TA0104A Tripath Technology Inc., TA0104A Datasheet - Page 11

• Manufacturer Part Number: TA0104A
• Manufacturer: Tripath Technology Inc.

VN12 Supply
VN12 is an additional supply voltage required by the TA0104A. VN12 must be 12 volts more positive
than the nominal V
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
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
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
11
SNEG
supply rather than to ground (PGND). Figure 3 shows the correct way to power the TA0104A:
SNEG
. VN12 must track V
V
V
SNEG
S
S
V
V
S
S
).
Figure 3
Figure 4
Care must be exercised with this method because some IC
PGND
-55V
5V
SNEG
12V
5V
, so if an unregulated supply is used for V
P GND
VN12
V5
V
V
SPOS
SNEG
A GND
AGND
V
VN12
V
T r i p a t h T e c h n o l o g y , I n c . - T e c h n i c a l I n f o r m a t i o n
V5
SNEG
SPOS
SNEG
TA104A – Rev. 3.1/06.00
.
SNEG
, the