AD7866 Analog Devices, AD7866 Datasheet - Page 17

• Manufacturer Part Number: AD7866
• Description: Dual 1MSPS, 12-Bit, 2-Channel SAR ADC with Serial Interface
• Manufacturer: Analog Devices

Specifications of AD7866

• Resolution (bits): 12bit
• # Chan: 4
• Sample Rate: 1MSPS
• Interface: Ser,SPI
• Analog Input Type: SE-Uni
• Ain Range: Uni (Vref),Uni (Vref) x 2,Uni 2.5V,Uni 5.0V
• Adc Architecture: SAR
• Pkg Type: SOP

Then, to place the AD7866 in normal mode, a dummy cycle
(1 µs to 4 µs approximately) should be initiated. If the first valid
conversion is performed directly after the dummy conversion,
care must be taken to ensure that adequate acquisition time has
been allowed. As mentioned earlier, when powering up from the
power-down mode, the part will return to track upon the first
SCLK edge applied after the falling edge of CS. However when
the ADC initially powers up after supplies are applied, the
track-and-hold will already be in track. This means that (assuming
REV. A
D
D
SCLK
D
D
OUT
OUT
D
D
SCLK
SCLK
OUT
OUT
OUT
OUT
CS
CS
CS
A
B
A
B
A
B
THE PART BEGINS
THE PART BEGINS
TO POWER UP
TO POWER UP
1
1
A
1
2
INVALID DATA
D
D
PARTIAL POWER-DOWN
SCLK
OUT
OUT
CS
THE PART ENTERS
A
B
INVALID DATA
INVALID DATA
Figure 17. Entering Partial Power-Down Mode
10
Figure 18. Exiting Partial Power-Down Mode
10
Figure 19. Entering Full Power-Down Mode
10
Figure 20. Exiting Full Power-Down Mode
THREE-STATE
1
t
POWER UP
2
POWERED UP; SEE POWER-UP
16
16
THE PART MAY BE FULLY
16
TIMES SECTION
THE PART BEGINS
–17–
TO POWER UP
one has the facility to monitor the ADC supply current and thus
determine which mode the AD7866 is in) if the ADC powers up
in the desired mode of operation and thus a dummy cycle is not
required to change mode, then neither is a dummy cycle required
to place the track-and-hold into track. If no current monitoring
facility is available, the relevant dummy cycle(s) should be
performed to ensure the part is in the required mode.
10
THREE-STATE
1
1
1
2
INVALID DATA
FULLY POWERED UP
THE PART IS
FULL POWER-DOWN
THE PART ENTERS
16
VALID DATA
VALID DATA
THREE-STATE
10
AD7866
16
16
16