AT1457 Datasheet, PDF (10/12 Pages) List of Unclassifed Manufacturers – 1-CELL LITHIUM AND LITHIUM POLYMER CHARGE MANAGEMENT IC

AT1457
Preliminary Product Information
1-Cell Lithium-Ion And Lithium-Polymer
Charge Management IC
3. Battery Temperature Monitor
The AT1457 continuously monitors temperature by measuring the voltage between
the TS and VSS pins. A negative or a positive temperature coefficient thermistor
(NTC or PTC) and external voltage divider typically develop this voltage. The
AT1457 compares this voltage against its internal VTS1 and VTS2 threshold to
determine if charging is allowed.
The resistor value of RT1 and RT2 ars calculated by the following equations:
For NTC Thermistor
R_{T 1}
=
5 × R_TH
3 × (R_TC
×
−
R_TC
R_TH
)
R_{T 2}
=
5 × R_TH × R_TC
[(2 × R_TC ) − (7 × R_TH
)]
For PTC Thermistor
R_{T 1}
=
5 × R_TH
3 × (R_TH
× R_TC
− R_TC )
R_{T 2}
=
5 × R_TH × R_TC
[(2 × R_TH ) − (7 × R_TC
)]
RTC is the cold temperature resistance and RTH is the hot temperature resistance of
thermistor.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone]
WWW: http://www.aimtron.com.tw
Fax: [phone]
Email: [e-mail]
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