AD7357BRUZ Analog Devices Inc, AD7357BRUZ Datasheet - Page 7

• Manufacturer Part Number: AD7357BRUZ
• Description: IC ADC DUAL14BIT 4.2MSPS 16TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD7357BRUZ

• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Design Resources: DC-Coupled, Single-Ended-to-Differential Conversion Using AD8138 and AD7357 (CN0061)
• Number Of Bits: 14
• Sampling Rate (per Second): 4.2M
• Number Of Converters: 2
• Power Dissipation (max): 59mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP (0.173", 4.40mm Width)
• Resolution (bits): 14bit
• Input Channel Type: Differential
• Supply Voltage Range - Analogue: 2.25V To 2.75V
• Supply Voltage Range - Digital: 2.25V To 3.6V
• Supply: RoHS Compliant
• Sampling Rate: 4.2MSPS
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Table 5. Pin Function Descriptions
Pin No.
1, 2
3, 6
4
5, 11
7, 8
9
10
12
13, 14
15
16
Mnemonic
V
REF
REFGND
AGND
V
V
CS
DGND
SDATA
SCLK
V
INA+
INB−
DD
DRIVE
A
, V
, V
, REF
INB+
B
INA−
, SDATA
B
A
Description
Analog Inputs of ADC A. These analog inputs form a fully differential pair.
Reference Decoupling Capacitor Pins. Decoupling capacitors are connected between these pins and the
REFGND pin to decouple the reference buffer for each respective ADC. It is recommended to decouple each
reference pin with a 10 μF capacitor. Provided that the output is buffered, the on-chip reference can be taken
from these pins and applied externally to the rest of the system. The nominal internal reference voltage is
2.048 V and appears at these pins. These pins can also be overdriven by an external reference. The input
voltage range for the external reference is 2.048 V + 100 mV to V
Reference Ground. This is the ground reference point for the reference circuitry on the AD7357. Any external
reference signal should be referred to this REFGND voltage. Decoupling capacitors must be placed between
this pin and the REF
Analog Ground. This is the ground reference point for all analog circuitry on the AD7357. All analog input
signals should be referred to this AGND voltage. The AGND and DGND voltages should ideally be at the same
potential and must not be more than 0.3 V apart, even on a transient basis.
Analog Inputs of ADC B. These analog inputs form a fully differential pair.
Power Supply Input. The V
with a 0.1 μF capacitor and a 10 μF tantalum capacitor.
Chip Select. Active low, logic input. This input provides the dual function of initiating conversions on the
AD7357 and framing the serial data transfer.
Digital Ground. This is the ground reference point for all digital circuitry on the AD7357. This pin should
connect to the DGND plane of a system. The DGND and AGND voltages should ideally be at the same potential
and must not be more than 0.3 V apart, even on a transient basis.
Serial Data Outputs. The data output is supplied to each pin as a serial data stream. The bits are clocked out on
the falling edge of the SCLK input. 16 SCLK falling edges are required to access the 14 bits of data from the
AD7357. The data simultaneously appears on both data output pins from the simultaneous conversions of
both ADCs. The data stream consists of two leading zeros, followed by the 14 bits of conversion data. The data
is provided MSB first. If CS is held low for 18 SCLK cycles rather than 16, then two trailing zeros appear after the
14 bits of data. If CS is held low for an additional 18 SCLK cycles on either SDATA or SDATA
other ADC follows on the SDATA pins. This allows data from a simultaneous conversion on both ADCs to be
gathered in serial format on either SDATA or SDATA
Serial Clock. Logic input. A serial clock input provides the SCLK for accessing the data from the AD7357. This
clock is also used as the clock source for the conversion process.
Logic Power Supply Input. The voltage supplied at this pin determines at what voltage the interface operates.
This pin should be decoupled to DGND. The voltage at this pin may be different to that at V
A
and REF
REFGND
AGND
REF
REF
V
V
V
V
DD
INA+
INB+
INA–
INB–
range for the AD7357 is 2.5 V ± 10%. The supply should be decoupled to AGND
A
B
Figure 2. Pin Configuration
B
pins.
1
4
2
3
5
6
7
8
Rev. A | Page 7 of 20
(Not to Scale)
AD7357
TOP VIEW
A
16
15
14
13
12
11
10
9
V
SCLK
SDATA
SDATA
DGND
AGND
CS
V
DRIVE
DD
B
.
A
B
DD
.
A
B
DD
, the data from the
.
AD7357