HA12209F Datasheet, PDF (13/49 Pages) Hitachi Semiconductor – Audio Signal Processor for Cassette Deck(Dolby B-type NR with Recording System)

HA12209F
External components shown figure 8 gives frequency response to take 6dB boost. And cut off frequency
can request it, by lower formulas.
Gv
f1
f2
f1 =
1
[Hz]
2π · CEX3 · (REX3 + R0)
f2 =
1
[Hz]
2π · CEX3 · REX3
R0 = ^{REX1 · REX2} [Ω]
REX1 + REX2
f
Figure 9 Frequency Characteristic of Low-Boost
Bias Switch
This series built-in DC voltage generator for bias oscillator and its bias switches.
External resistor R8, R10 which corresponded with tape positions and bias out voltage are relater with
below.
Vbias =
R9
× (VCC – 0.7) [V]
(R10 or R8) + R9
Bias switch follows to a logic of 14 pin (B 120/70).
Note: A current that flows at bias out pin, please use it less than 5mA.
R10
BIAS (N) 26
R8
BIAS (C) 25
Vbias
R9
GND
Figure 10 External Components of Bias Block
Rev.2, Jun. 1999, page 13 of 49