Proper care in changing voltage gain

An external resistor can be connected in series with the feedback capacitor at pin 2 to reduce the voltage gain.

(See RNF-VG characteristic.)

IC usage notes

1.

Maximum ratings

If the IC is used in the vicinity of the maximum ratings, even a slight variation in conditions may cause the maximum ratings

to be exceeded, thereby leading to breakdown. Allow an ample margin of variation for supply voltage, etc. and use the IC in

the range where the maximum ratings are not exceeded.

2.

Pin-to-pin short

If power is applied when the space between pins is shorted, breakdown or deterioration may occur. When mounting the IC on

the board or applying power, make sure that the space between pins is not shorted with solder, etc.

3.

Radio applications

For use in radio applications, keep a good distance between IC and bar antenna.

4.

Printed circuit pattern

When designing the printed circuit pattern, make the power supply, output, and ground lines thicker and shorter and

determine the pattern and parts placement so that no feedback loop is formed between input and output. Place power

(See the sample printed circuit pattern.)

Description of external parts

Feedback capacitor (NF capacitor)

Decreasing the capacitor value makes the starting time earlier.

Bootstrap capacitor

Oscillation blocking capacitor

It is recommended to use a polyester film capacitor being good in

temperature characteristic, high frequency characteristic.

Output capacitor

Decoupling capacitor

Serves to reject ripple. The starting time depends on this capacitor.

Increasing the capacitor value makes the starting time later.

Power capacitor

Place as close to the power pin of the IC as possible.

Input bias resistor

Serves to apply input bias. The input impedance almost entirely

depends on this resistor value. If a variable resistor also serves for this

purpose, this resistor can be omitted. In this case, it is recommended

to use a resistor of 30 k

Ω.

Pd max − Ta

50

Ambient temperature, Ta – °C

LA4145

No.1339-2/5