參數(shù)資料
型號: MAX253CUA
廠商: MAXIM INTEGRATED PRODUCTS INC
元件分類: 其它接口
英文描述: Transformer Driver for Isolated RS-485 Interface
中文描述: SPECIALTY INTERFACE CIRCUIT, PDSO8
封裝: UMAX-8
文件頁數(shù): 11/16頁
文件大?。?/td> 230K
代理商: MAX253CUA
M
Transformer Driver for
Isolated RS -485 Interfac e
______________________________________________________________________________________
11
10μF
5V
MAX253
D1
D2
GND1
GND2
V
CC
1
8
6
2
7
1N5817
SD
4
1N5817
1CT
:
5CT*
49.9k
7
6
3
2
4
7
6
3
2
4
10k
24.9
2N3904
MAX480
MAX480
5V
0.1V to 0.5V
ISO
5V
78L05
IL300
4
3
2
1
5
6
24V UNREGULATED
49.9k
R
L
0k
to 1k
2N3904
*SEE TABLE 2
ISOLATION
BARRIER
V
IN
Figure 8. Typical 4mA to 20mA Application Circuit
Output-Ripple Filtering
A simple lowpass pi-filter (Figures 6 and 7) can be added
to the output to reduce output ripple noise to about
10mVp-p. The cutoff frequency shown is 21kHz. Since the
filter inductor is in series with the circuit output, minimize its
resistance so the voltage drop across it is not excessive.
Isolated 4mA to 20mA Analog Interfac e
The 4mA to 20mA current loop is a standard analog
signal range that is widely used in the process-control
industry for transducer and actuator control signals.
These signals are commonly referred to a distant
ground that may be at a considerably higher voltage
with respect to the local ground.
An analog signal in the range of 0.1V to 0.5V is applied
to the first MAX480 to generate a signal current in the
range of 20μA to 100μA. This low-level signal is trans-
ferred across the barrier by the Siemens IL300 linear
optocoupler. This device is unique in that it corrects
the dominant nonlinearity present in most optocou-
plers—the LED efficiency variation. The IL300 is really
two optocouplers in the same package sharing the same
LED; one detector is across the isolation barrier, the
other is on the same side as the LED (Figure 8). The lat-
ter detector is used to generate a feedback signal identi-
cal to the signal on the isolated side of the barrier. The
current signal transferred across the barrier is converted
back to a voltage that matches the input in the 100mV to
500mV range. This voltage is then transformed to the
final 4mA to 20mA current signal range by the second
MAX480, Darlington stage, and the 20
resistor.
Isolated ADC
Almost any serial-interface device is a candidate for
operation across an isolation barrier; Figure 10 illus-
trates one example. The MAX176 analog-to-digital
converter (ADC) operates from +5V and -12V supplies,
provided by the multiple-tapped secondary and linear
regulators. If some additional isolated power is needed
for signal conditioning, multiplexing, or possibly for a
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MAX253CUA+ 功能描述:功率驅(qū)動器IC Transformer Driver for Iso RS-485 Int RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
MAX253CUA+T 功能描述:功率驅(qū)動器IC Transformer Driver for Iso RS-485 Int RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
MAX253CUA-T 功能描述:功率驅(qū)動器IC RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
MAX253EPA 功能描述:功率驅(qū)動器IC RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube
MAX253EPA+ 功能描述:功率驅(qū)動器IC Transformer Driver for Iso RS-485 Int RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube