October 2009 Doc ID 8648 Rev 12 1/16
16
ST3243EB
ST3243EC
± 15 kV ESD protected 3 to 5.5 V, 400 kbps, RS-232
transceiver with auto power-down
Features
■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
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.
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
Table 1. Device summary
Order codes Temperature range Package Packaging
ST3243ECTR-E 0 to 70 °C TSSOP28 (tape and reel) 2500 parts per reel
ST3243EBTR - 40 to 85 °C TSSOP28 (tape and reel) 2500 parts per reel
www.st.com
Contents ST3243EB, ST3243EC
2/16 Doc ID 8648 Rev 12
Contents
1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Application circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Timing diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
ST3243EB, ST3243EC Pin configuration
Doc ID 8648 Rev 12 3/16
1 Pin configuration
Figure 1. Pin configuration
Table 2. Pin description
Pin n° Symbol Name and function
1C
2+ Positive terminal of inverting charge pump capacitor
2C
2- Negative terminal of inverting charge pump capacitor
3 V- -5.5 V Generated by the charge pump
4R1
IN First receiver input voltage
5R2
IN Second receiver input voltage
6R3
IN Third receiver input voltage
7R4
IN Fourth receiver input voltage
8R5
IN Fifth receiver input voltage
9T1
OUT First transmitter output voltage
10 T2OUT Second transmitter output voltage
11 T3OUT Third transmitter output voltage
12 T3IN Third transmitter input voltage
13 T2IN Second transmitter input voltage
14 T1IN First transmitter input voltage
Pin configuration ST3243EB, ST3243EC
4/16 Doc ID 8648 Rev 12
15 R5OUT Fifth receiver output voltage
16 R4OUT Fourth receiver output voltage
17 R3OUT Third receiver output voltage
18 R2OUT Second receiver output voltage
19 R1OUT First receiver output voltage
20 R2OUTB
Non-inverting complementary receiver output, always active
for wake-up
21 INVALID Output of the valid signal detector. Indicates if a valid RS-232
level is present on receiver inputs logic "1"
22 FORCEOFF Drive low to shut down transmitters and on-board power
supply. This over-rides all automatic circuitry and FORCEON
23 FORCEON Drive high to override automatic circuitry keeping transmitters
on (FORCEOFF must be high)
24 C1- Negative terminal of voltage-charge pump capacitor
25 GND Ground
26 VCC Supply voltage
27 V+ 5.5 V Generated by the charge pump
28 C1+ Positive terminal of voltage-charge pump capacitor
Table 2. Pin description (continued)
Pin n° Symbol Name and function
ST3243EB, ST3243EC Truth tables
Doc ID 8648 Rev 12 5/16
2 Truth tables
Table 3. Invalid truth table
RS-232 Signal present at any receiver input INVALID output
YES H
NO L
Table 4. Output control truth table
Force
ON
Force
OFF Valid receiver level Operation status TOUT ROUT R2OUTB
X 0 X Shutdown (Force OFF) HIGH Z HIGH Z ACTIVE
11 X Normal operating (Force
ON) ACTIVE ACTIVE ACTIVE
0 1 YES Normal operating
(Auto power-down) ACTIVE ACTIVE ACTIVE
01 NO Shutdown
(Auto power-down) HIGH Z ACTIVE ACTIVE
Maximum ratings ST3243EB, ST3243EC
6/16 Doc ID 8648 Rev 12
3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.
Table 5. Absolute maximum ratings
Symbol Parameter Value Unit
VCC Supply voltage -0.3 to 6 V
V+ Doubled voltage terminal (VCC -0.3) to 7 V
V- Inverted voltage terminal 0.3 to -7 V
V+ +|V-| 13 V
FORCEON,
FORCEOFF,
TIN
Input voltage -0.3 to 6 V
RIN Receiver input voltage range ± 25 V
TOUT Transmitter output voltage range ± 13.2 V
ROUT ROUTB
INVALID Receiver output voltage range -0.3 to (VCC + 0.3) V
tSHORT Short circuit duration on TOUT (one at a time) Continuous
Tstg Storage temperature range -65 to 150 °C
Table 6. ESD performance: transmitter outputs, receiver inputs
Symbol Parameter Test conditions Min. Typ. Max. Unit
ESD ESD protection voltage Human body model ± 15 kV
ESD ESD protection voltage IEC 1000-4-2 (contact discharge) ± 8kV
ST3243EB, ST3243EC Electrical characteristics
Doc ID 8648 Rev 12 7/16
4 Electrical characteristics
C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified.
Typical values are referred to TA = 25 °C.
C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified.
Typical values are referred to TA = 25 °C.
Table 7. Electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
IASHDN
Supply current auto
power-down
FORCEOFF = GND,FORCEON = VCC
All R_IN open or grounded 110µA
ISUPPLY Supply current FORCEON = FORCEOFF = VCC 0.3 1 mA
ISHDN Shutdown supply current FORCEOFF = GND 1 10 µA
Table 8. Logic input electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
VTIL Input logic threshold low T-IN, FORCEON, FORCEOFF 0.8 V
VTIH Input logic threshold high
T-IN, FORCEON, FORCEOFF
VCC = 3.3 V
VCC = 5 V
2
2.4
V
V
VTHYS
Transmitter input
hysteresis 0.5 V
IIL Input leakage current T-IN, FORCEON, FORCEOFF ± 0.01 ± 1.0 µA
IOL Output leakage current Receiver disabled ± 0.05 ± 10 µA
VOL Output voltage low IOUT = 1.6 mA 0.4 V
VOH Output voltage high IOUT = -1 mA VCC-0.6 VCC-0.1 V
Electrical characteristics ST3243EB, ST3243EC
8/16 Doc ID 8648 Rev 12
C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified.
Typical values are referred to TA = 25 °C, FORCEON = GND, FORCEOFF = VCC.
C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified.
Typical values are referred to TA = 25 °C.
Table 9. Auto power-down electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
VRITE
Receiver input threshold
to INVALID output voltage
HIGH (see Figure 3)
Positive threshold 2.7 V
Negative threshold 2.7 V
VRITD
Receiver input threshold
to INVALID output voltage
LOW (see Figure 3)
-0.3 0.3 V
VIOL
INVALID output voltage
LOW IOUT = 1.6 mA 0.4 V
VIOH
INVALID output voltage
HIGH IOUT = -1 mA VCC-0.6 V
tWU
Receiver or transmitter
edge transmitter enabled
(see Figure 3)
100 µs
tINVH
Receiver positive or
negative threshold to
INVALID HIGH
(see Figure 3)
0.2 µs
tINVL
Receiver positive or
negative threshold to
INVALID LOW
(see Figure 3)
30 µs
Table 10. Transmitter electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
VTOUT Output voltage swing All Transmitter outputs are loaded with
3kΩ to GND ± 5± 5.4 V
ROUT Output resistance VCC = V+ = V- = 0 V, VOUT = ± 2 V 300 10M Ω
ISC
Output short circuit
current VCC = 3.3 V ± 40 ± 60 mA
ILOutput leakage current VCC = 0 to 5.5V, transmitter output =
±12 V, transmitter disabled ± 25 µA
VOT Transmitter output voltage
T1IN = T2IN = GND,T3IN = VCC
T3OUT loaded with 3 kΩ to GND
T1OUT and T2OUT loaded with 2.5mA
each
± 5V
ST3243EB, ST3243EC Electrical characteristics
Doc ID 8648 Rev 12 9/16
C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified.
Typical values are referred to TA = 25 °C.
C1 - C4 = 0.1 µF, VCC = 3 V to 5.5 V, TA = -40 to 85 °C, unless otherwise specified.
Typical values are referred to TA = 25 °C.
Table 11. Receiver electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
VRIN
Receiver input voltage
operating range -25 25 V
VRIL
RS-232 Input threshold
low
TA = 25°C, VCC = 3.3 V
TA = 25°C, VCC = 5.0 V
0.6
0.8
1.1
1.4 V
VRIH
RS-232 Input threshold
high
TA = 25°C, VCC = 3.3 V
TA = 25°C, VCC = 5.0 V
1.6
1.9
2.4
2.4 V
VRIHYS Input hysteresis 0.5 V
RRIN Input resistance TA = 25°C 3 5 7 kΩ
Table 12. Timing characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
DRMaximum data rate RL = 3kΩ, CL= 1000 pF one transmitter
switching 250 400 kbps
tPHL
tPLH
Receiver propagation
delay RIN to ROUT
, CL = 150 pF 0.15 µs
tT_SKEW Transmitter skew 150 ns
tR_SKEW Receiver skew 70 ns
SRT Transition slew rate
TA = 25°C RL = 3k to 7kΩ, VCC = 3.3 V
measured from +3 V to -3 V or -3 V to +3 V
CL = 150 pF to 1000 pF
CL = 150 pF to 2500 pF
6
4
30
30
V/µs
V/µs
Application circuits ST3243EB, ST3243EC
10/16 Doc ID 8648 Rev 12
5 Application circuits
Figure 2. Application circuits
Table 13. Required minimum capacitance value (µF)
VCC (V) C1C2, C3, C4, CBYPASS
3 to 3.6 0.1 0.1
4.5 to 5.5 0.047 0.33
ST3243EB, ST3243EC Timing diagrams
Doc ID 8648 Rev 12 11/16
6 Timing diagrams
Figure 3. Auto power-down input levels
Figure 4. Auto power-down input timing
Package mechanical data ST3243EB, ST3243EC
12/16 Doc ID 8648 Rev 12
7 Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
ST3243EB, ST3243EC Package mechanical data
Doc ID 8648 Rev 12 13/16
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A 1.2 0.047
A1 0.05 0.15 0.002 0.004 0.006
A2 0.81 1.05 0.031 0.039 0.041
b0.190.30 0.007 0.012
c0.090.20 0.004 0.0079
D9.6 9.7 9.80.3780.382 0.386
E 6.2 6.4 6.6 0.244 0.252 0.260
E1 4.34.4 4.480.1690.1730.176
e 0.65 BSC 0.0256 BSC
K0° 8°0° 8°
L 0.45 0.60 0.75 0.0180.024 0.030
TSSOP28 mechanical data
0128292B
Package mechanical data ST3243EB, ST3243EC
14/16 Doc ID 8648 Rev 12
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A330 12.992
C 12.813.2 0.504 0.519
D 20.2 0.795
N60 2.362
T 22.4 0.882
Ao 6.87 0.2680.276
Bo 10.1 10.30.398 0.406
Ko 1.7 1.90.067 0.075
Po 3.94.1 0.1530.161
P 11.912.1 0.4680.476
Tape & reel TSSOP28 mechanical data
ST3243EB, ST3243EC Revision history
Doc ID 8648 Rev 12 15/16
8 Revision history
Table 14. Document revision history
Date Revision Changes
21-Jun-2004 6 Page 6 - IL (output leakage current) mA ==> µA
31-Mar-2006 7 Order codes updated and new template.
25-Oct-2006 8 Order codes updated.
24-Aug-2007 9 Order codes updated.
09-Jul-2008 10 Removed: SO-28 and SSOP28 packages.
28-Jul-2009 11 Removed: Flip-chip28 package, modified Table 1 on page 1.
16-Oct-2009 12 Modified Table 9 on page 8.
ST3243EB, ST3243EC
16/16 Doc ID 8648 Rev 12
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