adav400kstz-reel Analog Devices, Inc., adav400kstz-reel Datasheet - Page 14

• Manufacturer Part Number: adav400kstz-reel
• Description: Audio Codec With Embedded Sigmadsp Processor
• Manufacturer: Analog Devices, Inc.

ADAV400
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
As shown in this figure, 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.
Figure 19.
Rev. A | Page 14 of 36
There are two specifications to take into consideration when
choosing the regulator’s transistor. First, h
Second, the collector power dissipation, P
P
C
VDD
= (3.3 V − 1.8 V) × 135 mA = 202.5 mW
Figure 19. Voltage Regulator Design
+
ADAV400
+
FE
C
should be at least 100.
, must be greater than
+