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参数资料
| 型号： | A5191HRTLG-XTP |
| 厂商： | ON Semiconductor |
| 文件页数： | 13/14页 |
| 文件大小： | 0K |
| 描述： | MODEM HART SGL CMOS 32LQFP |
| 标准包装： | 1 |
| 系列： | * |
| 其它名称： | A5191HRTLG-XTPOSDKR |
A5191HRT
http://onsemi.com
8
Functional Description
The A5191HRT is a single-chip modem for use in
Highway Addressable Remote Transducer (HART) field
instruments and masters. The modem IC contains a transmit
data modulator with signal shaper, carrier detect circuitry, an
analog receiver, demodulator circuitry and a crystal
oscillator, as shown in the block diagram in Figure 1.
The modulator accepts digital data at its digital input TxD
and generates a sine shaped FSK modulated signal at the
analog output TxA. A digital “1” or mark is represented with
a frequency of 1200 Hz. A digital “0” or space is represented
with a frequency of 2200 Hz. The used bit rate is 1200 baud.
The demodulator receives the FSK signal at its analog
input, filters it with a band-pass filter and generates 2 digital
signals: RxD: Received Data and CD: Carrier Detect. At the
digital output RxD the original modulated signal is received.
CD outputs the Carrier Detect signal. It goes logic high if the
received signal is above 100 mVpp during 4 consecutive
carrier periods.
The oscillator provides the modem with a stable time base
using either a simple external resonator or an external clock
source.
Detailed Description
Modulator
The modulator accepts digital data in NRZ form at the
TxD input and generates the FSK modulated signal at the
TxA output.
Sine
Shaper
Numeric
Controlled
Oscillator
MODULATOR
TxA
TxD
RTS
FSK_OUT
Figure 5. Modulator Block Diagram
A logic “1” or mark is represented by a frequency fm =
1200 Hz. A logic “0”or space is represented by a frequency
fs = 2200 Hz.
t
tBIT = 833 ms
“1” = Mark
1.2 kHz
“0” = Space
2.2 kHz
tBIT = 454 ms
Figure 6. Modulation Timing
The Numeric Controlled Oscillator NCO works in a phase
continuous mode preventing abrupt phase shifts when
switching between mark and space frequency. The control
signal Request To Send RTSB enables the NCO. When
RTSB is logic low the modulator is active and A5191HRT
is in transmit mode. When RTSB is logic high the modulator
is disabled and A5191HRT is in receive mode.
The digital outputs of the NCO are shaped in the Wave
Shaper block to a trapezoidal signal. This circuit controls the
rising and falling edge to be inside the standard HART
waveshape limits. Figure 7 shows the transmit-signal forms
captured at TxA for mark and space frequency. The slew
rates are SRm = 1860 V/s at the mark frequency and SRs =
3300 V/s at the space frequency. For AREF = 1.235 V, TxA
will have a voltage swing from approximately 0.25 to 0.75
VDC.
t (ms)
0
VTxA
0.5 V
1
2
t (ms)
VTxA
“1” = Mark; fm =1.2 kHz
“0” = Space; fs =2.2 kHz
0
1
2
SRm = 1860 V/s
0.5 V
SRs = 3300 V/s
0.5 V
Figure 7. Modulator shaped output signal for Mark
and Space frequency at TxA pin.
Demodulator
The demodulator accepts a FSK signal at the RxA input
and reconstructs the original modulated signal at the RxD
output. Figure 8 illustrates the demodulation process.
tBIT
IDLE (mark)
LSB
MSB
IDLE (mark)
tBIT
8 data bits
D0
Start
D1
D2
D3
D4
D5
D6
D7
Stop
Par
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
FSK_IN
RxD
Figure 8. Modulation Timing
This HART bit stream follows a standard 11-bit UART
frame with 1 startbit, 8 databits, 1 paritybit (odd) and 1
stopbit. The communication speed is 1200 baud.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A5191HRTNG | 制造商:ON Semiconductor 功能描述:A5191HRTNG HART MODEM ASS - Bulk |
| A5191HRTNGEVB | 功能描述:网络开发工具 EVB HART MODEM QFN RoHS:否 制造商:Rabbit Semiconductor 产品:Development Kits 类型:Ethernet to Wi-Fi Bridges 工具用于评估:RCM6600W 数据速率:20 Mbps, 40 Mbps 接口类型:802.11 b/g, Ethernet 工作电源电压:3.3 V |
| A5191HRTNG-XTD | 功能描述:电信线路管理 IC A5191HRTNG HART MODEM RoHS:否 制造商:STMicroelectronics 产品:PHY 接口类型:UART 电源电压-最大:18 V 电源电压-最小:8 V 电源电流:30 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VFQFPN-48 封装:Tray |
| A5191HRTNG-XTDON | 制造商:Rochester Electronics LLC 功能描述: 制造商:ON Semiconductor 功能描述: |
| A5191HRTNG-XTP | 功能描述:电信线路管理 IC A5191HRTNG HART MODEM RoHS:否 制造商:STMicroelectronics 产品:PHY 接口类型:UART 电源电压-最大:18 V 电源电压-最小:8 V 电源电流:30 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VFQFPN-48 封装:Tray |
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