LM2574

http://onsemi.com

4

Characteristic

Symbol

Min

Typ

Max

Unit

ALL OUTPUT VOLTAGE VERSIONS

nA

–

25

100

–

–

200

Oscillator Frequency (Note 5)

kHz

–

52

–

47

52

58

42

–

63

V

–

1.0

1.2

–

–

1.4

Max Duty Cycle (“on”) (Note 7)

DC

93

98

–

%

Current Limit Peak Current (Notes 5 and 6)

A

0.7

1.0

1.6

0.65

–

1.8

mA

Output = 0 V

–

0.6

2.0

Output = – 1.0 V

–

10

30

Quiescent Current (Note 8)

mA

–

5.0

9.0

–

–

11

Standby Quiescent Current (ON/OFF Pin = 5.0 V (“off”))

µA

–

60

200

–

–

400

ON/OFF Pin Logic Input Level

V

2.2

1.4

–

2.4

–

–

Nominal Output Voltage

–

1.2

1.0

–

–

0.8

µA

–

15

30

–

0

5.0

3. External components such as the catch diode, inductor, input and output capacitors can affect the switching regulator system performance.

When the LM2574 is used as shown in the Figure 16 test circuit, the system performance will be as shown in the system parameters section

of the Electrical Characteristics.

5. The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which causes the regulated output

voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of the

IC by lowering the minimum duty cycle from 5% down to approximately 2%.

6. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to the output pin.

7. Feedback (Pin 4) removed from output and connected to 0 V.

8. Feedback (Pin 4) removed from output and connected to 12 V for the Adjustable, 3.3 V, and 5.0 V versions, and 25 V for the 12 V and 15 V

versions, to force the output transistor OFF.