DS2762 High-Precision Li+ Battery Monitor With Alerts

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POWER MODES

The DS2762 has two power modes: active and sleep. While in active mode, the DS2762 continually measures

current, voltage, and temperature to provide data to the host system and to support current accumulation and Li+

safety monitoring. In sleep mode, the DS2762 ceases these activities. The DS2762 enters sleep mode when any of

the following conditions occurs:

§

The PMOD bit in the Status Register has been set to 1 and the DQ line is low for longer than 2s (pack

disconnection).

§

§

The pack is disabled through the issuance of a SWAP command (SWEN bit = 1).

The DS2762 returns to active mode when any of the following occurs:

§

The PMOD bit has been set to 1 and the SWEN bit is set to 0 and the DQ line is pulled high (pack

connection).

§

The

PS pin is pulled low (power switch).

§

§

The pack is enabled through the issuance of a SWAP command (SWEN bit = 1).

The DS2762 defaults to active mode when power is first applied.

Li+ PROTECTION CIRCUITRY

During active mode, the DS2762 constantly monitors cell voltage and current to protect the battery from overcharge

(overvoltage), overdischarge (undervoltage), and excessive charge and discharge currents (overcurrent, short

circuit). Conditions and DS2762 responses are described in the following sections and summarized in Table 1 and

Figure 3.

Table 1. Li+ Protection Conditions and DS2762 Responses

ACTIVATION

CONDITION

THRESHOLD

DELAY

RESPONSE

RELEASE THRESHOLD

Overvoltage

CC high

Undervoltage

CC, DC high,

Sleep Mode

(1)

(charger connected)

Overcurrent, Charge

(2)

CC, DC high

(3)

Overcurrent, Discharge

(2)

DC high

(4)

Short Circuit

DC high

(4)

Note 1:

to exceed 2.2V.

Note 2:

Note 3:

Note 4:

protection condition prevents it). Discharging remains enabled during overvoltage, and the DS2762 re-enables the