AD9204BCPZ-40 Analog Devices Inc, AD9204BCPZ-40 Datasheet - Page 26

• Manufacturer Part Number: AD9204BCPZ-40
• Description: 10 Bit 40 Msps Dual Low Power ADC
• Manufacturer: Analog Devices Inc

Specifications of AD9204BCPZ-40

• Number Of Bits: 10
• Sampling Rate (per Second): 40M
• Data Interface: Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 97.7mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LFCSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD9204
The AD9204 is placed in power-down mode either by the SPI
port or by asserting the PDWN pin high. In this state, the ADC
typically dissipates 2.2 mW. During power-down, the output
drivers are placed in a high impedance state. Asserting the
PDWN pin low returns the AD9204 to its normal operating
mode. Note that PDWN is referenced to the digital output
driver supply (DRVDD) and should not exceed that supply
voltage.
Low power dissipation in power-down mode is achieved by
shutting down the reference, reference buffer, biasing networks,
and clock. Internal capacitors are discharged when entering power-
down mode and then must be recharged when returning to normal
operation. As a result, wake-up time is related to the time spent
in power-down mode, and shorter power-down cycles result in
proportionally shorter wake-up times.
When using the SPI port interface, the user can place the ADC
in power-down mode or standby mode. Standby mode allows
the user to keep the internal reference circuitry powered when
faster wake-up times are required. See the Memory Map section
for more details.
DIGITAL OUTPUTS
The AD9204 output drivers can be configured to interface with
1.8 V to 3.3 V CMOS logic families. Output data can also be
multiplexed onto a single output bus to reduce the total number of
traces required.
The CMOS output drivers are sized to provide sufficient output
current to drive a wide variety of logic families. However, large
drive currents tend to cause current glitches on the supplies that
may affect converter performance.
Applications requiring the ADC to drive large capacitive loads
or large fanouts may require external buffers or latches.
The output data format can be selected to be either offset binary
or twos complement by setting the SCLK/DFS pin when operating
in the external pin mode (see Table 12).
Table 13. Output Data Format
Input (V)
VIN+ − VIN−
VIN+ − VIN−
VIN+ − VIN−
VIN+ − VIN−
VIN+ − VIN−
Condition (V)
< −VREF − 0.5 LSB
= −VREF
= 0
= +VREF − 1.0 LSB
> +VREF − 0.5 LSB
Offset Binary Output Mode
00 0000 0000 0000
00 0000 0000 0000
10 0000 0000 0000
11 1111 1111 1111
11 1111 1111 1111
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As detailed in the AN-877 Application Note, Interfacing to High
Speed ADCs via SPI, the data format can be selected for offset
binary, twos complement, or gray code when using the SPI control.
Table 12. SCLK/DFS Mode Selection (External Pin Mode)
Voltage at Pin
AGND
DRVDD
Digital Output Enable Function (OEB)
The AD9204 has a flexible three-state ability for the digital
output pins. The three-state mode is enabled using the OEB
pin or through the SPI interface. If the OEB pin is low, the
output data drivers and DCOs are enabled. If the OEB pin is
high, the output data drivers and DCOs are placed in a high
impedance state. This OEB function is not intended for rapid
access to the data bus. Note that OEB is referenced to the digital
output driver supply (DRVDD) and should not exceed that
supply voltage.
When using the SPI interface, the data outputs and DCO of
each channel can be independently three-stated by using the
output disable (OEB) bit (Bit 4) in Register 0x14.
TIMING
The AD9204 provides latched data with a pipeline delay of
nine clock cycles. Data outputs are available one propagation
delay (t
Minimize the length of the output data lines and loads placed
on them to reduce transients within the AD9204. These
transients can degrade converter dynamic performance.
The lowest typical conversion rate of the AD9204 is 3 MSPS. At
clock rates below 3 MSPS, dynamic performance can degrade.
Data Clock Output (DCO)
The AD9204 provides two data clock output (DCO) signals
intended for capturing the data in an external register. The CMOS
data outputs are valid on the rising edge of DCO, unless the DCO
clock polarity has been changed via the SPI. See Figure 2 and
Figure 3 for a graphical timing description.
PD
) after the rising edge of the clock signal.
Twos Complement Mode
10 0000 0000 0000
10 0000 0000 0000
00 0000 0000 0000
01 1111 1111 1111
01 1111 1111 1111
SCLK/DFS
Offset binary (default)
Twos complement
SDIO/DCS
DCS disabled
DCS enabled (default)
OR
1
0
0
0
1