
AD7328
Data Sheet
Rev. C | Page 28 of 36
MODES OF OPERATION
Th
e AD7328 has several modes of operation that are designed
to provide flexible power management options. These options
can be chosen to optimize the power dissipation/throughput
rate ratio for different application requirements. The mode of
operation of th
e AD7328 is controlled by the power management
bits, Bit PM1 and Bit PM0, in the control register as shown in
Table 11. The default mode is normal mode, where all internal
circuitry is fully powered up.
NORMAL MODE
(PM1 = PM0 = 0)
This mode is intended for the fastest throughput rate perfor-
mance with t
he AD7328 being fully powered up at all times.
normal mode.
The conversion is initiated on the falling edge of CS, and the track-
section. The data on the DIN line during the 16 SCLK transfer
is loaded into one of the on-chip registers if the write bit is set.
The register is selected by programming the register select bits
1
16
3 CHANNEL I.D. BITS, SIGN BIT + CONVERSION RESULT
DATA INTO CONTROL/SEQUENCE/RANGE1/RANGE2
REGISTER
SCLK
CS
DOUT
DIN
04852-
035
Figure 48. Normal Mode
The
AD7328 remains fully powered up at the end of the con-
version if both PM1 and PM0 contain 0 in the control register.
To complete the conversion and access the conversion result
16 serial clock cycles are required. At the end of the conversion,
CS can idle either high or low until the next conversion.
Once the data transfer is complete, another conversion can be
initiated after the quiet time, tQUIET, has elapsed.
FULL SHUTDOWN MODE
(PM1 = PM0 = 1)
In this mode, all internal circuitry on th
e AD7328 is powered
down. The part retains information in the registers during full
shutdown. The
AD7328 remains in full shutdown mode until
the power management bits, Bit PM1 and Bit PM0, in the control
register are changed.
A write to the control register with PM1 = PM0 = 1 places the
part into full shutdown mode. The
AD7328 enters full shut-
down mode on the 15th SCLK rising edge when the control register
is updated.
If a write to the control register occurs while the part is in full
shutdown mode with the power management bits, Bit PM1 and
Bit PM0, set to 0 (normal mode), the part begins to power up
on the 15th SCLK rising edge when the control register is updated.
down mode. To ensure that t
he AD7328 is fully powered up,
tPOWER-UP should elapse before the next CS falling edge.
CS
1
16
1
16
SCLK
SDATA
DIN
INVALID DATA
CHANNEL IDENTIFIER BITS + CONVERSION RESULT
DATA INTO CONTROL REGISTER
tPOWER-UP
THE PART IS FULLY POWERED UP
ONCE
tPOWER-UP HAS ELAPSED
CONTROL REGISTER IS LOADED ON THE FIRST 15 CLOCKS,
PM1 = 0, PM0 = 0
TO KEEP THE PART IN NORMAL MODE, LOAD PM1 = PM0 = 0
IN CONTROL REGISTER
PART IS IN FULL
SHUTDOWN
PART BEGINS TO POWER UP ON THE 15TH
SCLK RISING EDGE AS PM1 = PM0 = 0
04852-
041
Figure 49. Exiting Full Shutdown Mode