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RDC-19220S Schematic ( PDF Datasheet ) - Data Device Corporation

Teilenummer RDC-19220S
Beschreibung 16-BIT MONOLITHIC TRACKING RESOLVER-TO-DIGITAL (R/D) CONVERTER
Hersteller Data Device Corporation
Logo Data Device Corporation Logo 




Gesamt 22 Seiten
RDC-19220S Datasheet, Funktion
RDC-19220/2S
16-BIT MONOLITHIC TRACKING
RESOLVER-TO-DIGITAL (R/D) CONVERTER
DESCRIPTION
The RDC-19220/2S is a lo w-cost, v ersatile, state-of-the-ar t 16-bit
monolithic Resolver-to-Digital (R/D) con verter. This single chip con-
verter off ers prog rammable f eatures such as resolution, bandwidth
and velocity output scaling.
Resolution prog ramming allo ws selection of 10, 12, 14, or 16 bits ,
with accuracies to 1.3 minutes. This feature combines the high track-
ing rate of a 10-bit converter with the precision and lo w-speed veloc-
ity resolution of a 16-bit con verter in one package.
The internal Synthesized Reference section eliminates errors due to
quadrature voltage. Previously, a 6 deg ree phase shift caused prob-
lems f or a 16-bit con verter. The synthesiz ed ref erence capability
ensures operation with a phase shift up to 45 deg rees. The velocity
output (VEL) from the RDC-19220/2S , which can be used to replace
a tachometer , is a 4 V signal ref erenced to g round. The full-scale
value of VEL is set by the user with a single resistor .
The RDC-19220/2S converter is available with operating temperature
ranges of 0° to +70°C, -40° to +85°C, and -55° to +125°C.
Make sure the next
Card you purchase
has...
®
FEATURES
Accuracy up to 1.3 Arc Minutes
Internal Synthesized Reference
+5 Volt Only Option
Programmable:
- Resolution: 10-, 12-, 14-, or 16-Bit
- Bandwidth
- Tracking Rate
Differential Resolver Input Mode
Velocity Output Eliminates
Tachometer
Built-In-Test (BIT) Output,
No 180° Hangup
-55° to +125°C Operating
Temperature
Programmable for LVDT Input
APPLICATIONS
The low cost, small size, high accuracy, and versatile performance of
the RDC-19220/2S con verter makes it ideal f or use in moder n high
performance motion control systems . Typical applications include
motor control, radar antenna positioning, machine tool control, robot-
ics, and process control. Class K and MIL-PRF-38534 processing are
also available.
Data Device Corporation
105 Wilbur Place
Bohemia, New York 11716
631-567-5600 Fax: 631-567-7358
www.ddc-web.com
FOR MORE INFORMATION CONTACT:
Technical Support:
1-800-DDC-5757 ext. 7771
© 1999, 2000 Data Device Corporation
http://www.Datasheet4U.com






RDC-19220S Datasheet, Funktion
GENERAL SETUP CONDITIONS
Note: For detailed application and technical inf ormation see the RD/RDC
Converter Applications Manual which is available for download from the
DDC web site @www.ddc-web.com.
DDC has e xternal component selection softw are which consid-
ers all the cr iteria below and, in a simple f ashion, asks the k ey
parameters (carrier frequency, resolution, bandwidth, and tr ack-
ing r ate) to der ive the e xter nal component v alues.
The f ollowing recommendations should be considered when
installing the RDC-19220/2S Resolver-to-Digital (R/D) converter:
1) When setting the bandwidth (BW) and Tracking Rate (TR)
(selecting fiv e e xternal components), the system require-
ments need to be considered. For the greatest noise immuni-
ty, select the minimum BW and TR the system will allow.
2) Power supplies are ±5V DC . For lowest noise perf ormance it
is recommended that a 0.1µF or larger cap be connected from
each supply to g round near the con verter pac kage. When
using +5V and -5V supplies to po wer the con verter, pins 22,
23, 25 and 26 must be no connection.
3) There are tw o inter nal ground planes to reduce analog input
noise due to digital g round currents. The resolver inputs and
velocity output are referenced to AGND. The digital inputs and
outputs are ref erenced to GND . The A GND and GND pins
must be tied together as close to the pac kage as possible, or
unstable results may occur.
RESOLVER
INPUT
(θ)
CT
+e
-
ERROR PROCESSOR
A1
S
B
+1
S S +1
10B
VCO
A2
S
H=1
VELOCITY
OUT
DIGITAL
POSITION
OUT (φ)
4) The BIT output, which is active low, is activated by an error of
approximately 100 LSBs. During nor mal oper ation, f or step
inputs or on power up, a large error can e xist.
5) Setup of bandwidth and velocity scaling for the optimized crit-
ically damped case should proceed as f ollows:
- Select the desired f BW (closed loop) based on overall
system dynamics.
- Select f carrier 3.5f BW
- Select the applications tracking rate (in accordance with TABLE 3)
and use appropriate values for R SET and R CLK
- Compute Rv =
Full Scale Velocity Voltage
Tracking Rate (rps) x 2 resolution x 50 pF x 1.25 V
- Compute CBW (pF) =
3.2 x Fs (Hz) x 108
Rv x (f BW)2
- Where Fs = 67 kHz for R CLK = 30 k
100 kHz for R CLK = 20 k
125 kHz for R CLK = 15 k
- Compute RB =
0.9
CBW x f BW
- Compute CBW
10
As an example:
Calculate component values for a 16-bit converter with 100Hz
bandwidth, a tracking rate of 10 RPS and a full scale v elocity
of 4 Volts.
- Rv =
4V
10 rps x 216 x 50 pF x 1.25 V
= 97655
-
Compute
CBW
(pF)
=
3.2 x 67 kHz x 108
97655 x 100 Hz2
= 21955 pF
-
Compute
RB
=
21955
x
0.9
10 -12
x
100
Hz
= 410 k
FIGURE 3. TRANSFER FUNCTION BLOCK DIAGRAM #2
GAIN = 4
OPEN LOOP
BA
(B = A/2)
(CRITICALLY DAMPED)
2A
ω (rad/sec)
-6 db/oct
10B
GAIN = 0.4
Note: DDC has software available to perform the previous calculations. Contact
DDC to request software or visit our web site at www.ddc-web.com to
download software.
6) Selecting a f BW that is too lo w relative to the maxim um appli-
cation tr acking r ate can create a spin-around condition in
which the con verter never settles . The relationship to insure
against spin-around is as follows (TABLE 2.):
CLOSED LOOP
fBW = BW (Hz) =
2A
π
2A
2 2A
ω (rad/sec)
FIGURE 4. BODE PLOTS
Data Device Corporation
www.ddc-web.com
TABLE 2. TRACKING/BW RELATIONSHIP
RPS (MAX)/BW
RESOLUTION
1 10
0.50 12
0.25 14
0.125
16
RDC-19220/2S
6 K-07/05-0

6 Page









RDC-19220S pdf, datenblatt
SIN
Ri
S1
Rf
-S
-
S3
RESOLVER
INPUT
S4
R i +S
Rf
A GND
COS
Ri
Rf
-C
+
Note: Five external BW components
as shown in Figures 1 and 2
are necessary for the R/D to
function.
-
Ri
S2
+C +
Rf
Ri
X 2 Vrms = Resolver L-L rms voltage
Rf
CONVERTER
Rf 6 k
S1 and S3, S2 and S4, and RH and RL should be ideally twisted shielded,
with the shield tied to AGND at the converter.
For 2V direct inputs use 10k Ohm matched resistors for Ri and Rf.
FIGURE 10A. DIFFERENTIAL RESOLVER INPUT
RESOLVER
INPUT
S1 1
S3 6
S4 16
S2 7
Ri
Ri
A GND
Ri
Ri
8 10
SIN
3
Rf
-S
2
+S
5
Rf
4
COS
13
Rf
-C
15
+C
Rf
12
-
+
Note: Five external BW components
as shown in Figures 1 and 2
are necessary for the R/D to
function.
-
+
CONVERTER
S1 and S3, S2 and S4, and RH and RL should be ideally twisted shielded, with the shield
tied to AGND at the converter.
For DDC-49530: Ri = 70.8 k ohms, 11.8 V input, synchro or resolver.
For DDC-49590: Ri = 270 k ohms, 90 V input, synchro or resolver.
Maximum addition error is 1 LSB, using recommended thin film package.
Input options affect DC offset gains and therefore carrier frequency ripple and jitter. Offset gains associated with differential
mode (offset gain for differential configuration = 1+Rf/Ri) and direct mode (offset gain for direct configuration = 1) show
differential mode will always be higher. Higher DC offsets cause higher carrier frequency ripple due to the demodulation
process. This carrier frequency ripple rides on top of the DC error signal, causing jitter. A higher carrier frequency versus
bandwidth ratio will help to decrease ripple and jitter associated with offsets. In summary, R/Ds with differential inputs are
more susceptible to offset problems than R/Ds in single-ended mode. R/Ds in higher resolutions, such as 16 bit, will further
compound offset issues due to higher internal voltage gains. Although the differential configuration has a higher DC offset
gain, the differential configuration's common mode noise rejection makes it the preferred input option. The tradeoffs should
be considered on a design to design basis.
FIGURE 10B. DIFFERENTIAL RESOLVER INPUT, USING DDC-49530/57470 (11.8 V), DDC-73089 (2V) OR
DDC-49590 (90 V)
Data Device Corporation
www.ddc-web.com
12
RDC-19220/2S
K-07/05-0

12 Page





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