AD5700 Datasheet, PDF (1/20 Pages) Analog Devices – Low Power HART Modem

Data Sheet
Low Power HART Modem
AD5700/AD5700-1
FEATURES
HART-compliant fully integrated FSK modem
1200 Hz and 2200 Hz sinusoidal shift frequencies
115 μA maximum supply current in receive mode
Suitable for intrinsically safe applications
Integrated receive band-pass filter
Minimal external components required
Clocking optimized for various system configurations
Ultralow power crystal oscillator (60 μA maximum)
External CMOS clock source
Precision internal oscillator (AD5700-1 only)
Buffered HART output—extra drive capability
8 kV HBM ESD rating
2 V to 5.5 V power supply
1.71 V to 5.5 V interface
−40°C to +125°C operation
4 mm × 4 mm LFCSP package
HART physical layer compliant
UART interface
APPLICATIONS
Field transmitters
HART multiplexers
PLC and DCS analog I/O modules
HART network connectivity
GENERAL DESCRIPTION
The AD5700/AD5700-1 are single-chip solutions, designed
and specified to operate as a HART® FSK half-duplex modem,
complying with the HART physical layer requirements. The
AD5700/AD5700-1 integrate all of the necessary filtering, signal
detection, modulating, demodulating and signal generation
functions, thus requiring few external components. The 0.5%
precision internal oscillator on the AD5700-1 greatly reduces
the board space requirements, making it ideal for line-powered
applications in both master and slave configurations. The maxi-
mum supply current consumption is 115 μA, making the AD5700/
AD5700-1 an optimal choice for low power loop-powered applica-
tions. Transmit waveforms are phase continuous 1200 Hz and
2200 Hz sinusoids. The AD5700/AD5700-1 contain accurate
carrier detect circuitry and use a standard UART interface.
Table 1. Related Products
Part No. Description
AD5755-1
Quad-channel, 16-bit, serial input, 4 mA to 20 mA and
voltage output DAC, dynamic power control, HART
connectivity
AD5421 16-bit, serial input, loop powered, 4 mA to 20 mA DAC
AD5410/
AD5420
Single-channel, 12-bit/16-bit, serial input, 4 mA to 20 mA
current source DACs
AD5412/
AD5422
Single-channel, 12-bit/16-bit, serial input, current
source and voltage output DACs
FUNCTIONAL BLOCK DIAGRAM
REG_CAP
CLKOUT XTAL1 XTAL2 XTAL_EN
V_CC
IOV_CC
DUPLEX
CD
RXD
TXD
RTS
OSC
FSK
MODULATOR
FSK
DEMODULATOR
AD5700/AD5700-1
DAC
BUFFER
ADC
BAND-PASS
FILTER AND
BIASING
HART_OUT
ADC_IP
HART_IN
CLK_CFG0
CLK_CFG1
VOLTAGE
REFERENCE
RESET
DGND
REF REF_EN
Figure 1.
AGND
FILTER_SEL
Rev. A
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