Electrical Characteristics — LM1577-ADJ, LM2577-ADJ
(Continued)
Specifications with standard type face are for T
J
= 25˚C, and those in
bold type face
apply over full
Operating Temperature
Range.
Unless otherwise specified, V
IN
= 5V, V
FEEDBACK
= V
REF
, and I
SWITCH
= 0.
LM1577-ADJ LM2577-ADJ
Symbol
Parameter
Conditions
Typical
Limit
(Notes 3, 4)
DEVICE PARAMETERS
I
L
V
SAT
Switch Leakage
Current
Switch Saturation
Voltage
NPN Switch
Current Limit
THERMAL PARAMETERS (All Versions)
θ
JA
θ
JC
θ
JA
θ
JC
θ
JA
θ
JA
θ
JA
Thermal Resistance
K Package, Junction to Ambient
K Package, Junction to Case
T Package, Junction to Ambient
T Package, Junction to Case
N Package, Junction to
Ambient (Note 8)
M Package, Junction
to Ambient (Note 8)
S Package, Junction to
Ambient (Note 9)
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions the device is intended to
be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see the Electrical
Characteristics.
Note 2:
Due to timing considerations of the LM1577/LM2577 current limit circuit, output current cannot be internally limited when the LM1577/LM2577 is used as a
step-up regulator. To prevent damage to the switch, its current must be externally limited to 6.0A. However, output current is internally limited when the LM1577/
LM2577 is used as a flyback or forward converter regulator in accordance to the Application Hints.
Note 3:
All limits guaranteed at room temperature (standard type face) and at temperature extremes (boldface type). All limits are used to calculate Outgoing Quality
Level, and are 100% production tested.
Note 4:
A military RETS electrical test specification is available on request. At the time of printing, the LM1577K-12/883, LM1577K-15/883, and LM1577K-ADJ/883
RETS specifications complied fully with the boldface limits in these columns. The LM1577K-12/883, LM1577K-15/883, and LM1577K-ADJ/883 may also be procured
to Standard Military Drawing specifications.
Note 5:
All limits guaranteed at room temperature (standard type face) and at temperature extremes (boldface type). All room temperature limits are 100% produc-
tion tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
Note 6:
External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM1577/LM2577 is used
as shown in the Test Circuit, system performance will be as specified by the system parameters.
Note 7:
A 1.0 MΩ resistor is connected to the compensation pin (which is the error amplifier’s output) to ensure accuracy in measuring A
VOL
. In actual applications,
this pin’s load resistance should be
≥10
MΩ, resulting in A
VOL
that is typically twice the guaranteed minimum limit.
Note 8:
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.
Note 9:
If the 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,
θ
JA
is 50˚C/W; with 1 square inch of copper area,
θ
JA
is 37˚C/W; and with 1.6 or more square inches of copper area,
θ
JA
is 32˚C/W.
Units
(Limits)
Limit
(Note 5)
V
SWITCH
= 65V
V
FEEDBACK
= 1.5V (Switch Off)
I
SWITCH
= 2.0A
V
COMP
= 2.0V (Max Duty Cycle)
V
COMP
= 2.0V
10
300/600
0.5
0.7/0.9
4.3
3.7/3.0
5.3/6.0
35
1.5
65
2
85
100
37
3.7/3.0
5.3/6.0
0.7/0.9
300/600
µA
µA(max)
V
V(max)
A
A(min)
A(max)
˚C/W
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