Datasheet

LM27313
SNVS487D –DECEMBER 2006–REVISED APRIL 2013 www.ti.com
Figure 17. Discontinuous Design, 5V–12V Boost
The voltage across the inductor during ON time is 4.8V. Minimum inductance value is found by:
L = V x (dt/dl) (17)
L = 4.8V x (0.524 µs / 0.8 mA) = 3.144 µH (18)
In this case, a 3.3 µH inductor could be used, assuming it provided at least that much inductance up to the 800
mA current value. This same analysis can be used to find the minimum inductance for any boost application.
INDUCTOR SUPPLIERS
Some of the recommended suppliers of inductors for this product include, but are not limited to, Sumida,
Coilcraft, Panasonic, TDK and Murata. When selecting an inductor, make certain that the continuous current
rating is high enough to avoid saturation at peak currents. A suitable core type must be used to minimize core
(switching) losses, and wire power losses must be considered when selecting the current rating.
SHUTDOWN PIN OPERATION
The device is turned off by pulling the shutdown pin low. If this function is not going to be used, the pin should be
tied directly to V
IN
. If the SHDN function will be needed, a pull-up resistor must be used to V
IN
(50kΩ to 100 kΩ is
recommended), or the pin must be actively driven high and low. The SHDN pin must not be left unterminated.
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