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UDG−03042

Temperature

Compensation

Self−Discharge

Timer

Discharge

Current

Charge

Current

Last Measured

Discharge (LMD)

Nominal Available

Charge (NAC)

Qualified

Transfer

Learning Count

Register (LCR)

Temperature, Voltage,

Average Current,

Other Data

Compensated

Available Charge

+

+

_

_

INPUTS

COMPUTATIONS

OUTPUTS

Rate and

Temperature

Compensation

+

_

Register Interface

bq27000, bq27200

SLUS556D – SEPTEMBER 2004 – REVISED MARCH 2006

FUNCTIONAL DESCRIPTION (continued)

A learning cycle can be disqualified by any of the following conditions:

1. Cold temperature: Temperature

≤ TCOMP[3:0] (°C) when the EDV1 threshold voltage is reached.

2. Light load: A capacity learning cycle is disqualified if average current is less than or equal to 2 times the

initial standby load when the EDV1 threshold voltage is reached.

3. Fast voltage drop: VOLT

≤ (EDV1 – 256 mV) before EDV1 is set.

4. Excessive charging: Cumulative Charge > 255 NAC counts (910 µVh) during a learning discharge cycle

(alternating discharge/charge/discharge before EDV1 is set).

5. Reset: VDQ is cleared on all resets.

6. Excessive self-discharge: NAC reduction from self-discharge estimate (0.195%) performed 64 times.

7. Self-discharge at termination of learning cycle. If self-discharge estimate causes NAC

≤ LMD/16, VDQ is

cleared.

NAC is adjusted by charge and discharge coulometric measurements except when battery full or empty

conditions are detected. NAC = LMD is forced when IMIN = 1 (full detection) unless Temperature

≤ TCOMP[3:0]

(

°C). During a discharge with VDQ = 1, NAC is not allowed to drop below LMD/16 until EDV1 = 1. If EDV1 = 1

occurs when NAC > LMD/16, NAC = LMD/16 will be forced. NAC = 0 is forced if EDVF = 1.

Figure 4. Operational Overview

The bqJUNIOR stores all calculated information in RAM, which is backed up by the voltage on the RBI input.

EEPROM registers store permanent user data. The memory map for bq27000/bq27200 is shown in Table 1.

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