FQP14N15 View Datasheet(PDF) - Tripath Technology Inc.

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FQP14N15

STEREO 200W (6Ω) CLASS-T DIGITAL AUDIO AMPLIFIER DRIVER USING DIGITAL POWER PROCESSINGtm TECHNOLOGY

Tripath Technology Inc. 

Tripath Technology, Inc. - Technical Information

are fully operational. There is a delay of approximately 200 milliseconds between the de-

assertion of MUTE and the un-muting of the TK2150.

Sleep

When a logic high signal is supplied to SLEEP, the two channels on the TP2150 will be shutdown

and the outputs will be muted. When a logic level low is supplied to SLEEP, both channels are

fully operational.

Turn-on & Turn-off Noise

If turn-on or turn-off noise is present in a TK2150 amplifier, the cause is frequently due to other

circuitry external to the TK2150. While the TK2150 has circuitry to suppress turn-on and turn-off

transients, the combination of the power supply and other audio circuitry with the TK2150 in a

particular application may exhibit audible transients. One solution that will completely eliminate

turn-on and turn-off pops and clicks is to use a relay to connect/disconnect the amplifier from the

speakers with the appropriate timing at power on/off. The relay can also be used to protect the

speakers from a component failure (e.g. shorted output MOSFET), which is a protection

mechanism that some amplifiers have. Circuitry external to the TK2150 would need to be

implemented to detect these failures.

DC Offset

While the DC offset voltages that appear at the speaker terminals of a TK2150 amplifier are

typically small, Tripath recommends that any offsets during operation be nulled out of the

amplifier with a circuit like the one shown connected to IN1 and IN2 in the Test/Application

Circuit.

It should be noted that the DC voltage on the output of a TK2150 amplifier with no load in mute

will not be zero. This offset does not need to be nulled. The output impedance of the amplifier in

mute mode is approximately 10KΩ. This means that the DC voltage drops to essentially zero

when a typical load is connected.

HMUTE

The HMUTE pin on the TC2001 is a 5V logic output that indicates various fault conditions within

the device. These conditions include: over-current, overvoltage and undervoltage. The HMUTE

output is capable of directly driving an LED through a series 2kΩ resistor.

Over-current Protection

The TK2150 has over-current protection circuitry to protect itself and the output transistors from

short-circuit conditions. The TK2150 uses the voltage across a resistor RS (measured via

OCS1HP, OCS1HN, OCS1LP and OCS1LN of the TP2150) that is in series with each output

MOSFET to detect an over-current condition. RS and ROCR are used to set the over-current

threshold. The OCS pins must be Kelvin connected for proper operation. See “Circuit Board

Layout” in Application Information for details.

When the voltage across ROCR becomes greater than VTOC (approximately 1.0V) the TC2001 will

shut off the output stages of its amplifiers. The occurrence of an over-current condition is latched

in the TK2150 and can be cleared by toggling the MUTE input or cycling power.

Setting Over-current Threshold

RS and ROCR determine the value of the over-current threshold, ISC:

ISC = 3580 x (VTOC – IBIAS * ROCR)/(R OCR * RS)

ROCR = (3580 x VTOC)/(ISC * RS+3580 * IBIAS)

where:

21

TK2150 – Rev. 1.0/12.02

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