tb62731fug TOSHIBA Semiconductor CORPORATION, tb62731fug Datasheet - Page 9

• Manufacturer Part Number: tb62731fug
• 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.
may become less than the desired value.
make sure that surge current IFP (mA) does not flow to the LED.
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 = 1.8 ( Ω ), I
Take a current error of ± 10% (not including R_sens error) into consideration.
The IC has a minimum output P
At that time, if the product of mean current I
If the IC is not connected to the output-side capacitor (for smoothing), the set current I
At that time, because the current flowing to the LED is a pulse current with a maximum peak value of 270 mA,
Toshiba recommend use of components with low reactance (parasitic inductance) and minimized PCB wiring.
Toshiba also recommend allocating components in the application circuit diagram as near each other as possible.
I
o
(mA) = 36 (mV) ÷ R_sens ( Ω )
o
(mA) to be set is roughly calculated as follows:
Relation between set current IO and setting resistance R_sens
o
= 320 (mA, choke coil = 47 µ H).
40
30
20
10
10 9.1 8.2 6.8 5.6 4.7
0
Resistance for setting current R_sens (Ω)
o
= 20 (mA).
(typical value: V
: I o (mA)
o
and output voltage V
CC
Figure 4
3.3 2.7 2.2 2 1.8 1.5
=
9
3.6 V, Ta
=
25°C)
o
exceeds P
1.2
1
o
= 320 (mW), mean current I
o
. The mean output current I
o
can be obtained.
TB62731FUG
2006-06-14
o
o