Datasheet

LM2677
www.ti.com SNVS077I –MAY 2004–REVISED JUNE 2012
All Output Voltage Versions Electrical Characteristics (continued)
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, Sync pin open circuited..
Symbol Parameter Conditions Typ Min Max Units
θ
JA
Thermal NDZ Package, Junction to Ambient
(1)
65 °C/W
Resistance
θ
JA
NDZ Package, Junction to Ambient
(2)
45
θ
JC
NDZ Package, Junction to Case 2
θ
JA
KTW Package, Junction to Ambient
(3)
56
θ
JA
KTW Package, Junction to Ambient
(4)
35
θ
JA
KTW Package, Junction to Ambient
(5)
26
θ
JC
KTW Package, Junction to Case 2 ++
θ
JA
NHM Package, Junction to Ambient
(6)
55
°C/W
θ
JA
NHM Package, Junction to Ambient
(7)
29
(1) Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with ½ inch leads in a
socket, or on a PC board with minimum copper area.
(2) Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with ½ inch leads
soldered to a PC board containing approximately 4 square inches of (1 oz.) copper area surrounding the leads.
(3) Junction to ambient thermal resistance for the 7 lead DDPAK/TO-263 mounted horizontally against a PC board area of 0.136 square
inches (the same size as the DDPAK/TO-263 package) of 1 oz. (0.0014 in. thick) copper.
(4) Junction to ambient thermal resistance for the 7 lead DDPAK/TO-263 mounted horizontally against a PC board area of 0.4896 square
inches (3.6 times the area of the DDPAK/TO-263 package) of 1 oz. (0.0014 in. thick) copper.
(5) Junction to ambient thermal resistance for the 7 lead DDPAK/TO-263 mounted horizontally against a PC board copper area of 1.0064
square inches (7.4 times the area of the DDPAK/TO-263 package) of 1 oz. (0.0014 in. thick) copper. Additional copper area will reduce
thermal resistance further. See the thermal model in Switchers Made Simple software.
(6) Junction to ambient thermal resistance for the 14-lead VSON mounted on a PC board copper area equal to the die attach paddle.
(7) Junction to ambient thermal resistance for the 14-lead VSON mounted on a PC board copper area using 12 vias to a second layer of
copper equal to die attach paddle. Additional copper area will reduce thermal resistance further. For layout recommendations, refer to
Application Note AN-1187 (SNOA401).
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