LM2577N-12 National Semiconductor, LM2577N-12 Datasheet - Page 6

• Manufacturer Part Number: LM2577N-12
• Description: SIMPLE SWITCHER Step-Up Voltage Regulator
• Manufacturer: National Semiconductor

www.national.com
DEVICE PARAMETERS
I
V
THERMAL PARAMETERS (All Versions)
L
JA
JC
JA
JC
JA
JA
JA
Specifications with standard type face are for T
Range. Unless otherwise specified, V
SAT
Symbol
Electrical Characteristics — LM1577-ADJ, LM2577-ADJ
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 M
this pin’s load resistance should be 10 M , resulting in A
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,
Switch Leakage
Current
Switch Saturation
Voltage
NPN Switch
Current Limit
Thermal Resistance
resistor is connected to the compensation pin (which is the error amplifier’s output) to ensure accuracy in measuring A
Parameter
JA
is 50˚C/W; with 1 square inch of copper area,
IN
V
V
I
V
V
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)
SWITCH
SWITCH
FEEDBACK
COMP
COMP
= 5V, V
= 2.0V (Max Duty Cycle)
= 2.0V
VOL
= 2.0A
J
= 65V
FEEDBACK
= 25˚C, and those in bold type face apply over full Operating Temperature
Conditions
that is typically twice the guaranteed minimum limit.
= 1.5V (Switch Off)
= V
REF
6
, and I
JA
is 37˚C/W; and with 1.6 or more square inches of copper area,
SWITCH
Typical
100
0.5
4.3
1.5
10
35
65
85
37
2
= 0.
LM1577-ADJ LM2577-ADJ
(Notes 3, 4)
300/600
0.7/0.9
3.7/3.0
5.3/6.0
Limit
(Continued)
(Note 5)
300/600
0.7/0.9
3.7/3.0
5.3/6.0
Limit
VOL
. In actual applications,
JA
µA(max)
(Limits)
is 32˚C/W.
V(max)
A(max)
A(min)
Units
˚C/W
µA
V
A