AD7609BSTZ Analog Devices Inc, AD7609BSTZ Datasheet - Page 25

• Manufacturer Part Number: AD7609BSTZ
• Description: 58T8900
• Manufacturer: Analog Devices Inc

Specifications of AD7609BSTZ

• Resolution (bits): 18bit
• Sampling Rate: 250kSPS
• Input Channel Type: Differential
• Data Interface: Serial, SPI
• Supply Voltage Range - Analog: 4.75V To 5.25V
• Rohs Compliant: Yes

CONVERSION CONTROL
Simultaneous Sampling on All Analog Input Channels
The
channels. All channels are sampled simultaneously when both
CONVST x pins (CONVST A, CONVST B) are tied together. A
single CONVST x signal is used to control both CONVST x inputs.
The rising edge of this common CONVST x signal initiates
simultaneous sampling on all analog input channels.
The
perform the conversions. The conversion time for all ADC
channels is t
conversions are in progress, so that when the rising edge of
CONVST x is applied, BUSY goes logic high and transitions low
at the end of the entire conversion process. The falling edge of
the BUSY signal is used to place all eight track-and-hold
amplifiers back into track mode. The falling edge of BUSY also
indicates that the new data can now be read from the parallel
bus (DB[15:0]) or the serial data lines, D
AD7609
AD7609
CONV
allows simultaneous sampling of all analog input
contains an on-chip oscillator that is used to
DATA: DB[15:0]
. The BUSY signal indicates to the user when
FRSTDATA
CONVST A
CONVST B
Figure 42. Simultaneous Sampling on Channel Sets Using Independent CONVST A/CONVST B Signals—Parallel Mode
CS, RD
BUSY
V1 TO V4 TRACK-AND-HOLD
ENTER HOLD
t
OUT
5
A and D
t
CONV
OUT
B.
ON ALL 8 CHANNELS
V5 TO V8 TRACK-AND-HOLD
ENTER HOLD
AD7609 CONVERTS
Rev. 0 | Page 25 of 36
V1
Simultaneously Sampling Two Sets of Channels
The
sampled simultaneously in two sets. This can be used in power
line protection and measurement systems to compensate for
phase differences between PT and CT transformers. In a 50 Hz
system, this allows for up to 9° of phase compensation, and in a
60 Hz system, it allows for up to 10° of phase compensation.
This is accomplished by pulsing the two CONVST x pins inde-
pendently and is only possible if oversampling is not in use.
CONVST A is used to initiate simultaneous sampling of the first
set of channels (V1 to V4). CONVST B is used to initiate
simultaneous sampling on the second set of analog input
channels (V5 to V8), as illustrated in Figure 42. On the rising
edge of CONVST A, the track-and-hold amplifiers for the first
set of channels are placed into hold mode. On the rising edge
of CONVST B, the track-and-hold amplifiers for the second set
of channels are placed into hold mode. The conversion process
begins after both rising edges of CONVST x have occurred;
therefore, BUSY goes high on the rising edge of the later
CONVST x signal. The falling edge of BUSY also indicates that
the new data can now be read from the parallel bus or the serial
data lines, D
read process when using two separate CONVST x signals.
Connect all unused analog input channel to AGND. The results
for any unused channels are still included in the data read
because all channels are always converted.
V2
AD7609
OUT
also allows the analog input channels to be
A and D
V8
OUT
B. There is no change to the data
AD7609