LM1577, LM2577

SNOS658D – JUNE 1999 – REVISED APRIL 2013

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Electrical Characteristics—LM1577-ADJ, LM2577-ADJ (continued)

Symbol

Parameter

Conditions

Typical

LM1577-ADJ

LM2577-ADJ

Units

(Limits)

Error Amp

±200

μA

Output Current

±130/±90

±130/±90

μA(min)

±300/±400

±300/±400

μA(max)

Soft Start Current

5.0

μA

2.5/1.5

2.5/1.5

μA(min)

7.5/9.5

7.5/9.5

μA(max)

D

Maximum Duty Cycle

95

%

93/90

93/90

%(min)

12.5

A/V

OMP

Transconductance

Switch Leakage

10

μA

Current

300/600

300/600

μA(max)

Switch Saturation

0.5

V

Voltage

0.7/0.9

0.7/0.9

V(max)

NPN Switch

4.3

A

Current Limit

3.7/3.0

3.7/3.0

A(min)

5.3/6.0

5.3/6.0

A(max)

THERMAL PARAMETERS (All Versions)

Thermal Resistance

K Package, Junction to Ambient

35

K Package, Junction to Case

1.5

T Package, Junction to Ambient

65

T Package, Junction to Case

2

°C/W

85

100

37

(6)

Junction to ambient thermal resistance with approximately 1 square inch of pc board copper surrounding the leads. Additional copper

area will lower thermal resistance further. See thermal model in “Switchers Made Simple” software.

(7)

If the DDPAK/TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally

connected to the package. Using 0.5 square inches of copper area,

and with 1.6 or more square inches of copper area,

8

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