AD7686BRMZ Analog Devices Inc, AD7686BRMZ Datasheet - Page 21

• Manufacturer Part Number: AD7686BRMZ
• Description: IC ADC 16BIT 500KSPS 10-MSOP
• Manufacturer: Analog Devices Inc
• Series: PulSAR®r

Specifications of AD7686BRMZ

• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Bits: 16
• Sampling Rate (per Second): 500k
• Number Of Converters: 1
• Power Dissipation (max): 21.5mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP (0.118", 3.00mm Width)
• Resolution (bits): 16bit
• Input Channel Type: Pseudo Differential
• Supply Voltage Range - Analogue: 4.5V To 5.5V
• Supply Voltage Range - Digital: 1.8V To 5.8V, 2.3V To 5.8V
• Sampling Rate: 500kSPS
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-AD7686CBZ - BOARD EVALUATION FOR AD7686
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

SDO
CHAIN MODE, NO BUSY INDICATOR
This mode can be used to daisy-chain multiple AD7686s on a
3-wire serial interface. This feature is useful for reducing
component count and wiring connections, for example, in
isolated multiconverter applications or for systems with a
limited interfacing capacity. Data readback is analogous to
clocking a shift register.
A connection diagram example using two AD7686s is shown in
Figure 41 and the corresponding timing is given in Figure 42.
When SDI and CNV are low, SDO is driven low. With SCK low,
a rising edge on CNV initiates a conversion, selects the chain
mode, and disables the BUSY indicator. In this mode, CNV is
held high during the conversion phase and the subsequent data
readback. When the conversion is complete, the MSB is output
ACQUISITION
SDI
A
t
= SDI
HSCKCNV
CNV
SCK
SDO
A
= 0
B
B
CONVERSION
t
SSCKCNV
t
CONV
t
EN
SDI
AD7686
t
t
HSDO
DSDO
CNV
SCK
A
D
D
1
A
B
15
15
Figure 42. Chain Mode, No BUSY Indicator Serial Interface Timing
Figure 41. Chain Mode, No BUSY Indicator Connection Diagram
t
SDO
SSDISCK
D
D
2
A
B
14
14
D
D
3
A
B
13
13
t
SCKL
Rev 0 | Page 21 of 28
SDI
t
HSDISC
14
AD7686
CNV
SCK
B
t
D
D
15
CYC
A
B
onto SDO and the AD7686 enters the acquisition phase and
powers down. The remaining data bits stored in the internal
shift register are then clocked by subsequent SCK falling edges.
For each ADC, SDI feeds the input of the internal shift register
and is clocked by the SCK falling edge. Each ADC in the chain
outputs its data MSB first, and 16 × N clocks are required to
readback the N ADCs. The 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 and consequently more AD7686s in the chain, provided the
digital host has an acceptable hold time. The maximum
conversion rate may be reduced due to the total readback time.
For instance, with a 3 ns digital host set-up time and 3 V
interface, up to four AD7686s running at a conversion rate of
360 kSPS can be daisy-chained on a 3-wire port.
1
1
ACQUISITION
t
SDO
SCK
t
SCKH
t
D
D
ACQ
16
A
B
0
0
D
17
A
15
D
18
CLK
CONVERT
DATA IN
A
14
DIGITAL HOST
30
D
31
A
1
D
32
A
0
AD7686