Datasheet

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LT1796

1796f

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Overvoltage Fault Protected

CAN Transceiver

■

Protected from Overvoltage Line Faults to ±60V

■

ESD Protection to IEC-1000-4-2 Level 4

±15kV Air Gap Test

±8kV Contact Mode Test

■

ISO 11898 Compatible

■

High Input Impedance Supports Up to 256 Nodes

■

Controlled Slew Rates for EMI Emissions Control

■

High Impedance Outputs When Off or

Powered Down

■

Short-Circuit Protection On All Outputs

■

Thermal Shutdown Protection

■

Pin Compatible with Philips PCA82C251

■

Industrial Control Data Networks

■

Automotive Systems

■

HVAC Controls

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

The LT

1796 CAN transceiver provides built-in fault toler-

ance to survive in industrial and automotive environ-

ments. Discrete protection devices are not needed. Bus

interface pins can withstand voltage faults up to ±60V with

respect to ground with no damage to the device. Faults

may occur while the transceiver is active, shut down or

powered off. On-chip ESD protection withstands up to

±15kV air discharges and ±8kV contact mode discharges

tested per IEC-1000-4-2. Loss of power or ground con-

nections does not damage the IC.

The circuit operates with data rates up to 125kbaud. A slew

control pin allows control of transmitted data pulse edges

to control EMI and reflection problems on imperfectly

terminated lines. High output current drive allows the use

of inexpensive PVC cable with impedance as low as 72Ω.

The 100kΩ input impedance allows up to 256 transceivers

per data network.

The LT1796 is available in 8-lead PDIP and SO packages.

Fault Protected CAN Bus Network

120Ω

1796 TA01

120Ω

LT1796

TXD

RXD

REF

GND

0.1µF

LT1796

TXD

RXD

REF

GND

0.1µF

125kbps CANH and CANL Driver Output

CANH-CANL

2V/DIV

CANH

2V/DIV

CANL

2V/DIV

TXD IN

5V/DIV

1796 TA02

Summary of content (8 pages)

PAGE 1
LT1796 Overvoltage Fault Protected CAN Transceiver U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Protected from Overvoltage Line Faults to ±60V ESD Protection to IEC-1000-4-2 Level 4 ±15kV Air Gap Test ±8kV Contact Mode Test ISO 11898 Compatible High Input Impedance Supports Up to 256 Nodes Controlled Slew Rates for EMI Emissions Control High Impedance Outputs When Off or Powered Down Short-Circuit Protection On All Outputs Thermal Shutdown Protection Pin Compatible with Philips PCA82C251 The LT®1796 CAN tr
PAGE 2
LT1796 W U U U W W W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) ORDER PART NUMBER Supply Voltage (VCC) .............................................. 44V RS Slope Control Input Voltage ................ – 0.3V to 44V VREF Reference Output Pin ......................... – 0.3V to 7V Driver Input Voltage .................................. – 0.3V to 44V CANH, CANL Data Line Pins ...................... – 80V to 80V Receiver Output Voltages ............................– 0.
PAGE 3
LT1796 DC ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 4.75V to 5.25V, VRS = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS VTH Differential Input Threshold Voltage for Receiver VRS = 0V, – 7V < VCM < 12V VRS = 5V, – 7V < VCM < 12V ∆VTH Receiver Input Hysteresis – 7V < VCM < 12V VOH Receiver Output High Voltage VCC = 4.
PAGE 4
LT1796 U W TYPICAL PERFOR A CE CHARACTERISTICS Dominant State Bus Voltage vs RL Supply Current vs Data Rate Transmitting, 50% Duty Cycle 3.0 24 TA = 25° C TA = 25° C SUPPLY CURRENT (mA) 2.5 VOD (V) 2.0 1.5 1.0 23 22 21 0.
PAGE 5
LT1796 U W TYPICAL PERFOR A CE CHARACTERISTICS Receiver Propagation Delay vs Temperature Receiver Thresholds vs Temperature 400 tRXDOFF AND tRXDON (ns) 0.80 0.75 VTH (V) VTH RISING 0.70 VTH FALLING 0.65 0.60 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 1796 G10 350 tRXDOFF 300 tRXDON 250 200 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 1796 G11 U U U PI FU CTIO S TXD (Pin 1): Driver Input. Logic-level thresholds are set by VREF.
PAGE 6
LT1796 W BLOCK DIAGRA TEST CIRCUIT VCC 5V 3 0.1µF 3 TXD 1 RS 8 DRIVER 1 TXD 7 CANH 60Ω SLOPE/ STANDBY CANH 6 CANL 30pF RXD 100pF 6 CANL GND VREF RS REFERENCE VOLTAGE 5 VREF 7 RX 4 RXD 4 2 5 8 RS 1796 F01 1796 BD 2 Figure 1. Switching Test Circuit GND W UW TI I G DIAGRA S 5V 5V TXD 2.5V TXD 2.5V 2.5V 2.5V 0V 0V VDIFF = VCANH – VCANL VDIFFHI VDIFF 50% 25% VDIFFLO 2V RXD 0.8V 0V tTXDON tTXDOFF tLBOFF 1796 F02 Figure 2.
PAGE 7
LT1796 U PACKAGE DESCRIPTIO N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .400* (10.160) MAX 8 7 6 5 1 2 3 4 .255 ± .015* (6.477 ± 0.381) .300 – .325 (7.620 – 8.255) .065 (1.651) TYP .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 8.255 +0.889 –0.381 .130 ± .005 (3.302 ± 0.127) .045 – .065 (1.143 – 1.651) ) .120 (3.048) .020 MIN (0.508) MIN .018 ± .003 (0.457 ± 0.076) .100 (2.54) BSC N8 1002 NOTE: 1.
PAGE 8
LT1796 U TYPICAL APPLICATIO Low EMI, Slew Limited CANBUS Network RT 120Ω RT 120Ω 5V 5V 0.1µF 0.