Datasheet

V
IN
(V)
MAX LOAD CURRENT (mA)
0
200
400
600
800
1000
1200
2 3 4 5 6 7 8 9 10 11
V
OUT
= 5V
V
OUT
= 8V
V
OUT
= 10V
V
OUT
= 12V
V
OUT
= 18V
LMR62014
SNVS735B –OCTOBER 2011–REVISED APRIL 2013 www.ti.com
Figure 22. Max. Load Current (typ) vs V
IN
DESIGN PARAMETERS V
SW
AND I
SW
The value of the FET "ON" voltage (referred to as V
SW
in the equations) is dependent on load current. A good
approximation can be obtained by multiplying the "ON Resistance" of the FET times the average inductor
current.
FET on resistance increases at V
IN
values below 5V, since the internal N-FET has less gate voltage in this input
voltage range (see Typical Performance Characteristics curves). Above V
IN
= 5V, the FET gate voltage is
internally clamped to 5V.
The maximum peak switch current the device can deliver is dependent on duty cycle. For higher duty cycles, see
Typical Performance Characteristics curves.
THERMAL CONSIDERATIONS
At higher duty cycles, the increased ON time of the FET means the maximum output current will be determined
by power dissipation within the LMR62014 FET switch. The switch power dissipation from ON-state conduction is
calculated by:
P
(SW)
= DC x I
IND
(AVE)
2
x R
DS
(ON) (11)
There will be some switching losses as well, so some derating needs to be applied when calculating IC power
dissipation.
INDUCTOR SUPPLIERS
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
(approximately
50k-100kΩ recommended). The SHDN pin must not be left unterminated.
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