- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377765 > LTC1874EGN (LINEAR TECHNOLOGY CORP) Quadruple 2-Input Positive-AND Gate 14-VQFN -40 to 85 PDF資料下載
參數(shù)資料
| 型號： | LTC1874EGN |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Quadruple 2-Input Positive-AND Gate 14-VQFN -40 to 85 |
| 中文描述： | 1 A SWITCHING CONTROLLER, 650 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, PLASTIC, SSOP-16 |
| 文件頁數(shù)： | 6/12頁 |
| 文件大?。?/td> | 180K |
| 代理商： | LTC1874EGN |
6
LTC1874
(Refer to Functional Diagram)
The LTC1874 is a dual, constant frequency current mode
switching regulator. The two switching regulators func-
tion identically but independent of each other. The follow-
ing description of operation is written for a single
switching regulator.
Main Control Loop
During normal operation, the external P-channel power
MOSFET is turned on by the oscillator and turned off when
the current comparator (I
CMP
) resets the RS latch. The
peak inductor current at which I
CMP
resets the RS latch is
controlled by the voltage on the I
TH
/RUN pin, which is the
output of the error amplifier EAMP. An external resistive
divider connected between V
OUT
and ground allows the
EAMP to receive an output feedback voltage V
FB
. When the
load current increases, it causes a slight decrease in V
FB
relative to the 0.8V reference, which in turn causes the
I
TH
/RUN voltage to increase until the average inductor
current matches the new load current.
The main control loop is shut down by pulling the I
TH
/RUN
pin low. Releasing I
TH
/RUN allows an internal 0.5
μ
A
current source to charge up the external compensation
network. When the I
TH
/RUN pin reaches 0.35V, the main
control loop is enabled with the I
TH
/RUN voltage then
pulled up to its zero current level of approximately 0.7V.
As the external compensation network continues to charge
up, the corre
sponding output current trip level follows,
allowing normal operation.
Comparator OVP guards against transient overshoots
greater than 7.5% by turning off the external P-channel
power MOSFET and keeping it off until the fault is
removed
.
Burst Mode Operation
The controller enters Burst Mode operation at low load
currents. In this mode, the peak current of the inductor is
set as if V
ITH
/RUN = 1V (at low duty cycles) even though
the voltage at the I
TH
/RUN pin is at a lower value. If the
inductor’s average current is greater than the load require-
ment, the voltage at the I
TH
/RUN pin will drop. When the
I
TH
/RUN voltage goes below 0.85V, the sleep signal goes
high, turning off the external MOSFET. The sleep signal
goes low when the I
TH
/RUN voltage goes above 0.925V
and the controller resumes normal operation. The next
oscillator cycle will turn the external MOSFET on and the
switching cycle repeats.
Dropout Operation
When the input supply voltage decreases towards the
output voltage, the rate of change of inductor current
during the ON cycle decreases. This reduction means that
the external P-channel MOSFET will remain on for more
than one oscillator cycle since the inductor current has not
ramped up to the threshold set by EAMP. Further reduc-
tion in input supply voltage will eventually cause the
P-channel MOSFET to be turned on 100%, i.e., DC. The
output voltage will then be determined by the input voltage
minus the voltage drop across the MOSFET, the sense
resistor and the inductor.
Undervoltage Lockout
To prevent operation of the P-channel MOSFET below safe
input voltage levels, an undervoltage lockout is incorpo-
rated into the controller. When the input supply voltage
drops below approximately 2.0V, the P-channel MOSFET
and all circuitry is turned off except the undervoltage
block, which draws only several microamperes.
Short-Circuit Protection
When the output is shorted to ground, the frequency of the
oscillator will be reduced to about 120kHz. This lower
frequency allows the inductor current to safely discharge,
thereby preventing current runaway. The oscillator’s fre-
quency will gradually increase to its designed rate when
the feedback voltage again approaches 0.8V.
Overvoltage Protection
As a further protection, the overvoltage comparator in the
controller will turn the external MOSFET off when the
feedback voltage has risen 7.5% above the reference
voltage of 0.8V. This comparator has a typical hysteresis
of 20mV.
OPERATIOU
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1875 | 15mA Quiescent Current 1.5A Monolithic Synchronous Step-Down Regulator |
| LTC1875EGN | 15mA Quiescent Current 1.5A Monolithic Synchronous Step-Down Regulator |
| LTC1877 | High Efficiency Monolithic Synchronous Step-Down Regulator(高效率,單片同步步降穩(wěn)壓器) |
| LTC1878 | High Efficiency Monolithic Synchronous Step-Down Regulator(高效率,單片同步步降穩(wěn)壓器) |
| LTC1911-15 | Low Noise, High Efficiency, Inductorless Step-Down DC/DC Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1874EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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 ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1874EGN#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP RoHS:否 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:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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 ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1874EGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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 ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1875EGN | 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#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)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。