LTC4098EPDC-1-PBF(RevB) 데이터 시트보기 (PDF) - Linear Technology

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LTC4098EPDC-1-PBF
(Rev.:RevB)

USB Compatible Switching Power Managers/Li-Ion Chargers with Overvoltage Protection

Linear Technology 

LTC4098/LTC4098-1

APPLICATIONS INFORMATION

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

RNTC|COLD = Value of thermistor at the cold trip point

RNTC|HOT = Value of thermistor at the hot trip point

rCOLD = Ratio of RNTC|COLD to R25

rHOT = Ratio of RNTC|HOT to R25

RNOM = Primary thermistor bias resistor (see Figure 9a)

R1 = Optional temperature range adjustment resistor

(see Figure 9b)

The trip points for the LTC4098/LTC4098-1’s temperature

qualification are internally programmed at 0.349 • NTCBIAS

for the hot threshold and 0.765 • NTCBIAS for the cold

threshold.

Therefore, the hot trip point is set when:

RNTC|HOT • NTCBIAS = 0.349 • NTCBIAS

RNOM + RNTC|HOT

and the cold trip point is set when:

RNTC|COLD • NTCBIAS = 0.765 • NTCBIAS

RNOM + RNTC|COLD

NTCBIAS

4

RNOM

100k

NTC

5

LTC4098/LTC4098-1

NTC BLOCK

0.765 • NTCBIAS

–

+

TOO_COLD

T

RNTC

100k

–

0.349 • NTCBIAS +

TOO_HOT

+

0.1V

–

NTC_ENABLE

NTCBIAS

4

RNOM

105k

NTC

5

LTC4098/LTC4098-1

NTC BLOCK

0.765 • NTCBIAS

–

+

TOO_COLD

R1

12.7k

T

RNTC

100k

–

0.349 • NTCBIAS +

+

0.1V

–

TOO_HOT

NTC_ENABLE

(9a)

40981 F09a

(9b)

Figure 9. NTC Circuits

40981 F09b

40981fb

25

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