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參數(shù)資料
| 型號： | LT3512MPMS#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.8 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PDSO12 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-16/12 |
| 文件頁數(shù)： | 4/26頁 |
| 文件大?。?/td> | 244K |
| 代理商： | LT3512MPMS#PBF |
LT3512
12
3512fa
APPLICATIONS INFORMATION
Figure 5. Maximum Voltages for SW Pin Flyback Waveform
Figure 6. DZ Clamp
3512 F06
LS
D
Z
during that time, oscillation may occur at the output as
the current control loop will lose its ability to regulate. The
following equation based on maximum input voltage must
also be followed in selecting primary-side magnetizing
inductance:
LPRI ≥
tON(MIN) VIN(MAX)
IPEAK(MIN)
tON(MIN) = 100ns
IPEAK(MIN) = 100mA
Leakage Inductance and Clamp Circuits
Transformer leakage inductance (on either the primary or
secondary) causes a voltage spike to appear at the primary
after the output switch turns off. This spike is increasingly
prominent at higher load currents where more stored en-
ergy must be dissipated. When designing an application,
adequate margin should be kept for the effect of leakage
voltage spikes. In most cases the reflected output voltage
on the primary plus VIN should be kept below 100V. This
leaves at least 50V of margin for the leakage spike across
line and load conditions. A larger voltage margin will be
needed for poorly wound transformers or for excessive
leakage inductance. Figure 5 illustrates this point. Minimize
transformer leakage inductance.
A clamp circuit is recommended for most applications.
Two circuits that can protect the internal power switch
include the RCD (resistor-capacitor-diode) clamp and the
DZ (diode-Zener) clamp. The clamp circuits dissipate the
stored energy in the leakage inductance. The DZ clamp
is the recommended clamp for the LT3512. Simplicity of
design, high clamp voltages, and low power levels make the
DZ clamp the preferred solution. Additionally, a DZ clamp
ensures well defined and consistent clamping voltages.
Figure 5 shows the clamp effect on the switch waveform
and Figure 6 shows the connection of the DZ clamp.
Proper care must be taken when choosing both the diode
and the Zener diode. Schottky diodes are typically the best
choice, but some PN diodes can be used if they turn on
fast enough to limit the leakage inductance spike. Choose
a diode that has a reverse-voltage rating higher than the
maximum switch voltage. The Zener diode breakdown
voltage should be chosen to balance power loss and switch
<100V
<150V
VSW
VLEAKAGE
tOFF > 400ns
without Clamp
TIME
tSP < 150ns
<100V
<140V
<150V
VSW
tOFF > 400ns
with Clamp
TIME
tSP < 150ns
3512 F05
voltage protection. The best compromise is to choose the
largest voltage breakdown. Use the following equation to
make the proper choice:
VZENER(MAX) ≤ 150V – VIN(MAX)
For an application with a maximum input voltage of 72V,
choose a 68V VZENER which has VZENER(MAX) at 72V, which
will be below the 78V maximum.
The power loss in the clamp will determine the power rat-
ing of the Zener diode. Power loss in the clamp is highest
at maximum load and minimum input voltage. The switch
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| LT3513EUHF#PBF | 功能描述:IC REG 5-OUT FOR TFT-LCD 38QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設備封裝:48-QFN（7x7） 包裝:管件 |
| LT3513EUHF#TRPBF | 功能描述:IC REG 5-OUT FOR TFT-LCD 38QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設備封裝:48-QFN（7x7） 包裝:管件 |
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| LT3513EUHF-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:2MHz High Current 5-Output Regulator for TFT-LCD Panels |
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