LTC1348I_技术文档

LTC1348

3.3V/5V Low Power RS232

3-Driver/5-Receiver Transceiver

U

DESCRIPTIO

EATURE

S

F

The LTC^®1348 is a 3-driver/5-receiver RS232 transceiver

with very low supply current. The charge pump only

requires five 0.1µF capacitors. The LTC1348 provides full

RS232 output levels when operated over a wide supply

range of 3V to 5.5V

■

Low Supply Current: 600µA at 3.3V

Supply Current in Shutdown: 0.2µA

Supply Current in Receiver Alive Mode: 15µA

ESD Protection over ±10kV

Operates from a Single 3V to 5.5V Supply

Operates to 120kBaud with 0.1µF Flying Capacitors

Three-State Outputs Are High Impedance When Off

Output Overvoltage Does Not Force Current

Back into Supplies

The transceiver operates in one of four modes: Normal,

ReceiverDisable,ReceiverAliveandShutdown.InNormal

or Receiver Disable mode, I_CCis only 600µA at 3.3V and

800µA at 5V in the no load condition. In Shutdown mode,

the supply current is further reduced to 0.2µA. In Receiver

Alive mode, all five receivers are kept alive and the supply

current is 15µA. All RS232 outputs assume a high imped-

ance state in Shutdown or Receiver Alive mode or with the

power off. The receiver outputs assume a high impedance

state in Receiver Disable or with the power off.

■

RS232 I/O Lines Can Be Forced to ±25V

Without Damage

Flowthrough Architecture

O U

PPLICATI

S

A

■

Notebook Computers

Palmtop Computers

Printers

The LTC1348 is fully compliant with all data rate and

overvoltage RS232 specifications. The transceiver oper-

ates up to 120kbaud with all drivers loaded with 1000pF,

3kΩ.Bothdriveroutputsandreceiverinputscanbeforced

to ±25V without damage and can survive multiple ±10kV

ESD strikes.

Portable Instruments

, LTC and LT are registered trademarks of Linear Technology Corporation.

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TYPICAL APPLICATI

Supply Current

3-Drivers/5-Receivers with Shutdown

1.6

–

+

V

1

2

28

27

26

25

24

23

22

21

20

19

18

17

16

15

V

LTC1348

C4

0.1µF

C5

0.1µF

1.4

1.2

1.4

1.2

C2

C3

0.1µF

3

0.1µF

QUIESCENT

CURRENT

4

DR 1 IN

RX1 OUT

DR 2 IN

RX2 OUT

RX3 OUT

RX4 OUT

DR 3 IN

RX5 OUT

DREN

V

CC

1.0

0.8

0.6

0.4

0.2

1.0

0.8

0.6

0.4

0.2

5

V

= 5V

CC

C1

0.1µF

6

V

CC

= 3.3V

7

DR 1 OUT

RX1 IN

8

SHUTDOWN

CURRENT

V

CC

OR 5V

= 3.3V

9

DR 2 OUT

RX2 IN

10

11

12

13

14

RX3 IN

0

–20

0

40

60

80

–40

20

RX4 IN

TEMPERATURE (˚C)

DR 3 OUT

RX5 IN

RXEN

LT1348 •TA02

GND

LT1348 • TA01

1

LTC1348

W W W

U

/O

ABSOLUTE AXI U RATI GS

(Note 1)

PACKAGE RDER I FOR ATIO

TOP VIEW

ORDER PART

Supply Voltage (V_CC) ................................................ 6V

Input Voltage

Driver ....................................... –0.3V to V_CC+ 0.3V

Receiver ............................................... – 25V to 25V

Driver/Receiver Enable Pin ........ –0.3V to V_CC+ 0.3V

Output Voltage

+

–

NUMBER

V

C2

1

2

3

4

5

6

7

8

9

28

V

+

27 C3

26 C3

–

LTC1348CG

LTC1348CSW

LTC1348IG

V

25 DR1 IN

24 RX1 OUT

23 DR2 IN

22 RX2 OUT

21 RX3 OUT

20 RX4 OUT

19 DR3 IN

18

CC

+

C1

–

LTC1348ISW

DR1 OUT

RX1 IN

Driver ................................................... – 25V to 25V

Receiver .................................... – 0.3V to V_CC+ 0.3V

Short-Circuit Duration

DR2 OUT

RX2 IN 10

RX3 IN 11

RX4 IN 12

DR3 OUT 13

RX5 IN 14

V⁺................................................................... 30 sec

V^–................................................................... 30 sec

Driver Output.............................................. Indefinite

Receiver Output.......................................... Indefinite

Operating Temperature Range

RX5 OUT

17 DREN

16 RXEN

15 GND

G PACKAGE

SW PACKAGE

28-LEAD PLASTIC SSOP

28-LEAD PLASTIC SO

LTC1348C................................................ 0°C to 70°C

LTC1348I............................................ –40°C to 85°C

Storage Temperature Range ................ – 65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

T_JMAX= 125°C, θ_JA= 96°C/W (G)

_JMAX= 125°C, θ_JA= 85°C/W (SW)

T

Consult factory for Military grade parts.

DC ELECTRICAL CHARACTERISTICS

V_CC= 3V to 5.5V, C1 to C4 = 0.1µF, unless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Any Driver

Output Voltage Swing

V

CC

= 3.3V, 3k to GND

Positive

Negative

●

5.0

–5.0

6.2

– 6.0

V

Logic Input Voltage Level

Logic Input Current

Input Low Level (V

Input High Level (V

= High)

= Low), V = 3.3V

= Low), V = 5V

●

0.8

V

µA

mA

µA

OUT

2.0

2.4

OUT

CC

V

IN

V

IN

= V

= 0V

●

5

–35

CC

–5

±12

±10

Output Short-Circuit Current

Output Leakage Current

V

OUT

= 0V

Shutdown (Note 3) or Receiver Alive Mode (Note 4),

= ±20V

●

±500

V

OUT

Any Receiver

Input Voltage Thresholds

Input Threshold (Receiver Alive Mode)

Input Low Threshold (Normal Mode)

Input High Threshold (Normal Mode)

0.8

1.5

1.3

1.7

2.4

V

Hysteresis

Input Resistance

Output Voltage

Normal Mode

0.3

5

0.2

V

kΩ

V

IN

= ±10V

3

7

0.4

Output Low, I

Output High, I

= – 1.6mA

= 160µA

●

OUT

V

– 0.6V

CC

OUT

Output Short-Circuit Current

Output Leakage Current

Sinking Current, V

Shutdown (Note 3), 0V ≤ V

= V

–3

–20

1

mA

µA

OUT

CC

≤ V

●

10

OUT

CC

2

LTC1348

DC ELECTRICAL CHARACTERISTICS

V_CC= 3V to 5.5V, C1 to C4 = 0.1µF, unless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Power Supply Generator

+

V Output Voltage

I

= 0mA

= 8mA

= 0mA

8.0

7.5

–8.0

–7.0

V

OUT

–

V Output Voltage

OUT

= –8mA

Supply Rise Time

Shutdown to Turn-On

0.2

ms

Power Supply

V

CC

Supply Current

No Load (Note 2) V = 3.3V

●

0.6

0.8

15

2.0

2.5

30

mA

µA

CC

No Load (Note 2) V = 5V

CC

Receiver Alive Mode (Note 4) V = 3.3V or 5V

CC

Supply Leakage Current (V

)

Shutdown (Note 3)

●

0.2

10

0.8

µA

V

CC

Driver/Receiver Enable Threshold Low

Driver/Receiver Enable Threshold High

V

= 3.3V

= 5V

2.0

2.4

CC

V

CC

AC ELECTRICAL CHARACTERISTICS

V_CC= 3V to 5.5V, C1 to C4 = 0.1µF, unless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

250

8

MAX

UNITS

Maximum Data Rate

Slew Rate

R = 3k, C = 1000pF, One Driver Switching

120

kbps

V/µs

µs

L

V

= 5V, R = 3k, C = 51pF

30

CC

L

= 3.3V, R = 3k, C = 2500pF

3

L

(Figure 1)

L

Driver Propagation Delay

(TTL to RS232)

t

●

2.5

4

HLD

LHD

Receiver Propagation Delay

(RS232 to TTL)

t

(Figure 2) (Normal Mode)

(Figure 2) (Receiver Alive Mode)

●

0.3

0.2

1.0

0.2

1

4

µs

HLR

LHR

HLR

LHR

The

●

denotes specifications which apply over the full operating

Note 3: Supply current measurement in Shutdown is performed with

and V = 0V.

temperature range (0°C ≤ T ≤ 70°C for Commercial grade and

V

DREN

A

RXEN

–40°C ≤ T ≤ 85°C for Industrial grade).

Note 1: Absolute Maximum Ratings are those values beyond which the life

A

Note 4: Supply current measurement in Receiver Alive mode is performed

with V = 0V and V = V

.

CC

DREN

RXEN

of the device may be impaired.

Note 2: Supply current is measured with driver and receiver outputs

unloaded. The V

and V

= V .

RXEN CC

DREN

3

LTC1348

TYPICAL PERFORMANCE CHARACTERISTICS

W

U

Supply Current

Driver Output Voltage High/Low

vs Load Capacitance (C_L)

Driver Output Voltage High/Low

vs Load Capacitance (C_L)

vs Driver Data Rate

50

40

30

20

10

0

7

6

5

4

3

2

1

0

–1

–2

–3

–4

–5

–6

–7

7

6

5

4

3

2

1

0

3 OUTPUT LOADED

120kbps

64kbps

OUTPUT HIGH

250kbps

64kbps

120kbps

3kΩ // 2500pF

20kbps

OUTPUT HIGH

20kbps

V

CC

= 3.3V

V

= 3.3V

CC

0.1µF FLYING CAPACITORS

ALL DRIVERS LOADED 3kΩ + C

1 DRIVER DRIVEN

0.1µF FLYING CAPACITORS

L

ALL DRIVERS DRIVEN AND

1 OUTPUT LOADED

3kΩ // 2500pF

–1

–2

–3

–4

–5

–6

–7

LOADED 3kΩ + C

L

OUTPUT LOW

64kbps

20kbps

64kbps

120kbps

1000

120kbps

250kbps

1000

V

= 3.3V

50

CC

20kbps

4000

0

100

150

200

250

3000

4000

5000

0

2000

3000

5000

0

2000

DRIVER DATA RATE

LOAD CAPACITANCE (pF)

LTC1348 G02

LTC1348 G01

LTC1348 G03

Driver Leakage in SHUTDOWN

Driver Output Voltage High/Low

Driver Short-Circuit Current

vs Temperature (°C)

7

6

5

4

3

2

1

0

45

20

18

16

14

12

10

8

V

= 3.3V

CC

V

CC

= 3.3V

40

35

30

25

20

15

10

5

V

CC

= 3V

V

CC

= 3.3V

OUTPUT HIGH

–

I

SC

+

I

SC

ALL DRIVERS

LOADED WITH 3kΩ

V

= –20V

= 20V

–1

–2

–3

–4

–5

–6

–7

OUT

OUTPUT LOW

6

V = 3V

CC

V

= 3.3V

V

OUT

CC

4

0

10

20

30

40

50

60

70

0

10

20

30

40

60

70

50

–40 –20

0

20

40

80 100

60

TEMPERATURE (°C)

LTC1348 G04

LTC1348 G06

LTC1348 G05

With V_CC= 3.3V

All Driver Outputs Loaded with

3kΩ, 1000pF. 1 Driven at 250kbps

DRIVEN DRIVER

OUTPUT

DRIVER

INPUT

LTC1348 G07

4

LTC1348

U

PI FU CTIO S

V_CC: 3V to 5.5V Input Supply Pin. This pin should be

decoupled with a 0.1µF ceramic capacitor.

efficiency,thecapacitor’seffectiveseriesresistanceshould

be less than 1Ω. Ceramic capacitors are recommended.

GND: Ground Pin.

DR IN: RS232 Driver Input Pins. Inputs are TTL/CMOS

compatible. The inputs of unused drivers can be left

unconnected since 300k input pull-up resistors to V_CCare

included on chip. To minimize power consumption, the

internaldriverpull-upresistorsaredisconnectedfromV_CC

in the Shutdown or Receiver Alive mode.

RXEN: TTL/CMOS Compatible Enable Pin. Refer to Table

1 for its functional description.

DREN: TTL/CMOS Compatible Enable Pin. Refer to Table

1 for its functional description.

V⁺: Positive Supply Output (RS232 Drivers). This pin

requires an external capacitor C = 0.1µF for charge stor-

age. The capacitor may be tied to ground or V_CC. With

multipledevices, the V⁺andV^–pinsmaybeparalleledinto

common capacitors. For large numbers of devices, in-

creasing the size of the shared common storage capaci-

tors is recommended to reduce ripple.

V^–: Negative Supply Output (RS232 Drivers). This pin

requires an external capacitor C = 0.1µF for charge

storage.

DR OUT: DriverOutputsatRS232Voltage Levels. Outputs

are in a high impedance state when in the Shutdown,

Receiver Alive mode or V_CC= 0V. The driver outputs are

protected against ESD to ±10kV for human body model

discharges.

RX IN: Receiver Inputs. These pins can be forced to ±25V

withoutdamage. Thereceiverinputsareprotectedagainst

ESD to ±10kV for human body model discharges. Each

receiverprovides0.4Vofhysteresisfornoiseimmunity.In

Receiver Alive mode all receivers have no hysteresis.

C1⁺, C1^–, C2⁺, C2^–, C3⁺, C3^–: Commutating Capacitor

Inputs. These pins require three external capacitors C =

0.1µF: one from C1⁺to C1^–, another from C2⁺to C2^–and

another from C3⁺to C3^–. To maintain charge pump

RX OUT: Receiver Outputs with TTL/CMOS Voltage Lev-

els. Outputs are in a high impedance state when in the

Shutdown or Receiver Disable mode to allow data line

sharing.

Table 1. Functional Description

MODE

RX ENABLE

DR ENABLE

DRIVERS

RECEIVERS

I

CC

TYP

Shutdown

0

All Drivers Shutdown.

All Driver Outputs Assume High Impedance.

All Driver Pull-Up Resistors Disconnect

All Receivers Shutdown.

All Receiver Outputs Assume High Impedance.

0.2µA

From V

.

CC

Receiver

Disable

0

1

0

1

All Drivers Alive.

All Receiver Outputs in Three-State.

All Receivers Alive.

600µA at

3.3V,

800µA at

5V

Receiver

Alive

All Drivers Shutdown.

All Driver Outputs in Three-State.

All Driver Pull-Up Resistors Disconnect

15µA

From V

.

CC

Normal

All Drivers Alive.

All Receivers Alive.

600µA at

3.3V,

800µA at

5V

5

LTC1348

U

W

SWITCHI G TI E WAVEFOR S

V

CC

1.7V

DRIVER

INPUT

RX

INPUT

1.3V

1.4V

0V

+

V

CC

DRIVER

OUTPUT

RX

OUTPUT

2.4V

0V

–

0.8V

V

0V

t

LHD

t

LHR

HLD

HLR

LTC1348 • F01

LTC1348 • F02

Figure 1. Driver Propagation Delay Timing

Figure 2. Receiver Propagation Delay Timing

TEST CIRCUITS

ESD Test Circuit

DRIVER

OUTPUT

DRIVER

–

+

DRIVER

V

1

2

3

V

28

INPUT

LTC1348

+

–

51pF

3k

0.1µF

C2

27 C3

26

0.1µF

–

+

C3

25

C2

V

4

CC

LTC1348 • F03

DR1 IN

C1

5

6

24

23

RX1 OUT

DR2 IN

0.1µF

Figure 3. Driver Timing Test Load

–

C1

7

8

22

21

20

19

18

17

16

15

DR1 OUT

RX2 OUT

RX3 OUT

RX4 OUT

DR3 IN

RX5 OUT

DREN

RX1 IN

9

DR2 OUT

RX2 IN

RX

OUTPUT

10

11

12

13

14

RS232 LINE PINS

PROTECTED TO ±10kV

RX INPUT

RX

RX3 IN

51pF

RX4 IN

DR3 OUT

RX5 IN

RXEN

GND

LTC1348 • F04

LT1348 • TC

Figure 4. Receiver Timing Test Load

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APPLICATIONS INFORMATION

Power Supply

low as 2.2V. The charge pump requires three external

flying capacitors to operate; 0.1µF ceramic capacitors are

adequate for most applications. For applications requiring

extremely high data rates or abnormally heavy output

loads, 0.33µFflyingcapacitorsarerecommended. Bypass

and output capacitor values should match those of the

flying capacitors and all capacitors should be mounted as

close to the package as possible.

The LTC1348 includes an onboard voltage-tripling charge

pump capable of generating ±8V from a single 3.3V

supply. This allows the LTC1348 drivers to provide guar-

anteed ±5V RS232-compliant voltage levels with a 3.3V

supply. With all outputs loaded with 3kΩ, the LTC1348

can typically swing ±5V with voltages as low as 2.85V. It

will meet the ±3.7V EIA562 levels with supply voltages as

6

LTC1348

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APPLICATIONS INFORMATION

High Data Rates

the same circuit with a single 1000pF/3kΩ loaded driver

driven at 250kbaud, and the other two drivers loaded but

not toggling. This closely approximates the actual behav-

iorofanRS232serialport,withonlyonedriver(TX)driven

at high speed and the other two drivers (RTS and DTR)

drivenatarelativelylowdatarateoratDC. Underthesame

conditions, the LTC1348 can go as fast as 350kbaud and

still meet EIA562 (±3.7V) minimum driver output levels.

The LTC1348 maintains true RS232 ±5V minimum driver

outputevenathighdatarates. Figure5showsatestcircuit

with 2m wires connecting the two test chips. Both chips

are run from 3.3V supplies. Figure 6 shows the typical line

waveforms with all three drivers, loaded with 1000pF and

3kΩ,togglingsimultaneouslyat120kbaud.Figure7shows

–

+

V

1

2

3

V

28

LTC1348

+

–

0.1µF

C2

27 C3

0.1µF

26

0.1µF

–

+

C3

C2

4

25

V

CC

DR1 IN

C1

5

6

24

23

RX1 OUT

DR2 IN

DRIVER OUTPUT

–

C1

7

8

9

DR1 OUT

22

21

20

19

18

17

16

15

RX2 OUT

RX3 OUT

RX4 OUT

DR3 IN

RX5 OUT

DREN

RX1 IN

DR2 OUT

10

11

12

13

14

RECEIVER OUTPUT

DRIVER INPUT

RX2 IN

RX3 IN

RX4 IN

DR3 OUT

RXEN

RX5 IN

GND

1000pF

LTC1348 G06

–

+

1

V

28

27

26

Figure 6. Driver Test Result at 120kbps

LTC1348

+

C2

2

3

0.1µF

C3

0.1µF

–

C2

C3

25

4

5

6

V

CC

DRIVER 1 IN

+

C1

24

23

RX1 OUT

0.1µF

DRIVER 2 IN

C1

7

8

9

22

21

20

19

18

17

16

15

DR1 OUT

RX1 IN

RX2 OUT

RX3 OUT

RX4 OUT

DRIVER 3 IN

RX5 OUT

DREN

DR2 OUT

RX2 IN

10

11

12

13

14

DRIVER OUTPUT

RX3 IN

RX4 IN

1000pF

DR3 OUT

RX5 IN

RXEN

RECEIVER OUTPUT

DRIVER INPUT

GND

LT1348 • F05

Figure 5. Data Rate Evaluation Circuit

LTC1348 G07

Figure 7. Driver Test Results at 250kbps

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

7

LTC1348

U

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

G Package

28-Lead Plastic SSOP (0.209)

(LTC DWG # 05-08-1640)

0.397 – 0.407*

(10.07 – 10.33)

0.205 – 0.212**

(5.20 – 5.38)

0.068 – 0.078

(1.73 – 1.99)

28 27 26 25 24 23 22 21 20 19 18

16 15

17

0° – 8°

0.301 – 0.311

(7.65 – 7.90)

0.0256

(0.65)

BSC

0.005 – 0.009

(0.13 – 0.22)

0.022 – 0.037

(0.55 – 0.95)

0.002 – 0.008

(0.05 – 0.21)

0.010 – 0.015

(0.25 – 0.38)

*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

5

7

8

1

2

3

4

6

9 10 11 12 13 14

G28 SSOP 0694

SW Package

28-Lead Plastic Small Outline (Wide 0.300)

(LTC DWG # 05-08-1620)

0.697 – 0.712*

(17.70 – 18.08)

0.291 – 0.299**

(7.391 – 7.595)

0.037 – 0.045

(0.940 – 1.143)

0.093 – 0.104

0.010 – 0.029

28 27 26 25 24 23 22 21 20 19 18

16 15

17

× 45°

(2.362 – 2.642)

(0.254 – 0.737)

0° – 8° TYP

0.050

(1.270)

TYP

0.394 – 0.419

(10.007 – 10.643)

NOTE 1

0.009 – 0.013

NOTE 1

0.004 – 0.012

(0.102 – 0.305)

(0.229 – 0.330)

0.014 – 0.019

(0.356 – 0.482)

0.016 – 0.050

(0.406 – 1.270)

NOTE:

1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.

THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

2

3

5

7

8

9

10 11 12 13 14

1

4

6

S28 (WIDE) 0396

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

RELATED PARTS

PART NUMBER

LT1137A

LTC1327

LT1330

DESCRIPTION

COMMENTS

3-DR/5-RX RS232 Transceiver

3-DR/5-RX RS562 Transceiver

3-DR/5-RX RS232

±15kV IEC-801-2 ESD Protection

3.3V Operation

3V Logic Interface

LT1331

3-DR/5-RX RS232/RS562 Transceiver

3-DR/5-RX Micropower RS232 Transceiver

5V RS232 or 3V RS562 Operation

5 Receivers Active in Shutdown

LTC1347

1348fa LT/GP 0197 5K REV A • PRINTED IN USA

LINEAR TECHNOLOGY CORPORATION 1994

Linear Technology Corporation

●

1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900

8

●

FAX: (408) 434-0507 TELEX: 499-3977 www.linear-tech.com


型号：	LTC1348I
厂家：	Linear
描述：	3.3V/5V Low Power RS232 3-Driver/5-Receiver Transceiver 3.3V / 5V低功耗RS232 3驱动器/ 5接收器收发器驱动器
文件：	总8页 (文件大小：247K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC1348I [Linear]

相关型号：

LTC1348IG

LTC1348IG#TRPBF

LTC1348IN

LTC1348IS

LTC1348ISW

LTC1348ISW#PBF

LTC1348ISW#TR

LTC1348ISW#TRPBF

LTC1348_15

LTC1349

LTC1349C

LTC1349CG