Application information

TSH344

12/17

3.2

Power supply considerations

Correct power supply bypassing is very important for optimizing performance in low and

high-frequency ranges. Bypass capacitors should be placed as close as possible to the IC

necessary to improve the PSRR in low frequencies. For better quality bypassing, a capacitor

higher frequencies.

Figure 28. Circuit for power supply bypassing

Figure 29 shows how the power supply noise rejection evolves versus frequency depending

on how carefully the power supply decoupling is achieved.

Figure 29. Improvement of power supply noise rejection

C

LF

+

C

HF

TSH344

R

G

B

4

5

10k

100k

1M

10M

100M

-80

-70

-60

-50

-40

-30

-20

-10

0

C

LF

=100uF

C

HF

=470nF

without

capacitor

Vcc=5V

Load=150

Ω

PSRR=20 log (

Frequency (Hz)