FEDL2302DIGEST-05
OKI Semiconductor
ML2302
SPEAKER DRIVING AMPLIFIER
The ML2302 contains two OP amplifiers for driving a speaker; SPOUT– which is the inverting type output for a
voice multiplication signal SPIN and SPOUT+ which is the non-inverting type output.
Though SPOUT+ alone can be used, when differential outputs are used, it is possible to gain not only an amplitude
two times that of when a single OP amplifier is used but also a good volume even if a low power supply voltage is
used. The connection diagram of differential outputs are shown below.
C1
R1
R2
AOUT
SPIN
SPOUT–
SPOUT+
20 kΩ
20 kΩ
VR
Note 1: The gain of a speaker amplifier is determined by R1 and R2.
R2
R1
V (SPOUT–) = –
• V(SPIN)
R2
R1
V (SPOUT+) = –V(SPOUT–) =
• V(SPIN)
Note 2: C1 is an AC coupling capacitance. The cut-off frequency at a low field is determined by the following
equation.
Select a value of C1 in accordance with a pass band.
1
fc =
(Hz)
2 × π × C1 × R1
17/24
OKI [ OKI ELECTRONIC COMPONETS ]
