ADM3493ARZ Analog Devices Inc, ADM3493ARZ Datasheet - Page 11

• Manufacturer Part Number: ADM3493ARZ
• Description: IC TXRX RS-422/485 3.3V 8-SOIC
• Manufacturer: Analog Devices Inc
• Type: Transceiverr

Specifications of ADM3493ARZ

• Number Of Drivers/receivers: 1/1
• Protocol: RS422, RS485
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Device Type: Differential Line Transceiver
• Ic Interface Type: RS422, RS485
• No. Of Drivers: 1
• Supply Voltage Range: 3V To 3.6V
• Driver Case Style: SOIC
• No. Of Pins: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CIRCUIT DESCRIPTION
The ADM3493 is a low power transceiver for RS-485 and
RS-422 communications. The ADM3493 can transmit and
receive at data rates up to 250 kbps in a half duplex
configuration. Driver Enable (DE) and Receiver Enable ( RE )
pins are included when disabled; the driver and receiver
outputs are high impedance.
Table 5. Transmitting Truth Table
1
2
Table 6. Receiving Truth Table
1
2
REDUCED EMI AND REFLECTIONS
The ADM3493 is a slew rate limited transceiver, minimizing
EMI and reducing reflections caused by improperly terminated
cables.
X = Don’t care.
High-Z = High Impedance.
X = Don’t care.
High-Z = High Impedance
RE
RE
X
X
0
0
0
1
0
1
Transmitting Inputs
1
1
Receiving Inputs
RO
DE
NOTES
1. R
RE
DI
DE
DE
0
0
0
0
1
1
0
0
T
IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE.
ADM3493
D
Inputs Open
R
DI
≥+0.2 V
≤−0.2 V
X
X
1
0
A - B
1
1
X
1
High-Z
High-Z
A
B
R
Transmitting
V
T
B
0
1
CC
Outputs
R1
R2
Receiving
ADM3493
Outputs
2
2
High-Z
RO
1
0
1
High-Z
High-Z
RO
R
Figure 28. ADM3493 Typical Half Duplex RS-485 Network
A
1
0
2
RE
MAXIMUM NUMBER OF TRANSCEIVERS ON BUS = 256
A
2
2
DE
Shutdown
Shutdown
Normal
Normal
Normal
Mode
B
Normal
Normal
Normal
DI
Mode
D
Rev. 0 | Page 11 of 12
LOW POWER SHUTDOWN MODE
A low power shutdown mode is initiated by bringing both RE
high and DE low. The ADM3493 does not shut down unless
both the driver and receiver are disabled (high impedance). In
shutdown, the ADM3493 typically draws only 2 nA of supply
current. For the ADM3493, the t
the part was in the low power shutdown mode; the t
enable times assume the receiver or driver was disabled, but the
part was not shut down.
DRIVER OUTPUT PROTECTION
Two methods are implemented to prevent excessive output
current and power dissipation caused by faults or by bus
contention. Current limit protection on the output stage
provides immediate protection against short circuits over the
whole common-mode voltage range (see Typical Performance
Characteristics). In addition, a thermal shutdown circuit forces
the driver outputs into a high impedance state if the die
temperature rises excessively.
PROPAGATION DELAY
Skew time is simply the difference between the low-to-high and
high-to-low propagation delay. Small driver/receiver skew times
help maintain a symmetrical mark-space ratio (50% duty cycle).
The receiver skew time, |t
The driver skew time is typically under 100 ns.
TYPICAL APPLICATIONS
The ADM3493 transceiver is designed for bidirectional data
communications on multipoint bus transmission lines. Figure
22 shows a typical network application’s circuits. To minimize
reflections, the line should be terminated at both ends in its
characteristic impedance, and stub lengths off the main line
should be kept as short as possible. The slew rate limited
ADM3493 is tolerant of imperfect termination.
RO
R
A
RE
DE
B
ADM3493
DI
D
PRLH
R
T
A
B
- t
PRHL
PSH
ADM3493
|, is 20 ns for the ADM3493.
and t
R
PSL
D
enable times assume
ADM3493
RO
RE
DE
DI
PZH
and t
PZL