參數(shù)資料
型號(hào)： LM3420AM5-16.8
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 電源管理
英文描述： Lithium-Ion Battery Charge Controller
中文描述： 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5
封裝： MINIATURE, SOT-23, 5 PIN
文件頁(yè)數(shù)： 12/17頁(yè)
文件大小： 384K
代理商： LM3420AM5-16.8
V
REG
External Voltage Trim
(Continued)
R
increase
= 26x10
5
/%incr
R
decrease
= (150x10
5
/%decr) 176x10
3
For LM3420-8.4
R
increase
= 26x10
5
/%incr
R
decrease
= (154x10
5
/%decr) 181x10
3
For LM3420-12.6
R
increase
= 28x10
5
/%incr
R
decrease
= (259x10
5
/%decr) 287x10
3
For LM3420-16.8
R
increase
= 29x10
5
/%incr
R
decrease
= (364x10
5
/%decr) 392x10
3
Application Information
The LM3420 regulator/driver provides the reference and
feedback drive functions for a Lithium-Ion battery charger. It
can be used in many different charger configurations using
both linear and switching topologies to provide the precision
needed for charging Lithium-Ion batteries safely and effi-
ciently. Output voltage tolerances better than 0.5% are pos-
sible without using trim pots or precision resistors. The cir-
cuits shown are designed for 2 cell operation, but they can
readily be changed for either 1, 3 or 4 cell charging applica-
tions.
One item to keep in mind when designing with the LM3420 is
that there are parasitic diodes present. In some designs, un-
der special electrical conditions, unwanted currents may
flow. Parasitic diodes exist from OUT to IN, as well as from
GROUND to IN. In both instances the diode arrow is pointed
toward the IN pin.
Application Circuits
The circuit shown in Figure 5 performs constant-current,
constant-voltage charging of two Li-Ion cells. At the begin-
ning of the charge cycle, when the battery voltage is less
than 8.4V, the LM3420 sources no current from the OUT pin,
keeping Q2 off, thus allowing the LM317 Adjustable voltage
regulator to operate as a constant-current source. (The
LM317 is rated for currents up to 1.5A, and the LM350 and
LM338 can be used for higher currents.) The LM317 forces
a constant 1.25V across R
LIM
, thus generating a constant
current of
I
LIM
= 1.25V/R
LIM
Transistor Q1 provides a disconnect between the battery
and the LM3420 when the input voltage is removed. This
prevents the 85 μA quiescent current of the LM3420 from
eventually discharging the battery. In this application Q1 is
used as a low offset saturated switch, with the majority of the
base drive current flowing through the collector and crossing
over to the emitter as the battery becomes fully charged. It
provides a very low collector to emitter saturation voltage
(approximately 5 mV). Diode D1 is also used to prevent the
battery current from flowing through the LM317 regulator
from the output to the input when the DC input voltage is re-
moved.
As the battery charges, its voltage begins to rise, and is
sensed at the IN pin of the LM3420. Once the battery voltage
reaches 8.4V, the LM3420 begins to regulate and starts
sourcing current to the base of Q2. Transistor Q2 begins
DS012359-1
FIGURE 5. Constant Current/Constant Voltage Li-Ion Battery Charger
DS012359-11
FIGURE 6. Low Drop-Out Constant Current/Constant Voltage 2-Cell Charger
L
www.national.com
12
相關(guān)PDF資料
PDF描述
LM3420AM5-12.6 Lithium-Ion Battery Charge Controller
LM3420-16.8 Lithium-Ion Battery Charge Controller
LM3420-12.6 Lithium-Ion Battery Charge Controller
LM3420M5X-8.4 Lithium-Ion Battery Charge Controller
LM3420M5-8.4 Lithium-Ion Battery Charge Controller
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM3420AM5-4.2 功能描述:IC CTRLR LIION BAT CHRG SOT23-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 功能:充電管理 電池化學(xué):鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:3.75 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應(yīng)商設(shè)備封裝:SOT-23-5 包裝:剪切帶 (CT) 產(chǎn)品目錄頁(yè)面:669 (CN2011-ZH PDF) 其它名稱:MCP73831T-2ACI/OTCT
LM3420AM5-8.2 制造商:Rochester Electronics LLC 功能描述:LI ION BATTERY CHARGE CTRLR - Bulk
LM3420AM5-8.2/NOPB 功能描述:IC CTRLR LITH BATT CHRGR SOT23-5 RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 功能:充電管理 電池化學(xué):鋰離子（Li-Ion）、鋰聚合物（Li-Pol） 電源電壓:3.75 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應(yīng)商設(shè)備封裝:SOT-23-5 包裝:剪切帶 (CT) 產(chǎn)品目錄頁(yè)面:669 (CN2011-ZH PDF) 其它名稱:MCP73831T-2ACI/OTCT
LM3420AM5-8.4 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel
LM3420AM5-8.4/NOPB 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel
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