PR4401 Datasheet, PDF (7/12 Pages) List of Unclassifed Manufacturers – 0.9V Boost Driver for White LEDs PR4401/4402 Requires Only One External Component

LED DRIVER PR4401/PR4402
Connection from Battery
Due to high peak currents, it is important to connect the PR4401/PR4402 to the battery
with short, low resistance wires, to achieve the best performance. A voltage drop along the
wire affects LED current, efficiency and minimum startup and operating voltage.
This is most critical for applications with low inductivity and high current.
In cases where a longer wire from the battery cannot be avoided, a capacitor should be
placed close to the Vcc and Gnd pin of PR4401. Typically capacitors between 220nF and
1µF are used.
With PR4402 operated at higher currents, a blocking capacitor is usually necessary even
if wires or board layout are optimized.
Using Different Battery Types
The input voltage must be 1.90V at maximum. At higher voltages the circuit may not
trigger and start up correctly. Therefore operation with one Alkaline, NiCd, or NiMH cell
(AA or AAA type) is recommended.
Alkaline button cells can also be used for supply. However, since high peak currents are
drawn from the battery, button cells are recommended only with inductors of 22µH or
more, depending on the battery type. A capacitor at the supply pins of PR4401 may also
improve performance with button cells.
Lithium batteries are not suitable due to their higher voltage.
Approximate battery lifetime:
Battery
AA (Mignon, LR 6/AM-3)
AAA (Micro, LR 03/AM-4)
Battery Lifetime, typical
L1= 22µH, LED mean current 12mA
55 h
22 h
Battery Lifetime, typical
L1= 10µH, LED mean current 23mA
27 h
8h
Conditions: one white LED connected, measured with single 1.5V TDK Alkaline battery.
Battery lifetime depends on battery capacity and operating conditions. Therefore the times
indicated here can only give a rough indication of achievable times.
Connecting several LEDs in parallel
When several LEDs are connected in parallel, it is necessary to match the forward voltage
of these LEDs, to achieve a uniform brightness. The total current of all LEDs together
corresponds approximately to the mean output current for operation with one LED.
Vbat =1.2V or 1.5V ^L1=10µH
Vcc
Vout
Gnd
PR4401
Matching
White
LEDs
© PREMA Semiconductor GmbH 2006-2008
Page 7/12
Rev 0908