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參數(shù)資料
| 型號： | LM2746MXA |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Low Voltage N-Channel MOSFET Synchronous Buck Regulator Controller |
| 中文描述： | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | PLASTIC, TSSOP-14 |
| 文件頁數(shù)： | 20/24頁 |
| 文件大?。?/td> | 1087K |
| 代理商： | LM2746MXA |
Application Information
(Continued)
P
SW
= 0.5 x V
IN
x I
OUT
x (t
r
+ t
f
) x f
SW
P
SW
= 0.5 x 3.3V x 4A x 300kHz x 31ns
P
SW
= 61.38mW
The FDS6898A has a typical turn-on rise time t
r
and turn-off
fall time t
of 15ns and 16ns, respectively. The switching
losses for this type of dual N-Channel MOSFETs are
0.061W.
FET Conduction Loss (P
CND
)
P
CND
= P
CND1
+ P
CND2
P
CND1
= I
2OUT
x R
DS(ON)
x k x D
P
CND2
= I
2OUT
x R
DS(ON)
x k x (1-D)
R
= 13m
and the factor is a constant value (k = 1.3)
to account for the increasing R
DS(ON)
of a FET due to heat-
ing.
P
CND1
= (4A)
2
x 13m
x 1.3 x 0.364
P
CND2
= (4A)
2
x 13m
x 1.3 x (1 - 0.364)
P
CND
= 98.42mW + 172mW = 270.42mW
There are few additional losses that are taken into account:
IC Operating Loss (P
IC)
P
IC
= I
Q_VCC
x V
CC
,
where I
Q-VCC
is the typical operating V
CC
current
P
IC
= 1.5mA x 3.3V = 4.95mW
FET Gate Charging Loss (P
GATE
)
P
GATE
= n x V
CC
x Q
GS
x f
SW
P
GATE
= 2 x 3.3V x 3nC x 300kHz
P
GATE
= 5.94mW
The value n is the total number of FETs used and Q
GS
is the
typical gate-source charge value, which is 3nC. For the
FDS6898A the gate charging loss is 5.94mW.
Input Capacitor Loss (P
CAP
)
where,
Here n is the number of paralleled capacitors, ESR is the
equivalent series resistance of each, and P
CAP
is the dissi-
pation in each. So for example if we use only one input
capacitor of 24 m
.
P
CAP
= 88.8mW
Output Inductor Loss (P
IND
)
P
IND
= I
2OUT
* DCR
where DCR is the DC resistance. Therefore, for example
P
IND
= (4A)
2
x 11m
P
IND
= 176mW
Total System Efficiency
P
TOTAL
= P
FET
+ P
IC
+ P
GATE
+ P
CAP
+ P
IND
L
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|---|---|
| LM2746MXA/NOPB | 功能描述:IC REG CTRLR BUCK PWM VM 14TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| LM2746MXAX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Low Voltage N-Channel MOSFET Synchronous Buck Regulator Controller |
| LM2746MXAX/NOPB | 功能描述:IC REG CTRLR BUCK PWM VM 14TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:100% 電源電壓:8.2 V ~ 30 V 降壓:無 升壓:無 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:0°C ~ 70°C 封裝/外殼:8-DIP（0.300"，7.62mm） 包裝:管件 產(chǎn)品目錄頁面:1316 (CN2011-ZH PDF) |
| LM2747 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Synchronous Buck Controller with Pre-bias Startup, and Optional Clock Synchronization |
| LM2747-19AEVAL | 功能描述:電源管理IC開發(fā)工具 LM2747 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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