SIM6800M datasheet(30/52 Pages) SANKEN

30 / 52 page

SIM6800M Series

SIM6800M-DSE Rev.1.5

SANKEN ELECTRIC CO., LTD

Jul. 18, 2018

http://www.sanken-ele.co.jp/en

14.2.3

Body Diode Steady-state Loss, PSD

Steady-state loss in the body diode of a power

MOSFET can be computed by using the VSD vs. ISD

curves, listed in Section 15.3.1. As expressed by the

curves in Figure 14-3, linear approximations at a range

the ISD is actually used are obtained by: VSD =

α × I

SD +

β.

The values gained by the above calculation are then

applied as parameters in Equation (9), below. Hence, the

equation to obtain the body diode steady-state loss, PSD,

is:

PSD= 12π�VSD(φ)×ISD(φ)×(1−DT)×dφ

=12α�12−43πM×cosθ�IM2

+√2πβ�12−π8M×cosθ�IM. (9)

Where:

VSD is the source-to-drain diode forward voltage of the

power MOSFET (V),

ISD is the source-to-drain diode forward current of the

power MOSFET (A),

DT is the duty cycle, which is given by

DT=1+M×sin(φ+θ)

2 ,

M is the modulation index (0 to 1),

cosθ is the motor power factor (0 to 1),

IM is the effective motor current (A),

α is the slope of the linear approximation in the V

SD vs.

ISD curve, and

β is the intercept of the linear approximation in the

VSD vs. ISD curve.

Figure 14-3.

Linear Approximate Equation of

VSD vs. ISD Curve

14.2.4

Estimating Junction Temperature

of Power MOSFET

The junction temperature of all power MOSFETs

operating, Tj, can be estimated with Equation (10):

Tj=Rj−C×{(PON+PSW+PSD)×6}+TC. (10)

Where:

Rj-C is the junction-to-case thermal resistance (°C/W)

of all the power MOSFETs operating, and

TC is the case temperature (°C), measured at the point

defined in Figure 3-1.

0.0

0.5

1.0

1.5

2.0

2.5

0.0

1.0

2.0

3.0

4.0

5.0

SD (A)

VCC = 15 V

°C

125

°C

y = 0.2888x + 0.8758

SIM6800M Datasheet(PDF) 30 Page - Sanken electric

SIM6800M Datasheet(HTML) 30 Page - Sanken electric

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

Datasheet Download

Link URL