tb62732fu TOSHIBA Semiconductor CORPORATION, tb62732fu Datasheet - Page 13

• Manufacturer Part Number: tb62732fu
• Description: Step-up Dc/dc Converter For White Led Driver
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Application Evaluation Circuit Example 4
(the evaluation result example by the small coil: Coil
6.8 µH is the most suitable when serial 3 to 4 LEDs are turned on by I
4.7 µH is recommended when serial 2 LEDs are turned on steadily in the range of V
Note11: It doesn't surely need to connect C
25
20
15
25
20
15
3
3
The effect which becomes stable has I
3.2
3.2
3.4
3.4
V
V
IN
IN
– Efficiency/I
– Efficiency/I
3.6
3.6
V
V
IN
IN
3.0 to 4.3 V
(V)
(V)
3.8
3.8
V
IN
=
F
F
4 LEDs efficiency
4 LEDs I F
2 LEDs efficiency
2 LEDs I F
4
4
L1 : SUMITOMO CXLD140-6R8
S-Di : TOSHIBA CUS02 30 A/1 V
LED : NICHIA NSCW215T
4.2
4.2
ON
OFF
3
.
85
80
75
70
65
85
80
75
70
65
F
SHDN
V
in the decrease voltage expected.
L1 = 6.8 µH S-Di
CC
GND
13
A
K
<Measurement>
The efficiency of the V
The I
Note 12: The value is our company actual
Number
Number
of LED
of LED
25
20
15
2
3
4
2
3
4
=
3
F
CXLD140-6R8)
of the V
measurement value. The result has the
possibility to be different by the measurement
environment.
3.2
F
I
= 20 mA.
F
Efficiency (%)
3 to 4
80.3 to 84.9
77.2 to 82.8
74.1 to 80.4
19.4 to 21.0
19.5 to 20.5
19.6 to 20.7
LEDs
IN
3.4
I
V
F
IN
= 3.0 to 4.3 V range
(mA)
– Efficiency/I
3.6
V
IN
IN
IN
= 3.0 to 4.3 V range
(V)
3.8
> 4.5 V.
V
F
3 LEDs efficiency
3 LEDs I F
Average Efficiency
CC
4
Dependence (%)
TB62732FU
4.2
82.9
80.2
77.6
(%)
7.6
5.1
5.3
2006-06-14
85
80
75
70
65