6.4 Thermal Information
| THERMAL METRIC(1)(2) |
LM2585 |
UNIT |
| KTT (DDPAK/TO-263 |
NDH (TO-220) |
| 5 PINS |
5 PINS |
| RθJA |
Junction-to-ambient thermal resistance |
56(5) |
65(3) |
°C/W |
| 35(6) |
45(4) |
| 26(7) |
— |
| RθJC |
Junction-to-case thermal resistance |
2 |
2 |
°C/W |
(2) External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM2587 is used as shown in
Figure 61 and
Figure 62, system performance will be as specified by the system parameters.
(3) Junction-to-ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with ½ inch leads in a socket, or on a PC board with minimum copper area.
(4) Junction-to-ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with ½ inch leads soldered to a PC board containing approximately 4 square inches of (1oz.) copper area surrounding the leads.
(5) Junction-to-ambient thermal resistance for the 5 lead TO-263 mounted horizontally against a PC board area of 0.136 square inches (the same size as the TO-263 package) of 1 oz. (0.0014 in. thick) copper.
(6) Junction-to-ambient thermal resistance for the 5 lead TO-263 mounted horizontally against a PC board area of 0.4896 square inches (3.6 times the area of the TO-263 package) of 1 oz. (0.0014 in. thick) copper.
(7) Junction-to-ambient thermal resistance for the 5 lead TO-263 mounted horizontally against a PC board copper area of 1.0064 square inches (7.4 times the area of the TO-263 package) of 1 oz. (0.0014 in. thick) copper. Additional copper area reduces thermal resistance further. See the thermal model in Switchers Made Simple® software.