STK6877 데이터 시트보기 (PDF) - SANYO -> Panasonic

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STK6877

Reversible Brush-Type DC Motor Driver (output current: 8 A)

SANYO -> Panasonic 

STK6877

2. Hybrid IC Internal Average Power Dissipation (Pd)

Of the power dissipations within the hybrid IC, the following components have large power dissipations: the FETs that

are the upper PWM elements in the H bridge structure, the lower FETs that form the motor direction reversing loop, and

the flywheel FET body diode. This can be expressed as shown below from experiment (from the output current

waveform in the figure below).

Pd = upper FETs + lower FETs + body diode losses

= Vst × IM × fp × tON + Vst × IM + Vdf × IM × fp × tOFF

Vst: FET saturation voltage (V)

IM: Motor output current (A)

Vdf: FET body diode forward voltage (V)

fp: Chopping frequency (Hz)

Figure 3 IM Waveform Model

Figures 5 and 6 show the IO vs. Vst and IO vs. Vdf characteristics.

Figure 4 Model Circuit Diagram

Figure 5 IO vs. Vst

3. Junction Temperature, Tj

The junction temperatures Tj (°C) for each element (F1, F2,

F3 and F4) can be derived from the formula below from the

power dissipation Pds (W) for each element and the

junction thermal resistances θj-c (°C/W).

Tj = Tc + θj-c × Pds (°C)

Pds: Loss per element

Note that the thermal resistances for the power elements are

as follows.

F1, F2, F3, F4 θj-c = 4 (°C/W)

F1, F2, F3, F4, ASO

Ta = 25°C

1 pulse

Figure 6 IO vs. Vdf

No. 4874-4/8

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