TA0104A Datasheet, PDF (11/18 Pages) Tripath Technology Inc. – STEREO 500W (4Ω) CLASS-T DIGITAL AUDIO AMPLIFIER DRIVER USING DIGITAL POWER PROCESSING (DPPTM) TECHNOLOGY

Tripath Technology, Inc. - Technical Information
VN12 Supply
VN12 is an additional supply voltage required by the TA0104A. VN12 must be 12 volts more positive
than the nominal V_SNEG. VN12 must track V_SNEG, so if an unregulated supply is used for V_SNEG, the
design of the supply for VN12 must behave accordingly. Generating the VN12 supply requires some
care.
The proper way to generate the voltage for VN12 is to use a 12V-supply voltage referenced to the
V_SNEG supply rather than to ground (PGND). Figure 3 shows the correct way to power the TA0104A:
V_SPOS
V5
V_S
5V
PGND
V_S
12V
AGND
VN12
V_SNEG
Figure 3
One method to generate the VN12 supply voltage is to use a positive 12V IC regulator to drop PGND
down to 12V (relative to V_SNEG). Care must be exercised with this method because some IC
regulators such as the LM340 series will not function properly with a large voltage drop across the
regulator, resulting in damage to the TA0104A.
Generating the VN12 voltage per Figure 4 is NOT recommended. Most power supplies only source
current from the positive terminal and will not be capable of generating the current required by VN12.
Furthermore, problems can arise since VN12 will not track movements in V_SNEG.
V_SPOS
V5
V_S
5V
P GND
A GND
-55V
V_S
VN12
V_SNEG
Figure 4
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TA104A – Rev. 3.1/06.00