TA2123AF
(4) Treble boost
The EQ terminal is synchronizes with the BST SW, and the input impedance is changed.
BST OFF: 100kΩ (typ.)
BST ON: 1.9kΩ (typ.)
The voltage gain increase 6 dB (typ.) at high frequency range in case that the capacitor CX is connected
between the EQ terminal and the PW NF terminal.
PW IN 28
PW NF 29
+ PWA / B
−
EQ30
Fig.6 Treble boost
(5) Cross talk of output coupling type
In case of output coupling mode, the cross talk is determined by resistor RL and capacitor C which are
connected with power amplifier output as shown in Fig.7.
The formula is shown below.
G (ω) = 1 / 2 [1 + jωC (RL / 2)]
CT = 20ℓog|Gv| = 20ℓog [1 / 2 [ 1+ (w / w0 )2 ]], ω0 = 1 / C (RL / 2)
At f = 1kHz, C1 = 220µF, RL = 32Ω, The cross talk becomes about 33 dB.
PWA
R2
PWC
PWB
RL
+
RL
VREF
~
+
Fig.7 Cross talk of output coupling type
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2002-10-30