LTC3550EDHC-1#TR Linear Technology, LTC3550EDHC-1#TR Datasheet - Page 21

• Manufacturer Part Number: LTC3550EDHC-1#TR
• Description: IC,Battery Management,CMOS,LLCC,16PIN,PLASTIC
• Manufacturer: Linear Technology
• Type: Battery Chargerr

Specifications of LTC3550EDHC-1#TR

• Battery Type: Li-Ion
• Output Current: 800mA
• Output Voltage: 4.2V
• Operating Supply Voltage (min): 2.5V
• Operating Supply Voltage (max): 5.5V
• Operating Temp Range: -40C to 85C
• Mounting: Surface Mount
• Pin Count: 16
• Operating Temperature Classification: Industrial
• Lead Free Status / Rohs Status: Not Compliant

and high load currents is important. With this information
we can calculate L using Equation (1),
Substituting V
f
APPLICATIO S I FOR ATIO
O
= 1.5MHz in Equation (3) gives:
L
∆ =
I
=
L
1 5
.
V
f
O
MHz
OUT
•
1 875
L
OUT
.
• 1
• (
⎛
⎝ ⎜
= 1.875V, V
240
U
V
−
mA
V
V
OUT
CC
U
)
•
⎞
⎠ ⎟
⎛
⎝ ⎜
CC
V
1
CC
−
= 4.2V, ΔI
V
1 875
CC
VIA TO V
.
W
4 2
.
C
IN
V
Figure 6. DC-DC Converter Suggested Layout
Figure 5. DC-DC Converter Layout Diagram
V
OUT
+
–
L
⎞
⎠ ⎟
= 240mA and
=
C
2
U
IN
GND
. . 88µH
6
7
8
V
V
GND
OUT
CC
LTC3550-1
17
C
GND
A 2.2µH inductor works well for this application. For best
effi ciency choose a 720mA or greater inductor with less
than 0.2Ω series resistance. C
rent rating of at least 0.3A = I
and C
cases, a ceramic capacitor will satisfy this requirement.
Figure 7 shows the complete circuit along with its ef-
fi ciency curve.
OUT
SW
10
9
OUT
V
BOLD LINES INDICATE
HIGH CURRENT PATHS
C
OUT
OUT
will require an ESR of less than 0.25Ω. In most
–
SW
+
V
OUT
VIA TO V
3550-1 F05
L1
CC
L1
3550-1 F06
LOAD(MAX)
IN
will require an RMS cur-
LTC3550-1
/2 at temperature
21
35501f