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INTRODUCTION
The circuit shown in FIGURE 1, the SDC-14560 Block Diagram,
consists of three main parts: the signal input; a feedback loop,
whose elements are the control transformer, demodulator, error
processor, VCO and up-down counter; and digital interface cir-
cuitry including various latches and buffers.
SIGNAL INPUTS
The SDC-14560 series offers three input options: synchro,
resolver, and direct. In a synchro or resolver, shaft angle data is
transmitted as the ratio of carrier amplitudes across the input ter-
minals. Synchro signals, which are of the form sin
θcosωt,
sin(
θ + 120°)cosωt, and sin(θ + 240°)cosωt are internally con-
verted to resolver format; sin
θcosωt and cosθcosωt. Direct inputs
accept
1 Vrms inputs in resolver form, (sin
θcosωt and cosθ
cos
ωt) and are buffered prior to conversion. FIGURE 2 illustrates
synchro and resolver signals as a function of the angle
θ.
The solid state signal and reference inputs are true differential
inputs with high AC and DC common mode rejection.
Input
3
Data Device Corporation
www.ddc-web.com
SDC-14560
Q-10/03-0
TABLE 1. SDC-14560 SPECIFICATIONS (CONTD)
PARAMETER
UNIT
VALUE
TRANSFORMERS
CHARACTERISTICS (contd)
Signal Transformer
Carrier Frequency Range
Breakdown Voltage to GND
Minimum Input Impedances
(Balanced)
90 V L-L
26 V L-L
11.8 V L-L
60 Hz TRANSFORMERS
Reference Transformer
Carrier Frequency Range
Input Voltage Range
Input Impedance
Input Common-Mode Voltage
Output Description
Output Voltage
Power Required
Signal Transformer
Carrier Frequency Range
Input Voltage Range
Input Impedance
Input Common Mode Voltage
Output Description
Output Voltage
Power Required
360- 1000 Hz
700 V peak
Synchro ZIN(ZSO) Resolver ZlN
180
100k
-
30k
20k
30k
47 - 440 Hz
80 - 138 V rms; 115 V rms
nominal resistive
600 k
min resistive
500 V rms transformer isolated
+R (in phase with RH-RL)
and - R (in phase with RL- RH)
derived from op-amps. Short
Circuit proof.
3.0 V nominal riding on ground
reference V. Output Voltage level
tracks input level.
4 mA typ, 7 mA max from
+15 V supply.
47 - 440 Hz
10 - 100 V rms L-L; 90 V rms
L- L nominal
148 k
min L-L balanced
resistive
±500 V rms transformer isolated
Resolver output,
- sine (- S) + cosine (+C)
derived from op-amps.
Short circuit proof.
1.0 V rms nominal riding on
ground reference V.
Output voltage level tracks
input level.
4 mA typ, 7 mA max from
+15 V supply.
Note:
(1) Pin programmable.
(2) See TABLE 6.
30
90
150
210
270
330
360
θ
(DEGREES)
CCW
In
Phase
with
RL-RH
of
Converter
and
R2-R1
of
CX.
0
S1-S3 = V
SIN
θ
MAX
S3-S2 = V
SIN(
θ + 120°)
MAX
S2-S1 = V
SIN(
θ + 240°)
MAX
- V
MAX
+ V
MAX
30
90
150
210
270
330
360
θ
(DEGREES)
CCW
In
Phase
with
RH-RL
of
Converter
and
R2-R4
of
RX.
0
S2-S4 = V
COS
θ
MAX
S1-S3 = –V
SIN(
θ)
MAX
- V
MAX
+ V
MAX
Standard Synchro Control Transmitter (CX) Outputs as a Function of CCW Rotation
From Electrical Zero (EZ).
FIGURE 2. SYNCHRO AND RESOLVER SIGNALS
Standard Resolver Control Transmitter (RX) Outputs as a Function of CCW
Rotation From Electrical Zero (EZ) With R2-R4 Excited.
SOLID-STATE BUFFER INPUT PROTECTION -
TRANSIENT VOLTAGE SUPPRESSION
The solid-state signal and reference inputs are true differential
inputs with high AC and DC common rejection, so most applica-
tions will not require units with isolation transformers. Input
impedance is maintained with power off. The current AC peak
+DC common mode voltage should not exceed the values in
TABLE 1.
The 90 V line-to-line systems may have voltage transients which
exceed the 500 V specification. These transients can destroy the
thin-film input resistor network in the hybrid. Therefore, 90 VL-L
solid-state input modules may be protected by installing voltage
suppressors as shown. Voltage transients are likely to occur
whenever synchro or resolver are switched on and off. For
instance, a 1000 V transient can be generated when the prima-
ry of a CX or TX driving a synchro or resolver input is opened.
See FIGURE 3.
FEEDBACK LOOP
The feedback loop produces a digital angle
φ which tracks the
analog input angle
θ to within the specified accuracy of the con-