LTC4006EGN-2#TR Linear Technology, LTC4006EGN-2#TR Datasheet - Page 13

• Manufacturer Part Number: LTC4006EGN-2#TR
• Description: IC CHARGER BATTERY 4A 16-SSOP
• Manufacturer: Linear Technology

Specifications of LTC4006EGN-2#TR

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 6 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Output Current: 4A
• Output Voltage: 12.6V
• Operating Supply Voltage (min): 6V
• Operating Supply Voltage (max): 28V
• Operating Temp Range: -40C to 85C
• Package Type: SSOP N
• Mounting: Surface Mount
• Pin Count: 16
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
Soft-Start
The LTC4006 is soft started by the 0.12µF capacitor on the
I
then ramp up at a rate set by the internal 40µA pull-up
current and the external capacitor. Battery charging
current starts ramping up when I
and full current is achieved with I
capacitor, time to reach full charge current is about 2ms
and it is assumed that input voltage to the charger will
reach full value in less than 2ms. The capacitor can be
increased up to 1µF if longer input start-up times are
needed.
Input and Output Capacitors
The input capacitor (C2) is assumed to absorb all input
switching ripple current in the converter, so it must have
adequate ripple current rating. Worst-case RMS ripple
current will be equal to one half of output charging current.
Actual capacitance value is not critical. Solid tantalum low
ESR capacitors have high ripple current rating in a rela-
tively small surface mount package, but caution must be
used when tantalum capacitors are used for input or
output bypass . High input surge currents can be created
when the adapter is hot-plugged to the charger or when a
battery is connected to the charger. Solid tantalum capaci-
tors have a known failure mechanism when subjected to
very high turn-on surge currents. Only Kemet T495 series
of “Surge Robust” low ESR tantalums are rated for high
surge conditions such as battery to ground.
The relatively high ESR of an aluminum electrolytic for C1,
located at the AC adapter input terminal, is helpful in
reducing ringing during the hot-plug event. Refer to Appli-
cation Note 88 for more information.
Highest possible voltage rating on the capacitor will mini-
mize problems. Consult with the manufacturer before use.
Alternatives include new high capacity ceramic (at least
20µF) from Tokin, United Chemi-Con/Marcon, et al. Other
alternative capacitors include OS-CON capacitors from
Sanyo.
The output capacitor (C3) is also assumed to absorb
output switching current ripple. The general formula for
capacitor current is:
TH
pin. On start-up, I
U
TH
pin voltage will rise quickly to 0.5V,
U
TH
TH
W
voltage reaches 0.8V
at 2V. With a 0.12µF
U
For example:
EMI considerations usually make it desirable to minimize
ripple current in the battery leads, and beads or inductors
may be added to increase battery impedance at the 300kHz
switching frequency. Switching ripple current splits be-
tween the battery and the output capacitor depending on
the ESR of the output capacitor and the battery impedance.
If the ESR of C3 is 0.2Ω and the battery impedance is
raised to 4Ω with a bead or inductor, only 5% of the
current ripple will flow in the battery.
Inductor Selection
Higher operating frequencies allow the use of smaller
inductor and capacitor values. A higher frequency gener-
ally results in lower efficiency because of MOSFET gate
charge losses. In addition, the effect of inductor value on
ripple current and low current operation must also be
considered. The inductor ripple current ∆I
with higher frequency and increases with higher V
Accepting larger values of ∆I
inductances, but results in higher output voltage ripple
and greater core losses. A reasonable starting point for
setting ripple current is ∆I
∆I
CA1. Remember the maximum ∆I
mum input voltage. In practice 10µH is the lowest value
recommended for use.
Lower charger currents generally call for larger inductor
values. Use Table 4 as a guide for selecting the correct
inductor value for your application.
L
V
f = 300kHz, I
I
∆ =
RMS
exceed 0.6(I
DCIN
I
L
=
= 19V, V
( )( )
f L
0 29
1
.
(
RMS
V
V
MAX
OUT
BAT
BAT
( )( )
= 0.41A.
L f
) due to limits imposed by I
⎛
⎜
⎝
)
1
= 12.6V, L1 = 10µH, and
⎛
⎜
⎝
1–
1
–
L
V
V
V
OUT
= 0.4(I
V
IN
DCIN
BAT
L
⎞
⎟
⎠
⎞
⎟
⎠
allows the use of low
MAX
L
occurs at the maxi-
). In no case should
LTC4006
L
decreases
REV
13
IN
.
4006fa
and