ADAV400KSTZ datasheet(14/36 Pages) AD

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ADAV400

Rev. 0 | Page 14 of 36

HEADPHONE AMPLIFIER

The ADAV400 has an integrated stereo headphone amplifier

capable of driving 32 mW into a 32 Ω load.

VOLTAGE REGULATOR

The ADAV400 includes an on-chip voltage regulator that

enables the chip to be used in systems where a 1.8 V supply is

not available. The only external components needed are a PNP

transistor (such as FZT953), a single capacitor, and a single

resistor. The recommended design for the voltage regulator is

shown in Figure 19.

Here, VDD is the main system voltage (3.3 V). A voltage of 1.8 V

is generated at the transistor’s collector and is connected to the

DVDD pins. VDRIVE is an output from the internal regulator

circuit on the ADAV400 and is connected to the base of the

PNP transistor

ADAV400

VDD

Figure 19. Voltage Regulator Design

There are two specifications to take into consideration when

choosing the regulator’s transistor. First, hFE should be at least 100.

Second, the collector power dissipation, PC, must be greater than

PC = (3.3 V − 1.8 V) × 135 mA = 202.5 mW

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