A

8/97

12

TOP209/210

2

NOTES: (continued)

i. The 470

Ω 5 W load resistor at the DRAIN pin should be shorted. S1 & S2 should stay closed.

ii. The 40 V output supply should be replaced with a curve tracer capable of forcing 700 V.

iii. The curve tracer should initially be set at 0 V. The 0-50 V variable supply should be adjusted through a voltage

sequence of 0 V, 6.5 V, 4.2 V, and 6.5 V.

iv. The breakdown and the leakage measurements can now be taken with the curve tracer. The maximum

voltage from the curve tracer must be limited to 700 V under all conditions.

C. It is possible to start up and operate TOPSwitch at DRAIN voltages well below 36 V. However, the CONTROL pin

charging current is reduced, which affects start-up time and auto-restart frequency and duty cycle. Refer to the

characteristic graph on CONTROL pin charge current (I

PI-1733-122095

0.1

µF

47

µF

0-50 V

40 V

470

Ω

5 W

S2

S1

470

Ω

NOTE: This test circuit is not applicable for current limit or output characteristic measurements.

DC

S

S

Figure 12. TOPSwitch General Test Circuit.

Figure 10. TOPSwitch Duty Cycle Measurement.

Figure 11. TOPSwitch CONTROL Pin I-V Characteristic.

120

100

80

40

20

60

0

02

4

6

8

10

CONTROL Pin Voltage (V)

TYPICAL CONTROL PIN I-V CHARACTERISTIC

1

Slope

Dynamic

Impedance

=

PI-2048-050798

DRAIN

VOLTAGE

HV

0 V

90%

10%

90%

t2

t1

D =

t1

t2