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

The half-bridge power MOSFETs require a deadtime between when one transistor is turned off

and the other is turned on (break-before-make) in order to minimize shoot through currents. The

TC2001 has BBM0 and BBM1 that are logic inputs (connected to logic high or pulled down to

logic low) that control the break-before-make timing of the output transistors according to the

following table.

BBM1

BBM0

Delay

0

0

120 ns

0

1

80 ns

1

0

40 ns

1

1

0 ns

Table 1: BBM Delay

The tradeoff involved in making this setting is that as the delay is reduced, distortion levels

improve but shoot-through and power dissipation increase. All typical curves and performance

information were done with using the 40ns BBM setting. The actual amount of BBM required is

dependent upon other component values and circuit board layout, the value selected should be

verified in the actual application circuit/board.

It should also be verified under maximum

temperature and power conditions since shoot-through in the output MOSFETs can increase

under these conditions, possibly requiring a higher BBM setting than at room temperature.

Recommended MOSFETs

The following devices are capable of achieving full performance, both in terms of distortion and

efficiency, for the specified load impedance and voltage range.

Device Information – Recommended MOSFETs

Part Number

Manufacturer

Package

IRF520N

International Rectifier

100

9.7

25(max.)

0.20 (max.)

48

TO220

FQP13N10

Fairchild Semiconductor

100

12.8

12

0.142

65

TO220

STP14NF10

ST Microelectronics

100

14

15.5

0.16

60

TO220

IRF530N

International Rectifier

100

17

37(max.)

0.09 (max.)

70

TO220

BUK7575-100A

Philips Semiconductor

100

23

25

0.064

99

TO220

STP24NF10

ST Microelectronics

100

26

30

0.055

85

TO220

Note: The devices are listed in ascending current capability not in order of recommendation.

The following information represents qualitative data from system development using the TK2150

and the associated MOSFETs. Recommendations such as maximum supply voltages and gate

resistor values are dependent on the PCB layout and component location. The gate resistor

values were chosen to achieve about 18-80mA of idle current from the VPP supply. This value of

supply current is a good compromise between low power efficiency and high frequency THD+N

performance. As shown in Table 2 below, increasing the gate resistor value will improve high

frequency THD+N performance at the expense of idle current draw. The BBM setting was 40nS

in all cases. It should be understood that different MOSFETs will have different characteristics

and will require some adjustment to the gate resistor to achieve the same idle current.