DS2761 데이터 시트보기 (PDF) - Dallas Semiconductor -> Maxim Integrated

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DS2761

High-Precision Li+ Battery Monitor

Dallas Semiconductor -> Maxim Integrated 

DS2761

charge FET back on (unless another protection condition prevents it). Discharging remains enabled

during overvoltage, and the DS2761 re-enables the charge FET before VIN < VCE if a discharge current of

-80mA (VIS ≤ -2mV) or less is detected.

Undervoltage. If the voltage of the cell drops below undervoltage threshold VUV for a period longer than

undervoltage delay tUVD, the DS2761 shuts off the charge and discharge FETs, sets the UV flag in the

protection register, and enters sleep mode. The DS2761 provides a current-limited recovery charge path

from PLS to VDD to gently charge severely depleted cells during sleep mode.

Overcurrent, Charge Direction. The voltage difference between the IS1 pin and the IS2 pin (VIS = VIS1 -

VIS2) is the filtered voltage drop across the current-sense resistor. If VIS exceeds overcurrent threshold

VOC for a period longer than overcurrent delay tOCD, the DS2761 shuts off both external FETs and sets the

COC flag in the protection register. The charge current path is not re-established until the voltage on the

PLS pin drops below VDD - VTP. The DS2761 provides a test current of value ITST from PLS to VSS to pull

PLS down in order to detect the removal of the offending charge current source.

Overcurrent, Discharge Direction. If VIS is less than -VOC for a period longer than tOCD, the DS2761

shuts off the external discharge FET and sets the DOC flag in the protection register. The discharge

current path is not re-established until the voltage on PLS rises above VDD - VTP. The DS2761 provides a

test current of value ITST from VDD to PLS to pull PLS up in order to detect the removal of the offending

low-impedance load.

Short Circuit. If the voltage on the SNS pin with respect to VSS exceeds short-circuit threshold VSC for a

period longer than short-circuit delay tSCD, the DS2761 shuts off the external discharge FET and sets the

DOC flag in the protection register. The discharge current path is not re-established until the voltage on

PLS rises above VDD - VTP. The DS2761 provides a test current of value ITST from VDD to PLS to pull

PLS up in order to detect the removal of the short circuit.

Figure 3. Li+ PROTECTION CIRCUITRY EXAMPLE WAVEFORMS

VCELL

CHARGE

VIS

DISCHARGE

(1)

CC

tOVD

tOVD

tOCD

DC

tSCD

tOCD

SLEEP

MODE

VOV

VCE

VUV

VOC

0

-VOC

-VSC

VPLS

VSS

tUVD

VDD

VSS

ACTIVE

INACTIVE

(1) To allow the device to react quickly to short circuits, detection occurs on the SNS pin rather than on the

filtered IS1 and IS2 pins. The actual short-circuit detect condition is VSNS > VSC.

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