J112

3

Motorola Small–Signal Transistors, FETs and Diodes Device Data

NOTE 2

The Zero–Gate–Voltage Drain Current (IDSS), is the principle

determinant of other J-FET characteristics. Figure 10 shows

the relationship of Gate–Source Off Voltage (VGS(off) and

Drain–Source On Resistance (rds(on)) to IDSS. Most of the

devices will be within

±10% of the values shown in Figure 10.

This data will be useful in predicting the characteristic

variations for a given part number.

For example:

Unknown

rds(on) and VGS range for an J112

The electrical characteristics table indicates that an J112

has an IDSS range of 25 to 75 mA. Figure 10, shows rds(on) =

52 Ohms for IDSS = 25 mA and 30 Ohms for IDSS = 75 mA.

The corresponding VGS values are 2.2 volts and 4.8 volts.

2.0

3.0

5.0

7.0

10

20

0.5 0.7

1.0

2.0

3.0

5.0 7.0 10

20

30

50

ID, DRAIN CURRENT (mA)

Figure 6. Typical Forward Transfer Admittance

1.0

1.5

2.0

3.0

5.0

7.0

10

15

0.03 0.05

0.1

0.3 0.5

1.0

3.0 5.0

10

30

VR, REVERSE VOLTAGE (VOLTS)

Figure 7. Typical Capacitance

200

160

120

80

40

0

0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

VGS, GATE–SOURCE VOLTAGE (VOLTS)

Figure 8. Effect of Gate–Source Voltage

On Drain–Source Resistance

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

– 70

– 40

– 10

20

50

80

110

140

170

Tchannel, CHANNEL TEMPERATURE (°C)

Figure 9. Effect of Temperature On

Drain–Source On–State Resistance

Tchannel = 25°C

VDS = 15 V

Cgs

Cgd

Tchannel = 25°C

(Cds IS NEGLIGIBLE)

IDSS

= 10

mA

25

mA

50 mA

75 mA 100 mA

125 mA

Tchannel = 25°C

ID = 1.0 mA

VGS = 0

10

IDSS, ZERO–GATE–VOLTAGE DRAIN CURRENT (mA)

Figure 10. Effect of IDSS On Drain–Source

Resistance and Gate–Source Voltage

20 30

40 50 60

70 80 90 100 110 120 130 140 150

10

9.0

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0

100

90

80

70

60

50

40

30

20

10

0

Tchannel = 25°C

rDS(on) @ VGS = 0

VGS(off)