LTC3586EUFE-1#TRPBF Linear Technology, LTC3586EUFE-1#TRPBF Datasheet - Page 26

• Manufacturer Part Number: LTC3586EUFE-1#TRPBF
• Description: IC POWER MANAGER USB 38-QFN
• Manufacturer: Linear Technology

Specifications of LTC3586EUFE-1#TRPBF

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 4.35 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 38-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -

LTC3586/LTC3586-1
applicaTions inForMaTion
Over-Programming the Battery Charger
The USB high power specification allows for up to 2.5W to
be drawn from the USB port (5V • 500mA). The PowerPath
switching regulator transforms the voltage at V
above the voltage at BAT with high efficiency, while limiting
power to less than the amount programmed at CLPROG.
In some cases the battery charger may be programmed
(with the PROG pin) to deliver the maximum safe charging
current without regard to the USB specifications. If there
is insufficient current available to charge the battery at the
programmed rate, the PowerPath regulator will reduce
charge current until the system load on V
and the V
battery charger for more current than is available will
not cause the average input current limit to be violated.
It will merely allow the battery charger to make use of
all available power to charge the battery as quickly as
possible, and with minimal power dissipation within the
battery charger.
Alternate NTC Thermistors and Biasing
The LTC3586/LTC3586-1 provide temperature qualified
charging if a grounded thermistor and a bias resistor
are connected to NTC. By using a bias resistor whose
value is equal to the room temperature resistance of the
thermistor (R25) the upper and lower temperatures are
pre-programmed to approximately 40°C and 0°C, respec-
tively (assuming a Vishay “Curve 1” thermistor).
The upper and lower temperature thresholds can be ad-
justed by either a modification of the bias resistor value
or by adding a second adjustment resistor to the circuit.
If only the bias resistor is adjusted, then either the upper
or the lower threshold can be modified but not both. The
other trip point will be determined by the characteristics
of the thermistor. Using the bias resistor in addition to an
adjustment resistor, both the upper and the lower tempera-
ture trip points can be independently programmed with
the constraint that the difference between the upper and
lower temperature thresholds cannot decrease. Examples
of each technique are given below.
NTC thermistors have temperature characteristics which
are indicated on resistance-temperature conversion tables.

BUS
current limit is satisfied. Programming the
OUT
is satisfied
BUS
to just
The Vishay-Dale thermistor NTHS0603N011-N1003F, used
in the following examples, has a nominal value of 100k
and follows the Vishay “Curve 1” resistance-temperature
characteristic.
In the explanation below, the following notation is used.
The trip points for the LTC3586/LTC3586-1’s temperature
qualification are internally programmed at 0.349 • V
the hot threshold and 0.765 • V
Therefore, the hot trip point is set when:
and the cold trip point is set when:
Solving these equations for R
in the following:
and
By setting R
in r
to the Vishay Resistance-Temperature Curve 1 chart gives
a hot trip point of about 40°C and a cold trip point of about
0°C. The difference between the hot and cold trip points
is approximately 40°C.
R25 = Value of the Thermistor at 25°C
R
R
r
r
R
(see Figure 6a)
R1 = Optional temperature range adjustment resistor
(see Figure 6b)
R
R
R
R
HOT
COLD
HOT
NTC|HOT
NTC|COLD
NOM
NTC|HOT
NTC|COLD
NOM
NOM
= 0.536 and r
R
R
= Ratio of R
= Ratio of R
NTCHOT
NTC COLD
= Primary thermistor bias resistor
+
+
R
R
NOM
= Value of the thermistor at the hot trip point
|
|
= 0.536 • R
NTCHOT
NTC COLD
= Value of thermistor at the cold trip point
= 3.25 • R
|
|
equal to R25, the above equations result
NTC|COLD
COLD
NTC|COLD
•
•
V
NOM
NOM
V
BUS
BUS
= 3.25. Referencing these ratios
NTC|COLD
= 0 349
to R25
= 0 765
to R25
BUS
.
.
for the cold threshold.
and R
•
•
V
V
BUS
BUS
NTC|HOT
BUS
results
3586fb
for