ST3243EB
ST3243EC
± 15 kV ESD protected 3 to 5.5 V, 400 kbps, RS-232
transceiver with auto power-down
Features
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ESD protection for RS-232 I/O pins:
– ± 8 kV IEC 1000-4-2 contact discharge
– ± 15 kV human body model
1 µA supply current achieved when in auto
power-down
250 kbps minimum guaranteed data rate
Guaranteed 6 V/ms slew rate range
Guaranteed mouse drive ability
0.1 µF external capacitors
Meet EIA/TIA-232 specifications down to 3 V
Available in TSSOP28 package
The auto power-down feature functions when
FORCEON is low and FORCEOFF is high. During
this mode of operation, if the device does not
sense a valid RS-232 signal, the driver outputs
are disabled. If FORCEOFF is set low, both
drivers and receivers (expert R2B) are shut off,
and supply current is reduced to 1 µA.
Disconnecting the serial port or turning off the
peripheral drives causes the auto power-down
condition to occur.
Auto power-down can be disabled when
FORCEON and FORCEOFF are high, and should
be done when driving a serial mouse. With auto
power-down enabled, the device is activated
automatically when a valid signal is applied to any
receiver input.
Typical application are in notebook, subnotebook,
palmtop computers, battery-powered equipment,
handheld equipment, peripherals and printers.
TSSOP
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Description
The ST3243E device consists of 3 drivers, 5
receivers and a dual charge-pump circuit. The
device meets the requirements of EIA/TIA and
V.28/V.24 communication standards providing
high data rate capability and enhanced
electrostatic discharge (ESD) protection. All
transmitter outputs and receiver input are
protected to ± 8 kV USING IEC 1000-4-2 contact
discharge and ± 15 kV using the human body
model. The receiver R2 is always active to
implement a wake-up feature for serial port.
The ST3243E has a proprietary low-dropout
transmitter output stage enabling true RS-232
performance from a 3.0 V to 5.5 V supply with a
dual charge pump. The device is guaranteed to
run at data rates of 250 kbps while maintaining
RS-232 output levels.
Table 1.
Device summary
Temperature range
0 to 70 °C
- 40 to 85 °C
Package
TSSOP28 (tape and reel)
TSSOP28 (tape and reel)
Packaging
2500 parts per reel
2500 parts per reel
Order codes
ST3243ECTR-E
ST3243EBTR
October 2009
Doc ID 8648 Rev 12
1/16
www.st.com
16
Contents
ST3243EB, ST3243EC
Contents
1
2
3
4
5
6
7
8
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Application circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Timing diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2/16
Doc ID 8648 Rev 12
ST3243EB, ST3243EC
Pin configuration
1
Figure 1.
Pin configuration
Pin configuration
Table 2.
Pin description
Pin n°
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Symbol
C
2
+
C
2
-
V-
R1
IN
R2
IN
R3
IN
R4
IN
R5
IN
T1
OUT
T2
OUT
T3
OUT
T3
IN
T2
IN
T1
IN
Name and function
Positive terminal of inverting charge pump capacitor
Negative terminal of inverting charge pump capacitor
-5.5 V Generated by the charge pump
First receiver input voltage
Second receiver input voltage
Third receiver input voltage
Fourth receiver input voltage
Fifth receiver input voltage
First transmitter output voltage
Second transmitter output voltage
Third transmitter output voltage
Third transmitter input voltage
Second transmitter input voltage
First transmitter input voltage
Doc ID 8648 Rev 12
3/16
Pin configuration
Table 2.
Pin description (continued)
Pin n°
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Symbol
R5
OUT
R4
OUT
R3
OUT
R2
OUT
R1
OUT
R2
OUTB
INVALID
FORCEOFF
FORCEON
C
1
-
GND
V
CC
V+
C
1
+
ST3243EB, ST3243EC
Name and function
Fifth receiver output voltage
Fourth receiver output voltage
Third receiver output voltage
Second receiver output voltage
First receiver output voltage
Non-inverting complementary receiver output, always active
for wake-up
Output of the valid signal detector. Indicates if a valid RS-232
level is present on receiver inputs logic "1"
Drive low to shut down transmitters and on-board power
supply. This over-rides all automatic circuitry and FORCEON
Drive high to override automatic circuitry keeping transmitters
on (FORCEOFF must be high)
Negative terminal of voltage-charge pump capacitor
Ground
Supply voltage
5.5 V Generated by the charge pump
Positive terminal of voltage-charge pump capacitor
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Doc ID 8648 Rev 12
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