la4809m Sanyo Semiconductor Corporation, la4809m Datasheet - Page 8

• Manufacturer Part Number: la4809m
• Description: Monolithic Linear Ic Stereo Headphone Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

Continued from preceding page.
10. Operating power supply voltage range
11. Handling of NC pins (Pins 5, 8, and 11)
12. Heat protective circuit
13. Short-circuit between pins
14. Load short-circuit
15. Maximum rating
When the standby function is not to be used, Pin 3 may be interlocked with power supply as shown in Fig.7. However,
due care must be taken in this case because such interlock makes the effectiveness of the pop noise reduction circuit
null, resulting in extremely large pop noise at a time of rising and falling. There are also methods to reduce the pop
noise by using two capacitors as shown in Fig.8. If pop noise is to be suppressed sufficiently, CPU control of the
standby pin is recommended.
Note that the approximate inrush current; I3 into the standby pin is calculated as follows :
The applicable power supply voltage range varies depending on the setting conditions of the maximum output power
value. Use this range while taking into account the Pin 2 voltage. As a guideline, the supply voltage at the lowest point
to be used must be two times the Pin 2 voltage.
Note that the minimum operating supply voltage must be 3.6V.
NC pins are not connected to anything internally and may be left in the OPEN state. To enhance the heat sink effect as
much as possible, connection of NC pins to the GND line is recommended.
In particular, Pin 5 should be connected to the GND line so as to protect Pin 4 (the first output).
If the pins 4 and 5 section and the pins 5 and 6 section are bridged with solder simultaneously, the output pin enters the
powering (short to power) state, allowing the large current to flow into the output pin, resulting in deterioration or
damage of internal elements. Risk of deterioration or damage may be reduced when Pin 5 is connected to GND. When
the output pin voltage is about 0.7V or less, drive and power stages of the power amplifier circuit used becomes
inoperable. In this context, the protection in case of ground fault is provided.
The heat protective circuit is incorporated in IC and can reduce the risk of damage/deterioration in case of abnormal
heat generation due to certain reasons. This protective circuit is activated when the junction temperature : Ti of the chip
in IC increases to about 160°C, shutting OFF current supply to the power amplifier. The signal is not output anymore.
When the chip temperature lowers (to about 130°C), the circuit is automatically reset.
Note that this circuit is not always capable of preventing damage/deterioration and should be handled with utmost care.
In case of abnormal heating, turn OFF power supply immediately and identify the probable causes.
Power ON while leaving the pins in the short-circuit state may cause deterioration or damage. When installing IC to the
substrate, check if pins are short-circuited with solder before turning power supply ON.
Leaving the loads in the short-circuit state over a long period of time may cause deterioration or damage. Never
short-circuit loads.
When the product is used near the maximum rating, even the smallest change in the conditions may cause exceeding of
the maximum rating, possibly leading to the fracture accident. Take the sufficient fluctuation margin for the supply
voltage and always use the product within a range never exceeding the maximum rating. The package used for this IC
has the low heat sink effect as a single unit. When the working supply voltage is high, solder the backside heat sink pad
to ensure sufficient heat sink performance with copper foil of printed circuit board.
Pin 3 inrush current (unit : A) : I3 = (5 × V CC - 4) × 10
mode-B ⇒ V CC op = 6.2V to 17V
mode-A ⇒ V CC op = 4.2V to 17V
At change of the output power value due to external resistance ⇒ V CC op = 2 × V2 to 17V (V2 ⇒ Pin 2
voltage)
V CC
Rst
Fig.7
6
3
V CC
STBY
LA4809M
-5
/Rst
V CC
Rst
+
+
Fig.8
Cst2
Cst1
6
3
V CC
STBY
No.A1569-8/15