3

TC2574

0.5A Step-Down Switching Regulator

TC2574-1 1/6/00

ing junction temperature range that applies (Note 2), unless otherwise noted.

Symbol

Parameter

Test Conditions

Min

Typ

Max

Units

TC2574-ADJUSTABLE VERSION [(Note 1) Test Circuit Figure 2]

Feedback Bias Current

nA

—

25

100

—

—

200

Oscillator Frequency (Note 3)

—

52

—

kHz

52

58

–

63

Saturation Voltage

V

—

1.0

1.2

—

—

1.4

DC

Max Duty Cycle (“on”) [Note 5]

93

98

—

%

Current Limit Peak Current (Notes 3 and 4)

A

0.7

1.0

1.6

0.65

—

1.8

Output = 0 V

—

0.6

2.0

Output = – 1.0 V

—

10

30

Quiescent Current (Note 6)

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

ON/OFF Pin Input Current mA

µA

—

15

30

ON/OFF Pin Input Current mA

µA

—

0

5.0

NOTES: 1. External components such as the catch diode, inductor, input and output capacitors can affect the switching regulator system

performance. When the TC2574 is used as shown in the Figure 2 test circuit, the system performance will be as

shown in the system parameters section of the Electrical Characteristics.

3. The oscillator frequency reduces to approximately 18kHz 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%.

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

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

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

version, to force the output transistor OFF.