All Output Voltage Versions
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over full Operating Temperature
Range. Unless otherwise specified, V
IN
= 12V for the 3.3V, 5V, and Adjustable version, V
IN
= 25V for the 12V version, and
V
IN
= 30V for the 15V version. I
LOAD
= 500 mA.
Symbol
Parameter
Conditions
LM2576-XX
LM2576HV-XX
Typ
ON /OFF CONTROL Test Circuit
Figure 2
V
IH
V
IL
I
IH
I
IL
ON /OFF Pin
Logic Input Level
ON /OFF Pin Input
Current
ON /OFF Pin = 0V (ON)
0
10
V
OUT
= 0V
V
OUT
= Nominal Output Voltage
ON /OFF Pin = 5V (OFF)
1.4
1.2
12
30
2.2/2.4
1.0/0.8
V(Min)
V(Max)
µA
µA(Max)
µA
µA(Max)
Limit
(Note 2)
Units
(Limits)
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2:
All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). 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 3:
External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/
LM2576HV is used as shown in the
Figure 2
test circuit, system performance will be as shown in system parameters section of Electrical Characteristics.
Note 4:
Output pin sourcing current. No diode, inductor or capacitor connected to output.
Note 5:
Feedback pin removed from output and connected to 0V.
Note 6:
Feedback pin removed from output and connected to +12V for the Adjustable, 3.3V, and 5V versions, and +25V for the 12V and 15V versions, to force the
output transistor OFF.
Note 7:
V
IN
= 40V (60V for high voltage version).
Note 8:
Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with
1
⁄
2
inch leads in a socket, or on a PC
board with minimum copper area.
Note 9:
Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with
1
⁄
4
inch leads soldered to a PC board
containing approximately 4 square inches of copper area surrounding the leads.
Note 10:
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.
Note 11:
The oscillator frequency reduces to approximately 11 kHz in the event of an output short or an overload which causes the regulated output voltage to drop
approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycle
from 5% down to approximately 2%.
Typical Performance Characteristics
Normalized Output Voltage
Line Regulation
(Circuit of
Figure 2)
Dropout Voltage
DS011476-27
DS011476-28
DS011476-29
www.national.com
6
ETC [ ETC ]
