tb62732fu TOSHIBA Semiconductor CORPORATION, tb62732fu Datasheet - Page 6

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

A terminal
voltage
K terminal
voltage
IF currnet
C2 = 0.1 µF
20 mA/DIV
The Stae of the Peak Current Control
former page. The current pulse of the figure 4 is a charging current on the output side capacitor C
It could may set at about 48 to 54 mV.
320 mW.
0.5 V/DIV
Peak current control is the control that variability peak current pulse which shows in the figure 2 of the
It is supplied to LED as a discharge current on the C
And, as for the charging voltage wave form of the C
Peak currents are decreased with the internal circuit which a pin K should be input from the AC voltage wave.
A constant current is controlled as an average current in LED as that result.
Therefore, when R_sens = 2.7 Ω is connected, it can get I
The most suitable design has a boost up inductance worn by inductance 4.7 to 10 µH to the load power
And, make an inductance small when load power is low.
Keep "V
There are no relations with the control of the IC, and LED always comes to turn on.
Please, be careful.
5 V/DIV
Maximum On pulse
width = 85%
LED V
Pin A voltage
I
Pin A current (external
inductance current)
Pin K voltage (current
charged on capacitor)
A
IN
(peak)
(V
F
CC
) < LED V
F
Figure 3 Burst Control Waveforms
total" strictly as a condition about the LED between the pin A and the pin K.
t
Switching frequency
f
OSC
= 1.1 MHz
200 ns/DIV
2
6
, it feed back in the IC from the pin K.
2
and flows through the R_sens to GND.
F
Standby Operation
operation. When SHDN is set to Low, the operation
is standby; when High, the LED is turned on.
Current consumption in Standby Mode is 1 µA
(max).
Drive Waveform
the coil of the generator terminal, the feedback
voltage wave form of the K terminal, and I
of 19.6 mA at of 53 mV.
The SHDN pin is used to set normal or standby
A left figure is an actual drive waveform.
From the top, the switching voltage waveform of
It stabillizes it in the set I
with lowering I
It stabillizes it in the set I
with lowering I
A
A
(peak).
(peak).
TB62732FU
2006-06-14
o
2
.
o
F
of LED.