AD2S44TM14B Analog Devices Inc, AD2S44TM14B Datasheet - Page 9

• Manufacturer Part Number: AD2S44TM14B
• Description: IC SYNC-R/D CONV 14BIT 2CH 32DIP
• Manufacturer: Analog Devices Inc
• Type: R/D Converterr

Specifications of AD2S44TM14B

• Rohs Status: RoHS non-compliant
• Resolution (bits): 14 b
• Data Interface: Parallel
• Voltage Supply Source: Dual ±
• Voltage - Supply: ±14.25 V ~ 15 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 32-CDIP (0.900", 22.86mm)
• Sampling Rate (per Second): -

SCALING FOR NONSTANDARD SIGNALS
A feature of these converters is that the signal and reference inputs
can be resistively scaled to accommodate nonstandard input signal
and reference voltages that are outside the nominal ±10% limits of
the converter. Using this technique, it is possible to use a standard
converter with a personality card in systems where a wide range
of input and reference voltages are encountered.
The accuracy of the converter is affected by the matching accu-
racies of resistors used for external scaling. For resolver format
options, it is critical that the value of the resistors on the S1 (A)/
S1 (B) to S3 (A)/S3 (B) signal input pair be precisely matched to
the S4 (A)/S4 (B) to S2 (A)/S2 (B) input pair. For synchro options,
the three resistors on the S1, S2, and S3 pins must be matched. In
general, a 0.1% mismatch between resistor values contributes an
additional 1.7 arc minutes of error to the conversion. In addition,
imbalances in resistor values can greatly reduce the common-
mode rejection ratio of the signal inputs.
To calculate the values of the external scaling resistors, add
2.222 kΩ for each volt of signal in series with the S1, S2, S3, and
S4 pins (no resistor is required on the S4 pins for synchro options)
and add 3 kΩ extra per volt of reference in series with the R
pins and the R
DYNAMIC PERFORMANCE
The transfer function of the converter is as follows:
Open-loop transfer function
Closed-loop transfer function
where:
K
T
T
θ
θ
θ
θ
1
2
a
OUT
OUT
IN
IN
= 62000 sec
= 0.0061 sec.
= 0.001 sec.
θ
=
=
IN
1
K
s
HI
2
+
a
Figure 6. Transfer Function of AD2S44
pins.
×
sT
1
1
1
–2
.
+
+
+
sT
sT
s
1
2
K
S
1
2
+
a
2
K
sT
a
1
+
s
3
1 + sT
1 + sT
T
2
K
1
2
a
θ
OUT
LO
Rev. A | Page 9 of 12
The gain and phase diagrams are shown in Figure 7 and Figure 8.
ACCELERATION ERROR
A tracking converter employing a Type II servo loop does not
suffer any velocity lag. However, there is an additional error
due to acceleration. This error is defined using the acceleration
constant (K
The numerator and denominator must have consistent angular
units. For example, if K
tion is to be specified in degrees/sec
to be specified in degrees. Alternatively, the angular unit of measure
can also be in units such as radians, arc minutes, or LSBs.
K
a
–135
–180
–12
–15
180
135
–45
–90
= Input Acceleration/Error in Output Angle
–3
–6
–9
90
45
6
3
0
0
10
10
a
) of the converter
a
Figure 8. Phase Plot
Figure 7. Gain Plot
is expressed in sec
FREQUENCY (Hz)
FREQUENCY (Hz)
2
and the output angle error is
100
100
–2
, the input accelera-
AD2S44