LA4425A
The overvoltage protector (VCCX 6 21.5 V) inside the IC is used to cut all bias routes and reverse bias between B-E of output
stage elements, in order to increase the power line’s capability of handling positive surge. This means, of course, that a VCES
(VCBO) type output stage element is used instead of the VCEO (VCER) type.
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Load Resistance and Misoperation
It should be noted that when RL < 2 Ω and VCC is high, and the switch is turned ‘‘ON’’ when setting is for a signal (THD =
10 %), the ground detector (current × voltage Schmitt circuit) operates momentarily.
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Precautions on TaB
If power voltage is applied to the IC substrate (the heat sink on a set), the IC structure is such that the PN junctions may be
burned, causing deterioration or destruction. Consult Sanyo’s Quality Assurance Department with regard to the energy handling
capability (voltage peak value, pulse width). Also, the IC TaB (substrate) is connected to pin 3, large signal GND.
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Test of +VCC to Output Pin
Floating
The power pin is in a floating state when a power capacitor is connected, so if +VCC touches output lines a and b, the upper
power transistor inside the IC will be damaged.
The LA4425A has a protective bypass route inside the IC.
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Starting Time (ts)
This is set at 0.35 sec/typ, but it can be made shorter by making input capacitor Ci smaller, or longer by making it larger.
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Pop noise
The pop noise prevention circuit operates to reduce pop until Rg reaches 50 kΩ. However, if Rg is left open, the charging route
of input capacitor Ci is lost, so the pop noise reduction circuit stops operating and click noises become louder.
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VG/OSC
The voltage gain is fixed at 45 dB inside the IC. It is impossible to change it externally.
Phase compensation capacitors (350 pF/total) are connected between individual stages inside the IC, and the open loop gain is
low. In addition, the upper and lower drives are made equivalent so that final stage current gain is adjusted, providing a measure
against unwanted high-frequency parasitic oscillation peculiar to power IC’s.
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BTL Connection
Connection is impossible with IC alone.
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Reverse Mounting of IC
The pin assignment is such that there is no danger of damage.
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T.S.D (Thermal Shutdown) Operating Temperature
30 × 30 × 1.5 mm3 thick Al board
Ta = 25°C
TC(°C)
No.3309-7/8
ETC [ ETC ]
