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Final Electrical Specifications
LT1796 Overvoltage Fault Protected CAN Transceiver
December 2001
FEATURES
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DESCRIPTION
The LT(R)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 1Mbaud. 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 72. The 100k input impedance allows up to 256 transceivers per data network. The LT1796 is available in 8-lead PDIP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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Protected from Overvoltage Line Faults to 60V ESD Protection to IEC-1000-4-2 Level 4 15kV Air Gap Test 8kV Contact Mode Test High Input Impedance Supports Up to 256 Nodes Controlled Slew Rates for EMI Emissions Control Outputs Assume a High Impedance When Off or Powered Down Short-Circuit Protection On All Outputs Thermal Shutdown Protection Pin Compatible with Philips PCA82C251
APPLICATIO S
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Industrial Control Data Networks Automotive Systems HVAC Controls
TYPICAL APPLICATIO
RT 120 5V 0.1F
Fault Protected CAN Bus Network
RT 120 5V 0.1F 5V 0.1F 0.1F 5V
LT1796 7 TXD 1 D 6 RXD 4 R VREF GND 2 RS 8 5 RXD 4 TXD 1
LT1796 7 D 6 R VREF GND 2 RS 8 5 RXD 4 TXD 1
LT1796 7 D 6 R VREF GND 2 RS 8 5 5 6 7
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.
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LT1796 D 1 TXD
R VREF RS 8 GND 2
4
RXD
1796 TA01
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LT1796
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW TXD 1 D GND 2 VCC 3 RXD 4 R 7 6 5 8 RS CANH CANL VREF
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 .................................................. 0C to 70C LT1796I .............................................. - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
LT1796CN8 LT1796CS8 LT1796IN8 LT1796IS8 S8 PART MARKING 1796 1796I
N8 PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC SO
TJMAX = 150C, JA = 130C/W (N8) TJMAX = 150C, JA = 150C/W (S8)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DC ELECTRICAL CHARACTERISTICS
SYMBOL VCANH VCANL VOD PARAMETER CANH Output Voltage CANL Output Voltage Dominant State Differential Output Voltage
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 4.75V to 5.25V, VRS = 0V unless otherwise noted.
CONDITIONS VTXD = 0V, No Load VTXD = 0V, RL = 60 VTXD = 0V, No Load VTXD = 0V, RL = 60 VTXD = 0V, No Load, VCC = 4.75V VTXD = 0V, RL = 60, VCC = 4.75V VTXD = 0V, RL = 36, VCC = 4.75V VTXD = 5V, RL = 60 VTXD = 5V, No Load, VCC = 5V RL = 60, VCC = 5V
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MIN 3.8 2.8 0 0 3.0 1.5 1.2 - 10 2.7 2 2.8
TYP 4.4 3.5 0.5 1.3 3.6 2.0 1.7 0 3 2.5
MAX 5.0 4.6 0.9 1.6 5.0 4.2 4.2 10 3.5 3 2
UNITS V V V V V V V mV V V V V A mA mA mA mA mA mA mA mA k k mA mA mA
VREC VCMR VCMD VIH VIL IIN1 ISCH
Recessive State Differential Output Voltage Recessive State Common Mode Output Voltage Dominant State Common Mode Output Voltage TXD Input High Voltage TXD Input Low Voltage TXD Input Current CANH Short-Circuit Current
0 < VTXD < VCC VCANH = 0V, VTXD = 0V, VCC = 5.25V VCANH = - 36V, VTXD = 0V, VCC = 5.25V VCANH = - 60V, VTXD = 0V, VCC = 5.25V VCANH = 60V, VTXD = 0V, VCC = 5.25V 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 VTXD = 5V, - 7V < VCANH, VCANL < 12V VTXD = 5V, - 7V < VCANH, VCANL< 12V VRS = 5V, - 60V < VCANH, VCANL < 60V VTXD = 0V, - 60V < VCANH, VCANL < 60V VCC = 0V, - 60V < VCANH, VCANL < 60V
q q q q q q q q q q q q q q
-5 - 250 - 10 - 10 0 60 0 0 - 10 140 70 -3 -3 -3 -1 -1 1 1 1 -1 240 120
5 - 60 0 0 10 200 10 10 0 350 175 3 3 3
ISCL
CANL Short-Circuit Current
RIND
Differential Input Resistance CANH, CANL Input Resistance Input Fault Current (CANH, CANL)
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LT1796
DC ELECTRICAL CHARACTERISTICS
SYMBOL VTH VTH VOH VOL ISCR VREF VREFSC VRSSB IRS PARAMETER Differential Input Threshold Voltage for Receiver Receiver Input Hysteresis Receiver Output High Voltage Receiver Output Low Voltage Receiver Short-Circuit Current Reference Output Voltage Reference Output Short-Circuit Current RS Pin Standby Threshold RS Input Current
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 4.75V to 5.25V, VRS = 0V unless otherwise noted.
CONDITIONS VRS = 0V, - 7V < VCM < 12V VRS = 5V, - 7V < VCM < 12V - 7V < VCM < 12V VCC = 4.75V, IO = - 400A, VID = 500mV VCC = 4.75V, IO = 1.6mA, VID = 900mV 0V < VO < VCC , VCC = 5.25V - 100A < IREF < 100A 0 < VREF < VCC VCC = 5V VRS = 5V, VCC = 5V VRS = 0V, VCC = 5V RS = 47k, VCC = 5V Dominant Recessive Standby No Load, VRS = 0V, VTXD = 0V, VCC = 5.25V No Load, VRS = 0V, VTXD = 5V, VCC = 5.25V No Load, VRS = 5V, VCC = 5.25V
q q q q q q q q q q q q q q
MIN 0.5 0.5
TYP
MAX 0.9 0.9
UNITS V V mV V
70 3 7 2.25 - 20 2.5 - 270 - 90 2.8 0.1 - 200 - 60 4.3 3.8 0.8 3.6 0.15 20 2.5 0.4 85 2.7 20 4 10 - 140 - 40 7 7 1.5
V mA V mA V A A A mA mA mA
ICC
Supply Current
SWITCHI G CHARACTERISTICS
SYMBOL tBIT FMAX tTXDON tTXDOFF tLBON tLBOFF tRXDOFF tRXDON tRXDOFFSB tRXDONSB tWAKE SR + SR - PARAMETER Minimum Bit Time Maximum Data Rate Driver Input to Bus Active Driver Input to Bus Inactive Loopback Delay Active Loopback Delay Inactive Receiver Delay Off Receiver Delay On Receiver Delay Off, Standby Receiver Delay On, Standby Wake-Up Delay from Standby Positive Slew Rate Negative Slew Rate
The q denotes the specifications which apply over the full operating temperature range. VRS = 0V unless otherwise noted. (Note 2)
CONDITIONS (Note 3) (Note 3) Figures 1, 2 Figures 1, 2 Figures 1, 3 Figures 1, 3 Figures 1, 4 Figures 1, 4 VRS = 4V, Figures 1, 4 VRS = 4V, Figures 1, 4 Figures 1, 5 RS = 0k RS = 47k RS = 0k RS = 47k RS = 0k RS = 47k RS = 0k RS = 47k
q q q q q q q q q q q q q q q q q
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 = 25C.
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MIN 500
TYP
MAX 2
UNITS s kbps ns ns ns ns s s ns ns s s s V/s V/s V/s V/s
300 350 500 600 0.6 1.5 400 300 1.5 1 1 5 2 5 2 12 4 12 4
500 1000 1000 1500 1.5 3 600 600 4 4 15 65 30 65 10
Note 3: Bit time and data rate specifications are guaranteed by driver and receiver delay time measurements.
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LT1796
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 controls 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. GND (Pin 2): Ground. 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 0.1F 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. The RXD output is protected from fault conditions between -0.3V to 44V. 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. 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. 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. 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 500A 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.
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BLOCK DIAGRA
TEST CIRCUIT
5V 0.1F 3 1 TXD CANH 7 60 4 RXD CANL 6 100pF
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VCC 3 TXD 1 DRIVER RS RXD VREF 8 SLOPE/ STANDBY 7 4 5 REFERENCE VOLTAGE RX 6 CANL CANH 2 GND
1796 BD
30pF
GND VREF RS 2 5 8 RS
1796 F01
Figure 1. Switching Test Circuit
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LT1796
TI I G DIAGRA S
5V TXD 0V VDIFF = VCANH - VCANL VDIFFHI VDIFF VDIFFLO 25% tTXDOFF 50% 2.5V 2.5V
Figure 2. Driver Delay Waveforms
3.5V CANH 2.5V CANL = 2.5V RXD 2V 0.8V tRXDON tRXDOFF 3V 3V
Figure 4. Reciever Delay Waveforms
FU CTIO TABLES
Driver Output
INPUTS TXD 0 0 1 1 RS VRS < 3V VRS > 4V VRS < 3V VRS > 4V BUS TERMINALS CANH High Hi-Z Hi-Z Hi-Z CANL Low Hi-Z Hi-Z Hi-Z OPERATING STATE Dominant Standby Recessive Standby
Receiver Output
BUS VOLTAGE VBUS = VCANH - VCANL VBUS < 0.5V 0.5V VBUS 0.9V VBUS > 0.9V VBUS < 0.5V 0.5V VBUS 0.9V VBUS > 0.9V RS < 3V < 3V < 3V > 4V > 4V > 4V RXD High Indeterminate Low High Indeterminate Low RESPONSE TIME Fast Fast Fast Slow Slow Slow
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5V TXD 0V 2.5V 2.5V
RXD 0V
2V
0.8V tLBON
tTXDON
1796 F02
tLBOFF
1796 F03
Figure 3. Loopback Delay Waveforms
5V RS 0V 2.5V
RXD tWAKE
0.8V
1796 F05
1796 F04
Figure 5. Wake Up from Standby Waveforms
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LT1796
PACKAGE DESCRIPTIO U
N8 Package 8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400* (10.160) MAX 8 7 6 5 0.255 0.015* (6.477 0.381) 1 0.300 - 0.325 (7.620 - 8.255) 2 3 4 0.130 0.005 (3.302 0.127) 0.045 - 0.065 (1.143 - 1.651) 0.065 (1.651) TYP 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 0.003 (0.457 0.076)
N8 1098
0.009 - 0.015 (0.229 - 0.381)
(
+0.035 0.325 -0.015 8.255 +0.889 -0.381
)
0.100 (2.54) BSC
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 7 6 5
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
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0.053 - 0.069 (1.346 - 1.752)
0.004 - 0.010 (0.101 - 0.254)
0.014 - 0.019 (0.355 - 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) BSC
SO8 1298
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LT1796
TYPICAL APPLICATIO
5V 0.1F 3 LT1796 7 TXD 1 D 6 RXD 4 R VREF GND 2 RS 8 47k 5 5 VREF RS 8 6 7 0.1F
RELATED PARTS
PART NUMBER LTC485 LTC491 LTC1483 LTC1485 LTC1487 LT1785/LT1791 DESCRIPTION Low Power RS485 Interface Transceiver Differential Driver and Receiver Pair Ultralow Power RS485 Low EMI Transceiver RS485 Differential Bus Transceiver Ultralow Power RS485 with Low EMI, Shutdown and High Input Impedance 60V Fault-Protected RS485/RS422 Transceivers COMMENTS ICC = 300A Typ ICC = 300A Typ Controlled Driver Slew Rate 10Mbaud Operation Up to 256 Transceivers On the Bus 15kV ESD Protected
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
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Low EMI, Slew Limited CANBUS Network
RT 120 RT 120 5V 3 LT1796 D 1 TXD R 4 RXD GND 2
1796 TA03
47k
1796i LT/TP 1201 1.5K * PRINTED IN THE USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2001

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