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參數(shù)資料
| 型號： | LT3758HMSE#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)： | 3/36頁 |
| 文件大小： | 554K |
| 代理商： | LT3758HMSE#TRPBF |
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LT3758
11
3758fc
ApplicAtions inForMAtion
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. The LT3758 contains an undervoltage
lockout comparator A8 and an overvoltage lockout com-
parator A9 for the INTVCCsupply.TheINTVCCundervoltage
(UV) threshold is 4.5V (typical), with 0.5V hysteresis, to
ensure that the MOSFETs have sufficient gate drive voltage
before turning on. The logic circuitry within the LT3758 is
also powered from the internal INTVCC supply.
The INTVCC overvoltage 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 overvolt-
age threshold, 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 LT3758 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 LT3758 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 LT3758 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 LT3758 can drive at
a given VIN and switch frequency. A plot of the maximum
QG vs VIN at different frequencies to guarantee a minimum
4.7V INTVCC is shown in Figure 2.
Figure 2. Recommended Maximum QG vs VIN at Different
Frequencies to Ensure INTVCC Higher Than 4.7V
VIN (V)
1
Q
G(nC)
10
100
3758 F02
0
20
40
80
120
140
60
100
300kHz
1MHz
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| LT3758IDD#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:2,500 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) |
| LT3758IDD#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) |
| LT3758IDDPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Controller |
| LT3758IDDTRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Controller |
| LT3758IMSE#PBF | 功能描述:IC REG CTRLR PWM CM 10-MSOP 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) |
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