HA12179F is designed to operate on single supply. Please consult to HITACHI sales engineers when it will
use the split supply.
1. The lower limit of supply voltage depends on the line output reference level.
The minimum value of the overload margin is specified as 12 dB by Dolby Laboratories.
2. In th e reverse-vo ltage conditions such as 'D-GND is higher than VCC' or 'D-GND is lower than GND',
excessive current flows into the D-GND to destroy this IC. To prevent such destructio n, pay attentio n
to the followings on using.Therefore, Short-circuit the D-GND and GND directory on the board
mounting this IC.
For the single supply operation this device provides the reference voltage of half the supply voltage that is
the signal grounds. As the peculiarity of these devices, the capacitor for the ripple filter is very small about
1/100 compared with their usual value. The Reference voltage are provided for the left channel and the
right channel separately. The block diagram is shown as figure 1.
Figure 1 The Block Diagram of Reference Voltage Supply
Rev.1, Apr. 1994, page 10 of 40
Operating Mode Control
HA12179F provides electronic switching circuits. And each operating mode control are controlled by
parallel data (DC voltage).
Table 2Threshold Voltage
Pin No.LoHiUnitTest condition
14 15 16 17 1819–0.2 to 1.03.5 to 5.3V
Table 3Switching Truth Table
17120 µ (NORMAL)70 µ (METAL or CHROME)
19SER (FF or REV)REP (NORMAL SPEED)
Notes: 1. Each pins are on pulled down with 100 kΩ internal resi stor .
Therefore, it will be low-level when each pins are open.
2. Over shoot level and under shoot level of input signal must be the standardized (High: 5.3 V,
Low: –0.2 V)
3. Reducing pop noise is so much better for 10 kΩ to 22 kΩ resistor and 1 µF to 22 µF capacitor
shown Fig 2. But the resistor connected to MUTE terminal (pin 16) should be under 10 kΩ.
Input Pin Measure
INPUT Pin10 to 22kΩ
1 to 22µF
Figure 2 Interface for Reduction of Pop Noise
Rev.1, Apr. 1994, page 11 of 40
Input Block Diagram and Lev e l Diagram
Note: The each level shown above is typical value when offering PBOUT level to PBOUT pin. (EQ AMP.)
Gv = 40 dB, f = 1 kHz
HA12179F : 387.5mVrms (–6.0dBs)
Figure 3 Input Block Diagram
Adjustment of Playback Dolby Level
After replace R34 and R35 with a half-fix volume of 10 kΩ, adjust RECOUT level to be Dolby level with
Note on Connecting with Tape Head to IC
This IC has no internal resistor to give the DC bias current to equalizer amp., therefore the DC bias current
will give through the head. This IC provides the Vref buffer output pin for Rch and Lch separ ately (has
two Vref terminal). In case of use that the Rch and Lch reference of head are connected commonly, please
use one of Vref terminals of IC (47 pin or 52 pin) for head reference.
If both 47 pin and 52 pin of IC are connected, rush current give the great damage to IC. The application
circuit is shown in figure 4.
Rev.1, Apr. 1994, page 12 of 40
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