LTC3406ABES5-TRPBF View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC3406ABES5-TRPBF' PDF : 16 Pages View PDF
Applications Information
1
RUN
VFB 5
LTC3406AB
R2
2
–
GND
VOUT
+
COUT
L1
3 SW
VIN 4
CIN
BOLD LINES INDICATE HIGH CURRENT PATHS
R1
CFWD
+
V–IN
3406AB F05a
Figure 3. LTC3406AB Layout Diagram
LTC3406AB
VOUT
VIA TO VIN
R1
PIN 1
L1 SW
LTC3406AB
R2
CFWD
VIN
VIA TO VOUT
COUT
CIN
GND
3406AB F06a
Figure 4. LTC3406AB Suggested Layout
Design Example
As a design example, assume the LTC3406AB is used
in a single lithium-ion battery-powered cellular phone
application. The VIN will be operating from a maximum of
4.2V down to about 2.7V. The load current requirement
is a maximum of 0.6A but most of the time it will be in
standby mode, requiring only 2mA. Efficiency at both
low and high load currents is important. Output voltage
is 2.5V. With this information we can calculate L using
Equation (1),
L
=
(
1
f )( DIL
)
VOUT
1−
VOUT
VIN
(3)
Substituting VOUT = 2.5V, VIN = 4.2V, ∆IL = 240mA and
f = 1.5MHz in Equation (3) gives:
L
=
2.5V
1.5MHz(240mA)
1−
2.5V
4.2V
=
2.81µH
A 2.2µH inductor works well for this application. For best
efficiency choose a 720mA or greater inductor with less
than 0.2Ω series resistance.
CIN will require an RMS current rating of at least 0.3A@
ILOAD(MAX)/2 at temperature and COUT will require an ESR
of less than 0.25Ω. In most cases, a ceramic capacitor
will satisfy this requirement.
For more information www.linear.com/LTC3406AB
3406abfb
13
Share Link: 
