ST ST1480AB, ST1480AC User Manual

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

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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