Philips TDA9605H

1999 Apr 14 11

Philips Semiconductors Product speciﬁcation

Audio processor with head ampliﬁer for VHS hi-ﬁ TDA9605H

Table 2 Selection of recording modes

6.4.3 RECORD 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 (VCCH). Pin HMSW

is internally connected to pin RECOUT and the external

capacitor has no function in this mode.

The desired carrier mix ratio is set via I2C-bus control

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.

SIGNAL LEVEL ON

PIN RMHID RECORD MODE

LOW lower than 2.35 V record or record-mute

mode as deﬁned by

I2C-bus control

HIGH higher than2.65 V record-mute mode

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 Ω are

specified in Fig.14, but the component values are not

critical.

6.4.4 HEAD AMPLIFIER POWER SUPPLYAND GROUND

The head amplifier is supplied via a separate 5 V supply

(pin VCCH) and ground (pin GNDH).

A capacitor of 100 nF should be placed close to the device

between pins VCCH and GNDH for proper decoupling of

the power supply.

The head amplifier ground (pin GNDH) should be

connected to the main ground (pin GND).

Fig.6 Simplified circuit diagrams of the head amplifier modes.

handbook, full pagewidth

MGR841

35 kΩ

GNDH

AH2

PBIN2

PBIN1

HMSW

RECOUT

AH1

35 kΩ

GNDH

TDA9605H

35 PBIN2

PBIN1

HMSW

RECOUT

5 Ω

GNDH

AH2

AH1

VCCH

TDA9605H

a. Playback mode and record-mute mode. b. Record mode.