Transmitter Inputs
TTL/CMOS Receiver Outputs
Noninverting Receiver Output—active in shutdown
Output of the valid signal detector. Indicates if a valid RS-232 level is pres-
ent on receiver inputs logic “1”.
Drive low to shut down transmitters and on-board power supply. This over-
rides all automatic circuitry and FORCEON (Table 1).
Drive high to override automatic circuitry keeping transmitters on
(FORCEOFF must be high) (Table 1).
Negative terminal of the voltage doubler charge-pump capacitor
Ground
+3.0V to +5.5V Supply Voltage
+5.5V generated by the charge pump
Positive terminal of the voltage doubler charge-pump capacitor
The transmitters are inverting level translators that con-
vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They
guarantee a 120kbps data rate with worst-case loads of
3kΩ in parallel with 1000pF, providing compatibility with
PC-to-PC communication software (such as Laplink™).
Typically, the MAX3221/MAX3223/MAX3243 can oper-
ate at data rates of 235kbps. Transmitters can be paral-
leled to drive multiple receivers or mice (MAX3243).
Figure 1 shows a complete system connection.
When FORCEOFF is driven to ground, or the Auto-
Shutdown circuitry senses invalid voltage levels at all
receiver inputs, the transmitters are disabled and the
outputs are forced into a high-impedance state.
FUNCTION
RS-232 Transmitters
5