UG-382 Datasheet, PDF (3/8 Pages) Analog Devices – Evaluation Board for FSK AD5700/AD5700-1 HART Modem

Evaluation Board User Guide
UG-382
EVALUATION BOARD HARDWARE
POWER SUPPLIES
AGND and DGND are connected together on the board to
provide a single GND signal. To power the EVAL-AD5700-1EBZ,
supply 3.3 V between the VCC and GND inputs for the analog
supply of the AD5700/AD5700-1. With L5 inserted (default), this
also provides power to IOVCC.
LINK OPTIONS
A number of links on the evaluation board must be set for the
required operating setup before using the board. The functions
of these link options are described in detail in Table 2. The
default setup is using the on-chip reference, the crystal
oscillator, and the internal receive filter (see Table 1).
Table 1. Default Link Options
Link No.
CLK_CFG1
CLK_CFG0
XTAL_EN
FILTER_SEL
L1
L2
REF_EN
DUPLEX
L5
L6
L8
Option
A
A
A
B
A
A
B
A
Inserted
Not inserted
Inserted
Table 2. Link Functions
Link No.
Function
CLK_CFG1,
CLK_CFG0,
XTAL_EN
The AD5700/AD5700-1 support numerous clocking configurations to allow a simple, low cost solution. The
AD5700/AD5700-1 can use an external crystal or ceramic resonator, a CMOS input, or an internal RC oscillator
(AD5700-1 only). The CLK_CFG0, CLK_CFG1, and XTAL_EN links configure the clock generation as follows:
XTAL_EN CLK_CFG1 CLK_CFG0 CLKOUT
Description
B
A
A
No output
3.6864 MHz CMOS clock connected at XTAL1 pin
B
A
B
No output
1.2288 MHz CMOS clock connected at XTAL1 pin
B
B
A
No output
Internal oscillator enabled
B
B
B
1.2288 MHz output Internal oscillator enabled, CLKOUT enabled
A
A
A
No output
Crystal oscillator enabled
A
A
B
3.6864 MHz output Crystal oscillator enabled, CLKOUT enabled
A
B
A
1.8432 MHz output Crystal oscillator enabled, CLKOUT enabled
A
B
B
1.2288 MHz output Crystal oscillator enabled, CLKOUT enabled
FILTER_SEL, L1, L2 These link options set whether the internal or external receive band-pass filter is used at the HART input.
Setting FILTER_SEL to Position B and L1 and L2 to Position A sets the board to use the internal receive band-pass filter.
Setting FILTER_SEL to Position A and L1 and L2 to Position B sets the board to use the external receive band-pass filter.
REF_EN
This sets whether the internal or an external reference is used.
Position A—disables the internal reference, and a buffered external 2.5 V reference source must be applied at REF.
Position B—enables the internal 1.5 V reference and buffer.
DUPLEX
Allows the modulator and demodulator of the AD5700/AD5700-1 to be enabled at the same time.
Position A—the AD5700/AD5700-1 operate in half-duplex operation (controlled by RTS).
Position B—the AD5700/AD5700-1 operate in full duplex operation, with the modulator and demodulator of the
AD5700/AD5700-1 enabled at the same time.
L5
Allows VCC to be connected directly to IOVCC.
Inserted—VCC is connected to IOVCC.
Not inserted—VCC is disconnected from IOVCC.
L6
Do not insert this link.
L8
This link must be inserted.
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