- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44990 > LTC3404MPMS8#TRPBF (LINEAR TECHNOLOGY CORP) 1.5 A SWITCHING REGULATOR, 1650 kHz SWITCHING FREQ-MAX, PDSO8 PDF資料下載
參數(shù)資料
| 型號： | LTC3404MPMS8#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.5 A SWITCHING REGULATOR, 1650 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-8 |
| 文件頁數(shù)： | 2/16頁 |
| 文件大?。?/td> | 204K |
| 代理商： | LTC3404MPMS8#TRPBF |
10
LTC3404
3404fb
VFB
GND
LTC3404
0.8V
≤ VOUT ≤ 6V
R2
R1
3404 F03
Figure 3. Setting the LTC3404 Output Voltage
APPLICATIO S I FOR ATIO
WU
UU
inductor ripple current and consequent output voltage
ripple. Do not allow the core to saturate!
Kool M
μ (from Magnetics, Inc.) is a very good, low loss
core material for toroids with a “soft” saturation character-
istic. Molypermalloy is slightly more efficient at high
(>200kHz) switching frequencies but quite a bit more
expensive. Toroids are very space efficient, especially
when you can use several layers of wire, while inductors
wound on bobbins are generally easier to surface mount.
New designs for surface mount inductors are available
from Coiltronics, Coilcraft, Dale and Sumida.
CIN and COUT Selection
In continuous mode, the source current of the top MOS-
FET is a square wave of duty cycle VOUT/VIN. To prevent
large voltage transients, a low ESR input capacitor sized
for the maximum RMS current must be used. The maxi-
mum RMS capacitor current is given by:
CI
VV
V
IN
OMAX
OUT
IN
OUT
IN
required IRMS
()
[]12/
This formula has a maximum at VIN = 2VOUT, where
IRMS = IOUT/2. This simple worst-case condition is com-
monly used for design because even significant deviations
do not offer much relief. Note that the capacitor
manufacturer’s ripple current ratings are often based on
2000 hours of life. This makes it advisable to further derate
the capacitor, or choose a capacitor rated at a higher
temperature than required. Several capacitors may also be
paralleled to meet size or height requirements in the
design. Always consult the manufacturer if there is any
question.
The selection of COUT is driven by the required effective
series resistance (ESR). Typically, once the ESR require-
ment is satisfied, the capacitance is adequate for filtering.
The output ripple
ΔVOUT is determined by:
Δ Δ
+
V
I ESR
fC
OUT
L
OUT
1
8
where f = operating frequency, COUT = output capacitance
and
ΔIL = ripple current in the inductor. The output ripple
is highest at maximum input voltage since
ΔIL increases
with input voltage. For the LTC3404, the general rule for
proper operation is:
COUT required ESR < 0.25Ω
The choice of using a smaller output capacitance
increases the output ripple voltage due to the frequency
dependent term but can be compensated for by using
capacitor(s) of very low ESR to maintain low ripple
voltage. The ITH pin compensation components can be
optimized to provide stable high performance transient
response regardless of the output capacitor selected.
ESR is a direct function of the volume of the capacitor.
Manufacturers such as Taiyo-Yuden, AVX, Kemet, Sprague
and Sanyo should be considered for high performance
capacitors. The POSCAP solid electrolytic chip capacitor
available from Sanyo is an excellent choice for output bulk
capacitors due to its low ESR/size ratio. Once the ESR
requirement for COUT has been met, the RMS current
rating generally far exceeds the IRIPPLE(P-P) requirement.
When using tantalum capacitors, it is critical that they are
surge tested for use in switching power supplies. A good
choice is the AVX TPS series of surface mount tantalum,
available in case heights ranging from 2mm to 4mm. Other
capacitor types include KEMET T510 and T495 series and
Sprague 593D and 595D series. Consult the manufacturer
for other specific recommendations.
Output Voltage Programming
The output voltage is set by a resistive divider according
to the following formula:
VV
R
OUT =+
08
1
2
1
.
(2)
The external resistive divider is connected to the output,
allowing remote voltage sensing as shown in Figure 3.
相關PDF資料 |
PDF描述 |
|---|---|
| LTC3404IMS8#TRPBF | 1.5 A SWITCHING REGULATOR, 1650 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3406ABES5#PBF | 1.3 A SWITCHING REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO5 |
| LTC3406ABES5#TRM | 1.3 A SWITCHING REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO5 |
| LTC3406ABES5#TR | 1.3 A SWITCHING REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO5 |
| LTC3406B-2ES5#PBF | 1.3 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO5 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3405 | 制造商:LINEAR 制造商全稱:LINEAR 功能描述:Standalone 250mA Li-Ion Battery Charger in 2 × 2 DFN |
| LTC3405A | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5MHz, 300mA Synchronous Step-Down Regulator in ThinSOT |
| LTC3405A-1.375 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.375V, 1.5MHz, 300mA Synchronous Step-Down Regulators in ThinSOT |
| LTC3405A-1.5 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5V, 1.8V, 1.5MHz, 300mA Synchronous Step-Down Regulators in ThinSOT |
| LTC3405A-1.8 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5V, 1.8V, 1.5MHz, 300mA Synchronous Step-Down Regulators in ThinSOT |
發(fā)布緊急采購，3分鐘左右您將得到回復。