- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄377774 > LTC3408EDD (LINEAR TECHNOLOGY CORP) 1.5MHz, 600mA Synchronous Step-Down Regulator with Bypass Transistor PDF資料下載
參數(shù)資料
| 型號(hào)： | LTC3408EDD |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.5MHz, 600mA Synchronous Step-Down Regulator with Bypass Transistor |
| 中文描述： | 1.3 A SWITCHING REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 3 X 3 MM, 0.75 MM HEIGHT, PLASTIC, M0-229-WEED-1, DFN-8 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 156K |
| 代理商： | LTC3408EDD |
8
LTC3408
3408f
At output voltages below 0.6V, the switching frequency
decreases linearly to a minimum of approximately 700kHz.
This places the maximum ripple current (in forced con-
tinuous mode) at the highest input voltage and the lowest
output voltage. In practice, the resulting ouput ripple
voltage is 10mV to 15mV using the components specified
in Figure 1.
The DC current rating of the inductor should be at least equal
to the maximum load current plus half the ripple current to
prevent core saturation. Thus, a 660mA rated inductor
should be enough for most applications (600mA + 60mA).
For better efficiency, choose a low DC-resistance inductor.
Inductor Core Selection
Different core materials and shapes will change the size/
current and price/current relationship of an inductor.
Toroid or shielded pot cores in ferrite or permalloy mate-
rials are small and don’t radiate much energy but generally
cost more than powdered iron core inductors with similar
electrical characteristics. The choice of which style induc-
tor to use often depends more on the price versus size
requirements and any radiated field/EMI requirements
than on what the LTC3408 requires to operate. Table 1
shows some typical surface mount inductors that work
well in LTC3408 applications.
Table 1. Representative Surface Mount Inductors
PART
VALUE
NUMBER
(
μ
H)
Sumida
4.7
CDRH2D11
Sumida
4.7
CDRH2D18/LD
Sumida
4.7
CMD4D06
Murata
4.7
LQH32C
Taiyo Yuden
4.7
LBLQ2016
Toko
4.7
D312C
DCR
(
MAX)
0.135
MAX DC
CURRENT (A)
0.5
SIZE
WxLxH (mm
3
)
3.2 x 3.2 x 1.2
0.078
0.63
3.2 x 3.2 x 2.0
0.216
0.75
3.5 x 4.1 x 0.8
0.150
0.65
2.5 x 3.2 x 2.0
0.250
0.210
1.6 x 2.0 x 1.6
0.20
0.79
3.6 x 3.6 x 1.2
C
IN
and C
OUT
Selection
In continuous mode, the source current of the top MOSFET
is a square wave of duty cycle V
OUT
/V
IN
. To prevent large
voltage transients, a low ESR input capacitor sized for the
APPLICATIU
W
U
U
maximum RMS current must be used. The maximum
RMS capacitor current is given by:
C
requiredI
I
V
[
V
(
V
V
IN
RMS
OMAX
OUT
IN
OUT
IN
–
)]
/ 2
This formula has a maximum at V
IN
= 2V
OUT
, where I
RMS
= I
OUT
/2. This simple worst-case condition is commonly
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 re-
quired. Always consult the manufacturer if there is any
question.
The selection of C
OUT
is driven by the required effective
series resistance (ESR). Typically, once the ESR
requirement for C
OUT
has been met, the RMS current
rating generally far exceeds the I
RIPPLE(P-P)
requirement.
The output ripple V
OUT
is determined by:
+
V
I ESR
f C
8
OUT
OUT
1
where f = operating frequency, C
OUT
= output capacitance
and I
L
= ripple current in the inductor. For a fixed output
voltage, the output ripple is highest at maximum input
voltage since I
L
increases with input voltage.
Aluminum electrolytic and dry tantalum capacitors are
both available in surface mount configurations. In the case
of tantalum, it is critical that the capacitors are surge tested
for use in switching power supplies. An excellent choice is
the AVX TPS series of surface mount tantalum. These are
specially constructed and tested for low ESR so they give
the lowest ESR for a given volume. Other capacitor types
include Sanyo POSCAP, Kemet T510 and T495 series, and
Sprague 593D and 595D series. Consult the manufacturer
for other specific recommendations.
The bulk capacitance values in Figure 1(a) (C
IN
= 10
μ
F,
C
OUT
= 4.7
μ
F) are tailored to mobile phone applications, in
which the output voltage is expected to slew quickly
according to the needs of the power amplifier. Holding the
output capacitor to 4.7
μ
F facilitates rapid charging and
discharging. When the output voltage descends quickly in
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC3409 | 64 x 18 3.3-V asynchronous FIFO memory 56-SSOP 0 to 70 |
| LTC3409EDD | 600mA Low Vin Buck Regulator in 3mm x 3mm DFN |
| LTC3411EMS | 1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3411 | 1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3411EDD | 1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3408EDD#PBF | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)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(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3408EDD#TR | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)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(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3408EDD#TRPBF | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)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(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3409 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:600mA Low Vin Buck Regulator in 3mm x 3mm DFN |
| LTC3409A | 制造商:LINER 制造商全稱:Linear Technology 功能描述:600mA Low VIN Buck Regulator in 3mm × 3mm DFN |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。