MAX3535EEVKIT [MAXIM]

Center-Tapped, Full-Wave Rectifier Output;


型号：	MAX3535EEVKIT
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	Center-Tapped, Full-Wave Rectifier Output
文件：	总5页 (文件大小：108K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

19-0716; Rev 0; 12/06

MAX3535E Evaluation Kit

vluates:MAX35E

General Description

Features

The MAX3535E evaluation kit (EV kit) is a fully assem-

bled and tested PCB that contains a 2500V isolated

ꢀ Designed for 2500V

Isolation

RMS

ꢀ 1/8 RS-485 Unit Load

RS-485/RS-422 transceiver with ESD protection. The EV

kit circuit features a differential driver and one receiver.

The circuit’s receiver is a 1/8 unit load for the RS-485

bus and communicates up to 1000kbps. The MAX3535E

fail-safe circuitry and driver slew-rate features are demon-

strated and easily reconfigured.

ꢀ 1000kbps Full-Duplex RS-485/RS-422

Communication (Configurable for Half Duplex)

ꢀ +3.0V to +5.5VDC Input Range

ꢀ Isolated V

Output

CC2

Additionally, the EV kit features an H-bridge DC-DC

converter to power the isolated section of the MAX3535E

RS-485/RS-422 circuit. Input power to the circuit is

supplied by a +3V to +5.5VDC source. This circuit uses a

full-wave rectifier on the unregulated output and provides

unregulated voltage to the MAX3535E internal, linear

low-dropout (LDO) regulator. Using an H-bridge design

minimizes input ripple current and radiated noise.

Undervoltage lockout (UVLO) and thermal shutdown

provide for a robust, isolated RS-485/RS-422 transceiver

circuit and power supply. The surface-mount transformer

ꢀ Center-Tapped, Full-Wave Rectifier Output

ꢀ 420kHz Switching Frequency

ꢀ Undervoltage Lockout (UVLO) and Thermal

Shutdown

ꢀ Low-Cost Integrated-FET H-Bridge Design

ꢀ Fully Assembled and Tested

provides up to 2500V

galvanic isolation and the out-

RMS

put is powered from a center-tapped, full-wave rectifier

circuit to reduce output voltage ripple.

The isolated H-bridge DC-DC converter operation at

420kHz allows the use of ceramic-only output capaci-

tors and a small transformer.

Component List

Ordering Information

DESIGNATION QTY

DESCRIPTION

PART

TEMP RANGE

IC PACKAGE

10µF 10ꢀ, 10V X7R ceramic

capacitors (1206)

Murata GRM31CR71A106K

0.1µF 10ꢀ, 25V X7R ceramic

capacitors (0805)

Murata GRM21BR71E104K

30V, 200mA Schottky diode (SOT-23)

Central Semiconductor CBAT54C

MAX3535EEVKIT+

0°C to +70°C*

28 Wide SO

C1, C3

+Denotes a lead-free and RoHS-compliant EV Kit.

*This limited temperature range applies to the EV kit PCB only.

The MAX3535E IC temperature range is -40°C to +85°C.

C2, C4

Component Suppliers

JU1

3-pin header

2-pin headers

SUPPLIER

Central

PHONE

WEBSITE

JU2, JU3, JU4

631-435-1110 www.centralsemi.com

650-903-3800 www.haloelectronics.com

Not installed, resistors (0805)

10kΩ 1ꢀ resistor recommended

Semiconductor

R1, R2

R3, R4

HALO Electronics

100kΩ 5ꢀ resistors (0805)

Murata Mfg. Co., Ltd. 770-436-1300 www.murata.com

500µH, 3kV

1CT:1:33CT turns

RMS

Note: Indicate that you are using the MAX3535E when contact-

ing these component suppliers.

transformer (6 pin)

HALO Electronics TGMR-340NA5RL

—

MAX3535EEWI+ (28-pin Wide SO)

Shunts (JU1–JU4)

Rubber bumpers

PCB: MAX3535EEVKIT+

________________________________________________________________ Maxim Integrated Products

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.

MAX3535E Evaluation Kit

The MAX3535E fail-safe circuitry signals are also provid-

ed on the RO1 (receiver output) and RO2 (isolated receiv-

er output) PC pads. Either pad gives a logic-high if A-B is

> -10mV, or if A-B floats or shorts. A logic-low is given if

A-B is < -200mV. Refer to the Fail Safe section and Table

3 in the MAX3535E IC data sheet for additional informa-

tion on the fail-safe circuitry and operation.

Quick Start

Required Equipment

• One 5V, 1A current-limited power supply with built-in

current meter

• One voltmeter

• One logic signal generator

• One oscilloscope

The circuit’s input power is typically a +5VDC source,

or is operated from a +3V to +5.5VDC source with a

corresponding reduction in the output voltage on the

isolated side. The EV kit circuit’s DC source must pro-

vide at least 350mA of current, but can also be operat-

ed at lower voltages consistent with the UVLO limit.

Procedure

The MAX3535E EV kit is fully assembled and tested.

Follow the steps below to verify board operation.

Caution: Do not turn on the power supply until all con-

nections are completed.

The MAX3535E integrates a primary-side controller and

H-bridge drivers. The device contains an on-board

oscillator, protection circuitry, and internal FET drivers

to provide up to 500mW of power to the primary of

transformer T1.

1) Connect a voltmeter to the V

pads.

and SGND PC

CC2

2) Verify that a shunt is installed across pins 2-3 of

jumper JU1 (receiver enabled).

The MAX3535E driver slew rate is reconfigured using

jumper JU2 on the EV kit. The slew rate can be config-

ured for 400kbps (slow) operation to minimize EMI radi-

ation or 1000kbps (fast). See the Slew-Rate Selection

section for configuring the slew rate.

3) Verify that a shunt is not installed across the pins of

jumper JU2 (fast slew rate).

vluates:MAX35E

4) Verify that a shunt is installed across the pins of

jumpers JU3 and JU4 (half duplex).

5) Connect the +5V power supply to the V

pad.

The circuit’s H-bridge DC-DC converter powers the

MAX3535E isolated section of the circuit. One of the

benefits of the easy-to-use H-bridge DC-DC converter

topology is minimized input ripple current, and radiated

noise by the inherent balanced nature of the design,

with no interruption in the input current. UVLO and ther-

mal shutdown provide for a robust isolated supply.

Thermal-shutdown circuitry provides additional protec-

tion against damage due to overtemperature condi-

tions. The MAX3535E IC’s UVLO provides controlled

turn-on while powering up and during brownouts.

CC1

Connect the power supply’s ground to the GND

pad.

6) Turn on the power supply and verify that the volt-

meter at V

reads over +5V.

CC2

7) Apply a logic signal to the DI PCB pad and GND.

Using an oscilloscope, verify the signal at the A-B,

RO2, and RO1 output pads.

The +5V supply powering the MAX3535E EV kit must

be current limited at 1A.

The surface-mount transformer provides up to

Detailed Description

2500V

galvanic isolation and the output is powered

RMS

The EV kit features a MAX3535E IC in a 28-pin wide SO

surface-mount package and demonstrates the

from a center-tapped, full-wave rectifier circuit to

reduce output voltage ripple. The isolated H-bridge

DC-DC converter operation at 420kHz allows the use of

ceramic-only output capacitors and a small trans-

former. The switching-frequency duty cycle is fixed at

50ꢀ to control energy transfer to the isolated output

and to prevent DC current flow in the transformer.

MAX3535E 2500V

isolated RS-485/RS-422 trans-

RMS

ceiver with ESD protection. The circuit’s differential dri-

ver and receiver are configurable for full- or half-duplex

operation and can communicate up to 1000kbps. The

circuit is a 1/8 unit load on the receiver’s bus.

The EV kit features PCB pads to ease interfacing with

logic signals for the driver and receiver signals. On the

nonisolated side, the DI pad is the driver input pad and

the RO1 pad is the receiver-signal output pad. Resistor

The PCB is designed for 2500V isolation with 300 mils

spacing between the GND and SGND planes. Test

points TP1 (GND) and TP2 (SGND) are provided on the

PCB for probing the respective ground plane, or to con-

nect the GND to SGND planes for nonisolated evalua-

tion of the circuit.

R3 pulls the DI pad up to V

, and resistor R4 pulls

CC1

the DE pad up to V

. On the isolated side, the RO2

CC1

pad is the receiver output.

_______________________________________________________________________________________

MAX3535E Evaluation Kit

vluates:MAX35E

Jumper Selection

Table 1. Driver and Receiver Functions

(JU1)

The MAX3535E EV kit features several jumpers to

reconfigure the circuit’s receiver/driver enable circuits,

slew-rate control, and full- or half-duplex operation.

Additionally, PCB pads are provided for connecting an

MAX3535E

SHUNT

LOCATION

DRIVER/

RECEIVER

MODE

DE PIN

RE PIN

external load to the isolated output at V

and SGND.

CC2

Driver and Receiver Enable Selection

The MAX3535E EV kit features a 3-pin jumper (JU1) to

set the MAX3535E driver and receiver output-enable

modes. Table 1 lists the jumper options for the various

modes of operation. Refer to the MAX3535E IC data

sheet for more information on the MAX3535E DE and

RE pin’s driver/receiver modes of operation. See Table 3

for configuring the MAX3535E communication mode.

Connected Connected to Driver is enabled,

to RE and R4

DE and

receiver is

1-2

pulled up to

pulled up to disabled and vice

by R4

CC1

versa.

CC1

Connected

to DE PC

pad and R4

pulled up to

Receiver is

always on and

driver is enabled

with the DE

2-3*

(default)

Connected to

GND

Slew-Rate Selection

The MAX3535E EV kit features a 2-pin jumper (JU2) to

set the MAX3535E communication slew rate. Table 2

lists jumper options for configuring the slew rate that

will affect the maximum data rate. Refer to the

MAX3535E IC data sheet for more information on the

slew-rate configuration.

signal.

CC1

Connected

to DE PC

pad and R4

pulled up to

Independent

control of driver-

and receiver-

enable states.

Connected to

RE PC pad

only

None*

CC1

Full-/Half-Duplex Communication Configuration

The MAX3535E EV kit features two jumpers that set the

communication mode of operation (full duplex or half

duplex). Jumpers JU3 and JU4 configure the circuit for

the mode (see Table 3 for configuration options). See

Table 2 for reconfiguring the communication slew rate,

which also impacts the maximum communication

speed; see Table 1 for configuring the MAX3535E

receiver and driver modes of operation.

*To avoid bus contention, ensure that only one driver has con-

trol of the bus.

Table 2. Slew-Rate Functions (JU2)

SHUNT

LOCATION

SLEW-RATE

(DATA RATE)

SLO PIN

None

Not connected

Fast (up to 1000kbps)

Slow (up to 400kbps)

Connected to

SGND

Installed

Resistors R1 and R2 Configuration

Pads are provided for pullup and pulldown resistors for

the A-B lines, although the use of these resistors is

purely optional. Pullup and pulldown resistors are used

on the receiver inputs to guarantee a known state in the

event that all nodes on the bus are in receive mode, or

the cable becomes disconnected. The exact value for

these resistors varies with the application. For example,

a cable that is doubly terminated with 120Ω resistors

may use 750Ω, while an unterminated cable may use

10kΩ. These resistors are not required because the

MAX3535E has a fail-safe receiver designed to guaran-

tee a high output in the event a cable disconnects or

shorts between A-B. Use surface-mount 0805 case-size

resistors for R1 and R2.

Table 3. Communication Mode Functions

(JU3 and JU4)

JU3 SHUNT

LOCATION

JU4 SHUNT

LOCATION

COMMUNICATION

MODE

Installed

None

Installed

None

Half duplex

Full duplex

pin-for-pin transformer replacements for the TGM-340,

provided with the EV kit. For example, the TGM-350,

which has a 1:1 turns ratio and lowers the primary cur-

rent consumption, can be used in place of the default

transformer that has a 3:4 turns ratio. The lower turns

ratio causes the circuit to have a lower output voltage,

while being able to supply slightly more current. This

lower output voltage implies an increase of the lower

bound for the input-supply voltage. When used with the

TGM-350 transformer, the input-supply voltage range is

Evaluating Other Transformer

Configurations/Designs

Evaluating the HALO TGM-350NA Transformer

Use the layout of the MAX3535E EV kit to evaluate other

_______________________________________________________________________________________

MAX3535E Evaluation Kit

reduced to +3.6V to +5.5V. Other changes to the trans-

former turns ratio may be possible to suit the exact

needs of the application. Refer to the MAX3535E IC

data sheet for more information. Contact HALO

Electronics to obtain a TGM-350NA transformer.

(min). However, the circuit uses an isolated transformer

to transfer power from the primary side to the sec-

ondary side. The withstand voltage of the transformer,

as well as the MAX3535E, must be considered when

designing and testing the EV kit circuit. For example, if

less than 3kV isolation is needed, a smaller 2kV trans-

former can be used to save board area, but the entire

circuit will have only 2kV of isolation.

Smaller Transformer and 2kV Isolation Design

The transformer (T1) is an integral part of the dielectric-

withstand voltage of the EV kit circuit. The MAX3535E

IC is guaranteed to withstand 2500V

for one minute

RMS

VCC2

0.1µF

10µF

VCC2

OPEN

VCC1

ST1 ST2

CC2

VCC1

CC1

0.1µF

vluates:MAX35E

10µF

100kΩ

OPEN

100kΩ

VCC1

JU1

MAX3535E

JU3

JU4

RO1

VCC1

GND

R02

SLO

VCC2

GND1

GND2

VCC2

SGND

JU2

TP1

TP2

GND

SGND

Figure 1. MAX3535E EV Kit Schematic

_______________________________________________________________________________________

MAX3535E Evaluation Kit

vluates:MAX35E

Figure 2. MAX3535E EV Kit Component Placement Guide—

Component Side

Figure 3. MAX3535E EV Kit PCB Layout—Component Side

Figure 4. MAX3535E EV Kit PCB Layout—Solder Side

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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5

Boblet

is a registered trademark of Maxim Integrated Products, Inc.

MAX3535EEVKIT [MAXIM]

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