an30888b Panasonic Corporation of North America, an30888b Datasheet - Page 19

• Manufacturer Part Number: an30888b
• Description: High Brightness Led Driver Ic
• Manufacturer: Panasonic Corporation of North America

AN30888B
(1) Overview
AN30888B is a constant current LED driver. The IC works as a Boost /Buck-Boost/ Buck mode DCDC controller with external
MOSFET.
Operating input voltages ranges from 3 V to 15 V. The mode of operation depends on the number of LEDs to be driven and the supply
voltage level.
In general, please adhere to the following:
If total LED voltage drop is more than supply voltage, boost mode is adopted. If LED voltage drop is less than the supply voltage, buck
mode is adopted . If supply voltage is close to the total LED voltage drop, the Buck-Boost mode can be used. Please note that the
different mode of operation should be manually configured.
Output LED current can be designed ranges from 0 A and to a few amperes depending on the mode of operation, the external MOSFET
characteristic and feasible R
determines LED current by setting VFB_SEL pin with values of 32 mV or 202 mV under buck mode. By applying V
mV, user can achieve higher efficiency with lower power dissipation in R
current accuracy.
(2) Standby enable function
AN30888B enters standby mode when ENB pin is pulled low. During standby, the IC draws a small current of value less than 10 μA
from the power supply. This helps to achieve longer battery usage time. During Boost mode operation, although external MOSFET
cannot be turned on at standby condition, there is still a DC current path between the input and the LEDs through the inductor and
schottky diode. Thus it is important to make sure that during boost mode, the minimum forward voltage of the LED array must exceed
the maximum input voltage to ensure the LEDs remain off during standby mode.
Technical Data (continued)
Functions and properties descriptions
CS
value used. The control architecture uses current mode fix off time control. The V
) N LEDs
* V F
VIN
( V out
− − − =
- -
) * ( N LEDs
VF
VIN
Vout
− =
SDG00005AEB
CS
resistor. Applying 202 mV V
FB
voltage achieves better LED
FB
reference voltage
FB
voltage of 32
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