LTC1480IS8#PBF Datasheet LTC1480IS8#PBF, LTC1480IS8#TRPBF, LTC1480CS8#TRPBF | P4-P6

LTC1480

4

1480fa

TEMPERATURE (°C)

–40

2.0

OUTPUT VOLTAGE (V)

2.4

3.0

0

40

60

1480 G09

2.2

2.8

2.6

–20

20

80

100

V

CC

= 3.3V

I

O

= 8mA

TEMPERATURE (°C)

–40

OUTPUT VOLTAGE (V)

0.4

0.5

0.6

20 60

1480 G08

0.3

0.2

–20 0

40 80 100

0.1

0

V

CC

= 3.3V

I

O

= 8mA

PI FU CTIO S

UU U

TEMPERATURE (°C)

–40

TIME (ns)

12

10

8

6

4

2

0

20 60

1480 G07

–20 0

40 80 100

V

CC

= 3.3V

OUTPUT VOLTAGE (V)

3.30

OUTPUT CURRENT (mA)

–8

–10

–12

1.30

1480 G06

–6

–4

0

2.80

2.30

1.80

–2

–16

–14

3.05

2.55

2.05

1.55

V

CC

= 3.3V

T

A

= 25°C

OUTPUT VOLTAGE (V)

0

OUTPUT CURRENT (mA)

15

20

25

1.6

1480 G05

10

5

0

0.2 0.4 0.6 1.0 1.4 1.8

0.8

1.2

2.0

V

CC

= 3.3V

T

A

= 25°C

TEMPERATURE (°C)

–40

TIME (ns)

6.5

20

1480 G04

5.0

4.0

–20 0 40

3.5

3.0

7.0

6.0

5.5

4.5

60 80 100

V

CC

= 3.3V

TYPICAL PERFORMANCE CHARACTERISTICS

U

W

high, the driver outputs will be fed back to the receiver and

the receive output will correspond to the driver input.

DI (Pin 4): Driver Input. If the driver outputs are enabled

(DE HIGH) then a low on DI forces the outputs A LOW and

B HIGH. A HIGH on DI with the driver outputs enabled will

force A HIGH and B LOW.

GND (Pin 5): Ground.

A (Pin 6): Driver Output/Receiver Input.

B (Pin 7): Driver Output/Receiver Input.

V

CC

(Pin 8): Positive Supply. 3.0V < V

CC

< 3.6V.

RO (Pin 1): Receiver Output. If the receiver output is

enabled (RE LOW) and A > B by 200mV, then RO will be

HIGH. If A < B by 200mV, then RO will be LOW.

RE (Pin 2): Receiver Output Enable. A LOW enables the

receiver output, RO. A HIGH input forces the receiver

output into a high impedance state.

DE (Pin 3): Driver Outputs Enable. A HIGH on DE enables

the driver output. A, B and the chip will function as a line

driver. A low input will force the driver outputs into a high

impedance state and the chip will function as a line

receiver. If RE is high and DE is LOW, the part will enter a

low power (1µA) shutdown state. If RE is low and DE is

Receiver Output Low Voltage

vs Output Current

Receiver Output High Voltage

vs Output Current

Driver Skew vs Temperature

Receiver

⏐⏐

⏐t

PLH

– t

PHL

⏐⏐

⏐

vs Temperature

Receiver Output Low Voltage

vs Temperature

Receiver Output High Voltage

vs Temperature

LTC1480

5

1480fa

DI

3V

1.5V

t

PLH

t

r

t

SKEW

1/2 V

O

V

O

f = 1MHz, t

r

≤ 10ns, t

f

≤ 10ns

90%

10%

0V

B

A

V

O

–V

O

0V

90%

1.5V

t

PHL

t

SKEW

1/2 V

O

10%

t

f

V

DIFF

= V(A) – V(B)

1480 F05

SWITCHI G TI E WAVEFOR S

UW W

OUTPUT

UNDER TEST

C

L

S1

S2

V

CC

500Ω

1480 F04

3V

DE

A

B

DI

R

DIFF

C

L1

C

L2

RO

15pF

A

B

RE

1480 F03

LTC1480

RECEIVER

LTC1480

DRIVER

RECEIVER

OUTPUT

C

RL

1k

S1

S2

TEST POINT

V

CC

1k

1480 F02

V

OD

A

B

R

V

OC

1480 F01

TEST CIRCUITS

FU CTIO TABLES

UU

LTC1480 Transmitting

INPUTS OUTPUTS

RE DE DI B A

X1101

X1010

00XZZ

1 0 X Z* Z*

*Shutdown mode

LTC1480 Receiving

INPUTS OUTPUTS

RE DE A – B RO

00≥0.2V 1

00≤– 0.2V 0

0 0 Inputs Open 1

10 X Z*

*Shutdown mode

Figure 2. Receiver Timing Test Load

Figure 1. Driver DC Test Load

Figure 5. Driver Propagation Delays

Figure 4. Driver Timing Test Load

Figure 3. Driver/Receiver Timing Test Circuit

LTC1480

6

1480fa

LOGIC

V

CC

SD3

P1

D1

OUTPUT

SD4

D2

N1

1480 F10

P1

LOGIC

V

CC

P1

D1

OUTPUT

D2

N1

1480 F09

1.5V

t

ZL(SHDN)

, t

ZL

t

ZH(SHDN)

, t

ZH

1.5V

t

LZ

0.5V

t

HZ

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

3V

0V

RE

3.3V

V

OL

V

OH

0V

RO

1480 F08

f = 1MHz, t

r

≤ 10ns, t

f

≤ 10ns

1.5V

t

PHL

RO

–V

OD2

A – B

0V 0V

1.5V

t

PLH

OUTPUT

INPUT

V

OD2

V

OL

V

OH

1480 F07

f = 1MHz, t

r

≤ 10ns, t

f

≤ 10ns

1.5V

2.3V

t

ZH(SHDN)

,

t

ZH

t

ZL(SHDN)

,

t

ZL

1.5V

t

LZ

0.5V

t

HZ

OUTPUT NORMALLY LOW

OUTPUT NORMALLY HIGH

3V

0V

DE

3.3V

V

OL

V

OH

0V

A, B

1480 F06

f = 1MHz, t

r

≤ 10ns, t

f

≤ 10ns

APPLICATIO S I FOR ATIO

WUU

U

SWITCHI G TI E WAVEFOR S

UW W

CMOS Output Driver

The LTC1480 transceiver provides full RS485 compatibility

while operating from a single 3.3V supply. The RS485

specification requires that a transceiver withstand common

mode voltages of up to 12V or –7V at the RS485 line

connections. Additionally, the transceiver must be immune

to both ESD and latch-up. This rules out traditional CMOS

drivers, which include parasitic diodes from their driver

outputs to each supply rail (Figure 9). The LTC1480 uses a

proprietary process enhancement which adds a pair of

Schottky diodes to the output stage (Figure 10), preventing

Figure 9. Conventional

CMOS Output Stage

Figure 10.

LTC1480 Output Stage

Figure 6. Driver Enable and Disable Times

Figure 7. Receiver Propagation Delays

Figure 8. Receiver Enable and Disable Times

LTC1480IS8#PBF

LTC1480IS8#PBF

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