SM6780AS datasheet(6/11 Pages) NPC

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SM6780AS

NIPPON PRECISION CIRCUITS—6

Charging Modes

The SM6780AS has 3 modes of operation: quick

charge, supplemental charge, and pulse trickle mode.

The SM6780AS uses the various detection functions

to monitor the state of the battery and select the

charging mode automatically.

In quick charge mode, charging occurs at a rate set

by the external current source. In supplemental

charge mode, the battery is charged by current pulses

to the full stable capacity of the chemical substances

within the battery. Pulse trickle mode maintains the

level within the battery, compensating for internal

losses.

Quick (Supplemental) Charge Conditions — Battery Check

The SM6780AS monitors the battery voltage and

battery temperature to conﬁrm the values are within

the rated range of the battery during quick charge

and supplemental charging modes to realize a high-

stability battery charger.

If the battery voltage or battery temperature charging

rating is exceeded before quick charging mode ter-

minates, the charging mode is placed on hold. The

internal timer continues to operate, and pulse trickle

charging occurs. The LEDN output pulses at a rate of

approximately 1Hz. If the charging rating is

exceeded during supplemental charging mode, the

mode terminates and charging switches to pulse

trickle mode.

Figure 5. Charging mode, battery voltage and charging current

Supplemental

charge mode

Pulse trickle

mode

Quick charge mode

Quick charge

mode end

Start

Charge

complete

Hi-Z

Low

High-temperature quick charge hold state: VTEMP < VMXT (0.225 × VDD)

High-temperature quick charge hold release state: VTEMP > VHTS (0.25 × VDD)

Figure 6. Quick (supplemental) charge ranges

Maximum temperature

Voltage (0.225

× VDD)

VTEMP

VBATT

Pulse trickle

mode

Quick charge

mode

Quick charge

start

Pulse trickle

mode

Quick charge

mode

Power ON

High temperature sense

Voltage (0.25

× VDD)

Low temperature sense

Voltage (0.4

× VDD)

Quick charge

is suspended

Quick charge

restart

2.0V

Maximum cell

Voltage

Charge

valid range

Charge

valid range

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