SDT215 Ver la hoja de datos (PDF) - Linear Technology

Número de pieza

componentes Descripción

Fabricante

SDT215

N-CHANNEL LATERAL DMOS SWITCH

Linear Technology 

V+

D

VGS(th)

1µA

Figure 6. Threshold Voltage Test Configuration

Body Effect

For a MOSFET with a uniformly doped

substrate, the threshold voltage is proportional

to the square root of the applied source-to-body

voltage. The SD5000 family has a non-uniform

substrate, and the VGS(th) behaves somewhat

differently. Figure 7 shows the typical VGS(th)

variation as a function of the source-to-body

voltage VSB.

As the body voltage increases in the negative

direction, the threshold goes up. Consequently,

if VGS is small, the on-resistance of the channel

can be very high. Figure 8 shows the effects of

VSB and VGS on rDS(on). Therefore, to maintain a

low on-resistance it is preferable to bias the

body to a voltage close to the negative peaks of

VS and use a gate voltage as high as possible.

Charge Injection

Charge injection describes that phenomenon by

which a voltage excursion at the gate produces

an injection of electric charges via the gate-to-

drain and the gate-to-source capacitances into

the analog signal path. Another popular name

for this phenomenon is “switching spikes."

VGS(th)

S

1µA

VSB

3.0

2.5

2.0

1.5

1.0

0.5

0

4

8 12 16 20

VSB (V)

Figure 7. Threshold vs Source to Body Voltage

VD

1mA

D

VGS

S

VSB

300

VGS = 4 V

240

180

120

5V

60

10 V

0

0

4

8 12 16 20

VSB (V)

Figure 8. On Resistance vs Source to Body and

Gate to Source Voltages

4

Linear Integrated Systems, Inc. ● 4042 Clipper Ct. ● Fremont, CA 94538 ● Tel: 510 490-9160 ● Fax: 510 353-0261

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