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General Description

The MAX13487E evaluation kit (EV kit) is a fully assem-

bled and tested PCB that contains a half-duplex RS-

485/RS-422 AutoDirection-controlled transceiver with

ESD protection. The EV kit circuit features a differential

driver and receiver. The circuit’s receiver is a 1/4-unit

load for the RS-485 bus and can communicate up to

500kbps. The MAX13487E AutoDirection and reduced-

driver slew-rate features are demonstrated on the EV kit

circuit. The EV kit can also be used to evaluate the

MAX13488E IC, which can communicate up to 16Mbps.

Power for the transceiver circuit is provided by a MAX256

H-bridge DC/DC converter, which powers the isolated

section of the MAX13487E RS-485/RS-422 circuit. Input-

ripple current and radiated noise are minimized by using

an H-bridge design. The isolated H-bridge DC-DC con-

verter operates at 420kHz. Input power to the EV kit

circuit can be supplied by a +5V DC source.

The DC-DC converter circuit uses a surface-mount

transformer to provide galvanic isolation and a full-wave

rectifier, and provides a regulated +5V to the

MAX13487E. A MAX1659 linear low dropout (LDO) reg-

ulator provides the regulated output and up to 300mA

of current. The output current limit and thermal shut-

down provide for a robust isolated RS-485/RS-422

transceiver circuit and power supply. The transceiver

and power circuits and PCB are designed for

2500V

RMS

isolation.

Features

o Demonstrates MAX13487E AutoDirection Feature

o Designed for 2500V

RMS

Isolation

o 1/4 RS-485 Unit Loading

o 500kbps Half-Duplex RS-485/RS-422

Communication

o +5V DC Input Range

o Isolated +5V Output

o Center-Tapped Full-Wave Rectifier Output

o 420kHz Switching Frequency

o Output Current Limit and Thermal Shutdown

o Low-Cost Integrated-FET H-Bridge Design

o Also Evaluates MAX13488E (After IC

Replacement)

o Fully Assembled and Tested

Evaluates: MAX13487E/MAX13488E

MAX13487E Evaluation Kit

________________________________________________________________

Maxim Integrated Products

19-3204; Rev 1; 11/08

Component List

For pricing, delivery, and ordering information, please contact Maxim Direct 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

Denotes RoHS compliant.

PART TYPE

MAX13487EEVKIT# EV Kit

DESIGNATION

QTY

DESCRIPTION

C1 1

10µF ±10%, 10V X7R ceramic

capacitor (1206)

Murata GRM31CR71A106K

C2 1

0.47µF ±10%, 16V X7R ceramic

capacitor (0805)

Murata GRM219R71C474K

C3, C5, C6, C7

0.1µF ±10%, 16V X7R ceramic

capacitors (0603)

Murata GRM188R71C104K

C4 1

1µF ±10%, 16V X7R ceramic

capacitor (0805)

Murata GRM21BR71C105K

D1, D2 2

30V, 1A Schottky diodes (SOD123)

Diodes Inc. B130LAW

D3 1

15V, 350mW ±5% zener diode

(SOT-23)

C entr al S em i cond uctor C M P Z 5245B+

DESIGNATION

QTY

DESCRIPTION

JU1, JU3, JU4,

JU5, JU6

5 2-pin headers

JU2 1 3-pin header

R1 1 39.2kΩ ±1% resistor (0603)

R2, R9 2 100kΩ ±5% resistors (0603)

R4, R5 2 270Ω ±5% resistors (0805)

R6, R8 2 220Ω ±5% resistors (0805)

R7 1 120Ω ±5% resistor (0805)

T1 1

500µH, 1.5W, 3:8-turn, 400kHz

transformer (6-pin Gull Wing)

HALO Electronics TGM-380NARL

U1 1

Half-duplex, high-speed transceiver

(8 SO)

Maxim MAX13487EESA+

Summary of content (8 pages)

PAGE 1
9-3204; Rev 1; 11/08 MAX13487E Evaluation Kit The MAX13487E evaluation kit (EV kit) is a fully assembled and tested PCB that contains a half-duplex RS485/RS-422 AutoDirection-controlled transceiver with ESD protection. The EV kit circuit features a differential driver and receiver. The circuit’s receiver is a 1/4-unit load for the RS-485 bus and can communicate up to 500kbps. The MAX13487E AutoDirection and reduceddriver slew-rate features are demonstrated on the EV kit circuit.
PAGE 2
Evaluates: MAX13487E/MAX13488E MAX13487E Evaluation Kit Component List (continued) DESIGNATION QTY DESCRIPTION SUPPLIER PHONE WEBSITE U2 1 Integrated primary-side controller and H-bridge driver (8 SO-EP*) Maxim MAX256ASA+ CEL/NEC (California Eastern Laboratories/NEC) U3 1 Linear regulator (8 SO) Maxim MAX1659ESA+ Central Semiconductor Corp. 631-435-1110 www.centralsemi.com U4, U5 2 15Mbps CMOS photocouplers (5 SO) CEL/NEC PS9151-A Diodes, Inc. 805-446-4800 www.diodes.
PAGE 3
MAX13487E Evaluation Kit The MAX256 IC includes UVLO for controlled startup and provides controlled turn-on during power-up and during brownouts. If the input voltage at VIN falls below 1.9V (typ), the MAX256 IC will shut down. Surface-mount transformer T1 provides galvanic isolation and the VOUT output is powered from a centertapped full-wave rectifier circuit (D1 or D2) to reduce output-voltage ripple. It feeds a MAX1659 LDO regulator configured for +5V output.
PAGE 4
Evaluates: MAX13487E/MAX13488E MAX13487E Evaluation Kit RS-485 Bus Pullup/Pulldown and Termination Resistors Configuration Jumpers JU6 and JU4 are provided for connecting the mandatory pullup and pulldown resistors onto the RS-485 bus A and B lines, respectively. Pullup resistor R8 and pulldown resistor R6 define the voltage on the A and B lines in conjunction with R7 when the driver input (DI) is high. See Table 3 for configuring the pullup and pulldown resistors.
PAGE 5
SHDN PGND VIN TXD PGND RXD JU1 C1 10μF 10V 2 1 V0 VOUT CATHODE GND 2 3 U5 1 5 ANODE VDD VIN GND 3 V0 4 C7 0.1μF 2 R4 270Ω VOUT U2 ST2 GND GND ST1 R9 100kΩ MAX256 MODE 1 ANODE 4 3 VCC VCC CK_RS U4 CATHODE 5 VDD VIN R2 100kΩ R5 270Ω 4 C6 0.1μF C2 0.47μF 16V 2 1 TP1 3 2 1 JU3 1 2 PGND 5 7 6 8 JU2 VOUT GND TP2 RO 4 3 2 DI U1 GND A B VCC D2 D1 MAX13487E SHDN RE 4 3 6 5 4 T1 2 1 5 6 7 8 VOUT C5 0.1μF C3 0.
PAGE 6
Evaluates: MAX13487E/MAX13488E MAX13487E Evaluation Kit Figure 2. MAX13487E EV Kit Component Placement Guide— Component Side 6 Figure 3.
PAGE 7
MAX13487E Evaluation Kit Evaluates: MAX13487E/MAX13488E Figure 4.
PAGE 8
Evaluates: MAX13487E/MAX13488E MAX13487E Evaluation Kit Revision History REVISION NUMBER REVISION DATE DESCRIPTION 0 1/08 Initial release 1 11/08 Revised data sheet in several places with changes to resistors R6 and R8. PAGES CHANGED — 1, 2, 4, 5 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.