MAX3243ECWI Maxim, MAX3243ECWI Datasheet - Page 6

• Manufacturer Part Number: MAX3243ECWI
• Description: 15kV ESD-Protected / 1A / 3.0V to 5.5V / 250kbps / RS-232 Transceivers with AutoShutdown
• Manufacturer: Maxim

±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
The MAX3221E/MAX3223E/MAX3243E’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), over the
+3.0V to +5.5V V
in 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.
LapLink is a trademark of Traveling Software.
6
_______________Detailed Description
MAX3221E
_______________________________________________________________________________________
10
11
12
13
14
15
16
—
1
2
3
4
5
6
7
8
9
Dual Charge-Pump Voltage Converter
MAX3223E
10, 15
12, 13
9, 16
8, 17
PIN
CC
11
14
18
19
20
—
1
2
3
4
5
6
7
range. The charge pumps operate
MAX3243E
12, 13, 14
9, 10, 11
15–19
4–8
28
27
24
21
23
20
25
26
22
—
1
2
3
FORCEOFF
FORCEON
R2OUTB
INVALID
R_OUT
T_OUT
NAME
R_IN
GND
T_IN
C1+
C2+
V
C1-
C2-
EN
V+
V-
CC
Receiver Enable Control. Drive low for normal operation. Drive high to
force the receiver outputs (R_OUT) into a high-impedance state.
Positive terminal of the voltage doubler Charge-Pump Capacitor
+5.5V generated by the charge pump
Negative terminal of the voltage doubler Charge-Pump Capacitor
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
TTL/CMOS Receiver Outputs
Output of the Valid Signal Detector. INVALID is enabled high if a valid
RS-232 level is present on any receiver input.
TTL/CMOS Transmitter Inputs
Drive high to override automatic circuitry keeping transmitters and
charge pump on (FORCEOFF must be high) (Table 1).
RS-232 Transmitter Outputs
TTL/CMOS Noninverting Complementary Receiver Output. Always
active.
Ground
+3.0V to +5.5V Supply Voltage
Force-Off Input, active low. Drive low to shut down transmitters,
receivers (MAX3243E, except R2OUTB), and on-board charge pump.
This overrides all automatic circuitry and FORCEON (Table 1).
The transmitters are inverting level translators that con-
vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They
guarantee a 250kbps data rate with worst-case loads
of 3kΩ in parallel with 1000pF, providing compatibility
with PC-to-PC communication software such as
LapLink™. Transmitters can be paralleled to drive mul-
tiple receivers. The MAX3243E has been specifically
designed to drive serial mice. Figure 1 shows a com-
plete system connection.
When FORCEOFF is driven to ground, or the
AutoShutdown circuitry senses invalid voltage levels on
all receiver inputs, the transmitters are disabled and the
outputs are forced into a high-impedance state. When
powered off or shut down, the output can be driven up
to ±12V. The transmitter inputs do not have pull-up
resistors.
FUNCTION
RS-232 Transmitters
Pin Description