LT1796
Overvoltage Fault Protected
CAN Transceiver
Features
Description
Protected from Overvoltage Line Faults to ±60V
nn ESD Protection to IEC-1000-4-2 Level 4
±15kV Air Gap Test
±8kV Contact Mode Test
nn ISO 11898 Compatible
nn High Input Impedance Supports Up to 256 Nodes
nn Controlled Slew Rates for EMI Emissions Control
nn High Impedance Outputs When Off or
Powered Down
nn Short-Circuit Protection On All Outputs
nn Thermal Shutdown Protection
nn 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.
nn
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.
Applications
Industrial Control Data Networks
Automotive Systems
nn HVAC Controls
nn
nn
The LT1796 is available in 8-lead PDIP and SO packages.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
Fault Protected CAN Bus Network
RT
120Ω
RT
120Ω
125kbps CANH and CANL Driver Output
5V
5V
0.1µF
LT1796
TXD
RXD
1
4
7
0.1µF
7
CANH-CANL
2V/DIV
LT1796
D
1
D
6
6
R
VREF
GND
2
4
R
RS
8
5
5
TXD
RXD
VREF
RS
GND
8
2
CANH
2V/DIV
CANH
2V/DIV
TXD IN
5V/DIV
5V/DIV
1796 TA02
1796 TA01
1796fa
For more information www.linear.com/LT1796
1
LT1796
Absolute Maximum Ratings
Pin Configuration
(Note 1)
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
D
GND 2
VCC 3
R
RXD 4
8
RS
7
CANH
6
CANL
5
VREF
N8 PACKAGE
S8 PACKAGE
8-LEAD PDIP 8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 130°C/W (N8)
TJMAX = 150°C, θJA = 150°C/W (S8)
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1796CN8#PBF
LT1796CN8#TRPBF
LT1796 CN8
8-Lead PDIP
0°C to 70°C
LT1796CS8#PBF
LT1796CS8#TRPBF
1796
8-Lead Plastic SO
0°C to 70°C
LT1796IN8#PBF
LT1796IN8#TRPBF
LT1796I IN8
8-Lead PDIP
–40°C to 85°C
LT1796IS8#PBF
LT1796IS8#TRPBF
1796I
8-Lead Plastic SO
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
Electrical Characteristics
The l 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
2
1796fa
For more information www.linear.com/LT1796
LT1796
Electrical Characteristics
The l 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
VCMD
Dominant State Common Mode Output Voltage
VIH
TXD Input High Voltage
RL = 60Ω, VCC = 5V
MIN
TYP
MAX
●
2
2.5
3
●
2.8
UNITS
V
V
VIL
TXD Input Low Voltage
IIN1
TXD Input Current
0 < VTXD < VCC
●
–5
2
V
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
ISCL
CANL Short-Circuit Current, Dominant Mode
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
RIND
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
●
DC Electrical Characteristics
The l 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
MIN
l
l
0.5
0.5
3
TYP
MAX
0.9
0.9
UNITS
V
V
∆VTH
Receiver Input Hysteresis
–7V < VCM < 12V
VOH
Receiver Output High Voltage
VCC = 4.75V, IO = –400µA, VID = 500mV
l
70
mV
3.6
V
VOL
Receiver Output Low Voltage
VCC = 4.75V, IO = 1.6mA, VID = 900mV
l
ISCR
Receiver Short-Circuit Current
0V < VO < VCC , VCC = 5.25V
l
7
VREF
Reference Output Voltage
–100µA < IREF < 100µA
l
2.25
VREFSC
Reference Output Short-Circuit Current
0 < VREF < VCC
l
–20
VRSSB
RS Pin Standby Threshold
VCC = 5V
l
2.5
2.8
4
V
IRS
RS Input Current
VRS = 5V, VCC = 5V
VRS = 0V, VCC = 5V
RS = 47k, VCC = 5V
l
l
l
–270
–90
0.1
–200
–60
10
–140
–40
µA
µA
µA
ICC
Supply Current Dominant
Recessive
Standby
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
l
l
l
4.3
3.8
0.8
7
7
1.5
mA
mA
mA
0.15
0.4
V
20
85
mA
2.5
2.7
V
20
mA
1796fa
For more information www.linear.com/LT1796
3
LT1796
Switching Characteristics
The l denotes the specifications which apply over the full operating
temperature range. VRS = 0V unless otherwise noted. (Note 2)
SYMBOL PARAMETER
CONDITIONS
MIN
tBIT
Minimum Bit Time
(Note 3)
l
FMAX
Maximum Data Rate
(Note 3)
l
tTXDON
Driver Input to Bus Active
Figures 1, 2
tTXDOFF
tLBON
Driver Input to Bus Inactive
Figures 1, 2
Loopback Delay Active
TYP
MAX
8
125
UNITS
µs
kbps
RS = 0k
l
300
500
ns
RS = 47k
l
350
1000
ns
RS = 0k
l
500
1200
ns
RS = 47k
l
600
1500
ns
l
0.6
1.5
µs
Figures 1, 3
tLBOFF
Loopback Delay Inactive
Figures 1, 3
l
1.5
3
µs
tRXDOFF
Receiver Delay Off
Figures 1, 4
l
400
600
ns
tRXDON
Receiver Delay On
Figures 1, 4
l
300
600
ns
tRXDOFFSB Receiver Delay Off, Standby
VRS = 4V, Figures 1, 4
l
1.5
4
µs
tRXDONSB Receiver Delay On, Standby
VRS = 4V, Figures 1, 4
l
1
4
µs
1
15
µs
tWAKE
Wake-Up Delay from Standby
Figures 1, 5
l
SR+
Positive Slew Rate
RS = 0k
RS = 47k
l
l
5
2
12
7
65
30
V/µs
V/µs
SR–
Negative Slew Rate
RS = 0k
RS = 47k
l
l
5
2
36
5
65
15
V/µs
V/µs
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
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.
Typical Performance Characteristics
Dominant State Bus Voltage
vs RL
3.0
Supply Current vs Data Rate
Transmitting, 50% Duty Cycle
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
0
50
100
150
RL (Ω)
200
250
20
0
1796 G01
4
50
150
100
DATA RATE (Kbps)
200
250
1796 G03
1796fa
For more information www.linear.com/LT1796
LT1796
Typical Performance Characteristics
RS Pin Current vs RS
Negative Slew Rate vs RS
Positive Slew Rate vs RS
15
TA = 25°C
40
TA = 25°C
200
30
150
SR– (V/s)
100
20
5
10
50
0
20
0
60
40
RS (kΩ)
0
80
0
40
20
60
0
500
–20
ISC (mA)
600
tTXDOFF
300
tTXDON
1796 G06
90
TA = 25°C
80
0
25
50
TEMPERATURE (°C)
75
100
60
–40
–60
30
0
–120
–60
–40
–20
0
20
VCANH (V)
40
–10
–60
60
–40
–20
0
20
VCANL (V)
40
60
1796 G09
1796 G08
Receiver Propagation Delay vs
Temperature
400
tRXDOFF AND tRXDON (ns)
0.80
VTH (V)
40
10
Receiver Thresholds vs
Temperature
VTH RISING
0.70
VTH FALLING
0.65
0.60
–50
50
20
1796 G07
0.75
TA = 25°C
70
–100
–25
80
CANL Short-Circuit Current vs
Voltage
–80
100
0
–50
60
RS (kΩ)
CANH Short-Circuit Current vs
Voltage
20
200
40
20
1796 G05
Transmitter Propagation Delay vs
Temperature
400
0
RS (kΩ)
ISC (mA)
700
0
80
1796 G04
tTXDOFF AND tTXDON (ns)
TA = 25°C
10
SR+ (V/µs)
SLEW CONTROL CURRENT (µA)
250
–25
0
25
50
TEMPERATURE (°C)
75
100
350
tRXDOFF
300
tRXDON
250
200
–50
1796 G10
–25
0
25
50
TEMPERATURE (°C)
75
100
1796 G11
1796fa
For more information www.linear.com/LT1796
5
LT1796
Pin Functions
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.
6
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.
1796fa
For more information www.linear.com/LT1796
LT1796
Block Diagram
Test Circuit
VCC
5V
3
0.1µF
3
DRIVER
1
TXD
1
TXD
CANH
7
60Ω
RS
8
RXD
4
VREF
5
SLOPE/
STANDBY
4
RX
7
CANH
6
CANL
30pF
REFERENCE
VOLTAGE
RXD
CANL
100pF
6
GND VREF RS
2
5
8
RS
1796 F01
2
1796 BD
Figure 1. Switching Test Circuit
GND
Timing Diagram
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. Receiver Delay Waveforms
Figure 5. Wake Up from Standby Waveforms
Function Tables
Driver Output
Receiver Output
INPUTS
BUS TERMINALS
TXD
RS
CANH
CANL
OPERATING STATE
0
VRS < 3V
High
Low
Dominant
0
VRS > 4V
Hi-Z
Hi-Z
Standby
1
VRS < 3V
Hi-Z
Hi-Z
Recessive
1
VRS > 4V
Hi-Z
Hi-Z
Standby
BUS VOLTAGE
VBUS = VCANH – VCANL
RS
RXD
RESPONSE TIME
VBUS < 0.5V
4V
Indeterminate
Slow
VBUS > 0.9V
>4V
Low
Slow
1796fa
For more information www.linear.com/LT1796
7
LT1796
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
N Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510 Rev I)
.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
+0.889
8.255
–0.381
.130 ±.005
(3.302 ±0.127)
.045 – .065
(1.143 – 1.651)
)
.120
(3.048) .020
MIN
(0.508)
MIN
.018 ±.003
N8 REV I 0711
(0.457 ±0.076)
.100
(2.54)
BSC
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 Rev G)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
8
.245
MIN
.160 ±.005
.010 – .020
× 45°
(0.254 – 0.508)
NOTE:
1. DIMENSIONS IN
2
.053 – .069
(1.346 – 1.752)
0°– 8° TYP
.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)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
8
5
.150 – .157
(3.810 – 3.988)
NOTE 3
1
RECOMMENDED SOLDER PAD LAYOUT
.016 – .050
(0.406 – 1.270)
6
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
.008 – .010
(0.203 – 0.254)
7
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 REV G 0212
1796fa
For more information www.linear.com/LT1796
LT1796
Revision History
REV
DATE
DESCRIPTION
A
8/15
Increased tTXDOFF max limit
PAGE NUMBER
4
1796fa
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.
For more
information
www.linear.com/LT1796
9
LT1796
Typical Application
Low EMI, Slew Limited CANBUS Network
RT
120Ω
RT
120Ω
5V
5V
0.1μF
0.1μF
3
3
LT1796
TXD
RXD
1
4
7
7
LT1796
1
D
D
6
6
VREF
GND
2
4
R
R
5
RS
8
47k
5
TXD
RXD
VREF
RS
GND
8
2
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
LTC2875
±60V CAN Transceiver
3.3V or 5V Supply, 4Mbps Operation, 25kV ESD
10 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LT1796
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LT1796
1796fa
LT 0815 REV A • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2001
工商网监
湘ICP备2023018690号
