LV4985VH

4. pin 6 capacitor (C5)

This capacitor is a ripple filter capacitor. The internal resistors (600k

Ω + 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.

5. Power supply line capacitor (C6 and C7)

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 2.2

μF ceramic capacitor.

Note that when the power supply line is relatively unstable, the power supply capacitor C6 capacitance value must be

increased.

6. Load capacitance

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.

Recommended capacitance value : 1000pF to 0.1

μF

7. Headphone drive

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.

1ch

⇒ fc5 = 1/ (2π × C9 × (R9 + RL))

2ch

⇒ fc6 = 1/ (2π × C10 × (R10 + RL))

8. Standby pin (pin 9)

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.

State

Pin 9 voltage

Port A

Port B

Standby mode

0V to 0.3V

Low

Low

SE operating mode

1.3V to 1.7V

High

Low

BTL operating mode

2.3V to VCC

High

High

A-port

B-port

LV4985VH

VCC

VCC

STBY

STBY

STBY

CPU

R5

R6

9

A-port

CPU

R5

R5

9

9

3

Fig. 1

Fig. 2

Fig. 3

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 (1k

Ω 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 (30k

Ω), 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.

Pin 9 inflow current (unit : A) : I9 = 4.7

No.A1568-9/15