REV. B

–7–

AD2S99

AD2S99/AD2S93 TYPICAL CONFIGURATION

Figure 5 shows a typical circuit configuration for the AD2S99

Oscillator and the AD2S93 LVDT-to-Digital Converter. The

maximum level of the A and B transducer input signals to the

AD2S93 should be 1 V rms

± 20%. All the analog ground sig-

nals should be star connected to the AD2S93 AGND pin. If

shielded twisted pair cables are used for the LVDT signals, the

shields should also be terminated at the AD2S93 AGND pin.

The SYNREF output of the AD2S99 cannot be used as the

REF input signal for the AD2S93. The zero crossing reference

for the AD2S93 should be taken from the primary winding of

the LVDT through a phase lead or lag network. The phase com-

pensation network ensures that the REF input is phase coherent

with the A and B input signals to the AD2S93.

NC = NO CONNECT

NC

SIN

NC

DGND

COS

EXC

EXC

NC

AGND

NC

19

3

1

2

20

4

5

8

6

7

12 13

911

10

18

17

14

16

15

TOP VIEW

(Not to Scale)

AD2S99

4.7µF

4.7µF

0.1µF

0.1µF

SEC

PRI

LVDT

0.1µF

50k

Ω

4.7µF

0.1µF

4.7µF

SEL2 = GND

NC = NO CONNECT

26

27

28

4

2

3

15

18

17

16

12

14

13

25 24

21 20 19

23 22

1

56

9

10

11

78

R2

C2

C1

C3

R5

R6

R7

C4

DMODOUT

B

A

PHASE

COMP

LOS

TOP VIEW

(Not to Scale)

AD2S93

B

NC

LOS

GAIN

DIFF

AGND

A

DGND

DIR

NULL

OVR

Figure 5. AD2S99 and AD2S93 Example Configuration