ANALOG
W
DEVICES
I
-.
Digital-
to-Synchro
Converters
DSC1705/1706
I
FEATURES
Very Low Radius Vector Variation (Transformation
Ratio) (:to.1%)
High Accuracy (:t2 arc-mins at +25°C)
12- or 14.Bit Resolution
No 5 Volt Power Supply Required
MIL Spec/Hi Rei Versions Available
Internal 1.3VA Amplifiers
Internal Transformers (40PHz Option)
No Trims or Adjustments Necessary
APPLICATIONS
Driving Control Transformers
Driving Torque Receivers (with External Amplifiers)
Servo Mechanisms
Retransmission Systems
Positional Control
GENERAL DESCRIPTION
The DSC1705 and DSC1706 are Digital-to-Synchro and Digital-
to-Resolver converters capable of driving electromechanical
loads of up to 1.3VA.
They accept a 14- or 12-bit digital input representing angle
and a reference voltage of either 60Hz or 400Hz, and produce
a 3 wire or 4 wire output suitable for driving Synchros or
Resolvers.
The 400Hz converters contain internal1.3V A amplifiers as
well as output and reference transformers.
The 60Hz versions contain internal 1.3VA amplifiers but
require external output and reference transformers.
If it is necessary to drive a load requiring more than 1.3VA,
options for both the 400Hz and 60Hz converters are available
allowing the use of external amplifiers and transformers.
RADIUS VECTOR
One of the outstanding features of these converters is the
almost negligible Radius Vector variation (Transformation
Ratio).
OBS
OLE
TE
MODELS AVAILABLE
The two Digital to Synchro/Resolver converters described in
this data sheet differ primarily in the areas of resolution and
accuracy as follows:
Model DSC1705XYZ is a 14-bit converter with an overall
accuracy of :t4 arc-minutes.
Model DSC 1706XYZ is a 12-bit converter with an overall
accuracy of 18 arc-minutes.
The XYZ option code defines the option thus: (X) signifies
the operating temperature range, (Y) signifies the reference
frequency, (Z) signifies the output and the reference voltages,
whether the output is in ~ynchro or Resolver format and
whether external transformers are required.
RHi
II
REFER-
ENCE
TRANS.
FORMERS
SCOTT
TEE
TRANS-
FORMERS
53
On many Digital-to-Synchro converters presently available, the
individual sine and cosine outputs produced do not follow the
exact sine and cosine laws, and depending upon angle can vary
up to :t7%. This is not always important as the ratio of the sine
to the cosine, i.e., the tangent, is always correct to the speci-
fied accuracy of the converter. There are cases however, when
driving torque receivers and certain servo control loops when
this variation is unacceptable.
MSB
"
OIGiTAL INPUT WI
/
Principle of Operation
FUNCTIONAL DIAGRAM, DSC170S and DSC1706
The principle of operation of the converters described in
this data sheet is shown in the diagram above.
variationto lessthan to.l%. This meansthat
when
the
The design of the DSC1705 and DSC1706 has reduced this
convertersare usedin closedloop servosystems,the gain
of
the closed loop is independent of the digital input angle, thus
making reference correction unnecessary.
Model
ACCURACY.
RESOLUTION
INPUT CODE
REFERENCE VOLTAGE INPUT
With Internal Transformers
.
Low Level
High Level
External Transformer Options2
REFERENCE FREQUENCY
REFERENCE INPUT IMPEDANCE
With Internal Transformers
Low Level
.
High Level
External Transformer Options2
DIGITAL IN,PUT(TTL COMPATIBLE)
OUTPUT VOLTAGE AND FORMAT
With Internal1ransformers
Low Level
High Level
DSC170S
:1:4arc-minutes
14 Bits (lLSB
DSC1706
:t8 arc-minutes
=
1.3 arc-minutes)
12 Bits (lLSB
=
5.3
arc-minutes)
MSB
=
180°
14-BitsNaturalParallelBinarywith
12-Bits Natural Parallel Binary with
MSB
=
180°
26V rms
115V rms
4V rms
60Hz or 400Hz
.
.
.
.
.
.
.
.
20kQ
200kQ
lOkQ
lTTL Load
OBS
External :Transformer Options3
LOAD CAPABILITY
SHORT CIRCUIT PROTECTION
OUTPUT SETTLING TlME4
POWER SUPPLIES
Voltage
Current.
(a) No Load
(b) Full Load Mean
WARM-UP TIME
OPERATING
TEMPERATURE
RANGE
RADIUS VECTOR VARIATION
(Transformation Ratio)
INTERNAL TRANSFORMER ISOLATION
OLE
TE
90V rms Line-o-Line Synehro
or Resolver
7V rms Sineand Cosine
1.3VA
11.8V rms Line-to-Line Synchro
or Resolver
.
.
.
ContlDuous 5 minutes
for
50/Js for 180 Step
°
.
.
.
to.1% max Sineand Cosine
500V de
.
.
t15V de :1:5%
.
.
95mA per Line
225mAper Line
lsee to Full Accuracy
0 to +700C
Standard
.
.
.
.
.
.
.
STORAGE TEMPERATURE RANGE
SIZE
WEIGHT
MEAN TIME BETWEEN FAILURES
(MTBF) CALCULATED
NOTES
.Specifications
I
-55°C to +105°CExtended
-55°C to +125°C
3.125" x 2.625" x 0.8"
(79.4mm x 66.7mm x 20.3mm)
8 ounces(224 grams)max
150,000 Hours
.
.
same as DSC1705.
Accuracy applies over the full operating temperature range
of the option and for:
(a) :1:10%reference frequency and amplitude variation.
(b) 10% harmonic distortion on the reference.
(c) :t5% power supply variation.
(d) Any balanced load from no load to full load.
2 Refers to input to converter and not to external transformers.
3 Refers to output from internal converter amplifiers and not from
external transformers.
4 Dependent upon option and load conditions.
Specifications
subject to change without notice.
VOL. II, 13-10 SYNCHRO
&
RESOLVER CONVERTERS
I
CONNECTINGTHE CONVERTER
iQ..OHzptions. All these converters contain internal output
o
md reference transformers.
The digital input should be connected to pins "1" through
"12" on the DSC1706 and pins "1" through "14" on the
DSC1705, noting that pin "1" is the Most Significant
Bit (MSB).
"S1", "S2" and "S 3" should be connected to the appropriate
inputs on the synchro being driven. ("S4" is used also when
connection is mad~ to a resolver).
The reference should be connected to "RHi" and "RLo"
ensuring that the phase is correct.
"GND" is the common for both power supplies and digital
inputs.
60Hz Options. For 60Hz operation, an external transformer,
STM1679 is required.
The power supplies and digital input should be connected as
for the 400Hz version.
The STM1679 transformer should have its pins "SIN",
"COS" and "V" connected to the equivalent pins on the
converter. The "GND(SIG)" and "GND(REF)"should both
be connected to "GND" on the converter.
The outputs to the load should be taken from "Sl", "S2"
and "S3" on the STM1679 transformer ("S4" also in the
case of a resolver).
CONVERTER OUTLINE DIMENSIONS
AND PIN CONNECTION DIAGRAM
Dimensions shown in inches and (mm).
I"
0.8
120.3)
..L
0.2
(5.1/
2.825 188.7)
.
I
'I
-
~
NOTE
54 PRESENT
ON RESOLVER
OPTION ONLY
U
t---
:l
2.2155.4) 1
14
13
12
11
10
9
8
7
6
6
4
3
2
Pins
0.040"'0.OOI"dia.
Bra". hard goldplated.
I--
2.2155.41 1
14
13
12
11
10
9
8
7
5
6
4
3
1
(MSB)
OBS
STM1679
54
S3
S2
SI
+16
GND
-16
SIN
CO
I
+16
GN,D
I
-< -1
T
3.125
(79.4)
0.263(6.71
The reference input should be made to "RHi" and "RLo" on
the STM1679.
OLE
TE
TOP VIEW
~
T
..L
LO
R .
HI
1
(MSB)
--I
CONVERTER
WITHINTERNAL
TRANSFORMERS
I--
0.2GRID
TOP
VIEW
16.081
~
I I
V
I-
0.2
GRID
(6.08)
CONVERTER
REOUIRING
EXTERNAL
TRANSFORMERS
-I
1
NOTE
DIAGRAMS ABOVE SHOW DSC1706.
DSC1706 DOES NOT HAVE PINS "13" AND "14".
MATING SOCKET: CAMBION450-3388-01-03
TRANSFORMER (STM1679) OUTLINE DIMENSIONS
AND PIN CONNECTION DIAGRAM
l-
Dimensions shown in inches and (mm).
4.51114.31
-1
014
0
0
0
0
0
0
0
0
0
0
0
0
01
DSC
I
T
1.8
58
a:
Q
z
~
M3 FIXING
X
0.26
(6.3)
4 POSITIONS
DEEP
IN
BOTTOM
VIEW
PIN DIA. 0.040 t O.OOIDIA.
'HARD GOLD PLATE.
BRASS.
L
1(8.41
1.6
0.26
.
v
'S4 PIN PRESENT FOR RESOLVER OPTION ONLY
~
\
60Hz Connection
to
a Control Transformer
(Diagram Shows Bottom View of Modules)
BIT WEIGHT TABLE
Bit Number
1 (MSB)
2
3
4
5
6
7
8
9
10
11
12 (LSB for DSC1706)
13
Weight in Degrees
180.0000
90.0000
45.0000
22.5000
11.2500
5.6250
2.8125
1.4063
0.7031
0.3516
0.1758
0.0879
0.0439
0 O??O
OPERATION WITH EXTERNAL AMPLIFIERS OR
TRANSFORMER OTHER THAN STM1679
For certain applications, the power output required by the
load will be greater than the l.3V A supplied by the internal
amplifiers. Thus external amplifiers and transformers will
be needed. Products offered to fulfu11this requirement are:
SPA1695
STM1696
-
5VAoutput and referencetransformers (400Hz)
STM1697
-
5VA output and referencetransformers(60Hz)
-
Dual 5VA Amplifier
.
.
.
If you have a requirement for such produ~ts please reql,lest
. A" <"" £_- """""'1"In""
,
-
,-
---c-
'
WADING THE DSC's WITH
CONTROL TRANSFORMERS (CT's)
The most common device to be driven by Digital to Synchro
converters is the control transformer (CT)
The minimum power required to drive a CT can be expressed
as:
V2
3
(VA)
=TZ1 . 4
so
where V is the line to line voltage and Zso is the impedance
between one input terminal and the other two shorted to-
gether with the rotor open circuit. (Zso
PRACTICAL CONSIDERATIONS OF TUNING CT
WADS'
is sufficient."
2. Three capacitors must be used, one across SI and S2, one
across SI and 53 and one across S2 and S3.'
,
1. Th«apadto"
u",d "ttd
not be of high tole"",,.
20%
1
;
3. Voltage working and type of capacitors should be as
follows:
ll.8V Line-to-Line, options:
IS Volt ac working or greater,non-polarized tantalum
type.
90V Line-to-Line options:
100 Volt ac working or greater, for example, low K
c-eramic types.
4. For tuning Resolver loads, two capacitors only are required,
one connected between SI and S3 and the other connected
between S2 and S4.
'
=
Rso
+ j Xso)
'
For example, if a CT has a Zso of 700 + j 4900 and a line to
line voltage of 90 volts, then:
OBS
and (VA)
I
Zso
I =
J
7002
902
4950
+ 49002
=
4950
Ohms
3
=
'"4
=
1.23VA
TUNING CT
WADS
The load can be reduced by tuning the output with 3
capacitors as shown below.
01'
0
0
0
0
0
0
0
0
0
0
0
0
01
DSC
RLo
RH.
Capacitor Connection for Tuning CT's
C should be equal to:
Xso
2w (Rso 2 + Xso2)
The power required after tuning will be:
R
(VA) untuned
x Zso
so
OLE
TE
. .
IZss
CONTROL DIFFERENTIAL TRANSMITTERS (CDX's)
The loading on a DSC of these devices can be considered in a
similar way to that of CT's. However becasue a CT normally
follows a CDX, the effective Z will need to be calculated. This
value will normally be between 66% and 80% of the Zso
quoted for the CDX.
TORQUE RECEIVERS (TR's)
Torque receivers are mor~ difficult devices to drive than CT's
and CDX's, and in general external amplifiers and transformers
will be necessary. However, because of the lack of radius vector
variation, the DSC170S and DSC1706 are far more suited to
driving TR's than converters with a variation of 1:7%.
For a deviation of an angle 8, the drive current required will be:,
2 V
sin!
2
I
Therefore in the above example the capacitor value should be:
4900
2 x
21TX
400 (245 X 105)
=
40nF
and the power required after tuning will be:
700
1.23 x
49S0
=0.17VA
Note allowance should always be made for tolerances in the
CT windings, capacitors and fre9uency.
Points to be observed are:
(a) The TR should not be allowed to lock up.
(b) A phase lead equal to that specified for the TR should
be introduced into the reference input to the DSC.
(c) The reference should always be present on the TR and
the converter.
(d) The DSC output voltage should be matched exactly to
the voltage requirements of theTR.
CAUTIONS
(a) Do not connect a llSV reference to a 26V converter.
(b) Do not reverse the power supplies.
(c) Do not connect the reference to any other pins except
"RHi" and "RLo ".
ORDERING INFORMATION
When ordering, the converter part numbers should be suffixed
by an option code in order to fully define the item. All
standard options and their appropriate option codes are listed
below.
Line-to- Line
Output Voltage
and Format
11.8V
90.0V
11.8V
90.0V
11.8V
11.8V
Svnchro
Svnchro
Svnchro
Svnchro
Resolver
Resolver
Reference
Voltage
26V
llSV
26V
llSV
26V
26V
llSV
l1SV
Reference
Frequency
400Hz
400Hz
400Hz
400Hz
400Hz
400Hz
60Hz
60Hz
Part Number!
DSCI70SS11
DSC170SS12
DSCI70S611
DSC170S612
DRC170SS 18
DRC170S618
DSC170SS07 and STM1679522
DSC1705607 and STM1679622
Resolution
14 Bits
14 Bits
14 Bits
14 Bits
14 Bits
14 Bits
14 Bits
14 Bits
Operating
Temp. Range
0 to +70oC
0 to +70uC
-SSuC to +10SuC
-SSuC to +10SuC
0 to +70 C
-SSwC to +10SwC
0 to +70uC
-SS
C to +10S C
90.0V Synchro
90.0V Synchro
Note: 1. For 12-bit resolution, substitute DSC1706 in place of
DSC170S
in the above.
2. For options not shown above, consult the factory.
VOL.
I/, 13-12
SYNCHRO
&
RESOLVER
CONVERTERS
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