LA4809M Ver la hoja de datos (PDF) - SANYO -> Panasonic

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LA4809M

Stereo Headphone Amplifier

SANYO -> Panasonic 

LA4809M

7. Selection of the maximum output power value (handling of Pin 10)

This IC enables selection of two types of maximum output power value according to the handling method of Pin 10.

The regulator circuit for output power control is built in, in which, by changing the voltage of Pin 2, the regulator

voltage : Vreg is changed to enable selection of the maximum output power value.

Mode-A (PO max = 55mW) : Pin 10 set to the OPEN state

Pin 2 voltage : V2 = 2.1V,

Internal regulator voltage : Vreg = 4.2V,

Amplifier operating reference voltage : Vref = 2.1V

Mode-B (PO max = 160mW) : Pin 10 connected to the GND line

Pin 2 voltage : V2 = 3.1V,

Internal regulator voltage : Vreg = 6.2V,

Amplifier operation reference voltage : Vref = 3.1V

When the maximum output power value is to be changed under CPU

control, use the NPN transistor as shown in Fig.4, so that the Pin 10

voltage approaches the GND potential (0.1V or below) sufficiently.

VCC

PLS 22μA

10

10kΩ

from CPU

Fig.4

8. Change of the maximum output power value (by handling Pin 2)

Pin 2 voltage : V2 is determined from the constant-current source and internal resistance as shown in Fig.5.

Operating ⇒ Mode-A : 54kΩ used

Mode-B : 80kΩ (54kΩ + 26kΩ) used

Not operating (at a time of falling) ⇒ 157kΩ (54kΩ + 26kΩ + 77kΩ) used

The internal regulator voltage and amplifier operating reference voltage are generated from this Pin 2 voltage.

Regulator voltage : Vreg = V2 × 2

Amplifier operating reference voltage : Vref = V2 × 1

Accordingly, to change the maximum output power value, connect the resistance : Rrf between Pin 2 and GND as

shown in Fig.5. This will cause change in the Pin 2 voltage. Note that, in view of circuit operation, the Pin 2 voltage

must be set to 1.6V or above.

If the discharge constant is not to be changed, Use the NPN transistor to control the Rrf connection as shown in Fig.6.

VCC

39μA

RF 54kΩ 26kΩ

2

Rrf Crf

77kΩ

PLS-cnt

STBY-cnt

from CPU

Rrf

2 RF

Crf

3 STBY

Fig.5

Fig.6

9. Standby pin (Pin 3)

By controlling the standby pin, the mode can be changed over between standby and operation. Though this control is

possible directly by the CPU output port, the control may be exposed to adverse affect of digital noise from CPU. It is

recommended therefore to insert series resistance (1kΩ or more).

Standby mode ⇒ V3 = 0V to 0.6V

Operation mode ⇒ V3 = 2V to 9V (for VCC = 9V or above), V3 = 2V to VCC (for VCC = less than 9V)

Continued on next page.

No.A1569-7/15

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