TA2022 Ver la hoja de datos (PDF) - Tripath Technology Inc.

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TA2022

STEREO 90W (4Ω) CLASS-T™ DIGITAL AUDIO AMPLIFIER DRIVER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology Inc. 

Tripath Technology, Inc. - Technical Information

Protection Circuits

The TA2022 is guarded against over-current, over / under-voltage and over-temperature conditions.

If the device goes into an over-current or over / under-voltage condition, the HMUTE goes to a logic

HIGH indicating a fault condition. When this occurs, the amplifier is muted, all outputs are TRI-

STATED, and will float to approximately 2.5VDC.

Over-Current Protection

An over-current fault occurs if more than approximately 8 amps of current flows from any of the

amplifier output pins. This can occur if the speaker wires are shorted together or if one side of the

speaker is shorted to ground. An over-current fault sets an internal latch that can only be cleared if

the MUTE pin is toggled or if the part is powered down. See the over-current curves in the Typical

Characteristics section for more information.

Over/Under Voltage Protection

The TA2022 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 18) performs the same function for the negative rail, VNN. In the simplest

implementation, the supply is done via a single, external resistor per sense pin. This scheme is

referred to as the “single resistor” sense circuit. Figure 9 shows the single resistor sense circuit.

VNN

RVNNSENSE

TA2022

18 VNNSENSE

VPP

RVPPSENSE

19

VPPSENSE

Figure 9: Single Resistor Sense Circuit

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 TA2022 will be

muted. VPPSENSE is internally biased at 2.5V and VNNSENSE is biased at 1.25V. For the “single

resistor” sense case (as shown in the Application / Test Diagram), these bias points must be taken

into consideration when calculating the RVPPSENSE or RVNNSENSE resistor.

Once the supply comes back into the supply voltage operating range (as defined by the supply sense

resistors), the TA2022 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 TA2022 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.

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TA2022 – KLI/1.2/07-04

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