- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄39399 > LT3757HMSE#TRPBF (LINEAR TECHNOLOGY CORP) SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO10 PDF資料下載
參數(shù)資料
| 型號： | LT3757HMSE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | 3 X 3 MM, LEAD FREE, PLASTIC, MSOP-10 |
| 文件頁數(shù)： | 2/36頁 |
| 文件大?。?/td> | 436K |
| 代理商： | LT3757HMSE#TRPBF |
第1頁當前第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁第36頁
LT3757
10
3757fc
applicaTions inForMaTion
For applications where the SHDN/UVLO pin is only used
as a logic input, the SHDN/UVLO pin can be connected
directly to the input voltage VIN for always-on operation.
INTVCC Regulator Bypassing and Operation
An internal, low dropout (LDO) voltage regulator produces
the 7.2V INTVCC supply which powers the gate driver, as
shown in Figure 1. If a low input voltage operation is ex-
pected (e.g., supplying power from a lithium-ion battery
or a 3.3V logic supply), low threshold MOSFETs should
be used. The LT3757 contains an undervoltage lockout
comparator A8 and an overvoltage lockout comparator
A9 for the INTVCC supply. The INTVCC undervoltage (UV)
threshold is 2.7V (typical), with 100mV hysteresis, to
ensure that the MOSFETs have sufficient gate drive voltage
before turning on. The logic circuitry within the LT3757 is
also powered from the internal INTVCC supply.
The INTVCC overvoltage (OV) threshold is set to be 17.5V
(typical) to protect the gate of the power MOSFET. When
INTVCC is below the UV threshold, or above the OV thresh-
old, the GATE pin will be forced to GND and the soft-start
operation will be triggered.
The INTVCC regulator must be bypassed to ground im-
mediately adjacent to the IC pins with a minimum of 4.7F
ceramic capacitor. Good bypassing is necessary to supply
the high transient currents required by the MOSFET gate
driver.
In an actual application, most of the IC supply current is
used to drive the gate capacitance of the power MOSFET.
Theon-chippowerdissipationcanbeasignificantconcern
when a large power MOSFET is being driven at a high fre-
quency and the VIN voltage is high. It is important to limit
the power dissipation through selection of MOSFET and/
or operating frequency so the LT3757 does not exceed its
maximum junction temperature rating. The junction tem-
peratureTJcanbeestimatedusingthefollowingequations:
TJ = TA + PIC θJA
TA = ambient temperature
θJA = junction-to-ambient thermal resistance
PIC = IC power consumption
= VIN (IQ + IDRIVE)
IQ = VIN operation IQ = 1.6mA
IDRIVE = average gate drive current = f QG
f = switching frequency
QG = power MOSFET total gate charge
The LT3757 uses packages with an Exposed Pad for en-
hanced thermal conduction. With proper soldering to the
Exposed Pad on the underside of the package and a full
copper plane underneath the device, thermal resistance
(
θJA)willbeabout43°C/WfortheDDpackageand40°C/W
for the MSE package. For an ambient board temperature of
TA = 70°C and maximum junction temperature of 125°C,
the maximum IDRIVE (IDRIVE(MAX)) of the DD package can
be calculated as:
IDRIVE(MAX) =
(TJ TA)
(
θJA VIN)
IQ =
1.28W
VIN
1.6mA
The LT3757 has an internal INTVCC IDRIVE current limit
function to protect the IC from excessive on-chip power
dissipation. The IDRIVE current limit decreases as the VIN
increases (see the INTVCCMinimumOutputCurrentvsVIN
graph in the Typical Performance Characteristics section).
If IDRIVE reaches the current limit, INTVCC voltage will fall
and may trigger the soft-start.
BasedontheprecedingequationandtheINTVCCMinimum
Output Current vs VIN graph, the user can calculate the
maximum MOSFET gate charge the LT3757 can drive at
a given VIN and switch frequency. A plot of the maximum
QG vs VIN at different frequencies to guarantee a minimum
4.5V INTVCC is shown in Figure 2.
As illustrated in Figure 2, a trade-off between the operating
frequencyandthesizeofthepowerMOSFETmaybeneeded
in order to maintain a reliable IC junction temperature.
Prior to lowering the operating frequency, however, be
sure to check with power MOSFET manufacturers for their
most recent low QG, low RDS(ON) devices. Power MOSFET
manufacturingtechnologiesarecontinuallyimproving,with
newer and better performance devices being introduced
almost yearly.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT574AKNW | 1-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDIP28 |
| LT574ALNW | 1-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDIP28 |
| LT574AJNW | 1-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDIP28 |
| LT6350CDD#TRPBF | 1-CH 16-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDSO8 |
| LT6350HDD#TRPBF | 1-CH 16-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDSO8 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3757IDD | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Controller |
| LT3757IDD#PBF | 功能描述:IC REG CTRLR BST FLYBK INV 10DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,000 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR) |
| LT3757IDD#PBF | 制造商:Linear Technology 功能描述:DC-DC CONTROLLER SEPIC 1MHZ 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, SEPIC, 1MHZ, DFN-10 |
| LT3757IDD#TRPBF | 功能描述:IC REG CTRLR BST FLYBK INV 10DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝: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) |
| LT3757IDDPBF | 制造商:Linear Technology 功能描述:Boost Flyback SEPIC Controller DFN10EP |
發(fā)布緊急采購，3分鐘左右您將得到回復。