LTC4055EUF#TRPBF Linear Technology, LTC4055EUF#TRPBF Datasheet - Page 18

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

Specifications of LTC4055EUF#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 nearest 1% value for R
used to bias the NTC thermistor to get cold and hot trip
points of approximately 0°C and 44°C respectively. To
extend the delta between the cold and hot trip points a
resistor, R1, can be added in series with R
The values of the resistors are calculated as follows:
where R
R
trip points. Continuing the example from before with a
desired hot trip point of 50°C:
The fi nal solution is as shown if Figure 3b where R
121k, R1 = 13.3k and R
CURRENT LIMIT UNDERVOLTAGE LOCKOUT
An internal undervoltage lockout circuit monitors the input
voltage and keeps the current limit circuits of the part in
shutdown mode until V
lockout threshold. The current limit UVLO circuit has a
built-in hysteresis of 125mV. Furthermore, to protect
against reverse current in the power MOSFET, the current
limit UVLO circuit keeps the current limit shutdown if
V
is tripped, the current limit circuits will not come out of
shutdown until V
18
R
R
OUT
COLD
NOM
1 100
R
R
=
=
NOM
1
13.3k, 13.3k is nearest 1%
exceeds V
=
=
=
are the values of R
⎛
⎜
⎝
120.8k, 121k is nearest 1%
2 815 0 4086
k
NOM
R
=
2 815 0 4086
.
•
.
COLD
2 815 0 4086
⎡
⎢
⎣
R
.
⎛
⎜
⎝
0 4086
COLD
is the value of the bias resistor, R
2 815 0 4086
.
– .
– .
.
–
IN
– .
R
OUT
0 4086
. If the current limit UVLO comparator
–
HOT
.
R
– .
HOT
falls 50mV below the V
=
⎞
⎟
⎠
NTC
IN
•
100
NTC
(
rises above the undervoltage
NOM
R
= 100k at 25°C.
⎞
⎟
⎠
COLD
k
2 815 0 4086
at the desired temperature
• .
• .
.
(
is 115k. This is the value
(
3 266 0 3602
3 266 0 3602
–
R
– .
HOT
– .
NTC
– .
)
–
(see Figure 3b).
R
IN
HOT
)
voltage.
)
– .
HOT
0 3602
NOM
and
=
⎤
⎥
⎦
CHARGER UNDERVOLTAGE LOCKOUT
Internal undervoltage lockout circuits monitor the V
V
shut down until V
lockout threshold. The charger UVLO circuit has a built-
in hysteresis of 125mV. Furthermore, to protect against
reverse current in the power MOSFET, the charger UVLO
circuit keeps the charger shutdown if V
If the charger UVLO comparator is tripped, the charger
circuits will not come out of shutdown until V
V
SHUTDOWN
The LTC4055/LTC4055-1 can be shut down by forcing the
SHDN pin greater than 1V. In shutdown, the currents on
IN1/IN2, OUT and BAT are decreased to less than 2.5μA
and the internal battery charge timer is reset. All power
paths are put in a Hi-Z state.
SUSPEND
The LTC4055/LTC4055-1 can be put in suspend mode by
forcing the SUSP pin greater than 1V. In suspend mode
the ideal diode function from BAT to OUT and the output
charger are kept alive. The rest of the part is shut down
to conserve current and the battery charge timer is reset
if V
V
Many types of capacitors can be used for input bypassing.
However, caution must be exercised when using multilayer
ceramic capacitors. Because of the self resonant and high
Q characteristics of some types of ceramic capacitors, high
voltage transients can be generated under some start-up
conditions, such as connecting the charger input to a hot
power source. For more information, refer to Application
Note 88.
OUT
BAT
IN
OUT
and Wall Adapter Bypass Capacitor
by 50mV.
voltages and keep the charger circuits of the part
becomes less than V
IN
or V
OUT
rises above the undervoltage
BAT
.
BAT
exceeds V
OUT
exceeds
IN
OUT
4055fb
and
.