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| 型號(hào)： | LTC4007EUFD-1#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 4A, High Efficiency, Standalone Li-Ion Battery Charger; Package: QFN; No of Pins: 24; Temperature Range: -40°C to +125°C |
| 中文描述： | BATTERY CHARGE CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封裝： | 4 X 5 MM, LEAD FREE, PLASTIC, QFN-24 |
| 文件頁(yè)數(shù)： | 9/24頁(yè) |
| 文件大小： | 269K |
| 代理商： | LTC4007EUFD-1#PBF |
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17
LTC4007-1
40071f
Charger Switching Power MOSFET
and Diode Selection
Two external power MOSFETs must be selected for use
with the charger: a P-channel MOSFET for the top (main)
switch and an N-channel MOSFET for the bottom (syn-
chronous) switch.
The peak-to-peak gate drive levels are set internally. This
voltage is typically 6V. Consequently, logic-level threshold
MOSFETs must be used. Pay close attention to the BVDSS
specification for the MOSFETs as well; many of the logic
level MOSFETs are limited to 30V or less.
Selection criteria for the power MOSFETs include the “ON”
resistance RDS(ON), total gate capacitance QG, reverse
transfer capacitance CRSS, input voltage and maximum
output current. The charger is operating in continuous
mode at moderate to high currents so the duty cycles for
the top and bottom MOSFETs are given by:
Main Switch Duty Cycle = VOUT/VIN
Synchronous Switch Duty Cycle = (VIN – VOUT)/VIN.
The MOSFET power dissipations at maximum output
current are given by:
PMAIN = VOUT/VIN(IMAX)2(1 + δT)RDS(ON)
+ k(VIN)2(IMAX)(CRSS)(fOSC)
PSYNC = (VIN – VOUT)/VIN(IMAX)2(1 + δT)RDS(ON)
Where
δT is the temperature dependency of RDS(ON) and
k is a constant inversely related to the gate drive current.
Both MOSFETs have I2R losses while the PMAIN equation
includes an additional term for transition losses, which are
highest at high input voltages. For VIN < 20V the high
current efficiency generally improves with larger MOSFETs,
while for VIN > 20V the transition losses rapidly increase
to the point that the use of a higher RDS(ON) device with
lower CRSS actually provides higher efficiency. The syn-
chronous MOSFET losses are greatest at high input volt-
age or during a short circuit when the duty cycle in this
APPLICATIO S I FOR ATIO
WU
UU
switch in nearly 100%. The term (1 +
δT) is generally
given for a MOSFET in the form of a normalized RDS(ON) vs
temperature curve, but
δ = 0.005/°C can be used as an
approximation for low voltage MOSFETs. CRSS =QGD/VDS
is usually specified in the MOSFET characteristics. The
constant k = 2 can be used to estimate the contributions of
the two terms in the main switch dissipation equation.
If the charger is to operate in low dropout mode or with a
high duty cycle greater than 85%, then the topside
P-channel efficiency generally improves with a larger
MOSFET. Using asymmetrical MOSFETs may achieve cost
savings or efficiency gains.
The Schottky diode D1, shown in the Typical Application
on the back page, conducts during the dead-time between
the conduction of the two power MOSFETs. This prevents
the body diode of the bottom MOSFET from turning on and
storing charge during the dead-time, which could cost as
much as 1% in efficiency. A 1A Schottky is generally a
good size for 4A regulators due to the relatively small
average current. Larger diodes can result in additional
transition losses due to their larger junction capacitance.
The diode may be omitted if the efficiency loss can be
tolerated.
Calculating IC Power Dissipation
The power dissipation of the LTC4007-1 is dependent
upon the gate charge of the top and bottom MOSFETs
(QG1 & QG2 respectively) The gate charge is determined
from the manufacturer’s data sheet and is dependent upon
both the gate voltage swing and the drain voltage swing of
the MOSFET. Use 6V for the gate voltage swing and VDCIN
for the drain voltage swing.
PD = VDCIN (fOSC (QG1 + QG2) + IQ)
Example:
VDCIN = 19V, fOSC = 345kHz, QG1 = QG2 = 15nC,
IQ = 5mA
PD = 292mW
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC4007EUFD-1#TRPBF | 4A, High Efficiency, Standalone Li-Ion Battery Charger; Package: QFN; No of Pins: 24; Temperature Range: -40°C to +125°C |
| LTC4008EGN#PBF | 4A, High Efficiency, Multi-Chemistry Battery Charger; Package: SSOP; No of Pins: 20; Temperature Range: -40°C to +125°C |
| LTC4008EGN#TRPBF | 4A, High Efficiency, Multi-Chemistry Battery Charger; Package: SSOP; No of Pins: 20; Temperature Range: -40°C to +125°C |
| LTC4008EGN-1#PBF | 4A, High Efficiency, Multi-Chemistry Battery Charger; Package: SSOP; No of Pins: 20; Temperature Range: -40°C to +125°C |
| LTC4008EGN-1#TRPBF | 4A, High Efficiency, Multi-Chemistry Battery Charger; Package: SSOP; No of Pins: 20; Temperature Range: -40°C to +125°C |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4008 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:4A, High Efficiency, Standalone Li Battery Charger |
| LTC4008EGN | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學(xué):堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應(yīng)商設(shè)備封裝:SOT-6 包裝:帶卷 (TR) |
| LTC4008EGN#PBF | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 其它有關(guān)文件:STC3100 View All Specifications 特色產(chǎn)品:STC3100 - Battery Monitor IC 標(biāo)準(zhǔn)包裝:4,000 系列:- 功能:燃料，電量檢測(cè)計(jì)/監(jiān)控器 電池化學(xué):鋰離子（Li-Ion） 電源電壓:2.7 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:8-MiniSO 包裝:帶卷 (TR) 其它名稱:497-10526-2 |
| LTC4008EGN#TR | 功能描述:IC CTRLR CHARGR PWM CC/CV 20SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學(xué):堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應(yīng)商設(shè)備封裝:SOT-6 包裝:帶卷 (TR) |
| LTC4008EGN#TRPBF | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電池管理 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 功能:電池監(jiān)控器 電池化學(xué):堿性，鋰離子，鎳鎘，鎳金屬氫化物 電源電壓:1 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 供應(yīng)商設(shè)備封裝:SOT-6 包裝:帶卷 (TR) |
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