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參數(shù)資料
| 型號(hào)： | L6731B |
| 廠商： | 意法半導(dǎo)體 |
| 英文描述： | Transistor; Type: Amplifiers/Bipolar; VCEO (V): 25; Ic (A): 1; Pc (W): 0.8; hFE: 85 to 330; VCE (sat) (V) max: 0.5; Package: TO-92Mod |
| 中文描述： | 可調(diào)式降壓同步整流專用的DDR控制器內(nèi)存 |
| 文件頁數(shù)： | 18/24頁 |
| 文件大?。?/td> | 311K |
| 代理商： | L6731B |
Application details
L6731B
18/24
6
Application details
6.1
Inductor design
The inductance value is defined by a compromise between the transient response time, the
efficiency, the cost and the size. The inductor has to be calculated to sustain the output and the
input voltage variation to maintain the ripple current (
I
L
) between 20% and 30% of the
maximum output current. The inductance value can be calculated with the following
relationship:
Vout
I
Fsw
L
Where F
SW
is the switching frequency, Vin is the input voltage and Vout is the output voltage.
Increasing the value of the inductance reduces the ripple current but, at the same time,
increases the converter response time to a load transient. If the compensation network is well
designed, during a load transient the device is able to set the duty cycle to 100% or to 0%.
When one of these conditions is reached, the response time is limited by the time required to
change the inductor current. During this time the output current is supplied by the output
capacitors. Minimizing the response time can minimize the output capacitor size.
6.2
Output capacitors
The output capacitors are basic components for the fast transient response of the power
supply. They depend on the output voltage ripple requirements, as well as any output voltage
deviation requirement during a load transient. During a load transient, the output capacitors
supply the current to the load or absorb the current stored in the inductor until the converter
reacts. In fact, even if the controller recognizes immediately the load transient and sets the duty
cycle at 100% or 0%, the current slope is limited by the inductor value. The output voltage has
a first drop due to the current variation inside the capacitor (neglecting the effect of the ESL):
ESR
Iout
Vout
ESR
=
Moreover, there is an additional drop due to the effective capacitor discharge or charge that is
given by the following formulas:
2
Iout
Vout
COUT
Formula (4) is valid in case of positive load transient while the formula (5) is valid in case of
negative load transient. D
MAX
is the maximum duty cycle value that in the L6731D is 100%. For
a given inductor value, minimum input voltage, output voltage and maximum load transient, a
maximum ESR and a minimum Cout value can be set. The ESR and Cout values also affect
the static output voltage ripple. In the worst case the output voltage ripple can be calculated
with the following formula:
Usually the voltage drop due to the ESR is the biggest one while the drop due to the capacitor
discharge is almost negligible.
Vin
Vout
Vin
L
(2)
(3)
)
max
min
,
(
2
Vout
D
Vin
Cout
L
=
(4)
Vout
Cout
L
Iout
Vout
COUT
=
2
2
(5)
)
8
1
(
Fsw
Cout
ESR
I
Vout
L
+
=
(6)
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| L6731BTR | Transistor; Type: Amplifiers/Bipolar; VCEO (V): -25; Ic (A): -1; Pc (W): 0.8; hFE: 85 to 330; VCE (sat) (V) max: -0.5; Package: TO-92Mod |
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|---|---|
| L6731BTR | 功能描述:IC CTRLR ADJ STEP DOWN 16-TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| L6731D | 功能描述:DC/DC 開關(guān)控制器 Adjustable Step Down Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| L6731DTR | 功能描述:DC/DC 開關(guān)控制器 Adjustable Step Down Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| L6732 | 功能描述:DC/DC 開關(guān)控制器 Adjustable Step Down Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| L6732_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Adjustable step-down controller with synchronous rectification |
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