TB62732FUG Datasheet, PDF (12/18 Pages) Toshiba Semiconductor – Step-up DC/DC Converter for White LED Driver

Application Evaluation Circuit Example 3
(Example of evaluation result using a small coil: Coil 976AS-6R8)
6.8 µH is optimum for illumination of serial LEDs 4 to 3 using IF = 20 mA.
4.7 µH is recommended for steady illumination of serial LED 2 in the range VIN > 4.5 V.
V_IN =
3.0 to 4.3 V
L1 = 6.8 µH S-Di
3 to 4
LEDs
V_CC
A
ON
SHDN
OFF
K
GND
I_F
TB62732FUG
L1 : TOKO 976AS-6R8
S-Di: TOSHIBA CUS02 30 V/1 A
LED: NICHIA NSCW215T
Note 9: Connection of C₃ is not necessary in every case. .
The IF is expected to stabilize on decrease of voltage. .
V_IN – Efficiency/I_F
25
85
V_IN – Efficiency/I_F
25
85
80
80
20
75
20
75
70
4 LEDs efficiency
4 LEDs IF
15
65
3
3.2 3.4 3.6 3.8
4
4.2
V_IN (V)
70
3 LEDs efficiency
3 LEDs IF
15
65
3
3.2 3.4 3.6 3.8
4
4.2
V_IN (V)
V_IN – Efficiency/I_F
25
85
80
20
75
70
2 LEDs efficiency
2 LEDs IF
15
65
3
3.2 3.4 3.6 3.8
4
4.2
V_IN (V)
<Measurement>
Efficiency in the range VIN = 3.0 to 4.3 V
Number
of LED
Efficiency (%)
Average Efficiency
(%)
2
79.7 to 84.4
82.3
3
76.7 to 82.1
79.5
4
73.1 to 79.7
74.0
IF in the range VIN = 3.0 to 4.3 V
Number
of LED
I_F (mA)
V_CC Dependence (%)
2
19.4 to 21.1
8.1
3
19.5 to 20.5
5.1
4
19.6 to 20.7
5.3
Note 10: The above values have been obtained
through Toshiba’s own measurements.
However, results may vary according to the
measurement environment.
12
2006-06-14