T E C H N I C A L I N F O R M A T I O N
condition returns the TA3020 to normal operation. Please note that trip points specified in the
Electrical Characteristics table are at 25°C and may change over temperature.
The TA3020 has built-in over and under voltage protection for both the VPP and VNN supply rails.
The nominal operating voltage will typically be chosen as the supply “center point.” This allows the
supply voltage to fluctuate, both above and below, the nominal supply voltage.
VPPSENSE (pin 29) performs the over and undervoltage sensing for the positive supply, VPP.
VNNSENSE (pin 30) performs the same function for the negative rail, VNN. When the current
through RVPPSENSE (or RVNNSENSE) goes below or above the values shown in the Electrical
Characteristics section (caused by changing the power supply voltage), the TA3020 will be muted.
VPPSENSE is internally biased at 2.5V and VNNSENSE is biased at 1.25V.
Once the supply comes back into the supply voltage operating range (as defined by the supply
sense resistors), the TA3020 will automatically be unmuted and will begin to amplify. There is a
hysteresis range on both the VPPSENSE and VNNSENSE pins. If the amplifier is powered up in the
hysteresis band the TA3020 will be muted. Thus, the usable supply range is the difference between
the over-voltage turn-off and under-voltage turn-off for both the VPP and VNN supplies. It should be
noted that there is a timer of approximately 200mS with respect to the over and under voltage
sensing circuit. Thus, the supply voltage must be outside of the user defined supply range for
greater than 200mS for the TA3020 to be muted.
Figure 4 shows the proper connection for the Over / Under voltage sense circuit for both the
VPPSENSE and VNNSENSE pins.
V5
VNN
TA3020
RVNN2
RVNN2
RVNN1
30
29
VNNSENSE
V5
VPP
RVPP1
VPPSENSE
Figure 4: Over / Under voltage sense circuit
The equation for calculating RVPP1 is as follows:
VPP
VPPSENSE
R
VPP1
=
I
Set RVPP2
R
VPP1 .
=
22
TA3020, Rev 2.1, 01.01
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
