ISL26132 Datasheet, PDF (17/23 Pages) Intersil Corporation – Low-Noise 24-bit Delta Sigma ADC

ISL26132, ISL26134
Standby Mode Operation
The ADC can be put into standby mode to save power. Standby
mode reduces the power to all circuits in the device except the
crystal oscillator amplifier. To enter the standby mode, take the
SCLK signal high and hold it high after SDO/RDY falls. The
converter will remain in standby mode as long as SCLK is held
high. To return to normal operation, take SCLK back low and wait
for the SDO/RDY to fall to indicate that a new conversion has
completed. Figure 33 and Table 12 illustrate the details of
standby mode.
Supply currents are equal in Standby and Power-down modes
unless a Crystal is used. If the Crystal is used, the Crystal
amplifier is turned ON, even in the standby mode.
Performing Offset Calibration After Standby
Mode
To perform an offset calibration automatically upon returning
from standby, deliver 2 or more additional SCLKs following a
data read cycle, and then set and hold SCLK high. The device will
remain in Standby as long as SCLK remains high. A calibration
cycle will begin once SCLK is brought low again to resume
normal operation. Additional time will be required to perform the
calibration after returning from Standby. Figure 34 and Table 13
illustrate the details of performing offset calibration after
standby mode.
PARAMETER
t₉
t₁₀
t₁₁
DESCRIPTION
SCLK High after
SDO/RDY Low
Standby Mode Delay
SDO/RDY falling edge
after SCLK Low
TABLE 12. STANDBY MODE TIMING
MIN
SPEED = 1
0
SPEED = 0
0
SPEED = 1
12.5
SPEED = 0
100
SPEED = 1
50
SPEED = 0
400
MAX
12.44
99.94
60
410
UNITS
ms
PARAMETER
t₁₂
SDO/RDY
SCLK
TABLE 13. OFFSET CALIBRATION TIMING AFTER STANDY
DESCRIPTION
MIN
SDO/RDY Low after
SPEED = 1
108
SCLK Low
SPEED = 0
808
MAX
113
813
UNITS
ms
ms
STANDBY MODE
DATA READY AFTER CALIBRATION
23 22 21
0
1
24 25
t₁₀
BEGIN
23
CALIBRATION
t₁₂
FIGURE 34. OFFSET CALIBRATION WAVEFORMS AFTER STANDBY
17
FN6954.1
September 9, 2011