LV4985VH_0912 SANYO [Sanyo Semicon Device], LV4985VH_0912 Datasheet - Page 9

• Manufacturer Part Number: LV4985VH_0912
• Description: For Portable Electronic Device Use 1.2W x 2ch BTL Power Amplifier
• Manufacturer: SANYO [Sanyo Semicon Device]

4. pin 6 capacitor (C5)
5. Power supply line capacitor (C6 and C7)
6. Load capacitance
7. Headphone drive
8. Standby pin (pin 9)
This capacitor is a ripple filter capacitor. The internal resistors (600kΩ + 50kΩ) and C5 make up a low-pass filter that
is used to reduce the power supply ripple component and increase the ripple rejection ratio.
Note that inside the IC, the rising-transient-response-characteristic of the pin 6 voltage (reference voltage) is used to
activate the automatic pop noise reduction circuit. Therefore, when reducing the C5 capacitance value to increase the
voltage rise speed, the design should take into account that the pop noise increases during voltage rise.
The bypass capacitor C7 is used to remove the high frequency component that cannot be eliminated by the power
supply capacitor C6 (chemical capacitor). Place the bypass capacitor C7 as near to the IC as possible, and use a ceramic
capacitor with good high frequency characteristics.
When using a stabilized power supply, these capacitors can also be combined into a single 2.2μF ceramic capacitor.
Note that when the power supply line is relatively unstable, the power supply capacitor C6 capacitance value must be
increased.
When connecting a capacitor between the output pin and ground to suppress electromagnetic radiation or other
purposes, the effects of this capacitor may cause the power amplifier phase margin to be reduced, resulting in
oscillation. When adding this capacitor, care should be taken for the capacitance value.
When also using the BTL amplifier’s first amplifier as the headphone amplifier, it is recommended to adjust the level
by inserting series resistors R9 (R10) to the signal line as shown in Application Circuit Example-2.
Note that this series resistor, the headphone load resistance and the output coupling capacitors C9 (C10) make up a
high-pass filter, so this should be taken into account in the design. The cut-off frequencies are expressed by the
following formulas.
As shown in Figure1, by controlling the standby pin, the mode changeover can be made between standby mode,
single-ended (SE) operating mode, and BTL operating mode.
When not using the single-ended operating mode, a direct control is possible by connecting the standby pin to the CPU
output port. However, it is recommended to insert a series resistor R5 (1kΩ or more) as shown in Figure 2 in case the
pin is affected by the digital noise from CPU.
In addition, when not using the standby mode, the pin 9 can also be used interlocked with the power supply as shown in
Figure 3. Since there exists an internal current limiting resistor (30kΩ), the series resistor R5 can be eliminated, but the
current I9 expressed by the following formula flows through the pin 9, so this should be taken into account in the
design.
Standby mode
SE operating mode
BTL operating mode
A-port
B-port
CPU
Recommended capacitance value : 1000pF to 0.1μF
1ch ⇒ fc5 = 1/ (2π × C9 × (R9 + R L ))
2ch ⇒ fc6 = 1/ (2π × C10 × (R10 + R L ))
Pin 9 inflow current (unit : A) : I9 = 4.7 × 10
State
R5
R6
Fig. 1
STBY
Pin 9 voltage
1.3V to 1.7V
2.3V to V CC
0V to 0.3V
9
LV4985VH
Port A
High
High
Low
LV4985VH
-6
A-port
CPU
+ (V CC - 0.7)/(R5 + 30000)
Port B
High
Low
Low
Fig. 2
R5
9
STBY
V CC
R5
Fig. 3
No.A1568-9/15
STBY
V CC
9
3