NJW4100V datasheet(9/19 Pages) NJRC

9 / 19 page

NJW4100

- 9 -

Ver.2005-01-20

■FEATURE DESCRIPTION (CONTINUED)

2. Current Detection Block (CS1 pin, CS2 pin)

A current detection resistor RCSis inserted between pin CS1 and pin CS2 to monitor battery charge current.

The input voltage between pin CS1 and pin CS2 is amplified by the 12dB current detection amp and fed back to the charge

current control amp. (Figure 3)

2-1. Pre-Charge Current, Quick Charge Current (P-CHG pin, Q-CHG pin)

This will switch between charging with pre-charge current or quick charge current according to the level of the battery

voltage VBAT that is input from the VS pin.

VBAT x 0.475 to VBAT x 0.73

Pre-charge control

VBATx 0.73 to VBAT

Quick charge control

Pre-charge and quick charge current values are determined by the P-CHG pin and the Q-CHG pin voltage settings.

Settings are made according to the following formulae.

Pre-Charge Current Value

IP-CHG= (

x VREF(1.24V) / 4) / RCS

Quick Charge Current Value

IQ-CHG= (

x VREF(1.24V) / 4) / RCS

2-2. Full Charge Detection (F-CHG pin)

Charge termination is determined by a set full

charge current

IF-CHG., which is determined by a

voltage setting on the F-CHG pin.

IF-CHG= (

x VREF(1.24V) / 8) / RCS

When charging is terminated, LED-G turns on,

and the sequence moves to the re-charge

detection operation.

Figure 3. Block for Controlling Pre-Charge, Quick Charge,

and Block for Detecting Full Charge.

To OR

Circuit

Quick Charge

Detection

Full Charge

Detection

6dB

CVCC-ON

12dB

Quick/

Pre-Charge

RP1

RP2

RQ1

RQ2

Q-CHG

P-CHG

VREF

CS2

NFB

CS1

RB1

RB2

Rcs

CS2

F-CHG

RF1

RF2

VREF

To Charge

Output

Switch Pre/Quick

Charge Current

Control Block

To Charge Voltage

Control Amp

Charge Current

Control Amp

VBAT x 0.73

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