Tr i p ath Technol ogy, I n c. - Techni cal In fo rma t io n

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TK2150 – Rev. 1.0/12.02

In general, to enable placement as close to the TK2150, and minimize PCB parasitics, the

board.

Some components are not sensitive to location but are very sensitive to layout and trace routing.

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To maximize the damping factor and reduce distortion and noise, the modulator

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the load return. The output ground feedback signal should be taken from this star point.

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to 5V together. These connections will serve to minimize common mode noise via the

differential feedback.

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The feedback signals that come directly from the output inductors are high voltage and

high frequency in nature. If they are routed close to the input nodes, IN1 and IN2, the

high impedance inverting opamp pins will pick up noise. This coupling will result in

significant background noise, especially when the input is AC coupled to ground, or an

external source such as a CD player or signal generator is connected. Thus, care

should be taken such that the feedback lines are not routed near any of the input

section.

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To minimize the possibility of any noise pickup, the trace lengths of IN1 and IN2 should

be kept as short as possible. This is most easily accomplished by locating the input

should be located close to the TC2001 input section.

TK2150 Grounding

Proper grounding techniques are required to maximize TK2150 functionality and performance.

Parametric parameters such as THD+N, Noise Floor and Crosstalk can be adversely affected if

proper grounding techniques are not implemented on the PCB layout. The following discussion

highlights some recommendations about grounding both with respect to the TK2150 as well as

general “audio system” design rules.

The TK2150 is divided into three sections: the input section, which is the TC2001, the MOSFET

driver section, which is the TP2150, and the output (high voltage) section, which is the output

MOSFETs. On the TK2150 evaluation board, the ground is also divided into distinct sections,

Analog Ground (AGND) and Power Ground (PGND). To minimize ground loops and keep the

audio noise floor as low as possible, the two grounds must be only connected at a single point.

Depending on the system design, the single point connection may be in the form of a ferrite bead

or a PCB trace.

The analog ground, must be connected to pin 20 on the TC2001 and pins 2 and 5 on the TP2150.

The ground for the V5 power supply should connect directly to pin 20 of the TC2001. Additionally,

any external input circuitry such as preamps, or active filters, should be referenced to pin 20 on

the TC2001. Special care must be used when connecting the NC pins of the TP2150 in order to

achieve the best noise performance. Pins 1, 3, 4, 8, 11, 12, 18, 19, 20, 22, 23, 24, 25, 61, 62, 63,

64 should be tied to Analog Ground. All of the other NC pins of the TP2150 should be left

floating.

For the power section, Tripath has traditionally used a “star” grounding scheme. Thus, the load

ground returns and the power supply decoupling traces are routed separately back to the power

supply. In addition, any type of shield or chassis connection would be connected directly to the

ground star located at the power supply. These precautions will both minimize audible noise and

enhance the crosstalk performance of the TK2150.