LTC4055EUF#TRPBF Linear Technology, LTC4055EUF#TRPBF Datasheet - Page 17

• 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

OPERATION
THERMISTORS
The LTC4055/LTC4055-1 NTC trip points were designed
to work with thermistors whose resistance-temperature
characteristics follow Vishay Dale’s “R-T Curve 2.” The
Vishay NTHS0603N02N1002J is an example of such a
thermistor. However, Vishay Dale has many thermistor
products that follow the “R-T Curve 2” characteristic in
a variety of sizes. Furthermore, any thermistor whose
ratio of R
(Vishay Dale R-T Curve 2 shows a ratio of R
of 2.815/0.4086 = 6.89).
Power conscious designs may want to use thermistors
whose room temperature value is greater than 10k. Vishay
Dale has a number of values of thermistor from 10k to 100k
that follow the “R-T Curve 1.” Using these as indicated
in the NTC Thermistor section will give temperature trip
points of approximately 3°C and 47°C, a delta of 44°C. This
delta in temperature can be moved in either direction by
changing the value of R
R
Likewise a decrease in R
move the trip points to higher temperatures. To calculate
NOM
R
100k
will move both trip points to lower temperatures.
R
100k
NOM
V
NTC
NTC
15
16
NTC
COLD
0.29 • V
to R
0.74 • V
0.1V
NTC
HOT
NOM
NTC
NOM
with respect to R
(3a)
is about 7.0 will also work
LTC4055/LTC4055-1
–
+
–
+
+
–
NTC BLOCK
with respect to R
NTC
TOO_COLD
TOO_HOT
NTC_ENABLE
COLD
. Increasing
4055 F03a
to R
NTC
Figure 3. NTC Circuits
HOT
will
R
the following equation:
where R
cold temperature trip point. If you want to shift the trip points
to higher temperatures use the following equation:
where R
hot temperature trip point.
Here is an example using a 100k R-T Curve 1 thermistor
from Vishay Dale. The difference between the trip points
is 44°C, from before, and we want the cold trip point to
be 0°C, which would put the hot trip point at 44°C. The
R
NOM
NOM
R
R
R
NOM
NOM
NOM
R
121k
R1
13.3k
needed is calculated as follows:
for a shift to lower temperature for example, use
R
100k
NOM
V
NTC
NTC
15
16
NTC
COLD
HOT
=
=
=
=
R
R
3 266
0 4086
2 815
2 815
2 815
is the resistance ratio of R
R
.
.
.
COLD
is the resistance ratio of R
COLD
.
.
HOT
LTC4055/LTC4055-1
0.29 • V
0.74 • V
•
•
•
100
•
R
R
0.1V
R
NTC
NTC
NTC
NTC
NTC
k
=
at
at
LTC4055/LTC4055-1
(3b)
at
116
–
–
–
+
+
+
25
25
NTC BLOCK
25
°
°
k
°
C
C
C
NTC
NTC
TOO_COLD
TOO_HOT
NTC_ENABLE
at the desired
at the desired
4055 F03b
17
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