April 2009 Doc ID 6228 Rev 18 1/22
22
ST75185C
Multiple RS-232 drivers and receivers
Features
■Meets and exceeds the requirements of
EIA/TIA-232-E and ITUV.28 standard
■Single chip with easy interface between UART
and serial port connector of IBM PC/AT™ and
compatibles
■Designed to support data rates up to 120 kbps
■Pinout compatible with ST75C185
Description
The ST75185C contains three drivers and five
receivers. The pinout matches the DB9S
connector design in order to decrease the part
count, reduce the board space required and allow
easy interconnection of the UART and serial port
connector of IBM PC/AT™ and compatibles. The
bipolar circuits and processing of the ST75185C
provides a rugged low-cost solution for this
function at the expense of quiescent power and
external passive components relative to the
ST75C185.
The ST75185C complies with the requirements of
the EIA/TIA 232-E and ITU (formally CCITT) v.28
standards. These standards are for data
interchange between a host computer and
peripheral at signalling rates up to 20 k-bits/s. The
switching speeds of the ST75185C are fast
enough to support rates up to 120 K-bits/s with
lower capacitive loads (shorter cables). Inter-
operability at the higher signalling rates cannot be
assured unless the designer has design control of
the cable and the interface circuits at the both
ends. For inter-operability at signalling rates to
120 k-bits/s, use of EIA/ITA-423-B (ITU v.10) and
EIA/ITA-422-B (ITU v.11) standards are
recommended.
The ST75185C is characterized for operation over
the range of 0°C to 70 °C.
SO-20 TSSOP20
Table 1. Device summary
Order codes Temperature range Packages Packaging
ST75185CTR 0 to 70 °C TSSOP20 (tape and reel) 2500 parts per reel
ST75185CDR 0 to 70 °C SO-20 (tape and reel) 1000 parts per reel
www.st.com
Contents ST75185C
2/22 Doc ID 6228 Rev 18
Contents
1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 Application information: diodes on power supply . . . . . . . . . . . . . . . . 15
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ST75185C Pin configuration
Doc ID 6228 Rev 18 3/22
1 Pin configuration
Figure 1. Pin connection IEC logic symbol and logic diagram
Table 2. Pin description
Pin n° Symbol Name and function
1V
DD Supply voltage (+12 V)
2 RA1 First receiver input
3 RA2 Second receiver input
4 RA3 Third receiver input
5 DY1 First driver output
6 DY2 Second driver output
7 RA4 Fourth receiver input
8 DY3 Third driver output
9 RA5 Fifth receiver input
10 VSS Supply voltage (-12V)
11 GND Ground
12 RY5 Fifth receiver output
13 DA3 Third driver input
14 RY4 Fourth receiver output
15 DA2 Second driver input
16 DA1 First driver input
17 RY3 Third receiver output
18 RY2 Second receiver output
19 RY1 First receiver output
20 VCC Supply voltage (+5 V)
Maximum ratings ST75185C
4/22 Doc ID 6228 Rev 18
2 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 3. Absolute maximum ratings over operating free-air temperature range
Symbol Parameter Value Unit
VDD Supply voltage (1)
1. All voltage are with respect to the network ground terminal.
15 V
VSS Supply voltage (1) -15 V
VCC Supply voltage (1) 10 V
VIInput voltage range (Driver) -15 to 7 V
VIInput voltage range (Receiver) -30 to 30 V
VOOutput voltage range (Driver) -15 to 15 V
IOReceiver low level output current 20 mA
PDContinuous total power dissipation See dissipation rating table
TAOperating free-air temperature range 0 to 70 °C
TSTG Storage temperature range -65 to + 150 °C
TLLead temperature 1.6 mm. from case for 10 sec. 260 °C
Table 4. Dissipation rating table
Package Power rating
at TA ≤ 25°C
Derating factor
above TA = 25°C
Power rating
at TA ≤ 70°C
MICROPACKAGE (D) 1125 mW 9.0 mW/°C 720 mW
Table 5. Thermal data
Symbol Parameter TSSOP20 Unit
RthJC Thermal resistance junction-case 27.22 °C/W
RthJA Thermal resistance junction-ambient 114.5 (1) °C/W
1. This value is referred to single-layer PCB, JEDEC standard test board.
ST75185C Maximum ratings
Doc ID 6228 Rev 18 5/22
Table 6. Recommended operating conditions
Symbol Parameter Min. Max. Unit.
VDD Supply voltage 7.5 15 V
VSS Supply voltage -7.5 -15 V
VCC Supply voltage 4.5 5.5 V
VIDriver input voltage 0 VCC V
IOH High level output current Driver -6 mA
Receiver -0.5
IOL Low level output current Driver 6 mA
Receiver 16
TAOperating free-air temperature range 0 70 °C
Electrical characteristics ST75185C
6/22 Doc ID 6228 Rev 18
3 Electrical characteristics
Table 7. Supply currents
Symbol Parameter
Test conditions Value
Unit
VDD VSS Min. Typ. Max.
IDD Supply current from VDD
9-9
No load.
all inputs at
1.9V
15
mA12 -12 19
15 -15 25
9-9
No load.
all inputs at
0.8V
4.5
mA12 -12 5.5
15 -15 9
ISS Supply current from VSS
9-9
No load.
all inputs at
1.9V
-15
mA12 -12 -19
15 -15 -25
9-9
No load.
all inputs at
0.8V
-3.2
mA12 -12 -3.2
15 -15 -3.2
ICC Supply current from VCC
No load. All inputs at 5V
VCC = 5V 30 mA
ST75185C Electrical characteristics
Doc ID 6228 Rev 18 7/22
VDD = 9 V, VSS = -9 V, VCC = 5 V, unless otherwise specified.
Note: 1 The algebraic convention, where the more positive (less negative) limits designated as
maximum, is used in this datasheet for logic levels only (e.g. if - 10 V is a maximum, the
typical value is a more negative voltage).
2 Output short circuit conditions must maintain the total power dissipation below absolute
maximum ratings.
3 Test conditions are those specified by EIA-232-E and as listed above.
VDD = 12 V, VSS = -12 V, VCC = 5 V, TA = 25 °C
4 Measured between -3 V and 3 V points of output waveform (EIA-232-E conditions), all
unused inputs are tied.
Table 8. Driver electrical characteristics over operating free-air temperature range
Symbol Parameter Test conditions
Value
Unit
Min. Typ. Max.
VOH High level output voltage VIL = 0.8 V, RL = 3kΩ
(See Figure 3)67.5 V
VOL
Low level output voltage
(Note 3)
VIH = 1.9 V, RL = 3kΩ
(See Figure 3)-7.5 -6 V
IIH High level input current VI = 5 V (See Figure 4)10µA
IIL Low level input current VI = 0 V (See Figure 4)−1.6 mA
IOS(H)
High level short circuit
output current (Note 4)
VIL = 0.8 V, VO = 0 V
(See Figure 3)-4.5 −12 −19.5 mA
IOS(L)
Low level short circuit output
current
VIH = 2 V VO = 0 V
(See Figure 3)4.5 12 19.5 mA
ROOutput resistance VDD = VSS = VCC = 0 V
VO = -2 to 2 V (Note 3)300 Ω
Table 9. Driver switching characteristics
Symbol Parameter Test conditions
Value
Unit
Min. Typ. Max.
tPLH
Propagation Delay Time, Low to
High Level Output
RL = 3 to 7 kΩ CL = 15 pF
(See Figure 5, Figure 6)315 500 ns
tPHL
Propagation Delay Time, High to
Low Level Output
RL = 3 to 7 kΩ CL = 15 pF
(See Figure 5, Figure 6)75 175 ns
tTLH
Transition Time Low to High Level
Output
RL = 3 to 7 kΩ CL = 15 pF
(See Figure 5, Figure 6)60 100 ns
RL = 3 to 7 kΩ CL = 2500 pF
(Note 4, Figure 5, Figure 6)1.7 2.5 µs
tTHL
Transition Time High to Low Level
Output
RL = 3 to 7 kΩ CL = 15 pF
(See Figure 5, Figure 6)40 7.5 ns
RL = 3 to 7 kΩ CL = 2500 pF
(Note 4, Figure 5, Figure 6)1.5 2.5 µs
Electrical characteristics ST75185C
8/22 Doc ID 6228 Rev 18
Note: All typical values are at TA = 25 °C, VCC = 5 V, VDD = 9 V and VSS = -9 V
VDD = 12 V, VSS = -12 V, VCC = 5 V TA = 25 °C
Table 10. Receiver electrical characteristics over operating conditions
Symbol Parameter Test conditions
Value
Unit
Min. Typ. Max.
VT+ Positive going threshold voltage (See Figure 9)2.22.4V
VT- Negative going threshold voltage TA = 25 °C (See Figure 9) 0.75 0.97 V
Vhys Input hysteresis (VT+ - VT
-) 0.5 V
VOH High level output voltage IOH = -0.5mA VIH = 0.75 V 2.6 4 5 V
Inputs Open 2.6
VOL Low level output voltage VI = 3 V IOL = 10 mA 0.2 0.45 V
IIH High level input current VI = 25 V (See Figure 9)3.6 8.3
mA
VI = 3 V (See Figure 9)0.43
IIL Low level input current VI = -25 V (See Figure 9) -3.6 -8.3 mA
VI = -3 V (See Figure 9) -0.43
IOS Short-circuit output current VI = 0 V VO = 0 V
(See Figure 7)-3.4 -12 mA
Table 11. Receiver switching characteristics
Symbol Parameter Test conditions
Value
Unit
Min. Typ. Max.
tPLH
Propagation delay time low to high
level output
RL = 5 kΩ CL = 50 pF
(See Figure 9)400 1000 ns
tPHL
Propagation delay time high to low
level output
RL = 5 kΩ CL = 50 pF
(See Figure 9)70 150 ns
tTLH
Transition time low to high level
output
RL = 5 kΩ CL = 50 pF
(See Figure 9)200 525 ns
tTHL
Transition time high to low level
output
RL = 5 kΩ CL = 50 pF
(See Figure 9)20 60 ns
ST75185C Typical application
Doc ID 6228 Rev 18 9/22
4 Typical application
Figure 2. Application circuits
Figure 3. Driver test circuit for VOH, ISO(H) and ISO(L)
Typical application ST75185C
10/22 Doc ID 6228 Rev 18
Figure 4. Driver test circuit for IIH and IIL
Figure 5. Driver test circuit
Figure 6. Driver voltage waveforms
ST75185C Typical application
Doc ID 6228 Rev 18 11/22
Figure 7. Receiver test circuit for IOS
Figure 8. Receiver test circuit for VT, VOH, VOL
Figure 9. Receiver test circuit
Typical application ST75185C
12/22 Doc ID 6228 Rev 18
Note: 1 The pulse generator has the following characteristics: tW = 25 µs, PRR = 20 kHz,
ZO = 50
Ω
, tr = tf < 50 ns
2C
L includes probe and jig capacitance.
Figure 10. Receiver voltage waveforms
ST75185C Typical characteristics
Doc ID 6228 Rev 18 13/22
5 Typical characteristics
Figure 11. Driver voltage transfer
characteristics
Figure 12. Driver short circuit output current
vs. free-air temperature
Figure 13. Device supply current vs.
temperature
Figure 14. Driver output current vs. output
voltage
Typical characteristics ST75185C
14/22 Doc ID 6228 Rev 18
Figure 15. Driver output slew rate vs. load
capacitance
Figure 16. Receiver threshold vs. temperature
Figure 17. Receiver threshold vs. supply
voltage
ST75185C Application information: diodes on power supply
Doc ID 6228 Rev 18 15/22
6 Application information: diodes on power supply
Diodes placed in series with the VDD and VSS leads protect the ST75185C in the fault
condition in which the devices output are shorted to ±15 V and the power supplies are at low
state and provide low-impedance path to ground (see Figure 18).
Figure 18. Diodes on power supply
Package mechanical data ST75185C
16/22 Doc ID 6228 Rev 18
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.
ST75185C Package mechanical data
Doc ID 6228 Rev 18 17/22
Dim. mm. inch.
Min. Typ. Max. Min. Typ. Max.
A2.35 2.65 0.093 0.104
A1 0.1 0.30 0.004 0.012
B0.33 0.51 0.0130.020
C0.230.32 0.0090.013
D 12.60 13.00 0.496 0.512
E 7.4 7.6 0.291 0.299
e 1.27 0.050
H 10.00 10.65 0.394 0.419
h 0.25 0.75 0.010 0.030
L 0.4 1.27 0.016 0.050
k0° 8°0° 8°
ddd 0.100 0.004
SO-20 mechanical data
0016022D
Package mechanical data ST75185C
18/22 Doc ID 6228 Rev 18
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
D 6.4 6.5 6.6 0.252 0.256 0.260
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
TSSOP20 mechanical data
cE
b
A2
A
E1
D
1
PIN 1 IDENTIFICATION
A1 L
K
e
0087225C
ST75185C Package mechanical data
Doc ID 6228 Rev 18 19/22
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
T30.4 1.197
Ao 10.811 0.425 0.433
Bo 13.2 13.4 0.520 0.528
Ko 3.1 3.30.122 0.130
Po 3.94.1 0.1530.161
P 11.912.1 0.4680.476
Tape & reel SO-20 mechanical data
Package mechanical data ST75185C
20/22 Doc ID 6228 Rev 18
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 6.97.1 0.272 0.280
Ko 1.7 1.90.067 0.075
Po 3.94.1 0.1530.161
P 11.912.1 0.4680.476
Tape & reel TSSOP20 mechanical data
ST75185C
22/22 Doc ID 6228 Rev 18
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