Transformer Driver for

Isolated RS-485 Interface

4

_______________________________________________________________________________________

10

0

0

40

220

OUTPUT VOLTAGE vs. LOAD CURRENT

(FS = LOW)

2

8

LOAD CURRENT (mA)

80

6

4

1

3

9

7

5

20

60

140

120

100

160 180 200

CIRCUIT OF FIGURE 6

TURNS RATIO = 1:1

CIRCUIT OF FIGURE 6

TURNS RATIO = 1:1.3

CIRCUIT OF FIGURE 7

TURNS RATIO = 1:2.1

MEASURED AT TP1

10

0

0

40

220

OUTPUT VOLTAGE vs. LOAD CURRENT

(FS = HIGH)

2

8

LOAD CURRENT (mA)

80

6

4

1

3

9

7

5

20

60

140

120

100

160 180 200

CIRCUIT OF FIGURE 6

TURNS RATIO = 1:1

CIRCUIT OF FIGURE 6

TURNS RATIO = 1:1.3

CIRCUIT OF FIGURE 7

TURNS RATIO = 1:2.1

MEASURED AT TP1

CIRCUIT OF FIGURE 1

SWITCHING WAVEFORMS

(TWO CYCLES)

D1

D2

CIRCUIT OF FIGURE 1

SWITCHING WAVEFORMS

(BREAK BEFORE MAKE)

D1

D2

CIRCUIT OF FIGURE 6

TIME FROM SHUTDOWN TO POWER-UP

SD

TP1 (OUTPUT VOLTAGE)

____________________________Typical Operating Characteristics (continued)

100

0

0

40

120

200

EFFICIENCY vs. LOAD CURRENT

(FS = HIGH)

20

80

LOAD CURRENT (mA)

80

160

60

40

10

30

90

70

50

20

60

140

100

180