LM1577, LM2577
SNOS658D –JUNE 1999–REVISED APRIL 2013
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Electrical Characteristics—LM1577-ADJ, LM2577-ADJ (continued)
Specifications with standard type face are for TJ = 25°C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, VIN = 5V, VFEEDBACK = VREF, and ISWITCH = 0.
Symbol
Parameter
Conditions
Typical
LM1577-ADJ LM2577-ADJ
Units
(Limits)
Limit(1)(2)
Limit(3)
Error Amp
Output Current
VFEEDBACK = 1.0V to 1.5V
VCOMP = 1.0V
±200
μA
μA(min)
μA(max)
μA
±130/±90
±130/±90
±300/±400
±300/±400
ISS
Soft Start Current
VFEEDBACK = 1.0V
VCOMP = 0V
5.0
95
2.5/1.5
7.5/9.5
2.5/1.5
7.5/9.5
μA(min)
μA(max)
%
D
Maximum Duty Cycle
VCOMP = 1.5V
ISWITCH = 100 mA
93/90
93/90
%(min)
A/V
ΔISWITCH/ΔVC Switch
12.5
10
Transconductance
OMP
IL
Switch Leakage
Current
VSWITCH = 65V
VFEEDBACK = 1.5V (Switch Off)
μA
μA(max)
V
300/600
0.7/0.9
300/600
0.7/0.9
VSAT
Switch Saturation
Voltage
ISWITCH = 2.0A
VCOMP = 2.0V (Max Duty Cycle)
0.5
4.3
V(max)
A
NPN Switch
Current Limit
VCOMP = 2.0V
3.7/3.0
5.3/6.0
3.7/3.0
5.3/6.0
A(min)
A(max)
THERMAL PARAMETERS (All Versions)
θJA
θJC
Thermal Resistance
K Package, Junction to Ambient
K Package, Junction to Case
35
1.5
θJA
θJC
T Package, Junction to Ambient
T Package, Junction to Case
65
2
°C/W
(6)
(6)
(7)
θJA
θJA
θJA
N Package, Junction to Ambient
M Package, Junction to Ambient
S Package, Junction to Ambient
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, θJA is 50°C/W; with 1 square inch of copper area, θJA is 37°C/W;
and with 1.6 or more square inches of copper area, θJA is 32°C/W.
8
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