Standard Products
Datasheet
RDC5028C 16-Bit Monolithic Tracking
Rad Tolerant Resolver-To-Digital Converter
www.aeroflex.com/RDC
May 7, 2014
FEATURES
Enhanced version of the ACT5028B
Radiation performance
- Total dose: 1 Mrad(Si), Dose rate = 50 - 300 rads(Si)/s
- SEL:Immune up to 100 MeV-cm
2
/mg
+5V
DC
power only
Programmable: By using a few non critical external resistors and capacitors
- Resolution: 10, 12, 14 or 16 bit resolution
- Bandwidth
- Tracking rate
Low power: +5V @ 20 mA typ
45 to 30,000 Hz carrier frequency range
Accuracy:
- 10.0 Arc Minutes if not compensated by INL correction factors.
- 5.3 Arc Minutes using INL correction factors.
Differential instrument amplifiers resolver input
-55° to +125°C operating temperature
Digital interface logic voltage of 3.3V to 5V
Designed for aerospace and high reliability space applications
Packaging – Hermetic
- 52 Pin Ceramic QUAD flat package (CQFP), .956" SQ x .100"Ht
- Weight: 5.0g max
Evaluation board available for test and evaluation. See Aeroflex Application note AN5028-1
Aeroflex Plainview’s Radiation Hardness Assurance Plan is DLA Certified to MIL-PRF-38534, Appendix G.
APPLICATIONS
This single chip Resolver-to-Digital Converter (RDC) is used in shaft angle control systems, and is suitable for space
or other radiation environments that require > 1 Mrad(Si) total dose tolerance. The part is latchup free in heavy ion
environments (e.g., geosynchronous orbits) and is estimated to experience SEU induced errors of less than 15 minutes
of arc at a rate of 1 per device per 2 years when operating dynamically.
THEORY OF OPERATION
The RDC5028 converter is a single CMOS Type II tracking resolver to digital converter monolithic chip. It is
implemented using precision analog circuitry and digital logic. For flexibility, the converter bandwidth, dynamics and
velocity scaling are externally set with passive components. Refer to Figure 1, RDC5028 Block Diagram.
The converter is powered from +5VDC. Analog signals are referenced to signal ground, which is nominally V
CC
/2.
The converter consists of three main sections; the Analog Control Transformer (CT), the Analog Error Processor (EP)
and the Digital Logic Interface.
The CT has two analog resolver inputs (Sin and Cos) that are buffered by high impedance input instrumentation type
amplifiers and the 16 bit digital word which represents the output digital angle. The CT performs the ratiometric
trigonometric computation of:
SIN(A) sin(wt) COS(B) – COS(A) sin(wt) SIN(B) = SIN(A-B) sin(wt)
Utilizing amplifiers, switches, logic and resistors in precision ratios. “A” represents the resolver angle, “B“ represents
the digital angle and sin(wt) represents the resolver reference carrier frequency.
The Error Processor is configured as a critically damped Type II loop. The AC error, SIN (A-B) sin (wt) is full wave
demodulated using the reference squared off as its drive. This DC error is integrated in an analog integrator yielding a
velocity voltage which in turn drives a Voltage Controlled Oscillator (VCO). Note in the block diagram, hysterisis is
added to prevent dithering and disables counting when the error is less than 1 LSB. This VCO is an incremental
integrator (constant voltage input to position rate output) which, together with the velocity integrator, forms a Type II
loop. A lead is inserted to stabilize the loop and a lag is inserted at a higher frequency to attenuate the carrier
frequency ripple. The error processor drives the 16 bit digital output until it nulls out. Then angle “A” = “B”. The
digital output equals angle input to the accuracy of the precision control transformer. The various error processor
settings are done with external resistors and capacitors so that the converter loop dynamics can be easily controlled by
the user.The digital logic interface has a separate power line, VL
I
/
O
that sets the interface logic 1 level. It can b
e
set
anywhere from +3V to the +5V power supply.
SCD5028-2 Rev G
PIN DESCRIPTIONS
SIGNAL
+SIN
-SIN
+COS
-COS
+REF
-REF
BIT 1 (MSB)
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
BIT 9
BIT 10
BIT 11
BIT 12
BIT 13
BIT 14
BIT 15
BIT 16 (LSB)
SC1
SC2
49
48
45
47
1
50
51
52
14
13
16
15
17
18
8
6
9
10
5
4
27
3, 19, 23
26
2
DIRECTION
INPUT
INPUT
INPUT
PIN
22
21
25
24
11
12
28
29
30
31
32
34
35
36
37
38
39
40
41
42
43
44
SIGNAL DESCRIPTION
Analog Sine input from Synchro or Resolver. 1.3Vrms nominal
Analog Cosine input from Synchro or Resolver. 1.3Vrms nominal
Analog Reference input is typically a sine wave @ 1.3Vrms
Digital angle data. Parallel format. Natural binary positive logic.
Bit 1, most significant bit = 180°, Bit 2 = 90°, Bit 3 = 45° and so on.
In the 10 bit mode, Bit 10 is the LSB. Bits 11-16 are 0s.
In the 12 bit mode, Bit 12 is the LSB. Bits 13-16 are 0s.
In the 14 bit mode, Bit 14 is the LSB. Bits 15-16 are 0s.
In the 16 bit mode, Bit 16 is the LSB.
BIDIR
INPUT
ENABLE*
INH*
DATALOAD*
BUSY
CW/CCW
RIPPLE*
AC1
AC2
BPF1
BPF2
DEMOD1
DEMOD2
INTIN1
INTIN2
INT1
INT 2
VCOIN
V
CC
V
DD
A GND
D GND
VL
I
/
O
INPUT
INPUT
INPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
INPUT
OUTPUT
INPUT
OUTPUT
INPUT
POWER
POWER
POWER
Digital input. Sets the resolution.
SC1 SC2 Resolution
0
0
10 bit
0
1
12 bit
1
0
14 bit
1
1
16 bit
Logic 0 enables digital angle output. Otherwise it is high impedance.
Logic 0 freezes the digital angle output so that it can be safely read.
Logic 0 enables the digital angle lines to be inputs to preset the angle.
Logic 1 is for normal digital angle output.
A logic 1 pulse when the digital angle changes by 1 LSB.
For turns counting. Logic 1 = counting up (CW), logic 0 = counting
down (CCW).
Ripple clock for turns counting. A logic 0 pulse = a 0° transition in
either direction.
Differential AC error output
Differential AC error input to demodulator
Differential DC error output
Differential DC input to differential velocity integrator
Differential velocity output
Input to Voltage Controlled Oscillator
Analog Power In
Digital Power In
Analog Power ground
Digital Power ground
Digital input/output DC power supply. Sets logic 1 level. +3V to +5V
* Indicates Active Low Signal
SCD5028-2 Rev G 5/7/2014
3
Aeroflex Plainview
ABSOLUTE MAXIMUM RATINGS *
PARAMETER
Operating Temperature
Storage Temperature
Positive Power Supply Voltage (V
CC
= V
DD
)
Analog Output Current (Output Shorted to GND)
Digital Output Current (Output Shorted to GND)
Analog Input Voltage Range
Digital Input Voltage Range
Thermal Resistance Ø
JC
Specification
Maximum Junction Temperature
Lead Temperature (soldering, 10 seconds)
ESD Class 2 MIL-STD-883 Method 3015, 8
VALUE
-55°C to +125°C
-65°C to +150°C
-0.5 V to +7.0 V
32 mA Max
18.6 mA Max
-0.5 V to + (V
CC
+ 0.5 V)
-0.5 V to + (V
DD
+ 0.5 V)
1.25°C/W
135°C
300°C
2000 V to 3999 V
* Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device.
These are stress ratings only; functional operation beyond these operating conditions is not recommended and extended
exposure beyond these operating conditions may effect device reliability.
OPERATING CONDITIONS
(T
A
= -55°C to +125°C)
POWER SUPPLY
V
DD
= V
CC
I
DD
+ I
CC
9/
VL
I
/
O
PARAMETER
Operating Voltage
Operating Current
Interface Voltage
(T
A
= -55°C to +125°C)
MIN
4.5
-
3
TYP
5
20
3.3, 5
MAX
5.5
35
5.5
UNIT
V
DC
mA
V
DC
ELECTRICAL CHARACTERISTICS 2/, 5/, 6/
PARAMETER
Accuracy 4/ 8/ 9/
CONDITIONS
Add 1 LSB for total Error,
Using INL correction factors.
Add 1 LSB for total Error,
Not compensated by INL correction factors
Repeatability
Resolution per LSB
10 Bit Mode
12 Bit Mode
14 Bit Mode
16 Bit Mode
Max Tracking Rate
10 Bit Mode 3/
12 Bit Mode 3/
14 Bit Mode 3/
SCD5028-2 Rev G 5/7/2014
MIN
-
-
-
0.35
21.1
0.09
5.27
0.022
1.32
0.0055
0.33
TYP
+/-2
+/-4
-
-
-
-
-
-
-
-
-
-
-
-
MAX
+/-5.0
UNITS
Minutes
+/-10.0
1
-
-
-
-
-
-
-
-
-
-
-
LSB
Degrees
Minutes
Degrees
Minutes
Degrees
Minutes
Degrees
Minutes
RPS
RPS
RPS
Aeroflex Plainview
SC1 SC2
0
0
1
0
1
0
Bits Used
B1 - B10
B1 - B12
B1 - B14
4
1024
256
64
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