LTC4063 查看數據表（PDF） - Linear Technology

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LTC4063

Standalone Linear Li-Ion Charger with Micropower Low Dropout Linear Regulator

Linear Technology 

LTC4063

U

OPERATIO

protects the LTC4063 from excessive temperature and

allows the user to push the limits of the power handling

capability of a given circuit board without risk of damaging

the LTC4063. The charge current can be set according to

typical (not worst-case) ambient temperatures with the

assurance that the charger will automatically reduce the

current in worst-case conditions.

Undervoltage Lockout (UVLO)

An internal undervoltage lockout circuit monitors the input

voltage and keeps the charger in shutdown mode until VCC

rises above the undervoltage lockout threshold (3.8V).

The UVLO circuit has a built-in hysteresis of 200mV.

Furthermore, to protect against reverse current in the

power MOSFET, the UVLO circuit keeps the charger in

shutdown mode if VCC falls to less than 45mV above the

battery voltage. Hysteresis of 135mV prevents the charger

from cycling in and out of shutdown.

Manual Shutdown

At any point in the charge cycle, the charger can be put into

shutdown mode by pulling the CHGEN pin high. This

reduces the supply current to less than 65µA and the

battery drain current of the charger to less than 2µA. A new

charge cycle can be initiated by pulling the CHGEN pin low.

Pulling the LDOEN pin high puts the LDO into shutdown

mode reducing the battery drain current of the LDO to less

than 5µA. When both the CHGEN and LDOEN pins are

pulled high, the total battery drain current from the LTC4063

is less than 2µA. If shutdown is not required, leaving these

pins disconnected continuously enables the circuit.

Trickle Charge and Defective Battery Detection

When the BAT pin voltage is below the 2.9V trickle charge

threshold (VTRIKL), the charger reduces the charge current

to 10% of the programmed value. If the battery remains in

trickle charge for more than 25% of the total programmed

charge time, the charger stops charging and enters a

FAULT state, indicating that the battery is defective.1 The

LTC4063 indicates the FAULT state by driving the CHRG

open-drain output with a square wave. The duty cycle of

this oscillation is 50% and the frequency is set by CTIMER:

fCHRG

=

0.1µF • 3.1Hz

CTIMER

An LED driven by the CHRG output exhibits a blinking

pattern, indicating to the user that the battery needs

replacing. To exit the FAULT state, the charger must be

restarted either by toggling the CHGEN input or removing

and reapplying power to VCC.

Charge Status Output (CHRG)

The charge status indicator pin has two states: pull-down

and high impedance. In the pull-down state, an NMOS

transistor pulls down on the CHRG pin and can sink up to

10mA. A pull-down state indicates that the LTC4063 is

charging a battery and the charge current is greater than

IDETECT (which is set by the external resistor RDET). A high

impedance state indicates that the charge current has

dropped below IDETECT. In the case where the IDET pin is

left open (RDET = ∞, IDETECT = 0), a high impedance state

on CHRG indicates that the LTC4063 is not charging.

Low Dropout Linear Regulator (LDO)

The OUT pin provides a stable, regulated output voltage

powered from the battery. This output can power devices

such as memory or USB controllers from the battery when

there is no power applied to VCC.

The LDO can deliver 100mA of current with a nominal

dropout voltage of 150mV. It is designed to be stable with

a low ESR capacitor greater than 2µF on the OUT pin.

Furthermore, the LDO is capable of operating from a Li-Ion

battery voltage as low as 2.65V with less than 300mV of

dropout over the specified operating conditions. An und-

ervoltage lockout circuit automatically disables the LDO

when the battery voltage drops below 2.55V, reducing the

battery drain current to less than 5µA. The LDO can be dis-

abled by pulling the LDOEN pin high, reducing the battery

quiescent current to less than 5µA.

1The defective battery detection feature is only available when time termination is being used.

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