LTC3406B-2ES5#PBF Linear Technology, LTC3406B-2ES5#PBF Datasheet - Page 12

• Manufacturer Part Number: LTC3406B-2ES5#PBF
• Manufacturer: Linear Technology

Specifications of LTC3406B-2ES5#PBF

• Dc To Dc Converter Type: Step Down
• Pin Count: 5
• Input Voltage: 5.5V
• Output Voltage: 0.6 to 5.5V
• Switching Freq: 2.7MHz
• Output Current: 600mA
• Efficiency: 96%
• Package Type: TSOT-23
• Output Type: Adjustable
• Switching Regulator: Yes
• Load Regulation: 0.5%
• Line Regulation: 0.4%/V
• Mounting: Surface Mount
• Input Voltage (min): 2.5V
• Operating Temperature Classification: Industrial
• Number Of Outputs: 1
• Lead Free Status / RoHS Status: Compliant

APPLICATIO S I FOR ATIO
LTC3406B-2
Design Example
As a design example, assume the LTC3406B-2 is used in
a single lithium-ion battery-powered cellular phone
application. The V
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),
Substituting V
f = 2.25MHz in equation (3) gives:
12
L
L
=
=
( )
1 5
f
.
( )
MHz
1
∆
I
L
2 5
OUT
.
(
V
240
V
OUT
IN
= 2.5V, V
U
mA
will be operating from a maximum of
⎛
⎜
⎝
1
)
−
⎛
⎜
⎝
1
U
V
V
OUT
−
IN
IN
2 5
4 2
= 4.2V, ∆I
.
.
⎞
⎟
⎠
V
V
⎞
⎟ =
⎠
W
TO 4.2V
2.7V
1 87
V
.
IN
100
L
90
80
70
60
50
40
30
20
10
0.1
= 240mA and
µ
V
T
H
OUT
A
C
4.7µF
CER
= 25°C
U
IN
V
= 2.5V
IN
†
= 2.7V
OUTPUT CURRENT (mA)
** TAIYO YUDEN JHK316BJ106ML
1
*MURATA LQH32CN2R2M33
†
4
1
TAIYO YUDEN JMK212BJ475MG
V
RUN
(3)
Figure 7b
LTC3406B-2
Figure 7a
IN
GND
V
10
IN
2
= 3.6V
SW
V
V
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.
C
I
of less than 0.25Ω. In most cases, a ceramic capacitor will
satisfy this requirement.
For the feedback resistors, choose R1 = 316k. R2 can
then be calculated from equation (2) to be:
Figure 7 shows the complete circuit along with its effi-
ciency curve.
LOAD(MAX)
FB
IN
IN
= 4.2V
R
3
5
will require an RMS current rating of at least 0.3A ≅
100
2
=
316k
2.2µH*
3406B F07a
3406B G04
22pF
⎛
⎜
⎝
1M
V
/2 at temperature and C
0 6
1000
OUT
.
−
1 1 1000
⎞
⎟
⎠
C
10µF
CER
R
OUT
**
=
V
2.5V
OUT
k
OUT
will require an ESR
sn3406b2 3406b2fs