tb62732fu TOSHIBA Semiconductor CORPORATION, tb62732fu Datasheet - Page 8

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

Selection of R_sens
can be set according to the resistance.
LED may become less than the desired value.
380 mA, make sure that surge current I
LED becomes open.
becomes open, and to use small a zener diode of tolerance level.
(R_sens = 2.7 Ω)
Toshiba recommend 100 ohms or less.
Resistance between pin K and GND R_sens (Ω) is used for setting output current I
The mean current I
For example, when R_sens = 2.7 (Ω), I
The IC has a minimum output P
At that time, if the product of current I
If the IC is not connected to the smoothing capacitor, set mean current I
At that time, because the current which flows to the LED is a sine-wave current with a maximum peak value of
Toshiba recommend use of components with low reactance (parasitic inductance) and minimized PCB wiring.
A zener diode in an application circuit example of the figure 1 is necessary for the over-voltage protection when
It is recommended connecting a zener diode strongly because this driver doesn't have a voltage protection circuit.
A zener voltage is to satisfy the following condition.
Moreover, it is possible by connecting the figure 4 like R_ZD to be able to control output current when LED
The example of the IZD control by R_ZD connection.
Since it may have a bad influence on the characteristic of a driver,
i)
ii)
iii)
R_DZ (Ω)
I
Number of LEDs
Less than maximum output voltage of TB62732FU
Upper total series LED V
Less than maximum output capacitance C
o
100
(mA) = 36 (mV) ÷ R_sens (Ω)
18
2
3
4
O
(mA) to be set is roughly calculated as follows:
IZD (mA)
0.1
3
o
F
= 320 (mA).
Pin K voltage
FP
O
F
V (K)
= 18.5 (mA) and current error of ±12%.
48
50
52
LED and output voltage V
(mA) does not flow to the LED.
2
.
8
F
Figure 4 Application Circuit
LED exceeds P
F
GND
Note
LED can be obtained.
A
S-Di
K
O
. The mean output current I
o
IZD
= 320 (mW), current I
R_sens
0.47 µF
R_ZD
2.7 Ω
C2
TB62732FU
2006-06-14
F
IF
O