tb62732fug TOSHIBA Semiconductor CORPORATION, tb62732fug Datasheet - Page 12

• Manufacturer Part Number: tb62732fug
• Description: Step-up Dc/dc Converter For White Led Driver
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Application Evaluation Circuit Example 3
(Example of evaluation result using a small coil: Coil 976AS-6R8)
Note 9: Connection of C
6.8 µH is optimum for illumination of serial LEDs 4 to 3 using I
4.7 µH is recommended for steady illumination of serial LED 2 in the range V
25
20
15
25
20
15
3
3
The IF is expected to stabilize on decrease of voltage. .
3.2
3.2
3.4
3.4
V
V
IN
IN
3
– Efficiency/I
– Efficiency/I
3.6
3.6
V
V
is not necessary in every case. .
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 : TOKO 976AS-6R8
S-Di : TOSHIBA CUS02 30 V/1 A
LED : NICHIA NSCW215T
4.2
4.2
ON
OFF
85
80
75
70
65
85
80
75
70
65
SHDN
V
L1 = 6.8 µH S-Di
CC
GND
12
A
K
<Measurement>
Efficiency in the range V
I
Note 10: The above values have been obtained
Number
F
Number
of LED
of LED
in the range V
25
20
15
F
2
3
4
2
3
4
3
= 20 mA.
through Toshiba’s own measurements.
However, results may vary according to the
measurement environment.
3.2
I
F
Efficiency (%)
3 to 4
79.7 to 84.4
76.7 to 82.1
73.1 to 79.7
19.4 to 21.1
19.5 to 20.5
19.6 to 20.7
LEDs
3.4
I
V
IN
F
IN
IN
(mA)
= 3.0 to 4.3 V
– Efficiency/I
> 4.5 V.
3.6
V
IN
IN
(V)
3.8
= 3.0 to 4.3 V
V
F
3 LEDs efficiency
3 LEDs I F
Average Efficiency
CC
4
TB62732FUG
Dependence (%)
4.2
82.3
79.5
74.0
(%)
8.1
5.1
5.3
2006-06-14
85
80
75
70
65