Tripath Technology, Inc. - Technical Information
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
120 ns
80 ns
40 ns
0 ns
0
0
1
1
0
1
0
1
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
IRF520N
Manufacturer
BVDSS (V)
100
ID (A)
9.7
12.8
14
17
23
Qg (nC)
25(max.) 0.20 (max.)
12
15.5
RDS(on) Ω
(
)
PD (W)
48
65
60
70
Package
TO220
TO220
TO220
TO220
TO220
TO220
International Rectifier
Fairchild Semiconductor
ST Microelectronics
International Rectifier
Philips Semiconductor
ST Microelectronics
FQP13N10
STP14NF10
IRF530N
BUK7575-100A
STP24NF10
100
100
100
100
0.142
0.16
37(max.) 0.09 (max.)
25
30
0.064
0.055
99
85
100
26
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.
26
TK2150 – Rev. 1.0/12.02
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
