TSL230, TSL230A, TSL230B

PROGRAMMABLE LIGHT-TO-FREQUENCY CONVERTERS

SOES007B – OCTOBER 1992 – REVISED MARCH 1994

5–7

POST OFFICE BOX 655303

TYPICAL CHARACTERISTICS

0.998

0.997

0.996

0.995

2.5

3

3.5

4

4.5

0.999

1

OUTPUT FREQUENCY

vs

SUPPLY VOLTAGE

5

5.5

VDD – Supply Voltage – V

TA = 25°C

fO = 1 MHz

1.001

6

1.002

1.003

1.004

1.005

Figure 5

APPLICATION INFORMATION

power-supply considerations

For optimum device performance, power-supply lines should be decoupled by a 0.01-

µF to 0.1-µF capacitor with

short leads.

output interface

The output of the device is designed to drive a standard TTL or CMOS logic input over short distances. If lines

greater than 12 inches are used on the output, a buffer or line driver is recommended.

sensitivity adjustment

Sensitivity is controlled by two logic inputs, S0 and S1. Sensitivity is adjusted using an electronic iris technique

– effectively an aperture control – to change the response of the device to a given amount of light. The sensitivity

can be set to one of three levels: 1x, 10x or 100x, providing two decades of adjustment. This allows the

responsivity of the device to be optimized to a given light level while preserving the full-scale output-frequency

range. Changing of sensitivity also changes the effective photodiode area by the same factor.