TB62731FUG Datasheet, PDF (11/20 Pages) Marktech Corporate – Step-up DC-DC Converter for White LED Driver

TB62731FUG
The self-generated temperature Tup (°C) is calculated as follows:
Tup (°C) = ((0.32 − (0.32 × 0.7)) − (0.5 × 0.1 + 0.3 × 0.02 + 1.8 × 0.02 × 0.02)) × 260 = 10.2 (°C)
Thus, the derating start temperature Ts (°C) is calculated as follows:
Ts (°C) = 45 (°C) − 10.4 (°C) = 34.8 (°C)
As a result, Io is controlled in the recommended current range as shown in Figure 5.
Since saturation thermal resistance θja = 260 (°C/W) is the maximum value, θja = 210~260 (°C/W) is used as a
mounting condition.
Depending on the IC characteristics, peripherals, and use environment, the derating start temperature
fluctuates among ICs.
120
100
80
60
40
Change from T_s = 34.8°C (20 mA = 100%)
20
Change according to T_js
Recommended LED current range (converted by 25 mA)
0
0
25
50
75
100
Temperatures T_s (°C) and T_js (°C)
Figure 5 Derating Function of Set Current
11
2006-06-14