AD7760 Analog Devices, AD7760 Datasheet - Page 21

• Manufacturer Part Number: AD7760
• Description: 2.5 MSPS, 24-Bit, 100 dB Sigma-Delta ADC with On-Chip Buffer
• Manufacturer: Analog Devices

Specifications of AD7760

• Resolution (bits): 24bit
• # Chan: 1
• Sample Rate: 40MSPS
• Interface: Par
• Analog Input Type: Diff-Uni
• Ain Range: 4 V p-p,6.5 V p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: QFP

In the case where n is an odd number of MCLK cycles, the
modulator data output on Pins D [15:0] is output on the rising
edge of DRDY . In this case, the modulator data should be read
on the falling edge of MCLK when DRDY is logic low. Figure 45
shows timing details to be used when reading the modulator
output data where CDIV = 0 and there is an odd number of
MCLK cycles between the rising edge of RESET and the rising
edge of SYNC . The edge of MCLK that should be used under
these conditions is illustrated in Figure 45 by arrows on the
MCLK falling edges in question.
USING THE AD7760
IN MODULATOR OUTPUT MODE
The following is the recommended sequence for powering up
and using the AD7760:
1.
2.
3.
4.
Apply power.
Start the clock oscillator, applying MCLK.
Take RESET low for a minimum of one MCLK cycle.
Wait a minimum of two MCLK cycles after the rising edge
of RESET .
CS, RD/WR
D[0:15]
MCLK
DRDY
t
11
INVALID DATA
Figure 45. AD7760 Modulator Output Mode ( CDIV = 0, n is odd)
Rev. A | Page 21 of 36
t
9
MOD DATA M
t
19
t
20
Using this sequence results in an even number of MCLK cycles
between the rising edge of RESET and the rising edge of SYNC .
Therefore, when using this sequence with CDIV = 0, the interface
timing shown in Figure 43 should be implemented.
Note that whether the number of MCLK cycles between the
rising edge of RESET and SYNC is odd or even is irrelevant
when the AD7760 is operated with CDIV = 1.
When using the AD7760 in modulator output mode, the offset,
gain, and overrange registers are not operational. The only
registers that can be used are Control Register 1 and Control
Register 2.
5.
6.
7.
8.
t
10
Write to Control Register 2 to power up the ADC and the
differential amplifier as required. The correct clock divider
( CDIV ) ratio should be programmed at this time.
Write to Control Register 1 to set the bypass filter bits, BYP F1
and BYP F3 , and the decimation rate bits, DEC [2:0], to 0.
Wait a minimum of six MCLK cycles after the rising edge
of CS has been released.
Take SYNC low for a minimum of four MCLK cycles, if
required, to synchronize multiple parts.
MOD DATA M + 1
MOD D...
t
14
AD7760