MAX13487E_08 [MAXIM]
Evaluation Kit; 评估套件
| 型号： | MAX13487E_08 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Evaluation Kit |
| 文件： | 总8页 (文件大小：144K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3204; Rev 1; 11/08
MAX13487E Evaluation Kit
vluates:7/MAX1348E
General Description
Features
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.
o Demonstrates MAX13487E AutoDirection Feature
o Designed for 2500VRMS 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
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.
o Output Current Limit and Thermal Shutdown
o Low-Cost Integrated-FET H-Bridge Design
o Also Evaluates MAX13488E (After IC
Replacement)
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
o Fully Assembled and Tested
Ordering Information
PART
TYPE
MAX13487EEVKIT#
#Denotes RoHS compliant.
EV Kit
2500V
isolation.
RMS
Component List
DESIGNATION QTY
DESCRIPTION
DESIGNATION QTY
DESCRIPTION
10µF 10ꢀ, 10V X7R ceramic
capacitor (1206)
Murata GRM31CR71A106K
JU1, JU3, JU4,
5
2-pin headers
3-pin header
C1
C2
1
1
4
JU5, JU6
JU2
1
1
2
2
2
1
0.47µF 10ꢀ, 16V X7R ceramic
capacitor (0805)
Murata GRM219R71C474K
R1
39.2kΩ 1ꢀ resistor (0603)
100kΩ 5ꢀ resistors (0603)
270Ω 5ꢀ resistors (0805)
220Ω 5ꢀ resistors (0805)
120Ω 5ꢀ resistor (0805)
R2, R9
R4, R5
R6, R8
R7
0.1µF 10ꢀ, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K
C3, C5, C6, C7
500µH, 1.5W, 3:8-turn, 400kHz
transformer (6-pin Gull Wing)
HALO Electronics TGM-380NARL
1µF 10ꢀ, 16V X7R ceramic
capacitor (0805)
Murata GRM21BR71C105K
T1
1
1
C4
D1, D2
D3
1
2
1
Half-duplex, high-speed transceiver
(8 SO)
Maxim MAX13487EESA+
30V, 1A Schottky diodes (SOD123)
Diodes Inc. B130LAW
U1
15V, 350mW 5ꢀ zener diode
(SOT-23)
Central Semiconductor CMPZ5245B+
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX13487E Evaluation Kit
Component List (continued)
Component Suppliers
SUPPLIER
CEL/NEC
(California Eastern
Laboratories/NEC)
PHONE
WEBSITE
DESIGNATION QTY
DESCRIPTION
Integrated primary-side controller
and H-bridge driver (8 SO-EP*)
Maxim MAX256ASA+
408-588-2247 www.cel.com
U2
U3
1
1
Central
Semiconductor
Corp.
Linear regulator (8 SO)
Maxim MAX1659ESA+
631-435-1110 www.centralsemi.com
15Mbps CMOS photocouplers
(5 SO)
Diodes, Inc.
805-446-4800 www.diodes.com
U4, U5
2
HALO Electronics,
Inc.
CEL/NEC PS9151-A
650-903-3800 www.haloelectronics.com
—
—
—
6
4
1
Shunts (JU1–JU6)
Murata
Electronics North
America, Inc.
www.murata-
770-436-1300
Rubber bumpers
northamerica.com
PCB: MAX13487E Evaluation Kit#
*EP = Exposed pad.
Note: Indicate that you are using the MAX13487E or
MAX13488E when contacting these component suppliers.
Note: The +5V supply powering the MAX13487E EV kit
must be current-limited at 550mA and the output load
current for the output should be limited to less than
300mA.
Quick Start
Required Equipment
Before beginning, the following equipment is needed:
•
One +5V 550mA current-limited power supply with
a built-in current meter
Detailed Description of Hardware
The EV kit features a MAX13487E IC in an 8-pin SO sur-
face-mount package and demonstrates the ESD-
protected MAX13487E RS-485/RS-422 AutoDirection
transceiver. The differential driver and receiver are con-
figured for half-duplex operation and communicate up
to 500kbps. The transceiver circuit is a 1/4-unit load on
the receiver’s bus.
•
•
•
One voltmeter
One logic signal generator
One oscilloscope with a differential probe
Procedure
The MAX13487E 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
connections are completed.
The EV kit features PCB pads to ease interfacing with
the driver/receiver logic signals on the non-isolated side
using the TXD, RXD, and PGND pads, respectively. The
MAX13487E IC is powered from the isolated VOUT
supply. Photocoupler U4 provides isolation for the
receiver’s RO signal (RXD pad) and U5 provides isola-
tion for the data-in DI signal (TXD pad).
vluates:7/MAX1348E
1) Connect a voltmeter to the VOUT and GND PC pads.
2) Verify that a shunt is not installed across the pins of
jumper JU1 (U2 enabled).
3) Verify that a shunt is installed across pins 1-2 of
jumper JU2 (U1 enabled).
The EV kit demonstrates the MAX13487E slew-rate
limited driver, which minimizes EMI radiation.
Photocouplers U4 and U5 are rated for up to 15Mbps.
4) Verify that a shunt is installed across the pins of
jumpers JU3 (AutoDirection enabled), JU4 (pull-
down), JU6 (pullup), and JU5 (bus terminated).
The MAX13487E receiver signal is provided at the RO
pin. The RO pin will give a logic-high if A-B > +200mV.
A logic-low is given if A-B < -200mV. Refer to the
Transmitting and Receiving sections in the Function
Tables in the MAX13487E/MAX13488E IC data sheet
for additional information on the AutoDirection circuitry
operation. Also see the AutoDirection and Receiver
Enable Selection section in this document for configur-
ing the AutoDirection and receiver operation.
5) Connect the +5V power supply to the VIN pad.
Connect the power supply’s ground to the PGND pad.
6) Turn on the power supply and verify that the volt-
meter at VOUT reads +5V.
7) Using the logic signal generator, apply a +5V logic
signal to the TXD PCB pad and PGND.
8) Using the oscilloscope and differential probes, verify
the signal at the A-B pads (isolated side).
2
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MAX13487E Evaluation Kit
vluates:7/MAX1348E
The EV kit input power is typically a +5V DC source that
MAX256 thermally enhanced SO package. Test points
TP1 (PGND) and TP2 (GND) are provided on the PCB
for probing the respective ground plane or to connect
the PGND to GND planes for nonisolated evaluation of
the circuit.
provides at least 450mA of current to the MAX256 inte-
grated primary-side controller and H-bridge driver cir-
cuit. The MAX256 contains an on-board oscillator, pro-
tection circuitry, and internal H-bridge FETs to provide
power to the primary of the transformer T1. The MAX256
prevents cross conduction of the H-bridge MOSFETs by
implementing break-before-make switching. The
MAX256 programmable oscillator is programmed to
420kHz by resistor R1. The switching-frequency duty
cycle is fixed at 50ꢀ to control energy transfer to trans-
former T1 isolated output.
Jumper Selection
The MAX13487E EV kit features several jumpers to
reconfigure the receiver/driver enable circuits, and shut-
down for the MAX256 and MAX13487E ICs. Additionally,
PCB pads are provided for connecting an external load
to the isolated +5V output at VOUT and GND.
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.
Shutdown Control
The MAX13487E EV kit features two jumpers that con-
figure the shutdown mode of the circuit. Jumper JU1
configures the MAX256 DC-DC converter and JU2 con-
figures the MAX13487E IC for shutdown mode. See
Table 1 for placing the EV kit circuit or the desired IC in
shutdown mode.
Surface-mount transformer T1 provides galvanic isola-
tion and the VOUT output is powered from a center-
tapped full-wave rectifier circuit (D1 or D2) to reduce
output-voltage ripple. It feeds a MAX1659 LDO regula-
tor configured for +5V output. The LDO output is
current limited and features thermal shutdown to pro-
vide for a robust isolated supply at VOUT, which can
provide up to 300mA of current.
AutoDirection and Receiver Enable Selection
The MAX13487E EV kit features a 2-pin jumper (JU3) to
set the MAX13487E receiver mode of operation,
AutoDirection, or receiver output enabled. Refer to the
AutoDirection Circuitry section in the MAX13487E/
MAX13488E IC data sheet for more information on the
MAX13487E RE pin modes of operation. See Table 2
for configuring the receiver mode of operation using
jumper JU3.
The two-layer PCB is designed for 2500V
isolation,
RMS
with 300 mils spacing between the PGND and GND
planes. The bottom PCB PGND plane under U2 is uti-
lized as a thermal heat sink for power dissipation of the
Table 1. JU1 and JU2 Shutdown Mode Control
JU1 SHUNT
POSITION
JU2 SHUNT
POSITION
MAX256 MODE PIN
MAX13487E SHDN PIN
EV KIT OPERATION MODE
Not installed
Installed
Connected to VIN through R2
Connected to PGND
1-2
2-3
Connected to VOUT
Connected to GND
All ICs operational
Shutdown
MAX13487E shutdown, all other
ICs operational
Not installed
Connected to VIN through R2
2-3
Connected to GND
Table 2. Driver and Receiver JU3 Functions
SHUNT POSITION
RE PIN
MAX13487E AUTODIRECTION OR RECEIVER MODE
AutoDirection enabled*
Installed
Connected to VOUT
Not installed
Connected to GND through R9
Receiver RO output enabled
*To avoid bus contention, ensure that only one driver has control of the bus at a time.
_______________________________________________________________________________________
3
MAX13487E Evaluation Kit
RS-485 Bus Pullup/Pulldown and
Termination Resistors Configuration
Jumper JU5 is provided for terminating the A and B bus
lines when the MAX13487E EV kit is connected at the
end of an RS-485 bus. Resistor R7 provides 120Ω of ter-
mination when jumper JU5 is used. See Table 4 for con-
figuring the termination mode.
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. R6 and R8 can be higher valued if the
differential terminal resistor (R7) is not used.
Table 3. JU6, JU4 Functions, Pullup, Pulldown Resistors
SHUNT POSITION
A AND B LINE SIGNAL
None
Not pulled up or down
A signal pulled up, connected to VOUT
B signal pulled down to GND
Installed
Table 4. JU5 Functions, Bus Termination
SHUNT POSITION
A-B PINS AND RS-485 BUS TERMINATION
EV KIT BUS CONNECTION
Mid point
None
Not terminated
Installed
Terminated
End of bus line
Smaller Transformer and 2000V
Isolation Design
The EV kit’s two-layer PCB is designed for 2500V
Evaluating the MAX13488E IC and
RMS
Other Transformer Configurations/Designs
RMS
MAX13488E Evaluation
The MAX13487E EV kit can also evaluate the
MAX13488E IC. To evaluate the MAX13488E, replace
IC U1 with the MAX13488E. Note that the MAX13488E
driver slew rate is not limited and allows transmission
speeds of up to 16Mbps. Refer to the MAX13487E/
MAX13488E IC data sheet for additional information.
isolation, with 300 mils spacing between the PGND and
GND planes. Additionally, transformer T1 is rated for
3000V
and is an integral part of the dielectric with-
RMS
stand voltage of the EV kit circuit. Photocouplers U4
and U5 are guaranteed to withstand 3750V
.
RMS
vluates:7/MAX1348E
However, the circuit uses the isolated transformer to
transfer power from the primary side to the secondary
side and the withstand voltage of the transformer, as
well as photocouplers U4 and U5, so the PCB must be
considered when designing and testing the EV kit cir-
cuit. For example, if less than 2500V
isolation is
RMS
needed, a smaller 2000V
transformer may be used
RMS
to save board area, but then the entire circuit will have
only 2000V of isolation.
RMS
4
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MAX13487E Evaluation Kit
vluates:7/MAX1348E
Figure 1. MAX13487E EV Kit Schematic
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5
MAX13487E Evaluation Kit
Figure 2. MAX13487E EV Kit Component Placement Guide—
Component Side
Figure 3. MAX13487E EV Kit PCB Layout—Component Side
vluates:7/MAX1348E
6
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MAX13487E Evaluation Kit
vluates:7/MAX1348E
Figure 4. MAX13487E EV Kit PCB Layout—Solder Side
_______________________________________________________________________________________
7
MAX13487E Evaluation Kit
Revision History
REVISION REVISION
DESCRIPTION
PAGES
CHANGED
NUMBER
DATE
0
1
1/08
Initial release
—
11/08
Revised data sheet in several places with changes to resistors R6 and R8.
1, 2, 4, 5
vluates:7/MAX1348E
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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