LTC4055EUF-1#TRPBF Linear Technology, LTC4055EUF-1#TRPBF Datasheet - Page 20

• Manufacturer Part Number: LTC4055EUF-1#TRPBF
• Description: IC USB PWR MNGR BATT CHRGR 16QFN
• Manufacturer: Linear Technology

Specifications of LTC4055EUF-1#TRPBF

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-WQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC4055/LTC4055-1
OPERATION
The LTC4055/LTC4055-1 can be used above 46°C, but the
charge current will be reduced below 0.8A. The charge
current at a given ambient temperature can be approxi-
mated by:
Consider the above example with an ambient temperature
of 55°C. The charge current will be reduced to approxi-
mately:
Board Layout Considerations
In order to be able to deliver maximum charge current
under all conditions, it is critical that the Exposed Pad
on the backside of the LTC4055/LTC4055-1 package is
soldered to the board. Correctly soldered to a 2500mm
double-sided 1oz. copper board, the LTC4055/LTC4055-1
has a thermal resistance of approximately 37°C/W. Failure
to make thermal contact between the Exposed Pad on the
backside of the package and the copper board will result
in thermal resistances far greater than 37°C/W. As an
example, a correctly soldered LTC4055/LTC4055-1 can
deliver over 1A to a battery from a 5V supply at room
20
I
I
BAT
BAT
=
=
(
(
V
5
OUT
V
105
105
–
3
–
°
V
°
C
V
)
C T
BAT
–
•
–
37
55
)
A
°
°
• θ
C W
C
/
JA
Figure 4. LTC4055/LTC4055-1 vs Schottky Diode Forward Voltage Drop
=
74
I
I
MAX
FWD
50
°
0
V
C A
°
FWD
C
/
SLOPE: 1/R
=
0
.6 6 75A
SLOPE: 1/R
LTC4055
FWD
FORWARD VOLTAGE (V)
DIO,ON
2
SCHOTTKY
DIODE
temperature. Without a backside thermal connection, this
number could drop to less than 500mA.
STABILITY
The constant-voltage mode feedback loop is stable without
any compensation when a battery is connected. However,
a 1μF capacitor with a 1Ω series resistor to GND is recom-
mended at the BAT pin to keep ripple voltage low when
the battery is disconnected.
Ideal Diode from BAT to OUT
Forward regulation for the LTC4055/LTC4055-1 from BAT
to OUT has three operational ranges, depending on the
magnitude of the load current. For small load currents,
the LTC4055/LTC4055-1 will provide a constant-voltage
drop; this operating mode is referred to as “constant
V
drop will increase linearly with the current with a slope
of 1/R
“constant R
further, exceeding I
increase rapidly; this operating mode is referred to as
“constant I
following parameters: R
specifi ed with the aid of Figure 4.
ON
” regulation. As the current exceeds I
DIO,ON
CONSTANT
I
CONSTANT
R
CONSTANT
V
ON
ON
ON
ON
ON
; this operating mode is referred to as
” regulation. The characteristics for the
” regulation. As the current increases
MAX
4055 F04
, the forward voltage drop will
FWD
, R
ON
, V
FWD
FWD
, and I
, the voltage
FWD
4055fb
are