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AD2S105

Three-Phase Current Conditioner

Analog Devices 

AD2S105

CONVERTER OPERATION

The architecture of the AD2S105 is illustrated in Figure 3. The

AD2S105 is configured in the forward transformation which ro-

tates the stator coordinates to the rotor reference frame.

Vector Rotation

Position data, ␾, is loaded into the input latch on the positive

edge of the strobe pulse. (For detail on the timing, please refer

to the “timing diagram.”) The negative edge of the strobe signi-

fies that conversion has commenced. A busy pulse is subse-

quently produced as data is passed from the input latches to the

Sin and Cos multipliers. During the loading of the multiplier,

the busy pulse remains high preventing further updates of ␾ in

both the Sin and Cos registers.

The negative edge of the busy pulse signifies that the multipliers

are set up and the orthogonal analog inputs are then multiplied

real time. The resultant two outputs are accessed via the

PH/OP1 (Pin 7) and PH/OP4 (Pin 6).

For other configurations, please refer to “Transformation

Configuration.”

CONNECTING THE CONVERTER

Power Supply Connection

The power supply voltages connected to VDD and VSS pins

should be +5 V dc and –5 V dc and must not be reversed. Pin 4

(VDD) and Pin 41 (VDD) should both be connected to +5 V;

similarly, Pin 5 (VSS) and Pin 19 (VSS) should both be con-

nected to –5 V dc.

It is recommended that decoupling capacitors, 100 nF (ceramic)

and 10 µF (tantalum) or other high quality capacitors, are con-

nected in parallel between the power line VDD, VSS and AGND

adjacent to the converter. Separate decoupling capacitors should

be used for each converter. The connections are shown in Fig-

ure 4.

+5V

1

+ 100nF

10µF

GND

AGND

+

AD2S105

10µF

100nF

12

TOP VIEW

34

23

–5V

Figure 4. AD2S105 Power Supply Connection

ANALOG SIGNAL INPUT AND OUTPUT CONNECTIONS

Input Analog Signals

All analog signal inputs to AD2S105 are voltages. There are two

different voltage levels of three-phase (0°, 120°, 240°) signal in-

puts. One is the nominal level, which is ± 2.8 V dc or 2 V rms

and the corresponding input pins are PH/IP1 (Pin 17), PH/IP2

(Pin 15), PH/IP3 (Pin 13) and PH/IP4 (Pin 11).

The high level inputs can accommodate voltages from nominal

up to a maximum of ± VDD/VSS. The corresponding input pins

are PH/IPH1 (Pin 16), PH/IPH2 (Pin 14) and PH/IPH3 (Pin

12). The homopolar output can only be used in the three-phase

connection mode.

The converter can accept both two-phase format and three-

phase format input signals. For the two-phase format input, the

two inputs must be orthogonal to each other. For the three-

phase format input, there is the choice of using all three inputs

or using two of the three inputs. In the latter case, the third in-

put signal will be generated internally by using the information

of other two inputs. The high level input mode, however, can

only be selected with three-phase/three-input format. All these

different conversion modes, including nominal/high input level

and two/three-phase input format can be selected using two se-

lect pins (Pin 23, Pin 24). The functions are summarized in

Table I.

Table I. Conversion Mode Selection

Mode Description

CONV1 CONV2

(Pin 23) (Pin 24)

MODE1

MODE2

MODE3

2-Phase Orthogonal with 2 Inputs

Nominal Input Level

3-Phase (0°, 120°, 240°) with 3 Inputs

Nominal/High Input Level*

3-Phase (0°, 120°, 240°) with 2 Inputs

Nominal Input Level

NC

DGND

VDD

DGND

VDD

VDD

*The high level input mode can only be selected with MODE2.

MODE1: 2-Phase/2 Inputs with Nominal Input Level

In this mode, PH/IP1 and PH/IP4 are the inputs and the Pins

12 through 16 must be left unconnected.

MODE2: 3-Phase/3 Inputs with Nominal/High Input Level

In this mode, either nominal or high level inputs can be used.

For nominal level input operation, PH/IP1, PH/IP2 and PH/IP3

are the inputs, and there should be no connections to PH/IPH1,

PH/IPH2 and PH/IPH3; similarly, for high level input opera-

tion, the PH/IPH1, PH/IPH2 and PH/IPH3 are the inputs, and

there should be no connections to PH/IP1, PH/IP2 and PH/IP3.

In both cases, the PH/IP4 should be left unconnected. For high

level signal input operation, select MODE2 only.

MODE3: 3-Phase/2 Inputs with Nominal Input Level

In this mode, PH/IP2 and PH/IP3 are the inputs and the third

signal will be generated internally by using the information of

other two inputs. It is recommended that PH/IP1, PH/IPH1,

PH/IPH2, PH/IP4 and PH/IPH3 should be left unconnected.

–6–

REV. 0

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