參數(shù)資料
型號(hào)： LT1938IDD#PBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： 4 A SWITCHING REGULATOR, 3300 kHz SWITCHING FREQ-MAX, PDSO10
封裝： 3 X 3 MM, LEAD FREE, PLASTIC, MO-229WEED-2, DFN-10
文件頁(yè)數(shù)： 24/24頁(yè)
文件大小： 260K
代理商： LT1938IDD#PBF
LT1938
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1938fa
The LT1938 is a constant frequency, current mode step-
down regulator. An oscillator, with frequency set by RT,
enables an RS flip-flop, turning on the internal power
switch. An amplifier and comparator monitor the current
flowing between the VIN and SW pins, turning the switch
off when this current reaches a level determined by the
voltage at VC. An error amplifier measures the output
voltage through an external resistor divider tied to the FB
pin and servos the VC pin. If the error amplifier’s output
increases, more current is delivered to the output; if it
decreases,lesscurrentisdelivered.Anactiveclamponthe
VC pin provides current limit. The VC pin is also clamped to
the voltage on the RUN/SS pin; soft-start is implemented
by generating a voltage ramp at the RUN/SS pin using an
external resistor and capacitor.
An internal regulator provides power to the control cir-
cuitry. The bias regulator normally draws power from the
VIN pin, but if the BIAS pin is connected to an external
voltage higher than 3V bias power will be drawn from the
external source (typically the regulated output voltage).
This improves efficiency. The RUN/SS pin is used to place
the LT1938 in shutdown, disconnecting the output and
reducing the input current to less than 1A.
The switch driver operates from either the input or from
the BOOST pin. An external capacitor and diode are used
to generate a voltage at the BOOST pin that is higher than
the input supply. This allows the driver to fully saturate
the internal bipolar NPN power switch for efficient
operation.
The oscillator reduces the LT1938’s operating frequency
when the voltage at the FB pin is low. This frequency
foldback helps to control the output current during startup
and overload.
TheLT1938containsapowergoodcomparatorwhichtrips
when the FB pin is at 90% of its regulated value. The PG
output is an open-collector transistor that is off when the
output is in regulation, allowing an external resistor to pull
the PG pin high. Power good is valid when the LT1938 is
enabled and VIN is above 3.6V.
OPERATION
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT1939 制造商:LINER 制造商全稱:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller
LT1939EDD#PBF 功能描述:IC REG DL BUCK/LINEAR 12DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 拓?fù)?降壓（降壓）同步（3），線性（LDO）（2） 功能:任何功能 輸出數(shù):5 頻率 - 開(kāi)關(guān):300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅(qū)動(dòng)器:無(wú) 帶監(jiān)控器:無(wú) 帶序列發(fā)生器:是 電源電壓:5.6 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:*
LT1939EDD#TRPBF 功能描述:IC REG DL BUCK/LINEAR 12DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 拓?fù)?降壓（降壓）同步（3），線性（LDO）（2） 功能:任何功能 輸出數(shù):5 頻率 - 開(kāi)關(guān):300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅(qū)動(dòng)器:無(wú) 帶監(jiān)控器:無(wú) 帶序列發(fā)生器:是 電源電壓:5.6 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:*
LT1939EDD-PBF 制造商:LINER 制造商全稱:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller
LT1939EDD-TRPBF 制造商:LINER 制造商全稱:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller
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