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AD2S100

AC Vector Processor

Analog Devices 

AD2S100

TIMING DIAGRAMS

Busy Output

The state of converter is indicated by the state of the BUSY out-

put (Pin 44). 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.

STROBE

BUSY

t1

t2

tr

t4

tf

t3

Figure 7. AD2S100 Timing Diagram

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

tive strobe edge.

Table II. AD2S100 Timing Table

Parameter Min Typ Max Condition

t1

100 ns

STROBE Pulse Width

t2

30 ns

STROBE ↓ to BUSY ↑

t3

1.7 µs

2.5 µs BUSY Pulse Width

t4

100 ns

BUSY ↓ to STROBE ↑

tr

20 ns

BUSY Pulse Rise Time

with No Load

150 ns

BUSY Pulse Rise Time

with 68 pF Load

tf

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 AD2S100

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

100nF

10µF

+5V

PH/OP1

PH/OP3

PH/OP2

AGND

PH/IP4

12

PH/IP3

1

41

38 MSB

AD2S100

TOP VIEW

34

PH/IP2

16

PH/IP1

23

30

27

–5V

100nF

10µF

LSB

GND

Figure 8. Typical Circuit Configuration

APPLICATIONS

Forward and ReverseTransformation

The AD2S100 can perform both forward and reverse transfor-

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

chip operates with the core operator e+jφ, which performs a for-

ward transformation. The reverse transformation, e–jφ, is not

mentioned in the above sections of the data sheet simply to

avoid the confusion in the functionality and pinout. However,

the reverse transformation is very useful in many different appli-

cations, and the AD2S100 can be easily configured in a reverse

transformation configuration. Figure 9 shows four different

phase input/output connections for AD2S100 reverse transfor-

mation operation.

3 PHASE – 3 PHASE

FORWARD

TRANSFORMATION

AD2S100

Cosθ

Cos(θ +φ)

Cos(θ + 120°)

Cos(θ + 240°)

e+jφ

Cos(θ + φ + 120°)

Cos(θ + φ + 240°)

REVERSE

TRANSFORMATION

AD2S100

Cosθ

Cos(θ – φ)

Cos(θ + 120°)

Cos(θ + 240°)

e–jφ

Cos(θ – φ + 120°)

Cos(θ – φ + 240°)

2 PHASE – 2 PHASE

Cosθ

Sinθ

e+jφ

Cos(θ + φ)

Sin(θ + φ)

Cosθ

Sinθ

e–jφ

Cos(θ – φ)

Sin(θ – φ)

2 PHASE – 3 PHASE

Cosθ

Sinθ

e+jφ

Cos(θ + φ)

Cos(θ + φ + 120°)

Cos(θ + φ + 240°)

Cosθ

Sinθ

–1

3 PHASE – 2 PHASE

Cosθ

Cos(θ + 120°)

Cos(θ + 240°)

e+jφ

Cos(θ + φ)

Sin(θ + φ)

Cosθ

Cos(θ + 120°)

Cos(θ + 240°)

e–jφ

e–jφ

Cos(θ – φ)

Cos(θ – φ + 120°)

Cos(θ – φ + 240°)

Cos(θ – φ)

Sin(θ – φ)

–1

Figure 9. Reverse Transformation Connections

–8–

REV. A

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