LTC4069EDC-4.4#TRM Linear Technology, LTC4069EDC-4.4#TRM Datasheet - Page 14

• Manufacturer Part Number: LTC4069EDC-4.4#TRM
• Description: BATT CHARGER, LI ON, 750MA, 6DFN
• Manufacturer: Linear Technology

Specifications of LTC4069EDC-4.4#TRM

• Battery Type: Li-Ion
• Input Voltage: 5.5V
• Battery Charge Voltage: 4.4V
• Charge Current Max: 750mA
• Battery Ic Case Style: DFN
• No. Of Pins: 6
• No. Of Series Cells: 1
• Operating Temperature Range: -40°C To
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC4069
APPLICATIONS INFORMATION
Thermistors
The LTC4069 NTC trip points are designed to work with
thermistors whose resistance-temperature characteristics
follow Vishay Dale’s “R-T Curve 1.” The Vishay
NTHS0603N01N1003J is an example of such a thermistor.
However, Vishay Dale has many thermistor products that
follow the “R-T Curve 1” characteristic in a variety of sizes.
Furthermore, any thermistor whose ratio of R
is about 6 will also work (Vishay Dale R-T Curve 1 shows
a ratio of R
Designers may want to use thermistors whose room
temperature value is different than 100k. Vishay Dale
has a number of values of thermistor from 32k to 100k
that follow the “R-T Curve 1.” Using different R-T curves,
such as Vishay Dale “R-T Curve 2”, is also possible. This
curve, combined with LTC4069 internal thresholds, gives
temperature trip points of approximately –3°C (falling) and
42°C (rising), a delta of 45°C. This delta in temperature
can be moved in either direction by changing the value of
R
both trip points to higher temperatures. To calculate
14
NOM
with respect to R
R
8.87k
R1
604Ω
NOM
R
10k
NTC
COLD
6
0.016 • V
0.76 • V
0.35 • V
NTC
to R
CC
CC
CC
Figure 6. NTC Circuits
V
CC
HOT
NTC
of 3.266/0.5325 = 6.13).
. Increasing R
–
+
–
+
+
–
NOM
TOO HOT
NTC_ENABLE
TOO COLD
COLD
will move
4069 F06
to R
HOT
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 10k R-T Curve 2 thermistor
from Vishay Dale. The difference between the trip points
is 45°C, from before, and we want the cold trip point to
be 0°C, which would put the hot trip point at 45°C. The
R
The nearest 1% value for R
used to bias the NTC thermistor to get cold and hot trip
points of approximately 0°C and 45°C respectively. To
extend the delta between the cold and hot trip points, a
resistor, R1, can be added in series with R
6). The values of the resistors are calculated as follows:
where R
R
trip points. Continuing the example from before with a
desired trip point of 50°C:
NOM
NOM
COLD
R
R
R
R
R
NOM
NOM
NOM
NOM
1
needed is calculated as follows:
for a shift to lower temperature for example, use
=
are the values of R
COLD
NOM
HOT
⎛
⎝ ⎜
=
=
=
=
=
3 266
R
R
3 266
0 5325
3 266
3 266 0 5325
.
2 816
3
is the resistance ratio of R
is the value of the bias resistor and R
R
R
COLD
is the resistance ratio of R
.
COLD
.
.
.
.
. .
COLD
HOT
266
0 5325
.
− −
−
0 5325
•
•
•
−
•
.
R
R
10
R
.
R
NTC
NTC
HOT
NTC
k
NTC
=
NOM
at
at
⎞
⎠ ⎟
8 62
at
.
at the desired temperature
• R
25
25
25
is 8.66k. This is the value
(
°
°
k
COLD
C
C
°
C
NTC
NTC
−
NTC
R
at the desired
at the desired
HOT
(see Figure
)
−
HOT
R
HOT
4069fb
and