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Philips Semiconductors
Audio processor with head amplifier for VHS hi-fi
Table 2 Selection of recording modes
RM
LEVEL ON
SIGNAL
PIN RMHID
LOW
lower than 2.35 V
HIGH
higher than 2.65 V record-mute mode
6.4.3
R
ECORD MODE
The record mode is selected by setting bit AFM = 1 and
setting bits DOC, SHH and DETH from logic 001 to 111
and switching the RM control signal to LOW-level.
During the record mode actual recording is activated and
the recording current is output on pin RECOUT
(see Fig.6). Pins PBIN2 and PBIN1 form a connection to
the 5 V head amplifier supply voltage (V
is internally connected to pin RECOUT and the external
capacitor has no function in this mode.
The desired carrier mix ratio is set via I
bits DOC, SHH and DETH. A wide selection of recording
currents is available to fit different head and head
transformer specifications and are set via bits HAC2,
HAC1, HAC0 and range bit HRL. The setting of the carrier
mix ratio does not change the selected recording current.
handbook, full pagewidth
AH2
AH1
a. Playback mode and record-mute mode.
1999 Apr 14
RECORD MODE
record or record-mute
mode as defined by
2
I
C-bus control
). Pin HMSW
CCH
2
C-bus control
35 k
PBIN2
35
GNDH
RECOUT
36
35 k
PBIN1
37
HMSW
38
GNDH
GNDH
TDA9605H
Fig.6 Simplified circuit diagrams of the head amplifier modes.
The DC bias current on pin RECOUT is changed
proportional to the selected recording current for
optimizing the performance and minimizing the power
consumption for each recording current selected.
A Boucherot damping circuit is connected between
pin HMSW and ground to prevent head current resonance
peaking. A capacitor of 10 nF and a resistor of 470
specified in Fig.14, but the component values are not
critical.
6.4.4
H
EAD AMPLIFIER POWER SUPPLY AND GROUND
The head amplifier is supplied via a separate 5 V supply
(pin V
) and ground (pin GNDH).
CCH
A capacitor of 100 nF should be placed close to the device
between pins V
and GNDH for proper decoupling of
CCH
the power supply.
The head amplifier ground (pin GNDH) should be
connected to the main ground (pin GND).
PBIN2
AH2
RECOUT
AH1
PBIN1
HMSW
b. Record mode.
11
Product specification
TDA9605H
V CCH
35
36
V CCH
37
5
38
GNDH
TDA9605H
MGR841
are
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