Datasheet

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General Description

The MAX3480EA/MAX3480EB are electrically isolated

RS-485/RS-422 data-communications interfaces. The

RS-485/RS-422 I/O pins are protected against ±15kV

electrostatic discharge (ESD) shocks, without latchup.

Transceivers, optocouplers, and a transformer are all

included in one low-cost, 28-pin PDIP package. A sin-

gle +3.3V supply on the logic side powers both sides

of the interface.

The MAX3480EB features reduced-slew-rate drivers

that minimize EMI and reduce reflections caused by

improperly terminated cables, allowing error-free data

transmission at data rates up to 160kbps. The

MAX3480EA’s driver slew rate is not limited, allowing

transmission rates up to 2.5Mbps.

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.

The MAX3480EA/MAX3480EB are guaranteed to with-

stand 1260V

RMS

(1min) or 1520V

RMS

(1s). Their isolated

inputs and outputs meet RS-485/RS-422 specifications.

________________________Applications

Isolated RS-485/RS-422 Data Interface

Transceivers for EMI-Sensitive Applications

Industrial-Control Local Area Networks

Automatic Test Equipment

HVAC/Building Control Networks

Telecom

____________________________Features

♦ Isolated Data Interface Guaranteed to 1260V

RMS

(1min)

♦ ±15kV ESD Protection for I/O Pins

♦ Slew-Rate-Limited Data Transmission (160kbps for

MAX3480EB)

♦ High-Speed, Isolated, 2.5Mbps RS-485 Interface

(MAX3480EA)

♦ Single +3.3V Supply

♦ Current Limiting and Thermal Shutdown for

Driver Overload Protection

♦ Standard 28-Pin PDIP Package

♦ Allows Up to 128 Transceivers on the Bus

MAX3480EA/MAX3480EB

±15kV ESD-Protected, Isolated, 3.3V

RS-485/RS-422 Data Interfaces

________________________________________________________________ Maxim Integrated Products 1

AC1

AC2

ISO V

CC1

CC2

CC1

ISO RO DRV

ISO DI IN

ISO DE INV

CC3

GND1

ISO COM1

ISO DI DRV

ISO V

CC2

ISO DE DRV

GND2

CC4

ISO COM2

ISO RO LED

CC5

MAX1487E

MAX487E

ISOLATION BARRIER

TOP VIEW

MAX3480EA

MAX3480EB

PDIP

MAX845

Pin Configuration

19-1941; Rev 1; 3/06

Ordering Information

PART

TEMP

RANGE

PI N -

PA C K A G E*

D A T A

R A T E

( k b p s )

PKG

CODE

MAX3480EACPI

0°C to + 70°C

28 PDIP

2500

P28M-1

MAX3480EAEPI

- 40°C to + 85°C

28 PDIP

2500

P28M-1

MAX3480EBCPI

0°C to + 70°C

28 PDIP

250

P28M-1

MAX3480EBEPI

- 40°C to + 85°C

28 PDIP

250

P28M-1

*See the Reliability section at end of data sheet.

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Summary of content (16 pages)

PAGE 1
9-1941; Rev 1; 3/06 ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces The MAX3480EA/MAX3480EB are electrically isolated RS-485/RS-422 data-communications interfaces. The RS-485/RS-422 I/O pins are protected against ±15kV electrostatic discharge (ESD) shocks, without latchup. Transceivers, optocouplers, and a transformer are all included in one low-cost, 28-pin PDIP package. A single +3.3V supply on the logic side powers both sides of the interface.
PAGE 2
MAX3480EA/MAX3480EB ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces ABSOLUTE MAXIMUM RATINGS With Respect to GND Supply Voltage (VCC1, VCC2, VCC4, VCC5) .......-0.3V to +3.8V Supply Voltage (VCC3) ........................................-0.3V to +7V Control Input Voltage (SD, FS) ............-0.3V to (VCC3 + 0.3V) Receiver Output Voltage (RO).............-0.3V to (VCC5 + 0.3V) With Respect to ISO COM Control Input Voltage (ISO DE _)......-0.3V to (ISO VCC_ + 0.
PAGE 3
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces (VCC = VCC1 = VCC2 = VCC4 = VCC5 = +3.0V to +3.6V, FS = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Notes 1, 2) PARAMETER Driver Common-Mode Output Input Current (A, B) SYMBOL VOC ISO IIN CONDITIONS MIN TYP R = 27Ω or 50Ω, Figure 4 DE´ = 0, VCC = 0 or +3.6V MAX3480EA MAX3480EB VIN = +12V MAX UNITS 4 V 0.25 VIN = -7V -0.2 VIN = +12V 0.25 VIN = -7V mA -0.
PAGE 4
MAX3480EA/MAX3480EB ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces SWITCHING CHARACTERISTICS—MAX3480EB (VCC = VCC1 = VCC2 = VCC4 = VCC5 = +3.0V to +3.6V, FS = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) PARAMETER Driver Input to Output Propagation Delay SYMBOL tPLH tPHL CONDITIONS MIN Figures 4, 6; RDIFF = 54Ω, CL1 = CL2 = 100pF TYP MAX 1.5 3.0 1.2 3.
PAGE 5
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE 2.6 2.5 2.4 2.3 -70 -60 -50 -40 -30 120 100 80 60 2.2 -20 40 2.1 -10 20 2.0 0 20 40 60 0 80 -6 -4 TEMPERATURE (°C) -2 0 2 4 6 4 6 8 10 12 0.6 0.5 0.4 0.3 0.2 5.00 MEASURED AT ISO RO DRV IRO = 8mA 4.75 OUTPUT HIGH VOLTAGE (V) MAX3480EA/EB toc04 RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE MEASURED AT ISO RO DRV IRO = 8mA 0.
PAGE 6
Typical Operating Characteristics (continued) (VCC_ = +3.3V, TA = +25°C, Figure 1, unless otherwise noted.) MAX3480EA DRIVER ENABLE (AB) AND RECEIVER OUTPUT (RO) MAX3480EA/EB toc08 MAX3480EA SUPPLY CURRENT vs.
PAGE 7
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces PIN NAME FUNCTION PINS ON THE NONISOLATED SIDE 1 VCC1 Logic-Side (Nonisolated Side) +3.3V Supply Voltage Input. Connect to pins 2, 10, and 14. Logic-Side (Nonisolated Side) +3.3V Supply Voltage Input. Connect to pins 1, 10, and 14. 2 VCC2 3, 4 D1, D2 Boost-Voltage Generator Outputs. See Figures 1 and 2. 5, 12 GND1, GND2 Logic-Side Ground Inputs. Must be connected; not internally connected. 6 FS Frequency Switch Input.
PAGE 8
MAX3480EA/MAX3480EB ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces _________________________________________________Pin Description (continued) PIN NAME FUNCTION PINS ON THE ISOLATED RS-485/RS-422 SIDE 15 ISO RO LED 16 ISO COM2 Isolated Receiver-Output LED Anode (Input). If A > B by 200mV, ISO RO LED is high; if A < B by 200mV, ISO RO LED is low. Isolated-Supply Common Input. Connect to ISO COM1. Isolated Driver-Enable Drive Input.
PAGE 9
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces isolation barrier (Figure 1). Power is transferred from the logic side (nonisolated side) to the isolated side of the barrier through a center-tapped transformer. Signals cross the barrier through high-speed optocouplers. A single +3.3V supply on the logic side powers both sides of the interface. The MAX3480EA/MAX3480EB are electrically isolated, RS-485/RS-422 data-communications interface solutions.
PAGE 10
MAX3480EA/MAX3480EB ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces The MAX3480EB features reduced-slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission at data rates up to 160kbps. The MAX3480EA’s driver slew rates are not limited, allowing transmission rates up to 2.5Mbps. The frequency-select FS is connected to GND_ in normal operation, which selects a switching frequency of approximately 600kHz.
PAGE 11
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces ISOLATION BARRIER A ISOLATION BARRIER +3.3V +3.3V ´ DE R CL1 A VOD D ´ DI R RDIFF VID RO R B B VOC R3 A CL2 B Figure 3. Driver DC Test Load Figure 4. Driver/Receiver Timing Test Circuit S1 500Ω ISO VCC1, ISO VCC2 OUTPUT UNDER TEST CL S2 Figure 5. Driver Timing Test Load _______________________________________________________Switching Waveforms VCC_ - 0.4V ´ DI 0 VCC_ - 0.4V VCC_ - 0.4V 2 VCC_ - 0.
PAGE 12
MAX3480EA/MAX3480EB ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces __Switching Waveforms (continued) The MAX3480EA/MAX3480EB withstand 1260VRMS (1 min) or 1560VRMS (1s). The isolated outputs of these devices meet all RS-485/RS-422 specifications. Boost Voltage The MAX3480EA/MAX3480EB require external diodes on the primary of the transformer to develop the boost voltage for the power oscillator.
PAGE 13
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces RD 1500Ω CHARGE-CURRENT LIMIT RESISTOR IP 100% 90% DISCHARGE RESISTANCE Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES HIGHVOLTAGE DC SOURCE Cs 100pF STORAGE CAPACITOR DEVICE UNDER TEST 36.8% 10% 0 0 Figure 9. Human Body ESD Test Model ±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly.
PAGE 14
MAX3480EA/MAX3480EB ±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces closely represent those of discrete optocouplers, rather than the more robust characteristics of monolithic silicon ICs. The reliability testing programs for these multicomponent devices may be viewed on the Maxim website (www.maxim-ic.com) under Technical Support, Technical Reference, Multichip Products. driven through a series current-limiting resistor. Directly grounding these pins destroys the device.
PAGE 15
±15kV ESD-Protected, Isolated, 3.3V RS-485/RS-422 Data Interfaces MAX3480EA/MAX3480EB TERMINATING RESISTOR (ONE RESISTOR ON EACH END) B D 120Ω DE A A B A B DI RO R RE R RE RE R D RO DE D DI RO DE VIN DI VCC1 +3.0V TO +3.6V C1 22µF 6V C2 0.
PAGE 16
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) D1 N DIM A A1 A2 A3 B B1 C D1 E E1 e eA eB L 1 TOP VIEW E D A E1 A3 A1 A2 e B1 B FRONT VIEW MILLIMETERS MAX MIN 5.08 0.39 3.18 4.45 1.40 2.03 0.41 0.51 1.14 1.65 0.21 0.30 0.13 0.22 15.24 15.87 13.34 14.61 2.54 BSC 15.24 BSC 3.05 17.78 3.81 VARIATIONS: INCHES 0∞-15∞ L INCHES MAX MIN 0.200 0.015 0.125 0.