AD9214BRS-65 Analog Devices Inc, AD9214BRS-65 Datasheet - Page 13

• Manufacturer Part Number: AD9214BRS-65
• Description: A/D Converter (A-D) IC
• Manufacturer: Analog Devices Inc

Specifications of AD9214BRS-65

• No. Of Bits: 10 Bit
• Mounting Type: Surface Mount
• No. Of Channels: 1
• Interface Type: Parallel
• Package / Case: 28-SSOP
• Rohs Status: RoHS non-compliant
• Number Of Bits: 10
• Sampling Rate (per Second): 65M
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 220mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C

POWER SUPPLIES
The AD9214 has two power supplies, AV
and AGND supply power to all the analog circuitry, the inputs
and the internal timing and digital error correction circuits.
AV
the Typical Performance Characteristics section.
DrV
allowing the user to adjust the voltage level to match down-
stream logic.
DrV
loading capacitance, and the encode frequency. Designs that mini-
mize external load capacitance will reduce power consumption
and reduce supply noise that may affect ADC performance. The
maximum DrV
where N is the number of output bits, 10 in the case of the
AD9214. This maximum current is for the condition of every
output bit switching on every clock cycle, which can only occur
for a full scale square wave at the Nyquist frequency, f
In practice, I
switching, which will be determined by the encode rate and the
characteristics of the analog input signal. The performance
curves section provides a reference of I
for a 10.3 MHz sine wave driving the analog input.
Both power supply connections should be decoupled to ground
at or near the package connections, using high quality, ceramic
chip capacitors. A single ground plane is recommended for all
ground (AGND and DGND) connections.
The PWRDN control pin configures the AD9214 for a sleep
mode when it is logic HIGH. PWRDN floats logic LOW for
normal operation. In sleep mode, the ADC is not active, and
will consume less power. When switching from sleep mode to
normal operation, the ADC will need ~15 clock cycles to recover to
valid output data.
Digital Outputs
Care must be taken when designing the data receivers for the
AD9214. It is recommended that the digital outputs drive a
series resistor (e.g., 100 Ω) followed by a gate like the 74LCX821.
To minimize capacitive loading, there should be only one gate
on each output pin. An example of this is shown in the evaluation
board schematic in Figure 10. The series resistors should be
placed as close to the AD9214 as possible to limit the amount of
current that can flow into the output stage. These switching
currents are confined between ground (DGND) and the DrV
pins. Standard TTL gates should be avoided since they can
appreciably add to the dynamic switching currents of the AD9214.
ANALOG
SOURCE
SIGNAL
DD
DD
DD
50
supply current will vary slightly with encode rate, as noted in
current will vary depending on the voltage level, external
and DGND supply only the CMOS digital outputs,
10k
5k
I
DrV
DrV
AV
DD
DD
DD
DD
current can be calculated as
=
will be the average number of output bits
500
0.1 F
V
500
DrV
DD
×
+
–
VOCM
500
500
C
AD8138
–
+
LOAD
×
50
50
DrV
fencode
15pF
DD
DD
and DrV
versus encode rate
×
A
A
N
IN
IN
AD9214
DD
ENCODE
. AV
DD
DD
/2.
It should also be noted that extra capacitive loading will increase
output timing and invalidate timing specifications. Digital output
timing is guaranteed with 10 pF loads.
LAYOUT INFORMATION
The schematic of the evaluation board (Figure 10) represents a
typical implementation of the AD9214. A multilayer board is
recommended to achieve best results. It is highly recommended
that high quality, ceramic chip capacitors be used to decouple
each supply pin to ground directly at the device. The pinout of
the AD9214 facilitates ease of use in the implementation of high
frequency, high resolution design practices. All of the digital
outputs and their supply and ground pin connections are segre-
gated to one side of the package, with the inputs on the opposite
side for isolation purposes.
Care should be taken when routing the digital output traces. To
prevent coupling through the digital outputs into the analog
portion of the AD9214, minimal capacitive loading should be
placed on these outputs. It is recommended that a fan-out of
only one gate should be used for all AD9214 digital outputs.
The layout of the encode circuit is equally critical. Any noise
received on this circuitry will result in corruption in the digitiza-
tion process and lower overall performance. The Encode clock
must be isolated from the digital outputs and the analog inputs.
EVALUATION BOARD
The AD9214 evaluation board offers designers an easy way to
evaluate device performance. The user must supply an analog
input signal, encode clock reference, and power supplies. The
digital outputs of the AD9214 are latched on the evaluation
board, and are available with a data ready signal at a 40-pin
edge connector. Please refer to the evaluation board schematic,
layout, and Bill of Materials.
Power Connections
Power to the board is supplied via three detachable, 4-pin power
strips (U4, U9, and U10). These 12 pins should be driven as
outlined in the Table II.
Pin
1
3
5
7
9
11
2, 4, 6,
8, 10, 12
Please note that the +5 V and –5 V supplies are optional, and
only required if the user adds differential op amp Z1 to the board.
Table II. Power Supply Connections for AD9214
Evaluation Board
Designator
LVC
+5 V
–5 V
VCC
VDD
DAC
GND
External Supply
Required
3 V
+5 V
(Optional Z1 Supply)
–5 V
(Optional Z1 Supply)
3 V
3 V
5 V
Ground
AD9214