LTC4160EUDC-1#PBF Linear Technology, LTC4160EUDC-1#PBF Datasheet - Page 23

• Manufacturer Part Number: LTC4160EUDC-1#PBF
• Description: IC, BATT CHRG, Li-Ion, Li-Polymer, 1.2A, QFN20
• Manufacturer: Linear Technology

Specifications of LTC4160EUDC-1#PBF

• Battery Type: Li-Ion, Li-Polymer
• Input Voltage: 5.5V
• Battery Charge Voltage: 4.1V
• Charge Current Max: 1.2A
• Battery Ic Case Style: QFN
• No. Of Pins: 20
• No. Of Series Cells: 1
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
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 dissipa-
tion within the charger.
Battery Charger Stability Considerations
The LTC4160/LTC4160-1’s battery charger contains both a
constant-voltage and a constant-current control loop. The
constant-voltage loop is stable without any compensation
when a battery is connected with low impedance leads.
Excessive lead length, however, may add enough series
inductance to require a bypass capacitor of at least 1µF
from BAT to GND.
High value, low ESR MLCCs reduce the constant-voltage
loop phase margin, possibly resulting in instability. Up
to 22µF may be used in parallel with a battery, but larger
capacitors should be decoupled with 0.2Ω to 1Ω of series
resistance.
Furthermore, a 100µF capacitor in series with a 0.3Ω re-
sistor from BAT to GND is required to prevent oscillation
when the battery is disconnected.
In constant-current mode, the PROG pin is in the feed-
back loop rather than the battery voltage. Because of the
additional pole created by any PROG pin capacitance,
capacitance on this pin must be kept to a minimum. With
no additional capacitance on the PROG pin, the charger
is stable with program resistor values as high as 25k.
However, additional capacitance on this node reduces the
maximum allowed program resistor. The pole frequency at
the PROG pin should be kept above 100kHz. Therefore, if
the PROG pin has a parasitic capacitance, C
lowing equation should be used to calculate the maximum
resistance value for R
Alternate NTC Thermistors and Biasing
The LTC4160/LTC4160-1 provide temperature qualified
charging if a grounded thermistor and a bias resistor
R
PROG
≤
2
π •
100
kHz C
PROG
1
•
:
PROG
PROG
, the fol-
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.
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 LTC4160/LTC4160-1’s temperature
qualification are internally programmed at 0.349 • NTCBIAS
for the hot threshold and 0.765 • NTCBIAS for the cold
threshold.
R25 = Value of the thermistor at 25°C
R
trip point
R
trip point
r
r
R
(see Figure 7)
R1 = Optional temperature range adjustment resistor
(see Figure 8)
COLD
HOT
NTC|COLD
NTC|HOT
NOM
= Ratio of R
= Ratio of R
– Primary thermistor bias resistor
= Value of the thermistor at the hot
= Value of the thermistor at the cold
LTC4160/LTC4160-1
NTC|HOT
NTC|COLD
to R25
to R25
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