AD28msp01KST AD [Analog Devices], AD28msp01KST Datasheet - Page 17

• Manufacturer Part Number: AD28msp01KST
• Description: PSTN Signal Port
• Manufacturer: AD [Analog Devices]

REV. A
Single Power Supply Operation
Use of a single +5 V power supply is possible with the
AD28msp01. If a single supply is used, the analog power supply
input to the device must be properly filtered. The proper filter is
dependent on the noise present in your system.
PC Board Layout Considerations
Separate analog and digital ground planes should be provided
for the AD28msp01 in order to assure the characteristics of the
device’s ADC and DAC. The two ground planes should be con-
nected only at a single point. The point of connection may be at
the system power supply, at the PC board power connection, or
at any other appropriate location. Multiple connections between
the analog and digital ground planes should be avoided.
The ground planes should be designed such that all noise-
sensitive areas are isolated from one another and critical signal
traces (such as digital clocks and analog signals) are as short as
possible.
Each +5 V supply pin of the AD28msp01 should be bypassed to
ground with a 0.1 F capacitor. These capacitors should be low
inductance, monolithic, ceramic, and surface-mount. The ca-
pacitor leads and PC board traces should be as short as possible
to minimize inductive effects. In addition, a 10 F capacitor
should be connected between V
board power connection.
MCLK Frequency
The sigma-delta converters and digital filters of the AD28msp01
are specifically designed to operate at a master clock (MCLK)
frequency of 13.824 MHz. MCLK must equal 13.824 MHz to
guarantee the filter characteristics and sample rate of the ADC
and DAC. The AD28msp01 is not tested or characterized at
any other clock frequency.
Figure 15. Example Circuit for Single-Ended Output
V
OUT
GND
A
5
SSM-214
1
SSM2141
+12V
–12V
7
4
0.1 F
0.1 F
GND
GND
DD
A
A
and ground, near the PC
V
V
OUTP
OUTN
AD28msp01
–17–
DEFINITION OF SPECIFICATIONS
Typical (Typ) specifications represent nominal performance at
+25 C with V
Minimum (Min) and Maximum (Max) specifications are guar-
anteed across the full operating range, however, devices are
tested only at the indicated test conditions.
Absolute Gain
Absolute gain is a measure of converter gain for a known signal.
Absolute gain is measured with a 1.0 kHz sine wave at 0 dBm0.
The absolute gain specification is used as a reference for gain
tracking error specification.
Gain Tracking Error
Gain tracking error measures changes in converter output for
different signal levels relative to an absolute signal level. The ab-
solute signal level is 1 kHz at 0 dBm0 (equal to absolute gain).
Gain tracking error at 0 dBm0 is 0 dB by definition.
SNR
Signal-to-noise ratio is defined to be the ratio of the rms value of
the measured input signal to the rms sum of all the spectral
components in the specified passband, excluding dc and har-
monic components.
THD
Total harmonic distortion is defined to be the ratio of the rms
value of the measured input signal to the rms sum of the har-
monic components in the specified passband.
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies, f
f
products at sum and difference frequencies of mf
m, n = 0, 1, 2, 3, etc. Intermodulation terms are those for which
neither m nor n are equal to zero. This specification contains
the second order terms include (f
third order terms include (2f
(f
Idle Channel Noise
Idle channel noise is defined as the total signal energy measured
at the output of the device when the input is grounded (mea-
sured in the specified passband).
Crosstalk
Crosstalk is defined as the ratio of the amplitude of a 0 dB sig-
nal appearing on one channel to the amplitude of the same sig-
nal coupled onto the other, idle channel. Crosstalk is expressed
in dB.
Power Supply Rejection
Power supply rejection measures the susceptibility of a device to
noise on the power supply. Power supply rejection is measured
by modulating the power supply with a 1 kHz, 100 mV p-p sine
wave and measuring the relative level at the output.
Group Delay
Group delay is defined as the derivative of radian phase with re-
spect to radian frequency,
of the linearity of the phase response of a linear system. A linear
system with a constant group delay has a linear phase response.
The deviation of the group delay away from a constant indicates
the degree of nonlinear phase response of the system.
b
, any active device with nonlinearities will create distortion
a
– 2f
b
).
CC
and V
DD
set to +5 V.
a
+ f
b
a
), (2f
+ f
. Group delay is a measure
b
) and (f
a
– f
AD28msp01
b
), (f
a
– f
a
+ 2f
a
b
), and the
nf
b
), and
b
where
a
and