LTC1325CSW datasheet(12/24 Pages) LINER

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LTC1325

FUNCTIONAL DESCRIPTIO

Bit 3: Maximum Cell Voltage (FMCV)

The MCV bit indicates when the battery cell voltage has

exceeded the preset limit. The bit is set when VCELL is

greater than the voltage at the MCV pin.

FMCV

CONDITIONS

0VCELL < VMCV

1VCELL > VMCV

Bit 4: End Discharge Voltage (FEDV)

The EDV bit indicates when the battery cell voltage has

dropped below an internally preset limit. The bit is set

when the battery cell voltage at the output of the voltage

divider VCELL is less than 900mV.

FEDV

CONDITIONS

0VCELL > 900mV

1VCELL < 900mV

Bit 5: High Temperature Fault (FHTF)

The HTF bit indicates when the battery temperature is too

high. Using a negative TC thermistor, the bit is set when

the voltage at the TBAT pin is less than the voltage at the

HTF pin.

FHTF

CONDITIONS

0TBAT > VHTF

1TBAT < VHTF

Bit 6: Low Temperature Fault (FLTF)

The LTF bit indicates when the battery temperature is too

low. Using a negative TC thermistor, the bit is set when the

voltage at the TBAT pin is greater than the voltage at the

LTF pin.

FLTF

CONDITIONS

0TBAT < VLTF

1TBAT > VLTF

Bit 7: Timeout (tOUT)

The tOUT bit indicates that the battery charging time has

exceeded the preset limit. The bit is set when the internal

timer exceeds the limit set by the command bits TO0, TO1

and TO2.

TOUT

CONDITIONS

No Timeout Has Occurred

Timeout Has Occurred

Bit 8: Fail-Safe Occurred (FS)

The FS bit indicates that one of the fault detection circuits

halted the discharging or charging cycle. The bit is set

when an EDV, LTF, HTF, or tOUT fault occurs during

discharge. During charging, the bit is set when a MCV,

LTF, HTF, or tOUT fault occurs. The bit is reset by the

command word bit FSCLR.

CONDITIONS

No Fail-Safe Has Occurred

Fail-Safe Has Occurred

DETAILED DESCRIPTION

Fault Conditions

The LTC1325 monitors the battery for fault conditions

before and during discharge and charge (see Figure 3).

They include: battery removed/present (BATP), battery

reversed/shorted (BATR), maximum cell voltage exceeded

Figure 3. Fail-Safe or Fault Detection Circuitry

–

VDD

BATP

FMCV

PROGRAMMABLE

BATTERY

DIVIDER

1.8V

–

FEDV

–

BATR

VDD

VBAT

SENSE

MCV

900mV

100mV

TBAT

HTF

LTC1325 • F03

LTF

REG

RTRK

3.072V

LINEAR

REGULATOR

–

FHTF

–

FLTF

LTC1325CSW Datasheet(PDF) 12 Page - Linear Technology

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