Signal processing circuit for 2-D PSD

C4674, C4757, C4758, C7563

The followings are obtained with the conditions listed

on the left.

Output voltage amplitude

Position resolution

∆x=0.1 µm approx.

(calculated values)

∆y=0.1 µm approx.

s Absolute maximum ratings

DC circuit

AC circuit

Parameter

Symbol

C4674

C4757

C4758

C7563

Unit

Supply voltage

Vcc Max.

±18

V

Input current

Vcc Max. × 10

-5

A

Output short-circuit time

-

Continuous

s

Signal

processor

Operating temperature

Topr

0 to +50

°C

Transistor collector-emitter voltage

--

-

+50

V

-

-

-

2

A

LED driver

Pc

-

-

-

900

mW

s Specifications (Ta=25

Typical value

DC circuit

AC circuit

Parameter

Sy m bol

Condition

C4674

C4757

C4758

C7563

Unit

Rf

Factory setup prior to shipping

1 × 10

5

V/A

Feedback capacitance

Cf

Factory setup prior to shipping

100

22

pF

Input signal current *

5

Photocurrent with PSD

installed

1 × 10

A

Rise time

tr

O ut p ut res p o n s e ti m e

vers us m ov e m e nt of lig ht

spot positio n, m e a sur e d

with P S D in stalle d.

30

µs

PSD reverse bias voltage

-+5V

Output offset voltage

*

7

-10 to +10

mV

Vo

With PSD installed and

light spot falling on edge

of active area.

-10 to +10

V

O ut p ut n ois e (a n alo g divi der)

Vn

5

10

mVp-p

Signal

processor

Current consumption

Icc

*

7

±15±60

mA

Tr a n sistor c ollector curre nt

Ic

*

3

-

-

-

680

mAp-p

Repetition frequency

*

8

-

-

-

333

Hz

LED

driver

Output type

-

-

-

-

-

Open

collector

-

*3: Duty ratio: 3/100, pulse width: 90 µs, LED: Hamamatsu L1915-01 (sold separately)

*4: These resistors are lead types and inserted into sockets, so it can be easily to exchange by the user if necessary in a range

between 1 × 10

Ω. For more details, see the instruction manual that comes with the product.

*5: The circuit does not operate correctly when input signal level is not appropriate.

*6: Maximum output amplitude can be adjusted in a range of ±2 to ±10 V according to PSD type to be used.

*7: Measured without PSD and with LED turned off, while using a current source of 20 µA (X1=X2=Y1=Y2) substituting for PSD

photocurrent. In the case of C7563, however, pulse current with a duty ratio of 3/100 and a pulse width of 90 µs is supplied.

*8: Repetition frequency 333 Hz (duty ratio: 3/100, pulse width: 90 µs) cannot be modulated.

Constant voltage power supply: ±15 V, Power capacity: 0.1 A Min.

Ripple voltage: 3 mVp-p Max.

SIGNAL

PROCESSING CIRCUIT

C4674

2-D

PSD

REGULATED

POWER

SUPPLY *

VOLTMETER

VOLTMETER

+15 V

0 V

-15 V

+V

GND

-V

Xout

+

GND

-

Yout

+

GND

-

3

5

4

1

2

s Operating example (C4674)

2

KPSDC0034ED

Condition

1. Light source

LED (

λ=900 nm)

2. Light spot diameter

φ200 µm

3. PSD used

S1880 (12 × 12 mm)

4. PSD photocurrent

10 µA

5. Signal processing circuit

C4674

6. Frequency bandwidth

10 Hz

7. Voltmeter

KEITHLEY model 195 A