MMFT1N10E

4

Motorola TMOS Power MOSFET Transistor Device Data

FORWARD BIASED SAFE OPERATING AREA

The FBSOA curves define the maximum drain–to–source

voltage and drain current that a device can safely handle

when it is forward biased, or when it is on, or being turned on.

Because these curves include the limitations of simultaneous

high voltage and high current, up to the rating of the device,

they are especially useful to designers of linear systems. The

curves are based on an ambient temperature of 25

maximum junction temperature of 150

petitive pulses at various ambient temperatures can be de-

termined by using the thermal response curves. Motorola

Application Note, AN569, “Transient Thermal Resistance–

General Data and Its Use” provides detailed instructions.

SWITCHING SAFE OPERATING AREA

The switching safe operating area (SOA) is the boundary

that the load line may traverse without incurring damage to

the MOSFET. The fundamental limits are the peak current,

IDM and the breakdown voltage, BVDSS. The switching SOA

is applicable for both turn–on and turn–off of the devices for

switching times less than one microsecond.

Figure 7. Maximum Rated Forward Biased

Safe Operating Area

VGS = 20 V

SINGLE PULSE

TA = 25°C

10

0.1

1

0.1

0.01

0.001

1

10

100

VDS, DRAIN–TO–SOURCE VOLTAGE (VOLTS)

DC

20 ms

1 s

500 ms

100 ms

RDS(on) LIMIT

THERMAL LIMIT

PACKAGE LIMIT

Figure 8. Thermal Response

1.0

0.1

0.001

1.0E–05

1.0E–04

1.0E–03

1.0E–02

1.0E–01

1.0E+00

t, TIME (s)

0.1

0.01

0.2

0.02

0.01

D = 0.5

SINGLE PULSE

0.05

R

θJA(t) = r(t) RθJA

R

θJA = 156°C/W MAX

D CURVES APPLY FOR POWER

PULSE TRAIN SHOWN

READ TIME AT t1

TJ(pk) – TA = P(pk) R

θJA(t)

P(pk)

t1

t2

DUTY CYCLE, D = t1/t2

1.0E+01

COMMUTATING SAFE OPERATING AREA (CSOA)

The Commutating Safe Operating Area (CSOA) of Figure 10 defines the limits of safe operation for commutated source–drain

current versus re–applied drain voltage when the source–drain diode has undergone forward bias. The curve shows the limita-

tions of IFM and peak VDS for a given rate of change of source current. It is applicable when waveforms similar to those of Figure

9 are present. Full or half–bridge PWM DC motor controllers are common applications requiring CSOA data.

Device stresses increase with increasing rate of change of source current so dIS/dt is specified with a maximum value. Higher

values of dIS/dt require an appropriate derating of IFM, peak VDS or both. Ultimately dIS/dt is limited primarily by device, package,

and circuit impedances. Maximum device stress occurs during trr as the diode goes from conduction to reverse blocking.

VDS(pk) is the peak drain–to–source voltage that the device must sustain during commutation; IFM is the maximum forward

source–drain diode current just prior to the onset of commutation.

VR is specified at 80% rated BVDSS to ensure that the CSOA stress is maximized as IS decays from IRM to zero.

RGS should be minimized during commutation. TJ has only a second order effect on CSOA.

Stray inductances in Motorola’s test circuit are assumed to be practical minimums. dVDS/dt in excess of 10 V/ns was at-

tained with dIS/dt of 400 A/µs.