Linear Technology LTC1320 Datasheet

LTC1320

AppleTalk© Transceiver

EATU

F

■

Single Chip Provides Complete

RE

S

LocalTalk©/AppleTalk© Port

■

Low Power: ICC = 1.2mA Typ

■

Shutdown Pin Reduces ICC to 30µA Typ

■

Drivers Maintain High Impedance in Three-State
or with Power Off

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30ns Driver Propagation Delay Typ

■

5ns Driver Skew Typ

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Thermal Shutdown Protection

■

Drivers are Short-Circuit Protected

U

O

PPLICATI

A

■

LocalTalk Peripherals

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Notebook/Palmtop Computers

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Battery-Powered Systems

AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.

S

DUESCRIPTIO

The LTC1320 is an RS422/RS562 line transceiver de­signed to operate on LocalTalk networks. It provides one
differential RS422 driver, one single-ended RS562 driver,
two single-ended RS562 receivers, and one differential
RS422 receiver. The LTC1320 draws only 1.2mA quies­cent current when active and 30µA in shutdown, making
it ideal for use in battery-powered devices and other
systems where power consumption is a primary concern.

The LTC1320 drivers are specified to drive ±2V into 100Ω.
Additionally, the driver outputs three-state when disabled,
during shutdown, or when the power is off; they maintain
high impedance even with output common-mode volt­ages beyond the power supply rails. Both the driver
outputs and receiver inputs are protected against ESD
damage to beyond 5kV.

The LTC1320 is available in the 18-pin SOL package.

DATA IN

TX ENABLE

RX ENABLE

DATA OUT

SHUTDOWN

A

PPLICATITYPICAL

Typical LocalTalk Connection

5V

1

3

LTC1320

5

8

4

914

18

#1

–5V

22Ω

17

22Ω

16

22Ω

11

22Ω

10

O

22Ω

100pF

22Ω

100pF

22Ω

100pF

22Ω

100pF

U

LocalTalk

TRANSFORMER

1k

1k

LTC1320 • TA01

120Ω

DATA IN

SIGNALS

ON LINE

DATA OUT

(REMOTE

RECEIVER)

Output Waveforms

5V/DIV

2V/DIV

2V/DIV

5V/DIV

50ns/DIV

1

LTC1320

WU

U

PACKAGE

/

O

RDER I FOR ATIO

W

O

A

LUTEXI T

S

A

Supply Voltage (VDD)................................................ 7V

Supply Voltage (VSS) .............................................. –7V

Input Voltage (Logic Inputs) ......... –0.3V to VDD + 0.3V

Input Voltage (Receiver Inputs) ............................ ±15V

Driver Output Voltage (Forced) ............................. ±15V

Output Short-Circuit Duration......................... Indefinite

Operating Temperature Range ................... 0°C ot 70°C

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

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

DC ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OD

V

OC

V

OH

V

OL

I

DD

I

SS

Differential Driver Output Voltage No Load ● 8.0 V

Change in Magnitude of Driver RL = 100Ω (Figure 1) 0.2 V
Differential Output Voltage

Driver Common-Mode Output Voltage RL = 100Ω (Figure 1) 3 V
Output Common-Mode Range SD = 5V or Power Off ● ±10 V
Single-Ended Driver Output Voltage No Load ● ±4.0 V

Input High Voltage All Logic Input Pins ● 2.0 V
Input Low Voltage All Logic Input Pins ● 0.8 V
Input Current All Logic Input Pins ● ±1 ±20 µA
Three-State Output Current SD = 5V or Power Off, –10V < VO < 10V ● ±2 ±100 µA
Driver Short-Circuit Current –5V < VO < 5V ● 35 350 500 mA
Receiver Input Resistance – 7V < VIN < 7V ● 12 kΩ
Receiver Output High Voltage IO = –4mA ● 3.5 V
Receiver Output Low Voltage IO = 4mA ● 0.4 V
Receiver Output Short-Circuit Current 0V < VO < 5V ● 785mA
Receiver Output Three-State Current 0V < VO < 5V ● ±2 ±100 µA
Differential Receiver Threshold Voltage –7V < VCM < 7V ● –200 200 mV
Differential Receiver Input Hysteresis –7V < VCM < 7V 70 mV
Single-Ended Receiver Input Low Voltage ● 0.8 V
Single-Ended Receiver Input High Voltage ● 2V
Supply Current No Load, SD = 0V ● 1.2 3.0 mA

Supply Current No Load, SD = 5V ● 2 350 µ A

WUW

ARB

U
G

S

I

TOP VIEW

1

TXD

2

TXI

3

TXDEN

4

SD

5

RXEN

6

RXO

7

RXO

8

RXDO

9

GND

S PACKAGE

18-LEAD PLASTIC SOL

T

= 150°C, θJA = 100°C/W

JMAX

Consult factory for Industrial and Military grade parts.

18
17
16
15
14
13
12
11
10



V

DD

TXD–

+

TXD



TXO



V

SS

RXI
RXI

–

RXD

+

RXD

LTC1320 • PO01



VS = ±5V ±5%, TA = 0°C to 70°C (Notes 2, 3)

RL = 100Ω (Figure 1) ● 2.0 V

RL = 400Ω ● ±3.4 V

No Load, SD = 5V ● 30 350 µA

ORDER PART

NUMBER

LTC1320CS

2

LTC1320

TEMPERATURE (°C)

0

0

SUPPLY CURRENT (mA)

0.004

1.0

1.1

1.2

10 20 30 40

LTC1320 • G03

50 60 70

0.002

I

DD

I

SS

U

SWITCHI G CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

t

PLH, HL

t

SKEW

t

r, f

t

ENH, L

t

H, Ldis

t

PLH, HL

t

r, f

t

PLH, HL

t

ENH, L

t

H, Ldis

Differential Driver Propagation Delay RL = 100Ω, CL = 100pF (Figures 2, 8) ● 40 120 ns
Differential Driver Output to Output RL = 100Ω, CL = 100pF (Figures 2, 8) ● 10 50 ns
Differential Driver Rise/Fall Time RL = 100Ω, CL = 100pF (Figures 2, 8) ● 15 80 ns
Driver Enable to Output Active CL = 100pF (Figures 3, 4, 10) ● 50 150 ns
Driver Output Active to Disable CL = 15pF (Figures 3, 4, 10) ● 50 150 ns
Single-Ended Driver Propagation Delay RL = 450Ω, CL = 100pF (Figures 5, 11) ● 40 120 ns
Single-Ended Driver Rise/Fall Time RL = 450Ω, CL = 100pF (Figures 5, 12) ● 15 80 ns
Receiver Propagation Delay CL = 15pF (Figures 13, 14) ● 60 160 ns
Receiver Enable to Output Active CL = 100pF (Figures 6, 7, 15) ● 30 100 ns
Receiver Output Active to Disable CL = 15pF (Figures 6, 7, 15) ● 30 100 ns

VS = ±5V ±5%, TA = 0°C to 70°C (Notes 2, 3)

The ● denotes specifications which apply over the full operating
temperature range.

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

UW

LPER

5
4

OUTPUT HIGH

3
2
1
0

–1

OUTPUT SWING (V)

–2
–3
–4
–5

0

OUTPUT LOW

20

R

F

O

60

40

OUTPUT CURRENT (mA)

80

LTC1320 • G01

ATYPICA

100

CCHARA TERIST

E

C

Differential Output Swing vs
Load CurrentOutput Swing vs Load Current

10

8

6

4

2

DIFFERENTIAL OUTPUT SWING (V)

0

20

0

OUTPUT CURRENT (mA)

Note 2: All currents into device pins are positive; all currents out of
device pins are negative. All voltages are referenced to ground unless
otherwise specified.

Note 3: All typicals are given at VS = ±5V, TA = 25°C.

ICS

Supply Current vs Temperature

60

80

40

100

LTC1320 • G02

PI FU CTIO S

TXD (Pin 1): RS422 Differential Driver Input (TTL Compat­ible).

TXI (Pin 2): RS562 Single-Ended Driver Input (TTL com­patible.

TXDEN (Pin 3): RS422 Differential Driver Output Enable
(TTL Compatible). A high level on this pin forces the

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RS422 driver into three-state; a low level enables the
driver. This input does not affect the RS562 single-ended
driver.

SD (Pin 4): Shutdown Input (TTL Compatible). When this
pin is high, the chip is shut down: all driver outputs three­state and the supply current drops to 30µ A. A low on this
pin allows normal operation.

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