AD7853LARSZ Analog Devices Inc, AD7853LARSZ Datasheet - Page 32

• Manufacturer Part Number: AD7853LARSZ
• Description: IC ADC 12BIT SRL 200KSPS 24SSOP
• Manufacturer: Analog Devices Inc

Specifications of AD7853LARSZ

• Data Interface: 8051, QSPI™, Serial, SPI™ µP
• Number Of Bits: 12
• Sampling Rate (per Second): 100k
• Number Of Converters: 2
• Power Dissipation (max): 33mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SSOP (0.200", 5.30mm Width)
• Resolution (bits): 12bit
• Sampling Rate: 100kSPS
• Input Channel Type: Single Ended
• Supply Voltage Range - Analog: 3V To 5.5V
• Supply Voltage Range - Digital: 3V To 5.5V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7853/AD7853L
APPLICATION HINTS
Grounding and Layout
The analog and digital supplies to the AD7853/AD7853L are
independent and separately pinned out to minimize coupling
between the analog and digital sections of the device. The part
has very good immunity to noise on the power supplies as can
be seen by the PSRR vs. Frequency graph. However, care
should still be taken with regard to grounding and layout.
The printed circuit board that houses the AD7853/AD7853L
should be designed such that the analog and digital sections are
separated and confined to certain areas of the board. This facili-
tates the use of ground planes that can be separated easily. A
minimum etch technique is generally best for ground planes as it
gives the best shielding. Digital and analog ground planes
should only be joined in one place. If the AD7853/AD7853L is
the only device requiring an AGND to DGND connection, then
the ground planes should be connected at the AGND and
DGND pins of the AD7853/AD7853L. If the AD7853/AD7853L
is in a system where multiple devices require AGND to DGND
connections, the connection should still be made at one point
only, a star ground point which should be established as close as
possible to the AD7853/AD7853L.
Avoid running digital lines under the device as these will couple
noise onto the die. The analog ground plane should be allowed
to run under the AD7853/AD7853L to avoid noise coupling.
The power supply lines to the AD7853/AD7853L should use as
large a trace as possible to provide low impedance paths and
reduce the effects of glitches on the power supply line. Fast
switching signals like clocks should be shielded with digital
ground to avoid radiating noise to other sections of the board
and clock signals should never be run near the analog inputs.
Avoid crossover of digital and analog signals. Traces on opposite
sides of the board should run at right angles to each other. This
will reduce the effects of feedthrough through the board. A
microstrip technique is by far the best but is not always possible
with a double-sided board. In this technique, the component
side of the board is dedicated to ground planes while signals are
placed on the solder side.
–32–
Good decoupling is also important. All analog supplies should
be decoupled with 10 F tantalum in parallel with 0.1 F ca-
pacitors to AGND. All digital supplies should have a 0.1 F disc
ceramic capacitor to AGND. To achieve the best from these
decoupling components, they must be placed as close as pos-
sible to the device, ideally right up against the device. In systems
where a common supply voltage is used to drive both the AV
and DV
the system’s AV
10
should have the recommended analog supply decoupling capaci-
tors between the AV
AGND and the recommended digital supply decoupling ca-
pacitor between the DV
DGND.
Evaluating the AD7853/AD7853L Performance
The recommended layout for the AD7853/AD7853L is outlined
in the evaluation board for the AD7853/AD7853L. The evalua-
tion board package includes a fully assembled and tested evalua-
tion board, documentation, and software for controlling the
board from the PC via the EVAL-CONTROL BOARD. The
EVAL-CONTROL BOARD can be used in conjunction with
the AD7853/AD7853L evaluation board, as well as many other
Analog Devices evaluation boards ending in the CB designator,
to demonstrate/evaluate the ac and dc performance of the
AD7853/AD7853L.
The software allows the user to perform ac (fast Fourier trans-
form) and dc (histogram of codes) tests on the AD7853/AD7853L.
It also gives full access to all the AD7853/AD7853L on-chip
registers allowing for various calibration and power-down op-
tions to be programmed.
AD785x Family
All parts are 12 bits, 200 kSPS, 3.0 V to 5.5 V.
AD7853 – Single Channel Serial
AD7854 – Single Channel Parallel
AD7858 – Eight Channel Serial
AD7859 – Eight Channel Parallel
resistor between the AV
DD
of the AD7853/AD7853L, it is recommended that
DD
supply is used. In this case there should be a
DD
pin of the AD7853/AD7853L and
DD
pin of the AD7853/AD7853L and
DD
pin and DV
DD
pin. This supply
REV. B
DD