LTC3576EUFE#PBF Linear Technology, LTC3576EUFE#PBF Datasheet - Page 37

• Manufacturer Part Number: LTC3576EUFE#PBF
• Description: IC POWER MANAGER W/USB OTG 38QFN
• Manufacturer: Linear Technology

Specifications of LTC3576EUFE#PBF

• 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: -

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 LTC3576/LTC3576-1 provide temperature qualifi ed
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 modifi cation 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 modifi ed but not both. The
other trip point will be determined by the characteristics
APPLICATIONS INFORMATION
R
PROG
NTCBIAS
T
R
100k
NOM
R
100k
≤
NTC
NTC
Figure 9. Standard NTC Confi guration
2π • 100kHz • C
3
4
0.349 • NTCBIAS
0.765 • NTCBIAS
PROG
1
0.1V
:
LTC3576/LTC3576-1
PROG
NTC BLOCK
–
+
–
+
+
–
PROG
TOO_COLD
TOO_HOT
NTC_ENABLE
, the fol-
3576 F09
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.
R25 = Value of the Thermistor at 25°C
R
R
point
r
r
R
(see Figure 9)
R1 = Optional temperature range adjustment resistor
(see Figure 10)
COLD
HOT
NTC|COLD
NTC|HOT
NOM
NTCBIAS
T
R
105k
R1
12.7k
= Ratio of R
NOM
= Ratio of R
– Primary thermistor bias resistor
R
100k
NTC
NTC
Figure 10. Modifi ed NTC Confi guration
= Value of the thermistor at the hot trip
3
4
= Value of thermistor at the cold trip point
LTC3576/LTC3576-1
0.349 • NTCBIAS
0.765 • NTCBIAS
NTC|HOT
NTC|COLD
0.1V
LTC3576/LTC3576-1
to R25
NTC BLOCK
–
+
–
+
+
–
to R25
TOO_COLD
TOO_HOT
NTC_ENABLE
3576 F10
37
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