TCA2002 Datasheet, PDF (15/18 Pages) Tripath Technology Inc. – STEREO CLASS-T™ AUDIO CONTROLLER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology, Inc. - Technical Information
over current fault has occurred, the HMUTE will be pulled high for approximately 700mS. At this
point, HMUTE will go low, and the TCA2002 will begin its normal un-muting sequence for 250mS.
Thus, the typical retry time from an over-current fault is 950mS
If over-current detection is not needed, for example in the cases where the power stage has built in
over-current protection, simply connect OCD0 and OCD1 to AGND. This will disable the over-current
detection comparators in the TCA2002.
Over- and Under-Voltage Protection
The TCA2002 senses the power rails through external resistor networks connected to VNNSENSE
and VPPSENSE. The over- and under-voltage limits are determined by the values of the resistors in
the networks (see APPLICATION / TEST DIAGRAM). If the supply voltage falls outside the upper
and lower limits determined by the resistor networks, the TCA2002 will mute. The HMUTE pin will be
pulled high and the Yx and YxB pins will be low. The removal of the over-voltage, or under-voltage
condition, returns the amplifier to normal operation. Please note that trip points specified in the
Electrical Characteristics table are at 25°C and may change over temperature.
For applications where the TCA2002 is mated with a power stage that has built-in over and
undervoltage protection, this protection feature can be disabled by connecting a 30kohm resistor from
VPPSENSE (pin 19) to V5, and a 15k resistor from VNNSENSE (pin 17) to AGND. Please note that
the MUTE pin must be held high until all power supplies are stable to eliminate any possible power
supply sequencing problems.
The TCA2002 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 19) performs the over and undervoltage sensing for the positive supply, VPP.
VNNSENSE (pin 17) performs the same function for the negative rail, VNN. When the current
through R_VPPSENSE (or R_VNNSENSE) goes below or above the values shown in the ELECTRICAL
CHARACTERISTICS section (caused by changing the power supply voltage), the amplifier 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 amplifier will automatically be un-muted 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 amplifier 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 amplifier to be muted.
Figure 6 shows the proper connection for the Over / Under voltage sense circuit for both the
VPPSENSE and VNNSENSE pins.
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TCA2002 – KLi/0.95/04.06