ST3243
3 to 5.5V, 400Kbps, RS-232 Transceiver
with auto-powerdown
General features
s
1µA supply current achieved when in auto-
powerdown
250kbps minimum guaranteed data rate
Guaranteed 6V/µs slew rate range
Guaranteed mouse drive ability
0.1µF external capacitors
Meet EIA/TIA-232 specifications down to 3V
Available in SO-28, SSOP-28 and TSSOP28
SSOP
TSSOP
SOP
s
s
s
s
s
s
Description
The ST3243 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.
The receiver R2 is always active to implement a
wake-up feature for serial port.
The ST3243 has a proprietary low-dropout
transmitter output stage enabling true RS-232
performance from a 3.0V to 5.5V supply with a
dual charge pump. The device is guaranteed to
run at data rates of 250kbps while maintaining
RS-232 output levels.
The Auto-powerdown 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 1mA.
Disconnecting the serial port or turning off the
peripheral drives causes the auto-powerdown
condition to occur.
Auto-powerdown can be disabled when
FORCEON and FORCEOFF are high, and should
be done when driving a serial mouse. With Auto-
powerdown 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,
hand-held equipment, peripherals and printers.
Order code
Part number
ST3243CDR
ST3243CPR
ST3243CTR
ST3243BTR
Temperature range
0 to 70 °C
0 to 70 °C
0 to 70 °C
-40 to 85 °C
Package
SO-28 (Tape & Reel)
SSOP-28 (Tape & Reel)
TSSOP28 (Tape & Reel)
TSSOP28 (Tape & Reel)
Comments
1000 parts per reel
1350 parts per reel
2500 parts per reel
2500 parts per reel
March 2006
Rev 7
1/20
www.st.com
20
Contents
ST3243
Contents
1
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1
Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2
3
4
5
6
7
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Application circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2/20
ST3243
Pin configuration
1
Figure 1.
Pin
configuration
Pin configuration
Table 1.
Pin n°
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Pin description
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
R5
OUT
R4
OUT
R3
OUT
Name and function
Positive terminal of inverting charge pump capacitor
Negative terminal of inverting charge pump capacitor
-5.5V 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
Fifth receiver output voltage
Fourth receiver output voltage
Third receiver output voltage
3/20
Pin configuration
Table 1.
Pin n°
18
19
20
21
22
23
24
25
26
27
28
ST3243
Pin description
Symbol
R2
OUT
R1
OUT
R2
OUTB
INVALID
FORCEOFF
FORCEON
C
1
-
GND
V
CC
V+
C
1
+
Name and function
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
5.5V Generated by the charge pump
Positive terminal of voltage-charge pump capacitor
1.1
Table 2.
Truth table
FORCE OFF
0
1
T
OUT
HIGH Z
ACTIVE
Note:
R
OUT
HIGH Z
ACTIVE
Note:
R
2OUTB
ACTIVE
Note:
ACTIVE
Note:
Note:
If the part is in auto-powerdown mode (FORCE OFF = VCC, FORCE ON = GND) it is
shutdown, if no valid RS-232 levels are present on all receiver input
4/20
ST3243
Maximum ratings
2
Table 3.
Symbol
V
CC
V+
V-
V+ +|V-|
Maximum ratings
Absolute maximum ratings
Parameter
Supply voltage
Doubled voltage terminal
Inverted voltage terminal
Value
-0.3 to 6
(V
CC
-0.3) to 7
0.3 to -7
13
-0.3 to 6
±
25
±
13.2
-0.3 to (V
CC
+ 0.3)
Continuous
-65 to 150
°C
Unit
V
V
V
V
V
V
V
V
FORCEON,
Input voltage
FORCEOFF, T
IN
R
IN
T
OUT
R
OUT
R
OUTB
INVALID
t
SHORT
T
stg
Receiver input voltage range
Transmitter output voltage range
Receiver output voltage range
Short circuit duration on T
OUT
(one at a time)
Storage temperature range
Note:
1
Absolute Maximum Ratings are those values beyond which damage to the device may
occur. Functional operation under these condition is not implied. V+ and V- can have a
maximum magnitude of +7V, but their absolute addition can not exceed 13 V.
The device doesn’t meet 1KV ESD HBM
2
5/20
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