AD2S105

REV. 0

–8–

TIMING DIAGRAMS

Busy Output

The BUSY output will go HI at the negative edge of the

STROBE input. This is used to synchronize digital input data

and load the digital angular rotation information into the device

counter. The BUSY output will remain HI for 2

µs, and go LO

until the next strobe negative edge occurs.

Strobe Input

The width of the positive STROBE pulse should be at least

100 ns, in order to successfully start the conversion. The maxi-

mum frequency of STROBE input is 366 kHz, i.e., there should

be at least 2.73

µs from the negative edge of one STROBE pulse

to the next rising edge. This is illustrated by the following tim-

ing diagram and table.

t

1

t

2

t

3

t

4

STROBE

BUSY

t

f

t

r

Figure 7. AD2S105 Timing Diagram

Note: Digital data should be stable 25 ns before and after posi-

tive strobe edge.

Table II. AD2S105 Timing Table

Parameter

Min

Typ

Max

Condition

100 ns

STROBE Pulse Width

30 ns

STROBE

↓ to BUSY ↑

1.7

µs

2.5

µs

BUSY Pulse Width

100 ns

BUSY

↓ to STROBE ↑

20 ns

BUSY Pulse Rise Time

with No Load

150 ns

BUSY Pulse Rise Time

with 68 pF Load

10 ns

BUSY Pulse Fall Time

with No Load

120 ns

BUSY Pulse Fall Time

with 68 pF Load

TYPICAL CIRCUIT CONFIGURATION

Figure 8 shows a typical circuit configuration for the AD2S105

in a three phase, nominal level input mode (MODE2).

AD2S105

TOP VIEW

141

38

30

27

23

12

16

LSB

10

µF

100nF

10

µF

100nF

–5V

+5V

GND

MSB

PH/OP1

AGND

PH/IP4

PH/IP3

PH/IP2

PH/IP1

34

Figure 8. Typical Circuit Configuration

APPLICATIONS

Transformation Configuration

The AD2S105 can perform both forward and reverse transfor-

mations. The section “Theory of Operation” explains how the

chip operates with the core operator e

formed by providing a negative angle

φ. Figure 9 shows two

different phase input/output connections for AD2S105 reverse

transformation operation.

FORWARD

TRANSFORMATION

AD2S105

REVERSE

TRANSFORMATION

AD2S105

e

+j

φ

2 PHASE – 2 PHASE

Sin

θ

Cos

θ

Cos(

θ + φ)

Sin(

θ + φ)

Cos

θ

Sin

θ

Cos(

θ – φ)

Sin(

θ – φ)

e

–j

φ

–1

e

+j

φ

3 PHASE – 2 PHASE

Cos

θ

Cos(

θ + 120°)

Cos(

θ + 240°)

Cos(

θ + φ)

Sin(

θ + φ)

Cos

θ

Cos(

θ + 120°)

Cos(

θ + 240°)

Cos(

θ – φ)

Sin(

θ – φ)

e

–j

φ

Figure 9. Forward and Reverse Transformation Connections