AD7699BCPZ Analog Devices Inc, AD7699BCPZ Datasheet - Page 23

• Manufacturer Part Number: AD7699BCPZ
• Description: IC ADC 8CH 16BIT 500KSPS 20LFCSP
• Manufacturer: Analog Devices Inc

Specifications of AD7699BCPZ

• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Bits: 16
• Sampling Rate (per Second): 500k
• Number Of Converters: 1
• Power Dissipation (max): 32mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-VFQFN, CSP Exposed Pad
• Resolution (bits): 16bit
• Sampling Rate: 500kSPS
• Input Channel Type: Pseudo Differential, Single Ended
• Supply Voltage Range - Analog: 4.5V To 5.5V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

READ/WRITE SPANNING CONVERSION WITHOUT
A BUSY INDICATOR
This mode is used when the AD7699 is connected to any host
using an SPI, serial port, or FPGA. The connection diagram is
shown in Figure 36, and the corresponding timing is given in
Figure 37. For SPI, the host should use CPHA = CPOL = 0.
Reading/writing spanning conversion is shown, which covers
all three modes detailed in the Digital Interface section. For this
mode, the host must generate the data transfer based on the
conversion time. For an interrupt driven transfer, refer to the
next section, which uses a busy indicator.
A rising edge on CNV initiates a conversion, forces SDO to
high impedance, and ignores data present on DIN. After a
conversion is initiated, it continues until completion irrespective
of the state of CNV. CNV must be returned high before the safe
data transfer time, t
sion time, t
After the conversion is complete, the AD7699 enters the acquisi-
tion phase and powers down. When the host brings CNV low
after t
must enable the MSB of CFG at this time (if necessary) to begin
ACQUISITION
CONV
(n – 1)
CNV
SDO
SCK
DIN
(max), the MSB is enabled on SDO. The host also
CONV
, to avoid generation of the busy signal indicator.
t
DIS
DATA
t
SCKH
CONVERSION (n – 1)
, and then held high beyond the conver-
t
SCKL
t
END DATA (n – 2)
EN
t
DATA
CFG
LSB
14
END CFG (n)
t
SCK
>
t
LSB + 1
t
CONV
15
X
CONV
16/
30
LSB
X
Figure 37. Serial Interface Timing for the AD7699 Without a Busy Indicator
Figure 36. Connection Diagram for the AD7699 Without a Busy Indicator
NOTES
1. THE LSB IS FOR CONVERSION RESULTS OR THE CONFIGURATION REGISTER CFG (n – 1) IF.
15 SCK FALLING EDGES = LSB OF CONVERSION RESULTS.
29 SCK FALLING EDGES = LSB OF CONFIGURATION REGISTER.
ON THE 16TH OR 30TH SCK FALLING EDGE, SDO IS DRIVEN TO HIGH IMPENDANCE.
t
DIS
RETURN CNV HIGH
(QUIET
TIME)
FOR NO BUSY
UPDATE (n)
CFG/SDO
t
CYC
AD7699
t
CLSCK
t
EN
FOR SPI USE CPHA = 0, CPOL = 0.
CNV
SDO
SCK
DIN
CFG
MSB
MSB
Rev. 0 | Page 23 of 28
1
t
SDIN
BEGIN CFG (n + 1)
BEGIN DATA (n – 1)
MSB – 1
MSB – 1
CFG
2
ACQUISITION (n)
t
ACQ
t
HDIN
the CFG update. While CNV is low, both a CFG update and a
data readback take place. The first 14 SCK rising edges are used
to update the CFG, and the first 15 SCK falling edges clock out
the conversion results starting with MSB − 1. The restriction
for both configuring and reading is that they both must occur
before the t
of CFG[13:0] must be written, or they are ignored. In addition,
if the 16-bit conversion result is not read back before t
it is lost.
The SDO data is valid on both SCK edges. Although the rising
edge can be used to capture the data, a digital host using the
SCK falling edge allows a faster reading rate, provided it has an
acceptable hold time. After the 16
when CNV goes high (whichever occurs first), SDO returns to
high impedance.
If CFG readback is enabled, the CFG associated with the conver-
sion result is read back MSB first following the LSB of the
conversion result. A total of 30 SCK falling edges is required to
return SDO to high impedance if this is enabled.
SS
MISO
MOSI
SCK
DIGITAL HOST
t
t
HSDO
DSDO
DATA
time of the next conversion elapses. All 14 bits
t
t
EN
CNVH
t
DIS
CONVERSION (n)
END DATA (n – 1)
END CFG (n + 1)
CFG
LSB
14
t
DATA
LSB + 1
15
X
th
t
CONV
SEE NOTE
(or 30
16/
30
X
LSB
SEE NOTE
th
) SCK falling edge, or
t
RETURN CNV HIGH
DIS
(QUIET
TIME)
FOR NO BUSY
UPDATE (n + 1)
CFG/SDO
DATA
ACQUISITION
AD7699
(n + 1)
elapses,