LTC4098EUDC-3.6 View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC4098EUDC-3.6

USB Compatible Switching Power Manager/LiFePO4 Charger with Overvoltage Protection

Linear Technology 

LTC4098-3.6

APPLICATIONS INFORMATION

Solving these equations for RNTC|COLD and RNTC|HOT

results in the following:

RNTC|HOT = 0.25 • RNOM

and

RNTC|COLD = 3.26 • RNOM

By setting RNOM equal to R25, the previous equations

result in aHOT = 0.25 and aCOLD = 3.26. Referencing

these ratios to the Vishay Resistance-Temperature curve

1 chart gives a hot trip point of about 60°C and a cold trip

point of about 0°C. The difference between the hot and

cold trip points is approximately 60°C.

By using a bias resistor, RNOM, different in value from

R25, the hot and cold trip points can be moved in either

direction. The temperature span will change somewhat due

to the nonlinear behavior of the thermistor. The following

equations can be used to easily calculate a new value for

the bias resistor:

RNOM

=

αHOT

0.25

• R25

RNOM

=

αCOLD

3.26

• R25

where aHOT and aCOLD are the resistance ratios at the

desired  hot and cold trip points. Note that these equations

NTCBIAS

4

RNOM

100k

NTC

5

LTC4098-3.6 NTC BLOCK

0.765 • NTCBIAS

–

+

TOO_COLD

T

RNTC

100k

–

0.199 • NTCBIAS +

TOO_HOT

+

0.1V

–

NTC_ENABLE

NTCBIAS

4

RNOM

102k

NTC

5

LTC4098-3.6 NTC BLOCK

0.765 • NTCBIAS

–

+

TOO_COLD

R1

8.06k

T

RNTC

100k

–

0.199 • NTCBIAS +

+

0.1V

–

TOO_HOT

NTC_ENABLE

(9a)

409836 F09a

Figure 9. NTC Circuits

(9b)

409836 F09b

409836f

24

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