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參數(shù)資料
| 型號(hào)： | LTC1875EGN |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 15mA Quiescent Current 1.5A Monolithic Synchronous Step-Down Regulator |
| 中文描述： | 3 A SWITCHING REGULATOR, 605 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, PLASTIC, SSOP-16 |
| 文件頁(yè)數(shù)： | 10/20頁(yè) |
| 文件大?。?/td> | 257K |
| 代理商： | LTC1875EGN |
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10
LTC1875
1875f
OPERATIOU
Slope Compensation and Inductor Peak Current
Slope compensation is required in order to prevent sub-
harmonic oscillation at high duty cycles. It is accom-
plished by internally adding a compensating ramp to the
inductor current signal at duty cycles in excess of 40%. As
a result, the maximum inductor peak current is reduced for
duty cycles >40%. This is shown in the decrease of the
inductor peak current as a function of duty cycle graph in
Figure 3.
Figure 3. Maximum Inductor Peak Current vs Duty Cycle
APPLICATIOU
The basic LTC1875 application circuit is shown on the first
page of this data sheet. External component selection is
driven by the load requirement and begins with the selec-
tion of L followed by C
IN
and C
OUT
.
W
U
U
Inductor Value Calculation
The inductor selection will depend on the operating fre-
quency of the LTC1875. The internal nominal frequency is
550kHz, but can be externally synchronized from 350kHz
to 750kHz.
The operating frequency and inductor selection are inter-
related in that higher operating frequencies allow the use
of smaller inductor and capacitor values. However, oper-
ating at a higher frequency results in lower efficiency
because of increased switching losses.
The inductor value has a direct effect on ripple current. The
ripple current
I
L
decreases with higher inductance or
frequency and increases with higher input voltages.
=
( )( )
I
V
V
L
OUT
OUT
IN
1
1–
(1)
Accepting larger values of
I
L
allows the use of smaller
inductors, but results in higher output voltage ripple.
A reasonable starting point for setting ripple current is
I
L
= 0.3(I
MAX
).
The inductor value also has an effect on Burst Mode
operation. The transition to low current operation begins
when the inductor current peaks fall to approximately
500mA. Lower inductor values (higher
I
L
) will cause this
to occur at lower load currents, which can cause a dip in
efficiency in the upper range of low current operation. In
Burst Mode operation, lower inductance values will cause
the burst frequency to increase.
Inductor Selection
The inductor should have a saturation current rating
greater than the peak inductor current set by the current
comparator of LTC1875. Also, consideration should be
given to the resistance of the inductor. Inductor conduc-
tion losses are directly proportional to the DC resistance
of the inductor.
Manufacturers sometimes provide maxi-
mum current ratings based on the allowable losses in the
inductor.
Suitable inductors are available from Coilcraft, Coiltron-
ics, Dale, Sumida, Toko, Murata, Panasonic and other
manufacturers.
DUTY CYCLE (%)
0
M 2200
2000
1800
1600
1400
1200
1000
800
20
40
60
80
1875 F03
100
V
IN
= 3V
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1875EGN#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁(yè)面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC1875EGN#TR | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LTC1875EGN#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1.5A 16SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LTC1876EG | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC1876EG#PBF | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
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