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 transceiver provides built-in fault tolerance to survive in industrial and automotive environments. 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 connections 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. U APPLICATIO S ■ ■ ■ Industrial Control Data Networks Automotive Systems HVAC Controls The LT1796 is available in 8-lead PDIP and SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATIO Fault Protected CAN Bus Network RT 120Ω RT 120Ω 125kbps CANH and CANL Driver Output 5V 5V 0.1µF LT1796 1 4 1 D 4 R VREF 2 TXD IN 5V/DIV 6 R GND RXD 7 D 6 RXD TXD CANH 2V/DIV CANL 2V/DIV LT1796 7 TXD CANH-CANL 2V/DIV 0.1µF RS 8 5 5 5V/DIV VREF RS GND 8 2 1796 TA02 1796 TA01 1796f 1 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 ............................– 0.3V to 7V Operating Temperature Range LT1796C .................................................. 0°C to 70°C LT1796I .............................................. – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW TXD 1 8 RS GND 2 7 CANH VCC 3 6 CANL 5 VREF D R RXD 4 N8 PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC SO LT1796CN8 LT1796CS8 LT1796IN8 LT1796IS8 S8 PART MARKING 1796 1796I TJMAX = 150°C, θJA = 130°C/W (N8) TJMAX = 150°C, θJA = 150°C/W (S8) Consult LTC Marketing for parts specified with wider operating temperature ranges. 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 MIN TYP MAX UNITS VCANH CANH Output Voltage VTXD = 0V, No Load VTXD = 0V, RL = 60Ω ● ● 3.8 2.8 4.4 3.5 5.0 4.6 V V VCANL CANL Output Voltage VTXD = 0V, No Load VTXD = 0V, RL = 60Ω ● ● 0 0 0.5 1.3 0.9 1.6 V V VOD Dominant State Differential Output Voltage VTXD = 0V, No Load, VCC = 4.75V VTXD = 0V, RL = 60Ω, VCC = 4.75V VTXD = 0V, RL = 36Ω, VCC = 4.75V ● ● ● 3.0 1.5 1.2 3.6 2.0 1.7 5.0 4.2 4.2 V V V VREC Recessive State Differential Output Voltage VTXD = 5V, RL = 60Ω ● – 10 0 10 mV VCMR Recessive State Common Mode Output Voltage VTXD = 5V, RL = 60Ω, VCC = 5V ● 2.7 3 3.5 V VCMD Dominant State Common Mode Output Voltage RL = 60Ω, VCC = 5V ● 2 2.5 3 VIH TXD Input High Voltage ● 2.8 VIL TXD Input Low Voltage ● IIN1 TXD Input Current 0 < VTXD < VCC ● –5 5 µA ISCH CANH Short-Circuit Current, Dominant Mode VCANH = 0V, VCC = 5.25V VCANH = – 36V, VCC = 5.25V VCANH = – 60V, VCC = 5.25V VCANH = 60V, VCC = 5.25V ● ● ● ● – 250 – 10 – 10 0 –1 –1 1 – 60 0 0 10 mA mA mA mA VCANL = 5V, VTXD = 0V, VCC = 5.25V VCANL = 36V, VTXD = 0V, VCC = 5.25V VCANL = 60V, VTXD = 0V, VCC = 5.25V VCANL = – 60V, VTXD = 0V, VCC = 5.25V ● ● ● ● 60 0 0 – 10 1 1 –1 250 10 10 0 mA mA mA mA Differential Input Resistance VTXD = 5V, – 7V < VCANH, VCANL < 12V ● 140 240 350 kΩ CANH, CANL Input Resistance VTXD = 5V, – 7V < VCANH, VCANL< 12V ● 70 120 175 kΩ Input Fault Current (CANH, CANL) VRS = 5V, – 60V < VCANH, VCANL < 60V VTXD = 5V, – 60V < VCANH, VCANL < 60V VCC = 0V, – 60V < VCANH, VCANL < 60V ● ● ● –3 –3 –3 3 3 3 mA mA mA ISCL RIND CANL Short-Circuit Current, Dominant Mode V V 2 V 1796f 2 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 = 4.75V, IO = – 400µA, VID = 500mV ● VOL Receiver Output Low Voltage VCC = 4.75V, IO = 1.6mA, VID = 900mV ● ISCR Receiver Short-Circuit Current 0V < VO < VCC , VCC = 5.25V ● VREF Reference Output Voltage – 100µA < IREF < 100µA ● VREFSC Reference Output Short-Circuit Current 0 < VREF < VCC ● – 20 VRSSB RS Pin Standby Threshold VCC = 5V ● 2.5 IRS RS Input Current VRS = 5V, VCC = 5V VRS = 0V, VCC = 5V RS = 47k, VCC = 5V ● ● ● – 270 – 90 No Load, VRS = 0V, VTXD = 0V, VCC = 5.25V RL = 60Ω, VRS = 0V, VTXD = 5V, VCC = 5.25V RL = 60Ω, VRS = 5V, VCC = 5.25V ● ● ● ICC Supply Current Dominant Recessive Standby MIN ● ● TYP 0.5 0.5 MAX UNITS 0.9 0.9 V V 70 3 mV 3.6 V 0.15 0.4 V 7 20 85 mA 2.25 2.5 2.7 V 20 mA 2.8 4 V 0.1 – 200 – 60 10 – 140 – 40 µA µA µA 4.3 3.8 0.8 7 7 1.5 mA mA mA U SWITCHI G CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range. VRS = 0V unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS tBIT Minimum Bit Time (Note 3) FMAX Maximum Data Rate (Note 3) tTXDON Driver Input to Bus Active Figures 1, 2 tTXDOFF Driver Input to Bus Inactive MIN TYP 8 ● ● MAX 125 UNITS µs kbps RS = 0k ● 300 500 ns RS = 47k ● 350 1000 ns RS = 0k ● 500 1000 ns RS = 47k ● 600 1500 ns Figures 1, 3 ● 0.6 1.5 µs Figures 1, 2 tLBON Loopback Delay Active tLBOFF Loopback Delay Inactive Figures 1, 3 ● 1.5 3 µs tRXDOFF Receiver Delay Off Figures 1, 4 ● 400 600 ns tRXDON Receiver Delay On Figures 1, 4 ● 300 600 ns tRXDOFFSB Receiver Delay Off, Standby VRS = 4V, Figures 1, 4 ● 1.5 4 µs tRXDONSB Receiver Delay On, Standby VRS = 4V, Figures 1, 4 ● 1 4 µs tWAKE Wake-Up Delay from Standby Figures 1, 5 ● 1 15 µs SR + Positive Slew Rate RS = 0k RS = 47k ● ● 5 2 12 7 65 30 V/µs V/µs SR – Negative Slew Rate RS = 0k RS = 47k ● ● 5 2 36 5 65 15 V/µs V/µs Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Unless otherwise specified, testing done at VCC = 5V, TA = 25°C. Note 3: Bit time and data rate specifications are guaranteed by driver and receiver delay time measurements. 1796f 3 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 0.5 0 20 0 50 100 150 RL (Ω) 250 200 50 0 150 100 DATA RATE (Kbps) 200 1796 G03 1796 G01 RS Pin Current vs RS 40 TA = 25° C TA = 25° C TA = 25° C 200 30 SR– (V/µs) 10 SR+ (V/µs) SLEW CONTROL CURRENT (µA) Negative Slew Rate vs RS Positive Slew Rate vs RS 15 250 250 150 100 20 5 10 50 0 0 20 0 40 RS (kΩ) 60 80 0 0 40 20 60 80 0 20 40 60 80 RS (kΩ) RS (kΩ) 1796 G06 1796 G05 1796 G04 Transmitter Propagation Delay vs Temperature CANL Short-Circuit Current vs Voltage CANH Short-Circuit Current vs Voltage 700 90 20 TA = 25° C 600 0 500 –20 80 TA = 25° C tTXDOFF 300 tTXDON 200 –40 –60 50 40 30 20 –80 10 100 0 –50 60 ISC (mA) 400 ISC (mA) tTXDOFF AND tTXDON (ns) 70 –100 –25 0 25 50 TEMPERATURE (°C) 75 100 1796 G07 –120 –60 0 –40 –20 0 20 VCANH (V) 40 60 1796 G08 –10 –60 –40 –20 0 20 VCANL (V) 40 60 1796 G09 1796f 4 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. A logic input level higher than VREF turns the driver outputs off, releasing control of the CANH and CANL lines. A logic input less than VREF turns the driver outputs on, pulling CANH high and CANL low. An open TXD input will float high, turning the driver outputs off. The TXD input pin can withstand voltages from – 0.3V to 44V with no damage. CANL (Pin 6): CAN Bus Low Data Line. The CANL pin is one input to the receiver and the low driver output. In the dominant state (TXD low), the driver pulls the CANL pin to within 1V of GND. In the recessive state (TXD high), the driver output stays high impedance. The CANL pin is protected from voltage faults from – 60V to 60V in dominant, recessive, standby or powered off modes. On-chip ESD protection meets IEC-1000-4-2 levels. GND (Pin 2): Ground. CANH (Pin 7): CAN Bus High Data Line. The CANH pin is one input to the receiver and the high driver output. In the dominant state (TXD low), the driver pulls the CANH pin to within 1V of VCC. In the recessive state (TXD high), the driver output stays high impedance. The CANH pin is protected from voltage faults from – 60V to 60V in dominant, recessive, standby or powered off modes. On-chip ESD protection meets IEC-1000-4-2 levels. VCC (Pin 3): Positive Supply Input. Normal operation is with a 4.75V to 5.25V supply. Operation with supplies up to 44V is possible with unterminated bus lines. Operation at high voltages with normally terminated busses will result in excessive power dissipation and activation of the thermal shutdown circuit. VCC should be decoupled with a 0.1µF low ESR capacitor placed as close to the supply pin as possible. RXD (Pin 4): Receiver TTL Level-Logic Output. A high level output indicates a recessive state (zero-volt differential) bus. A dominant state forces a low receiver output. VREF (Pin 5): Reference Output. The reference voltage sets the TXD input threshold and the recessive bus common mode voltage at CANH and CANL. VREF is approximately VCC/2 for low voltage operation. When VCC > 7.5V, VREF maintains a 3.5V level. RS (Pin 8): Slope Control. This pin is a multifunction control pin. When RS is high (VRS > 4V), the circuit goes into a low power standby mode. In standby, the driver always stays in a high impedance (recessive) state. The receiver operates in a low power (slow) monitoring mode. Received data may be used to “wake-up” the system to full functionality. Full speed normal operation occurs if RS is tied low through a resistance of less than 3k. The current out of RS will be limited to about 500µA in the low state. Controlling the current out of RS with a resistor greater than 3k or by using a current source allows slew rate control of the data output onto CANH and CANL. 1796f 5 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. Driver Delay Waveforms tLBON 1796 F03 Figure 3. Loopback Delay Waveforms 3.5V 5V CANH 3V RS 3V 2.5V 2.5V 0V CANL = 2.5V 2V RXD 0.8V tRXDOFF tRXDON RXD 0.8V 1796 F05 tWAKE 1796 F04 Figure 4. Reciever Delay Waveforms Figure 5. Wake Up from Standby Waveforms U U FU CTIO TABLES Driver Output Receiver Output INPUTS BUS TERMINALS TXD RS CANH CANL OPERATING STATE BUS VOLTAGE VBUS = VCANH – VCANL RS RXD RESPONSE TIME 0 VRS < 3V High Low Dominant VBUS < 0.5V < 3V High Fast 0 VRS > 4V Hi-Z Hi-Z Standby 0.5V ≤ VBUS ≤ 0.9V < 3V Indeterminate Fast < 3V Low Fast Slow 1 VRS < 3V Hi-Z Hi-Z Recessive VBUS > 0.9V 1 VRS > 4V Hi-Z Hi-Z Standby VBUS < 0.5V > 4V High 0.5V ≤ VBUS ≤ 0.9V > 4V Indeterminate Slow VBUS > 0.9V > 4V Low Slow 1796f 6 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. DIMENSIONS ARE INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 7 6 5 N N .245 MIN .160 ±.005 1 .030 ±.005 TYP .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) 2 3 N/2 N/2 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) .053 – .069 (1.346 – 1.752) 0°– 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN 1 .014 – .019 (0.355 – 0.483) TYP INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) 2 3 4 .004 – .010 (0.101 – 0.254) .050 (1.270) BSC SO8 0502 1796f 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7 LT1796 U TYPICAL APPLICATIO Low EMI, Slew Limited CANBUS Network RT 120Ω RT 120Ω 5V 5V 0.1µF 0.1µF 3 3 LT1796 LT1796 7 7 TXD 1 4 4 R R 5 5 VREF GND RS 2 TXD 6 6 RXD 1 D D RXD VREF RS GND 8 2 8 47k 1796 TA03 47k RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC485 Low Power RS485 Interface Transceiver ICC = 300µA Typ LTC491 Differential Driver and Receiver Pair ICC = 300µA Typ LTC1483 Ultralow Power RS485 Low EMI Transceiver Controlled Driver Slew Rate LTC1485 RS485 Differential Bus Transceiver 10Mbaud Operation LTC1487 Ultralow Power RS485 with Low EMI, Shutdown and High Input Impedance Up to 256 Transceivers On the Bus LT1785/LT1791 60V Fault-Protected RS485/RS422 Transceivers 15kV ESD Protected 1796f 8 Linear Technology Corporation LT/TP 0203 2K • PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2001