tb62732fu TOSHIBA Semiconductor CORPORATION, tb62732fu Datasheet - Page 11

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

Application Evaluation Circuit Example 2
(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
Note 7: 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 CXML321610-7R0
S-Di : TOSHIBA CUS02 30 V/1 A
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 = 7.0 µH S-Di
CC
GND
11
A
K
<Measurement>
The efficiency of the V
The I
Note 8: The value is our company actual
Number
Number
of LED
of LED
25
20
15
2
3
4
2
3
4
=
3
F
CXML321610-7R0)
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
78.2 to 84.1
72.0 to 79.1
66.9 to 71.1
19.8 to 21.6
20.0 to 21.0
20.4 to 21.5
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
81.3
75.8
74.6
(%)
8.1
4.8
4.9
2006-06-14
85
80
75
70
65