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AD2S81AJP

Variable Resolution, Monolithic Resolver-to-Digital Converters

Analog Devices 

AD2S81A/AD2S82A

1M⍀

REFERENCE

INPUT

RESOLVER

SIGNAL

COS HIGH

REF LOW

COS LOW

SIN LOW

100nF

100nF

100k⍀

22nF

22nF

15k⍀

15k⍀

1.5nF

39k⍀ 110k⍀ 180k⍀

6.8nF

68⍀

470pF

4.7M⍀

VELOCITY

O/P

100nF

SIN HIGH

+12V

MSB

DATA

OUTPUT

6 5 4 3 2 1 44 43 42 41 40

7

39

PIN 1

8

IDENTIFIER

38

9

37

10

36

11

AD2S82A

35

12

TOP VIEW

34

(Not to scale)

13

33

14

32

15

31

16

30

17

29

18 19 20 21 22 23 24 25 26 27 28

RIPPLE CLK

DIRECTION

BUSY

DATA LOAD

COMPLEMENT

SC2

INHIBIT

DATA OUTPUT

LSB

+5V

BYTE SELECT

ENABLE

–12V

0V

Figure 11. Typical Circuit Configuration

TYPICAL CIRCUIT CONFIGURATION

Figure 11 shows a typical circuit configuration for the AD2S81A/

AD2S82A 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. Placing the values for R4, R6, C4 and C5 in the equa-

tion for KA gives a value of 2.7 × 106. The resistors are 0.125 W,

5% tolerance 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.

360

315

270

225

180

135

90

45

0

0

4

8

12

16

20

24

TIME – ms

Figure 12. Large Step Response Curves for Typical Circuit

Shown in Figure 11

For more information on resistive scaling of SIN, COS and

REFERENCE converter inputs, refer to the application note

“Circuit Applications of the 2S81 and 2S80 Resolver-to-Digital

Converters.”

APPLICATIONS

Control Transformer

The ratio multiplier of the AD2S82A can be used independently

of the loop integrators as a control transformer. In this mode the

resolver inputs θ are multiplied by a digital angle φ, any differ-

ence between and φ and θ will be represented by the AC ERROR

output as SIN ωt sin (θ–φ) or the DEMOD output as sin (θ–φ).

To use the AD2S81A/AD2S82A in this mode refer to the

“Control Transformer” application note.

Dynamic Switching

In applications where the user requires wide band response from

the converter, for example 100 rpm to 6000 rpm, superior per-

formance is achieved if the converters control characteristics are

switched dynamically. This reduces velocity offset levels at low

tracking rates. For more information on the technique refer to

“Dynamic Resolution Switching Using the Variable Resolution

Monolithic Resolver-to-Digital Converters.”

OTHER PRODUCTS

The AD2S80A is a monolithic resolver-to-digital converter

offering 10–16 bits of resolution and user selectable dynamics.

The AD2S80A is also available in 40-lead ceramic DIP, 44-lead

LCC and is qualified to MIL-STD 883B Rev C.

The AD2S46 is a highly integrated hybrid resolver/synchro to

digital converter packaged in a 28-lead ceramic DIP. The part

offers the user 1.3 arc minutes of accuracy over the full military

temperature range.

The AD2S34 is a dual channel 14-bit hybrid resolver-to-digital

converter packaged in a 1 in2 32-lead flatpack.

The 1740/41/42 are hybrid resolver/synchro to digital converters

which incorporate pico-transformer isolated input signal

conditioning.

REV. B

–15–

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