LTC1729 データシートの表示（PDF） - Linear Technology

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LTC1729

Li-Ion Battery Charger Termination Controllers

Linear Technology 

LTC1729 Series

APPLICATIO S I FOR ATIO

the NTC pin will float to 5V as soon as the Status pull-down

is open. This will force the state machine into the Hold

mode. The VC pin is pulled low which turns off the charger.

This circuit is shown in Figure 8.

In order to restart the charging process for a new battery,

the NTC pin will need to be momentarily brought below

0.2V or the VCC pin brought below the UVLO threshold.

The automatic battery detection features are disabled

during the Hold mode.

Using Status as a Charging Indicator

In many applications circuits shown in this data sheet, the

STATUS pin is used to indicate when C/10 has occurred

(charge current has dropped to 10% of the full charge

current). This C/10 number is not fixed, but is set by an

external resistor connected to the LTC1729 SENSE pin. A

100µA bias current through this resistor develops a volt-

age which is compared with the voltage across the charge

current sense resistor. When these voltages are equal, the

open-drain STATUS pin turns off. Connecting an LED to

the STATUS pin will give a visual indication during the

precondition trickle charge and the portion of the main

charge before C/10 has occurred.

By reducing the LTC1729 SENSE pin resistor to 0Ω, the

STATUS pin function can be changed to a charging indica-

tor (Figure 9). The LED on the STATUS pin will always go

off after the 3-hour charge cycle is completed, regardless

of the C/10 circuitry.

OVP

BAT

SENSE

200Ω

LTC1729-4.2

1

OVP

8

VCC

VCC

2

BAT

7

VC

VC

0.1µF

1µF 3

6

SENSE STATUS

4

GND

5

NTC

10k NTC THERMISTOR

NTHS1206N02 VISHAY/DALE

1729 F08

Figure 8. Terminate Charging at C/10

CHARGE

CURRENT

+ SENSE

RESISTOR

–

SENSE

BAT

IBIAS

–

COMP1

+

LTC1729

100µA

1729 F09

Figure 9. Modify C/10 Indication to Create Charging Indicator

11

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