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| 型号： | MAX253CSA |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 2/18页 |
| 文件大小： | 0K |
| 描述： | IC XFRMR DRIVER RS485 8-SOIC |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| 类型： | 驱动器 |
| 驱动器/接收器数： | 1/0 |
| 规程： | RS232，RS485 |
| 电源电压： | 4.5 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
Transformer Driver for
Isolated RS-485 Interface
* PC-Series Optocouplers, Sharp Electronics
USA Phone: (206) 834-2500
FAX: (206) 834-8903
Sharp Electronics, Europe GmbH
Germany Phone: (040) 2376-0
FAX: (040) 230764
__________Applications Information
Figures 3–5 are typical isolated RS-485/RS-232 data-inter-
face circuits. These circuits withstand 1800VRMS (1sec)
and are intended for industrial communications and control
applications where very high voltage transients, differential
ground potentials, or high noise may be encountered.
Table 2 lists transformer characteristics for the applica-
tions of Figures 3–10. Some suggested manufacturers
of transformers, transformer cores, and optocouplers
are listed in Table 3, along with their respective phone
and fax numbers.
Important layout considerations include:
For maximum isolation, the “isolation barrier” should not
be breached. Connections and components from one
side should not be located near those of the other side.
Since the optocoupler outputs are relatively high-
impedance nodes, they should be located as close
as possible to the Maxim interface IC. This mini-
mizes stray capacitance and maximizes data rate.
Refer to the MAX package information for pin spacing
and physical dimensions.
Isolated RS-485 Data Interface
The MAX253 power-supply transformer driver is
designed specifically for isolated RS-485 data-interface
applications. The application circuits of Figures 3 and 4
combine the MAX253 with a low-dropout linear regulator,
a transformer, several high-speed optocouplers, and a
Maxim RS-485 interface device. With a few modifica-
tions to these circuits, full-duplex communications can
be implemented by substituting the MAX481/MAX485
with the MAX490/MAX491 (for data rates up to 2.5Mbps)
or substituting the MAX483/MAX487 with the
MAX488/MAX489 (for data rates up to 250kbps).
The data transfer rates of the application circuits in
Figures 3 and 4 are critically limited by the optocou-
plers. Table 1 lists suggested optocouplers and the
appropriate Maxim interface device for data-transfer
rates up to 2.5Mbps.
Refer to the MAX1480 data sheet for a complete isolat-
ed RS-485 solution in one package.
Isolated RS-232 Data Interface
The MAX253 is ideal for isolated RS-232 data-interface
applications requiring more than four transceivers. The
1W power output capability of the MAX253 enables it to
drive more than 10 transceivers simultaneously. Figure 5
shows the typical application circuit for a complete
120kbps isolated RS-232 data interface. The figure
also shows how the Sharp PC417 optocouplers can be
replaced by the lower-cost 4N25 devices to achieve
data-transfer rates up to 9.6kbps.
For 3.3V operation, substitute the primary portion of
Figure 5 with the circuit of Figure 7.
For applications requiring two transceivers or fewer,
refer to the MAX250/MAX251 or MAX252 data sheet.
Isolated Power Supplies
The MAX253 is a versatile isolated power driver, capa-
ble of driving a center-tapped transformer primary from
a 5V or a 3.3V DC power supply (Figures 6 and 7). The
secondary can be wound to provide any isolated volt-
age needed at power levels up to 1W with a 5V supply,
or 600mW with a 3.3V supply. Figure 6 shows a typical
5V to isolated 5V application circuit that delivers up to
200mA of isolated 5V power.
In Figure 7, the MAX253 is configured to operate from a
3.3V supply, deriving a “boost” VCC for the MAX253 by
connecting diodes to both ends of the transformer pri-
mary. This produces nearly double the input supply,
and may be useful for other applications, as shown in
Figure 4. The average current in each MAX253 switch
must still be limited to less than 200mA, so the total
power available is approximately 600mW.
Table 1. Optocouplers and RS-485 Interface ICs for Various Data Rates
DATA RATE
FULL DUPLEX
RS-485 IC
HALF DUPLEX
RS-485 IC
OPTOCOUPLER
FOR DI / RO
OPTOCOUPLER
FOR DE
250kbps
MAX488/MAX489
MAX483/MAX487
PC417*
PC357T*
2.5Mbps
MAX490/MAX491
MAX481/MAX485
PC410*
PC357T
MAX253
10
Maxim Integrated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX253CSA+ | 功能描述:功率驱动器IC Transformer Driver for Iso RS-485 Int RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| MAX253CSA+T | 功能描述:功率驱动器IC Transformer Driver for Iso RS-485 Int RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| MAX253CSA-T | 功能描述:功率驱动器IC RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| MAX253CUA | 功能描述:功率驱动器IC RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| MAX253CUA+ | 功能描述:功率驱动器IC Transformer Driver for Iso RS-485 Int RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
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