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參數(shù)資料
| 型號： | LTC1731-4.2 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Lithium-Ion Linear Battery Charger Controller(4.2V鋰離子線性電池充電器) |
| 中文描述： | 鋰離子線性電池充電控制器（4.2V的鋰離子線性電池充電器） |
| 文件頁數(shù)： | 5/8頁 |
| 文件大?。?/td> | 154K |
| 代理商： | LTC1731-4.2 |
5
LTC1731-4.2
OPERATIOU
The LTC1731-4.2 is a linear battery charger controller. The
charge current is programmed by the combination of a
program resistor (R
PROG
) from the PROG pin to ground
and a sense resistor (R
SENSE
) between the V
CC
and SENSE
pins. R
PROG
sets a program current through an internal
trimmed 800
resistor setting up a voltage drop from V
CC
to the input of the current amplifier (CA). The current
amplifier servos the gate of the external P-channel MOSFET
to force the same voltage drop across R
SENSE
which sets
the charge current. When the potential at the BAT pin
approaches the preset float voltage, the voltage amplifier
(VA) will start sinking current which shrinks the voltage
drop across R
SENSE
, thus reducing the charge current.
Charging begins when the potential at V
CC
pin rises above
the UVLO level and a program resistor is connected from
the PROG pin to ground. At the beginning of the charge
cycle, if the battery voltage is below 2.457V, the charger
goes into trickle charge mode. The trickle charge current
is 10% of the full-scale current. If the cell voltage stays low
for one quarter of the total charge time, the charge
sequence will be terminated.
The charger goes into the fast charge constant-current
mode after the voltage on the BAT pin rises above 2.457V.
In constant-current mode, the charge current is set by the
combination of R
SENSE
and R
PROG
.
When the battery approaches the final float voltage, the
charge current will begin to decrease. When the current
drops to 10% of the full-scale charge current, an internal
comparator will turn off the pull-down N-channel MOSFET
at the CHRG pin and connect a weak current source to
ground to indicate an end-of-charge (
C
/10) condition.
An external capacitor on the TIMER pin sets the total
charge time. After a time-out occurs, the charging will be
terminated and the CHRG pin is forced to a high imped-
ance state. To restart the charge cycle, simply remove the
input voltage and reapply it, or float the PROG pin
momentarily.
For batteries like lithium-ion that require accurate final
float potential, the internal 2.457V reference, voltage
amplifier and the resistor divider provide regulation with
±
1% (max) accuracy. For NiMH and NiCd batteries, the
LTC1731-4.2 can be turned into a current source by
pulling the TIMER pin to V
CC
. When in the constant-
current only mode, the voltage amplifier, timer and the
trickle charge function are all disabled.
When the input voltage is not present, the charger goes
into a sleep mode, dropping I
CC
to 7
μ
A. This greatly
reduces the current drain on the battery and increases the
standby time. The charger can be shut down by floating the
PROG pin. An internal current source will pull it high and
clamp at 3.5V.
APPLICATIO
S I
N
FOR
ATIO
U
Charge Termination
The charger is off when any of the following conditions
exist: the voltage at the V
CC
pin is below 4.1V, the voltage
at the V
CC
pin is higher than 4.1V but is less than 54mV
above V
BAT
, or the PROG pin is floating. The DRV pin will
be pulled to V
CC
and the internal resistor divider is discon-
nected to reduce the current drain on the battery.
W
U
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the input
voltage and keeps the charger in shutdown mode until V
CC
rises above 4.1V. To prevent oscillation around
V
CC
= 4.1V, the UVLO circuit has built-in hysteresis.
Trickle Charge and Defective Battery Detection
At the beginning of the charging sequence, if the battery
voltage is low (below 2.457V) the charger goes into trickle
charge mode. The charge current is set to 10% of the full-
scale current. If the low cell voltage persists for one
quarter of the total charging time, the battery is considered
defective, charging will be terminated and the CHRG pin
output is forced to a high impedance state.
Shutdown
The LTC1731-4.2 can be forced into shutdown by float-
ing the PROG pin and allowing the internal 2.5
μ
A current
source to pull the pin above the 2.457V shutdown
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| LTC1731EMS8-4.1 | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標(biāo)準(zhǔn)包裝:61 系列:- 功能:電源管理 電池化學(xué):鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
| LTC1731EMS8-4.1#PBF | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標(biāo)準(zhǔn)包裝:61 系列:- 功能:電源管理 電池化學(xué):鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
| LTC1731EMS8-4.1#TR | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標(biāo)準(zhǔn)包裝:61 系列:- 功能:電源管理 電池化學(xué):鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
| LTC1731EMS8-4.1#TRPBF | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標(biāo)準(zhǔn)包裝:61 系列:- 功能:電源管理 電池化學(xué):鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:4.35 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:22-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:22-DFN（6x3）裸露焊盤 包裝:管件 |
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