Datasheet

LM2841, LM2842
SNVS540H –MARCH 2009–REVISED APRIL 2013 www.ti.com
Electrical Characteristics (continued)
Specifications in standard type face are for T
J
= 25°C and those with boldface type apply over the full Operating
Temperature Range ( T
J
= −40°C to +125°C). Minimum and Maximum limits are specified through test, design, or statistical
correlation. Typical values represent the most likely parametric norm at T
J
= +25°C, and are provided for reference purposes
only. Unless otherwise stated the following conditions apply: V
IN
= 12V.
Symbol Parameter Conditions Min
(1)
Typ
(2)
Max
(1)
Units
t
ON(min)
Minimum ON time See
(6)
100 150 ns
t
OFF(min)
Minimum OFF time X option 110 370 ns
Y option 104 200 ns
f
SW
LM2840/41/42X, V
FB
= 0.5V 325 550 750
kHz
LM2840/41/42X, V
FB
= 0V 140
Switching frequency
LM2840/41/42Y, V
FB
= 0.5V 0.95 1.25 1.50
MHz
LM2840/41/42Y, V
FB
= 0V 0.35
D
MAX
Maximum duty cycle LM2840/41/42X 88 94
%
LM2840/41/42Y 81 87
V
UVP
Undervoltage lockout On threshold 4.4 3.7
V
thresholds
Off threshold 3.5 3.25
V
SHDN
Shutdown threshold Device on 2.3 1.0
V
Device off 0.9 0.3
I
SHDN
Shutdown pin input bias current V
SHDN
= 2.3V
(5)
0.05 1.5
µA
V
SHDN
= 0V 0.02 1.5
THERMAL SPECIFICATIONS
R
θJA
Junction-to-Ambient Thermal See
(7)
121 °C/W
Resistance, SOT-6L Package
R
θJC
Junction-to-Case Thermal
94 °C/W
Resistance, SOT-6L Package
(6) Minimum On Time specified by design and simulation.
(7) All numbers apply for packages soldered directly onto a 3" x 3" PC board with 2 oz. copper on 4 layers in still air in accordance to
JEDEC standards. Thermal resistance varies greatly with layout, copper thickness, number of layers in PCB, power distribution, number
of thermal vias, board size, ambient temperature, and air flow.
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