3.3 V powered, 15 kV ESD protected,
up to 12 Mbps true RS-485/RS-422 transceiver
Features
■ ESD protection
– ±15 kV human body model
– ±8 kV IEC 1000-4-2 contact discharge
■ Operate from a single 3.3 V supply - no charge
pump required
■ Interoperable with 5 V logic
■ 1 µA low current shutdown mode max
■ Guaranteed 12 Mbps data rate
■ -7 to 12 common mode input voltage range
■ Half duplex versions available
■ Industry standard 75176 pinout
■ Current limiting and thermal shutdown for
driver overload protection
■ Guaranteed high receiver output state for
floating, shorted or terminated inputs with no
signal present
■ Allow up to 64 transceivers on the bus
ST1480AB
ST1480AC
DIP-8
thermal shutdown circuitry that places the driver
outputs into a high-impedance state.
The ST1480A input has a true fail-safe feature
that guarantees a logic high output if both inputs
are open circuit, shorted together or in the
presence of a termination with no signal on the
bus.
SO-8
Description
The ST1480A is ±15 kV ESD protected, 3.3 V low
power transceiver for RS-485 and RS-422
communications. The device contains one driver
and one receiver in half duplex configuration.
The ST1480A transmits and receives at a
guaranteed data rate of at least 12 Mbps.
All transmitter outputs and receiver inputs are
protected to ±15 kV using Human Body Model.
Driver is short-circuit current limited and is
protected against excessive power dissipation by
Figure 1. Device summary
Part number Temperature range Package Packaging
ST1480ACN 0 to 70 °C DIP-8 50 parts per tube / 40 tube per box
ST1480ACDR 0 to 70 °C SO-8 (tape & reel) 2500 parts per reel
ST1480ABDR -40 to 85 °C SO-8 (tape & reel) 2500 parts per reel
November 2007 Rev 3 1/22
www.st.com
22
Contents ST1480AB - ST1480AC
Contents
1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Test circuits and typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2/22
ST1480AB - ST1480AC Pin configuration
1 Pin configuration
Figure 2. Pin connections
Table 1. Pin description
Pin n° Symbol Name and function
1 RO Receiver output. If A>B by 200mV, RO will be high; if A<B by 200mV, RO will be low
2RE
3DE
4DI
5 GND Ground
6 A Non-inverting receiver input and non-inverting driver output
7 B Inverting receiver input and inverting driver output
8V
CC
Receiver Output Enable. RO is enabled when RE is low; RO is high impedance when RE
is high. If RE is high and DE is low, the device will enter a low power shutdown mode.
Driver Output Enable. The driver outputs are enabled by bringing DE high. They are high
impedance when DE is low. If RE is high DE is low, the device will enter a low-power
shutdown mode. If the driver outputs are enabled, the part functions as line driver, while
they are high impedance, it functions as line receivers if RE is low.
Driver input. A low on DI forces output A low and output B high. Similarly, a high on DI
forces output A high and output B low
Supply voltage: VCC= 3V to 3.6V
3/22
Truth tables ST1480AB - ST1480AC
2 Truth tables
Table 2. Truth table (driver)
Inputs Outputs
Mode
RE
XHHLH Normal
XHLHL Normal
LLXZZ Normal
H L X Z Z Shutdown
Note: X= Don’t care; Z=High impedance
Table 3. Truth table (receiver)
RE DE A-B RO
DE DI B A
Inputs Output
Mode
LL
LL
L L Inputs open H Normal
L L Inputs shorted H Normal
H L X Z Shutdown
≥ -0.015V H Normal
≤ -0.2V L Normal
Note: X= Don’t care; Z=High impedance
4/22
ST1480AB - ST1480AC Maximum ratings
3 Maximum ratings
Table 4. Absolute maximum ratings
Symbol Parameter Value Unit
V
CC
V
I
V
DI
V
DO
V
RI
V
RO
Supply voltage 7 V
Control input voltage (RE, DE) -0.3 to 7 V
Driver input voltage (DI) -0.3 to 7 V
Driver output voltage (A, B) ± 14 V
Receiver input voltage (A, B) ± 14 V
Receiver output voltage (RO) -0.3 to (VCC + 0.3) V
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. 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
5/22
Electrical characteristics ST1480AB - ST1480AC
4 Electrical characteristics
Table 6. Electrical characteristics
= 3 V to 3.6 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred
V
CC
to T
= 25 °C)
A
Symbol Parameter Test conditions Min. Typ. Max. Unit
I
SUPPLYVCC
I
SHDN
Shutdown supply current DE=0V, RE=VCC, DI=0V or VCC 0.002 1 µA
Power supply current No Load, DI=0V or V
DE=VCC,
RE=0V or V
CC
DE=0V,
RE
CC
=0V
1.3 2.2 mA
1.2 1.9 mA
Table 7. Logic input electrical characteristics
V
= 3 V to 3.6 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred
CC
to T
= 25 °C)
A
Symbol Parameter Test conditions Min. Typ. Max. Unit
Input logic threshold low DE, DI, RE 1.3 0.8 V
IL
Input logic threshold high DE, DI, RE 2 V
IH
Logic input current DE, DI, RE ± 2.0 µA
V
=12V 1 mA
Input current (A, B) DE=0V, VCC= 0 or 3.6V
IN
V
=-7V -0.8 mA
IN
V
I
I
V
IN1
IN2
Table 8. Transmitter electrical characteristics
V
= 3 V to 3.6 V, TA = -40 to 85 °C, unless otherwise specified. Typical values are referred
CC
to T
= 25 °C)
A
Symbol Parameter Test conditions Min. Typ. Max. Unit
R
= 100Ω (RS-422) (Figure 2)2 V
L
V
Differential drive output
OD
= 54Ω (RS-485) (Figure 2)1.5 V
R
L
R
= 60Ω (RS-485) (Figure 3)1.5 V
L
Change in magnitude of driver
ΔV
differential output voltage for
OD
complementary output states
= 54Ω or 100Ω (Figure 2)0.2V
R
L
(Note: 1)
V
Driver common mode output
OC
voltage
= 54Ω or 100Ω (Figure 2)3V
R
L
Change in magnitude of driver
ΔV
common mode output voltage
OC
= 54Ω or 100Ω (Figure 2)0.2V
R
L
(Note: 1)
I
OSD
Driver short circuit output
current
6/22
± 250 mA
ST1480AB - ST1480AC Electrical characteristics
Table 9. Receiver electrical characteristics
V
= 3V to 3.6V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred
CC
to T
= 25°C)
a
Symbol Parameter Test Conditions Min. Typ. Max. Unit
V
ΔV
V
V
I
OZR
R
I
OSR
Receiver differential
TH
threshold voltage
Receiver input hysteresis VCM = 0V 30 V
TH
Receiver output high
OH
voltage
Receiver output low
OL
voltage
3-State (high impedance)
output current at receiver
Receiver input resistance VCM = -7V to 12V 24 kΩ
RIN
Receiver short-circuit
current
V
= -7V to 12V, DE = 0 -0.2 -0.015 V
CM
I
= -4mA, VID = 200mV, (Figure 9)2 V
OUT
= 4mA, VID = -200mV, (Figure 4)0.4V
I
OUT
= 3.6V, VO = 0V to V
V
CC
= 0V to V
V
RO
CC
CC
760mA
± 1µA
Table 10. Driver switching characteristics
V
= 3V to 3.6V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred
CC
to T
= 25°C)
a
Symbol Parameter Test Conditions Min. Typ. Max. Unit
D
t
DD
t
TD
Maximum data rate 12 15 Mbps
R
= 60Ω, CL = 15pF, (Figure 5 and
R
Differential output delay
Differential output
transition time
L
Figure 6)
RL= 60Ω, CL = 15pF, (Figure 5 and
Figure 6)
18 30 ns
12 20 ns
t
PLH
t
PHL
t
PDS
t
PZL
t
PZH
t
PHZ
t
PLZ
t
SKEW
t
ZH(SHDN)
t
ZL(SHDN)
R
= 27Ω, CL = 15pF, (Figure 9 and
Propagation delay
|t
PLH - tPHL
| propagation
delay skew (Note 2)
L
Figure 10)
RL= 27Ω, CL = 15pF, (Figure 9 and
Figure 10)
18 30 ns
25ns
Output enable time RL= 110Ω, (Figure 11 and Figure 12)1935ns
Output enable time RL= 110Ω, (Figure 7 and Figure 8)3050ns
Output disable time RL= 110Ω, (Figure 7 and Figure 8)1935ns
Output disable time RL= 110Ω, (Figure 11 and Figure 12)3050ns
Differential output delay
skew
Driver enable from
shutdown to output high
Driver enable from
shutdown to output low
13ns
30 50 ns
19 35 ns
7/22
Electrical characteristics ST1480AB - ST1480AC
Table 11. Receiver switching characteristics
V
= 3V to 3.6V, TA = -40 to 85°C, unless otherwise specified. Typical values are referred
CC
to T
= 25°C)
a
Symbol Parameter Test Conditions Min. Typ. Max. Unit
t
PLH
t
PHL
t
RPDS
t
PZL
t
PZH
t
PHZ
t
PLZ
t
ZH(SHDN)
t
ZL(SHDN)
Propagation delay
|t
PLH - tPHL
| propagation
delay skew
Output enable time CRL = 15pF, (Figure 15 and Figure 19)1020ns
Output enable time CRL = 15pF, (Figure 15 and Figure 19)1020ns
Output disable time CRL = 15pF, (Figure 15 and Figure 19)1020ns
Output disable time CRL = 15pF, (Figure 15 and Figure 19)1020ns
Receiver enable from
shutdown to output high
Receiver enable from
shutdown to output low
= 0V to 3V, CL1 =15pF
V
ID
(Figure 13 and Figure 14)
VID= 0V to 3V, CL1 = 15pF
(Figure 13 and Figure 14)
= 15pF, (Figure 15 and Figure 19)1020ns
C
RL
= 15pF, (Figure 15 and Figure 19)2040µs
C
RL
30 50 ns
13ns
Note: 1 ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes
state.
2 Measured on |t
PLH
(A)-t
(A)| and |t
PHL
PLH
(B)-t
PHL
(B)|
3 The transceivers are put into shutdown by bring RE high and DE low. If the input are in state
for less than 80ns, the part are guaranteed not to enter shutdown. If the inputs are in this
state for at least 300ns, the parts are guaranteed to have entered shutdown.
8/22
ST1480AB - ST1480AC Test circuits and typical characteristics
5 Test circuits and typical characteristics
Figure 3. Driver and VOC test load
Figure 4. Driver VOD with varying common mode voltage test load
Figure 5. Receiver VOH and VOL test circuit
9/22
Test circuits and typical characteristics ST1480AB - ST1480AC
Figure 6. Drive differential output delay transition time test circuit
Figure 7. Drive differential output delay transition time waveform
Figure 8. Drive enable and disable times test circuit
10/22
ST1480AB - ST1480AC Test circuits and typical characteristics
Figure 9. Drive enable and disable times waveforms
Figure 10. Drive propagation time test circuit
Figure 11. Drive propagation time waveform
11/22
Test circuits and typical characteristics ST1480AB - ST1480AC
Figure 12. Drive enable and disable times test circuit
Figure 13. Drive enable and disable times waveforms
Figure 14. Receiver propagation delay time test circuit
12/22
ST1480AB - ST1480AC Test circuits and typical characteristics
Figure 15. Receiver propagation delay time waveforms
Figure 16. Receiver enable and disable times test circuit
Figure 17. Receiver enable and disable times waveform
13/22
Test circuits and typical characteristics ST1480AB - ST1480AC
Figure 18. Receiver enable and disable times waveform
Figure 19. Receiver enable and disable times waveform
Figure 20. Receiver enable and disable times waveform
14/22
ST1480AB - ST1480AC Test circuits and typical characteristics
Figure 21. Receiver output current vs output
Figure 23. Low level driver output capability Figure 24. High level driver output capability
low voltage
Figure 22. Receiver output current vs output
high voltage
Figure 25. Receiver input characteristics Figure 26. Driver short circuit current
15/22
Test circuits and typical characteristics ST1480AB - ST1480AC
Figure 27. Driver short circuit current
16/22
ST1480AB - ST1480AC Package mechanical data
6 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
17/22
Package mechanical data ST1480AB - ST1480AC
Plastic DIP-8 mechanical data
Dim.
Min. Typ. Max. Min. Typ. Max.
A 3.3 0.130
a1 0.7 0.028
B1.39 1.65 0.055 0.065
B1 0.91 1.04 0.036 0.041
b 0.5 0.020
b10.38 0.5 0.015 0.020
D 9.8 0.386
E 8.8 0.346
e 2.54 0.100
e3 7.62 0.300
e4 7.62 0.300
F 7.1 0.280
I4.8 0.189
L 3.3 0.130
Z 0.44 1.6 0.017 0.063
mm. inch.
18/22
P001F
ST1480AB - ST1480AC Package mechanical data
SO-8 mechanical data
Dim.
A1.35 1.75 0.053 0.069
A1 0.10 0.25 0.04 0.010
A2 1.10 1.65 0.043 0.065
B0.33 0.51 0.013 0.020
C0.19 0.25 0.007 0.010
D4.80 5.00 0.189 0.197
E 3.80 4.00 0.150 0.157
e 1.27 0.050
H5.80 6.20 0.228 0.244
h 0.25 0.50 0.010 0.020
L 0.40 1.27 0.016 0.050
k 8° (max.)
ddd 0.1 0.04
Min. Typ. Max. Min. Typ. Max.
mm. inch.
0016023/C
19/22
Package mechanical data ST1480AB - ST1480AC
Tape & reel SO-8 mechanical data
mm. inch.
Dim.
Min. Typ. Max. Min. Typ. Max.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N60 2.362
T 22.4 0.882
Ao 8.1 8.5 0.319 0.335
Bo 5.5 5.9 0.216 0.232
Ko 2.1 2.3 0.082 0.090
Po 3.9 4.1 0.153 0.161
P7.98.1 0.311 0.319
20/22
ST1480AB - ST1480AC Revision history
7 Revision history
Table 12. Document revision history
Date Revision Changes
02-May-2006 2 Order codes updated.
19-Nov-2007 3 Added Ta bl e 1 .
21/22
ST1480AB - ST1480AC
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