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參數(shù)資料
| 型號(hào)： | LM5007MMEP/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, PDSO8 |
| 封裝： | PLASTIC, MSOP-8 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大小： | 231K |
| 代理商： | LM5007MMEP/NOPB |
Electrical Characteristics (Continued)
Specifications with standard typeface are for T
J = 25C, and those with boldface type apply over full Operating Junction
Temperature range.V
IN = 48V, unless otherwise stated (Note 6).
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Minimum Off Time
Minimum Off Timer
FB = 0V
300
ns
Regulation and OV Comparators
FB Reference Threshold
Internal reference
Trip point for switch ON
2.445
2.5
2.550
V
FB Over-Voltage Threshold
Trip point for switch OFF
2.875
V
FB Bias Current
100
nA
Thermal Shutdown
Tsd
Thermal Shutdown Temp.
165
C
Thermal Shutdown Hysteresis
25
C
Thermal Resistance
θ
JA
Junction to Ambient
MUA Package
200
C/W
SDC Package
40
C/W
Note 4: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device
is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 5: For detailed information on soldering plastic MSOP and LLP packages, refer to the Packaging Data Book available from National Semiconductor
Corporation.
Note 6: All limits are guaranteed. All electrical characteristics having room temperature limits are tested during production with TA =TJ = 25C. All hot and cold limits
are guaranteed by correlating the electrical characteristics to process and temperature variations and applying statistical process control.
Note 7: The VCC output is intended as a self bias for the internal gate drive power and control circuits. Device thermal limitations limit external loading.
Note 8: The human body model is a 100pF capacitor discharge through a 1.5k
resistor into each pin. The machine model is a 200pF capacitor discharged directly
into each pin. The machine model ESD compliance level for Pin 5 is 150V. The human body ESD compliance level for Pin 7 and 8 is 1000V.
Note 9: For devices procurred in the LLP-8 package the Rds(on) limits are guaranteed by design characterization data only.
Detailed Operating Description
The LM5007EP Step Down Switching Regulator features all
of the functions needed to implement low cost, efficient,
Buck bias regulators. This high voltage regulator contains an
80V, 0.7A N-Channel Buck Switch. The device is easy to
apply and is provided in the MSOP-8 and the thermally
enhanced LLP-8 packages. The regulator is based on a
hysteretic control scheme using an on time inversely propor-
tional to Vin. This feature allows the operating frequency to
remain relatively constant with load and input voltage varia-
tions. The hysteretic control requires no control loop com-
pensation, while providing very fast load transient response.
An intelligent current limit scheme is implemented in the
LM5007EP with forced off time, after current limit detection,
which is inversely proportional to Vout. This current limiting
scheme reduces load current foldback. Additional protection
features include: Thermal Shutdown, Vcc undervoltage lock-
out, Gate drive undervoltage lockout and Max Duty Cycle
limiter. The LM5007EP can be applied in numerous applica-
tions to efficiently regulate step down higher voltage inputs.
This regulator is well suited for 48 Volt Telcom and the new
42V Automotive power bus ranges.
Hysteretic Control Circuit
Overview
The LM5007EP is a Buck DC-DC regulator that uses an on
time control scheme. The on time is programmed by an
external resistor and varies inversely with line input voltage
(Vin). The core regulation elements of the LM5007EP are the
feedback comparator and the on time one-shot. The regula-
tor output voltage is sensed at the feedback pin (FB) and is
compared to an internal reference voltage (2.5V). If the FB
signal is below the reference voltage, the buck switch is
turned on for a fixed time pulse determined by the line
voltage and a programming resistor (R
ON). Following the on
period the switch will remain off for at least the minimum off
timer period of 300ns. If the FB pin voltage is still below the
reference after the 300ns off time, the switch will turn on
again for another on time period. This switching behavior will
continue until the FB pin voltage reaches the reference
voltage level.
The LM5007EP operates in discontinuous conduction mode
at light load currents or continuous conduction mode at
heavier load currents. In discontinuous conduction mode,
current through the output inductor starts at zero and ramps
up to a peak value during the buck switch on time and then
back to zero during the off time. The inductor current remains
at zero until the next on time period starts when FB falls
below the internal reference. In discontinuous mode the
operating frequency can be relatively low and will vary with
load. Therefore at light loads the conversion efficiency is
maintained, since the switching losses decrease with the
reduction in load current and switching frequency. The ap-
proximate discontinuous mode operating frequency can be
calculated as follows:
In continuous conduction mode, current flows continuously
through the inductor and never ramps down to zero. In this
mode the operating frequency is greater than the discontinu-
ous mode frequency and remains relatively constant with
load and line variations. The approximate continuous mode
operating frequency can be calculated as follows:
LM5007EP
Enhanced
Plastic
www.national.com
5
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM5007MMX | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM5007MMX/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM5007MMXNOPB | 制造商:National Semiconductor 功能描述:Conv DC-DC Single Step Down 9V to 75V 8-Pin MSOP T/R |
| LM5007SD | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM5007SD/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
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