19-0453; Rev 0; 1/96
Co m p le t e , Is o la t e d , 3 .3 V
RS -4 8 5 /RS -4 2 2 Da t a In t e rfa c e
/MAX3480B
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
The MAX3480A/MAX3480B a re e le c tric a lly isola te d
RS-485/RS-422 d a ta -c ommunic a tions inte rfa c e s .
Transceivers, optocouplers, and a transformer are all
included in one low-cost, 28-pin DIP package. A single
+3.3V supply on the logic side powers both sides of the
interface.
♦ Isolated Data Interface to 1600V
(1 minute)
RMS
♦ Slew-Rate-Limited Data Transmission (MAX3480B)
♦ High-Speed, Isolated, 2.5Mbps RS-485 Interface
(MAX3480A)
♦ -7V to +12V Common-Mode Input Voltage Range
The MAX3480B features reduced-slew-rate drivers that
minimize EMI a nd re d uc e re fle c tions c a us e d b y
improperly terminated cables, allowing error-free data
tra ns mis s ion a t d a ta ra te s up to 250kb p s . The
MAX3480A’s driver slew rate is not limited, allowing
transmission rates up to 2.5Mbps.
with Respect to Isolated Ground
♦ Single +3.3V Supply
♦ Current Limiting and Thermal Shutdown for
Driver Overload Protection
♦ Standard 28-Pin DIP Package
These devices typically draw 180mA of quiescent sup-
ply current. The MAX3480B provides a low-power shut-
down mode in which it consumes only 0.2µA.
Drivers are short-circuit current limited and are protect-
ed against excessive power dissipation by thermal
shutdown circuitry that places the driver outputs into a
high-impedance state. The receiver input has a fail-safe
feature that guarantees a logic-high output if the input
is open circuit.
__________________P in Co n fig u ra t io n
The MAX3480A/MAX3480B typically withstand 1600V
RMS
(1 minute) or 2000V
(1 second). Their isolated inputs
RMS
and outputs meet RS-485/RS-422 specifications.
TOP VIEW
MAX3480A/B
________________________Ap p lic a t io n s
Isolated RS-485/RS-422 Data Interface
Transceivers for EMI-Sensitive Applications
Industrial-Control Local Area Networks
Automatic Test Equipment
V
AC1
CC1
1
2
28
27
26
25
24
23
22
21
V
CC2
AC2
D1
D2
ISO V
3
CC1
B
4
HVAC/Building Control Networks
ISO RO DRV
GND1
5
MAX845
MAX485
MAX487
6
FS
A
______________Ord e rin g In fo rm a t io n
SD
ISO DI IN
7
V
CC3
8
ISO DE IN
ISO COM1
DATA
DI
PART
TEMP. RANGE PIN-PACKAGE RATE
(kbps)
9
20
19
18
17
V
CC4
10
ISO DI DRV
MAX3480ACPI
MAX3480AEPI
MAX3480BCPI
MAX3480BEPI
0°C to +70°C 28 Plastic DIP
-40°C to +85°C 28 Plastic DIP
0°C to +70°C 28 Plastic DIP
-40°C to +85°C 28 Plastic DIP
2500
2500
250
ISO V
CC2
DE 11
ISO DE DRV
GND2
12
13
14
250
RO
16 ISO COM2
ISO RO LED
V
CC5
15
ISOLATION BARRIER
DIP
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800