Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsInterface ICsInterface IC - transceivers V.35 2/3 SOIC 28

LTC1345

Single Supply

V.35 Transceiver

■

Single Chip Provides All V.35 Differential Clock

and Data Signals

■

Operates From Single 5V Supply

■

Software Selectable DTE or DCE Configuration

■

Transmitters and Receivers Will Withstand

Repeated ±10kV ESD Pulses

■

Shutdown Mode Reduces I

to 1µA Typ

■

10MBaud Transmission Rate

■

Transmitter Maintains High Impedance When

Disabled, Shut Down, or with Power Off

■

Meets CCITT V.35 Specification

■

Transmitters are Short-Circuit Protected

The LTC

1345 is a single chip transceiver that provides the

differential clock and data signals for a V.35 interface from

a single 5V supply. Combined with an external resistor

termination network and an LT

1134A RS232 transceiver

for the control signals, the LTC1345 forms a complete low

power DTE or DCE V.35 interface port operating from a

single 5V supply.

The LTC1345 features three current output differential

transmitters, three differential receivers, and a charge

pump. The transceiver can be configured for DTE or DCE

operation or shut down using two Select pins. In the

Shutdown mode, the supply current is reduced to 1µA.

The transceiver operates up to 10Mbaud. All transmitters

feature short-circuit protection and a Receiver Output

Enable pin allows the receiver outputs to be forced into a

high impedance state. Both transmitter outputs and re-

ceiver inputs feature ±10kV ESD protection. The charge

pump features a regulated V

output using three external

1µF capacitors.

■

Modems

■

Telecommunications

■

Data Routers

Clock and Data Signals for V.35 Interface

DCEDTE

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

1µF

CC1

1µF 1µF1µF

1µF

273

1µF

LTC1345 LTC1345

627T500/1250

BI TECHNOLOGIES

627T500/1250 (SOIC) OR

899TR50/125 (DIP)

CC2

1µF

327

1µF

TXD (103)

SCTE (113)

TXC (114)

RXC (115)

RXD (104)

GND (102)

T T

CC1

10 14

LTC1345 • TA01

CC2

50Ω

125Ω

50Ω

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (12 pages)

PAGE 1
LTC1345 Single Supply V.35 Transceiver U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Single Chip Provides All V.35 Differential Clock and Data Signals Operates From Single 5V Supply Software Selectable DTE or DCE Configuration Transmitters and Receivers Will Withstand Repeated ±10kV ESD Pulses Shutdown Mode Reduces ICC to 1µA Typ 10MBaud Transmission Rate Transmitter Maintains High Impedance When Disabled, Shut Down, or with Power Off Meets CCITT V.
PAGE 2
LTC1345 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage, VCC .................................................. 6V Input Voltage Transmitters ........................... – 0.3V to (VCC + 0.3V) Receivers ............................................... – 18V to 18V S1, S2, OE ............................... – 0.3V to (VCC + 0.3V) Output Voltage Transmitters .......................................... – 18V to 18V Receivers ................................ – 0.
PAGE 3
LTC1345 AC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V ±5% (Notes 2, 3), unless otherwise specified.
PAGE 4
LTC1345 U W TYPICAL PERFOR A CE CHARACTERISTICS Receiver tPLH – tPHL vs Temperature Supply Current vs Temperature 20 VEE Voltage vs Temperature 140 VCC = 5V 30 –4.5 VCC = 5V VCC = 5V LOADED 10 5 0 –50 –25 75 50 25 TEMPERATURE (˚C) 0 100 125 25 NO LOAD 100 20 80 15 60 –50 –25 75 50 25 TEMPERATURE (˚C) 0 LTC1345 • TPC04 100 10 125 –5.0 VOLTAGE (V) CURRENT (mA) 120 CURRENT (mA) TIME (ns) 15 –5.5 –6.0 –6.
PAGE 5
LTC1345 U U U PI FU CTIO S Y3 (Pin 22): Transmitter 3 Noninverting Output. Y1 (Pin 26): Transmitter 1 Noninverting Output. Z2 (Pin 23): Transmitter 2 Inverting Output. Y2 (Pin 24): Transmitter 2 Noninverting Output VEE (Pin 27): Charge Pump Output. Connected to negative terminal of capacitor C3. Z1 (Pin 25): Transmitter 1 Inverting Output. C2 – (Pin 28): Capacitor C2 Negative Terminal.
PAGE 6
LTC1345 U W W SWITCHI G TI E WAVEFOR S 3V f = 1MHz: t r ≤ 10ns: t f ≤ 10ns 1.5V T 1.5V 0V t PLH t PHL VO 90% Y–Z VDIFF = V(Y) – V(Z) 50% 10% –VO 90% 50% 10% 1/2 VO tr tf Z VO Y tSKEW tSKEW LTC1345 • F03 Figure 3. V.35 Transmitter Propagation Delays VID f = 1MHz: t r ≤ 10ns: t f ≤ 10ns 0V B–A INPUT 0V –VID t PLH t PHL VOH R 1.5V OUTPUT 1.5V VOL LTC1345 • F04 Figure 4. V.35 Receiver Propagation Delays 3V 1.5V OE 0V f = 1MHz: t r ≤ 10ns: t f ≤ 10ns t ZL 1.
PAGE 7
LTC1345 U W U U APPLICATIO S I FOR ATIO Review of CCITT Recommendation V.35 Electrical Specifications V.35 is a CCITT recommendation for synchronous data transmission via modems. Appendix 2 of the recommendation describes the electrical specifications which are summarized below: 1. The interface cable is balanced twisted-pair with 80Ω to 120Ω impedance. 2. The transmitter’s source impedance is between 50Ω and 150Ω.
PAGE 8
LTC1345 U W U U APPLICATIO S I FOR ATIO Theory of Operation The transmitter output consists of complementary switched-current sources as shown in Figure 7. VCC A charge pump generates the regulated negative supply voltage (VEE) with three 1µF capacitors. Commutating capacitors C1 and C2 form a voltage doubler and inverter while C3 acts as a reservoir capacitor. To insure proper operation, the capacitors must have an ESR less than 1Ω. Monolithic ceramic or solid tantalum capacitors are good choices.
PAGE 9
LTC1345 U U W U APPLICATIONS INFORMATION 1µF 1µF 50Ω DTE T VCC1 5V 2 4 1 50Ω 28 3 27 1µF LTC1345 1µF 6 DX 7 DX 11 RX 12 RX 13 RX 10 9 26 1 25 2 24 3 23 4 20 14 19 13 18 12 17 11 16 10 15 9 5 7 4 T P TXD (103) S U T W AA T TXC (114) T V T T R T T X V RXD (104) T AA Y RXC (115) BI 627T500/ 1250 (SOIC) U W Y X P S SCTE (113) 3 22 1µF 1 28 T T R B GND (102) B A CABLE SHIELD A T 12 18 11 17 10 16 9 15 1 26 2 25
PAGE 10
LTC1345 U W U U APPLICATIONS INFORMATION RS422/RS485 Applications The receivers on the LTC1345 are ideal for RS422 and RS485 applications. Using the test circuit in Figure 9, the LTC1345 receivers are able to successfully reconstruct the data stream with the common-mode voltage meeting RS422 and RS485 requirements (12V to – 7V). RECEIVER OUTPUT 5V/DIV Figures 10 and 11 show that the LTC1345 receivers are very capable of reconstructing data at rates up to 10Mbaud.
PAGE 11
LTC1345 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. NW Package 28-Lead PDIP (Wide 0.600) (LTC DWG # 05-08-1520) 1.455* (36.957) MAX 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.505 – 0.560* (12.827 – 14.224) 0.600 – 0.625 (15.240 – 15.875) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.625 –0.015 +0.889 15.87 –0.381 ) 0.150 ± 0.005 (3.810 ± 0.127) 0.045 – 0.065 (1.143 – 1.651) 0.015 (0.381) MIN 0.070 (1.
PAGE 12
LTC1345 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. SW Package 28-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.697 – 0.712* (17.70 – 18.08) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0.394 – 0.419 (10.007 – 10.643) NOTE 1 0.291 – 0.299** (7.391 – 7.595) 1 2 3 4 5 6 7 8 9 10 11 12 13 0.037 – 0.045 (0.940 – 1.143) 0.093 – 0.104 (2.362 – 2.642) 0.010 – 0.029 × 45° (0.254 – 0.737) 14 0° – 8° TYP 0.009 – 0.013 (0.