LM2574

Micrel

M9999-122303

4

December 2003

Electrical Characteristics

Symbol

Parameter

Condition

Min

Typ

Max

Units

Device Parameters, Adjustable Regulator

I

B

Feedback Bias Current

V

50

100

nA

500

nA

Device Parameters, Fixed and Adjustable Regulators

f

o

Oscillator Frequency

Note 8

47

52

58

kHz

42

63

kHz

V

SAT

Saturation Voltage

I

(4)

0.8

1.2

V

1.4

V

DC

Max Duty Cycle (ON)

Note 5

93

98

%

I

CL

Current Limit

Peak Current, t

(4)

0.7

1.0

1.6

A

0.65

1.8

I

L

Output Leakage Current

V

2

mA

Note 6, Output = –1V

7.5

30

I

Q

Quiescent Current

Note 6

510

mA

I

STBY

Standby Quiescent Current

ON/OFF Pin = 5V (OFF)

50

200

µA

θ

JA

Thermal Resistance

85

°C/W

On/Off Control, Fixed and Adjustable Regulators Test Circuit

Figures 2, 3

V

IH

ON/OFF Input Level

V

2.2

1.4

V

2.4

V

V

IL

ON/OFF Input Level

V

1.2

1.0

V

0.8

V

I

IH

ON/OFF Logic Current

ON/OFF = 5V (OFF)

4

30

µA

I

IL

ON/OFF Logic Current

ON/OFF = 0V (ON)

0.01

10

µA

Notes:

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

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

6. Feedback (pin 4) removed from output and connected to 12V to force the output transistor OFF.

7. Junction-to-ambient thermal resistance with approximately 1 square inches of PC board copper surrounding the leads.

Test Circuit

PWR

GND

SIG

GND

ON/

OFF

OUT

FB

LM2574

(adjustable)

22µF

11DQ06

220µF

330µH

3.09k

1k

Figure 2. Adjustable Regulator Test Circuit

PWR

GND

SIG

GND

ON/

OFF

OUT

FB

LM2574–

3.3, 5

22

µF

11DQ06

220

µF

330

µH

Figure 3. Fixed Regulator Test Circuit