LM2678
All Output Voltage Versions
Electrical Characteristics
Limits appearing in
bold type face
apply over the entire junction temperature range of operation, −40˚C to 125˚C.
Specifications appearing in normal type apply for T
A
= T
J
= 25˚C. Unless otherwise specified V
IN
=12V for the 3.3V, 5V and
Adjustable versions and V
IN
=24V for the 12V version.
Symbol
I
Q
Parameter
Quiescent
Current
Conditions
Typ
Min
Max
Units
DEVICE PARAMETERS
V
FEEDBACK
= 8V
For 3.3V, 5.0V, and ADJ Versions
V
FEEDBACK
= 15V
For 12V Versions
I
STBY
Standby
Quiescent
Current
Current Limit
Output
Leakage
Current
Switch
On-Resistance
Oscillator
Frequency
Duty Cycle
Feedback Bias
Current
ON/OFF
Threshold
Voltage
ON/OFF Input
Current
Thermal
Resistance
ON/OFF Input = 0V
T Package, Junction to Ambient
(Note 5)
T Package, Junction to Ambient
(Note 6)
θ
JC
θ
JA
θ
JA
θ
JA
θ
JC
T Package, Junction to Case
S Package, Junction to Ambient
(Note 7)
S Package, Junction to Ambient
(Note 8)
S Package, Junction to Ambient
(Note 9)
S Package, Junction to Case
2
++
Note 1:
Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings indicate conditions under which of the device is
guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test condition, see the electrical Char-
acteristics tables.
Note 2:
ESD was applied using the human-body model, a 100pF capacitor discharged through a 1.5 kΩ resistor into each pin.
Note 3:
Typical values are determined with T
A
= T
J
= 25˚C and represent the most likely norm.
Note 4:
All limits are guaranteed at room temperature (standard type face) and at
temperature extremes (bold type face).
All room temperature limits are 100%
tested during production with T
A
= T
J
= 25˚C. All limits at temperature extremes are guaranteed via correlation using standard standard Quality Control (SQC) meth-
ods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
Note 5:
Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with
1
⁄
2
inch leads in a socket, or on a PC
board with minimum copper area.
Note 6:
Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with
1
⁄
2
inch leads soldered to a PC board
containing approximately 4 square inches of (1 oz.) copper area surrounding the leads.
4.2
6
mA
ON/OFF Pin = 0V
50
7
V
IN
= 40V, ON/OFF Pin = 0V
V
SWITCH
= 0V
V
SWITCH
= −1V
I
SWITCH
= 5A
Measured at Switch Pin
Maximum Duty Cycle
Minimum Duty Cycle
V
FEEDBACK
= 1.3V
ADJ Version Only
1
6
0.12
260
91
0
85
225
6.1/5.75
100/150
8.3/8.75
200
15
0.14/0.225
280
µA
A
µA
mA
Ω
kHz
%
%
nA
I
CL
I
L
R
DS(ON)
f
O
D
I
BIAS
V
ON/OFF
1.4
0.8
2.0
V
I
ON/OFF
θ
JA
θ
JA
20
65
45
2
56
35
26
45
µA
˚C/W
www.national.com
4
NSC [ NATIONAL SEMICONDUCTOR ]
