AD2S80A

–14–

OSCILLATOR

(e.g., OSC1758)

C3

R3

TWISTED PAIR SCREENED CABLE

RESOLVER

S2

S4

S3

S1

R1

R2

1

2

3

4

5

6

7

31

AD2S80A

REF I/P

COS I/P

ANALOG

GND

DIGITAL

GND

SIGNAL

GND

SIN I/P

POWER RETURN

Figure 7. Connecting the AD2S80A to a Resolver

CONNECTING THE RESOLVER

The recommended connection circuit is shown in Figure 7.

In cases where the reference phase relative to the input signals

from the resolver requires adjustment, this can be easily

achieved by varying the value of the resistor R2 of the HF filter

(see Figure 1).

Assuming that R1 = R2 = R and C1 = C2 = C

and Reference Frequency =

1

2

π RC

by altering the value of R2, the phase of the reference relative to

the input signals will change in an approximately linear manner

for phase shifts of up to 10 degrees.

Increasing R2 by 10% introduces a phase lag of 2 degrees.

Decreasing R2 by 10% introduces a phase lead of 2 degrees.

C

R

PHASE LEAD = ARC TAN

1

2 fRC

R

C

PHASE LAG = ARC TAN 2 fRC

Phase Shift Circuits

TYPICAL CIRCUIT CONFIGURATION

Figure 8 shows a typical circuit configuration for the AD2S80A

in a 12-bit resolution mode. Values of the external components

have been chosen for a reference frequency of 5 kHz and a

maximum tracking rate of 260 rps with a bandwidth of 520 Hz.

gives a value of 1.67

ance preferred values. The capacitors are 100 V ceramic, 10%

tolerance components.

For signal and reference voltages greater than 2 V rms a simple

voltage divider circuit of resistors can be used to generate the

correct signal level at the converter. Care should be taken to

ensure that the ratios of the resistors between the sine signal line

and ground and the cosine signal line and ground are the same.

Any difference will result in an additional position error.

For more information on resistive scaling of SIN, COS and

REFERENCE converter inputs refer to the application note,

“Circuit Applications of the 2S81 and 2S81 Resolver-to-Digital

Converters.”

RELIABILITY

The AD2S80A Mean Time Between Failures (MTBF) has been

calculated according to MIL-HDBK-217E, Figure 10 shows the

MTBF in hours in naval sheltered conditions for AD2S80A/

883B only.

REV. D