LA4145 Datasheet, PDF (2/5 Pages) Sanyo Semicon Device – 0.6 to 0.9 W AF Power Amplifier for Radio Cassette Recorders

LA4145
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
capacitor C₆, oscillation blocking capacitor C₃ as close to the IC pin as possible to prevent oscillation from occurring.
(See the sample printed circuit pattern.)
Description of external parts
C₁ (47 µF)
C₂ (100 µF)
C₃ (0.15 µF)
C₄ (470 µF)
C₅ (47 µF)
C₆ (470 µF)
R₁ (30 kΩ)
Feedback capacitor (NF capacitor)
Bootstrap capacitor
Oscillation blocking capacitor
Output capacitor
Decoupling capacitor
Power capacitor
Input bias resistor
Low cutoff frequency f_Ldepends on this capacitor.
f_L = 90 Hz for C₁ = 47 µF.
Decreasing the capacitor value makes the starting time earlier.
It is recommended to use a polyester film capacitor being good in
temperature characteristic, high frequency characteristic.
Serves to reject ripple. The starting time depends on this capacitor.
Increasing the capacitor value makes the starting time later.
Place as close to the power pin of the IC as possible.
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 kΩ.
Pd max − Ta
50 × 50 mm² PCB
Ambient temperature, Ta – °C
No.1339-2/5