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參數(shù)資料
| 型號： | LTM4612IV#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 940 kHz SWITCHING FREQ-MAX, PBGA133 |
| 封裝： | 15 X 15 MM, 2.82 MM HEIGHT, LEAD FREE, MO-222, LGA-133 |
| 文件頁數(shù)： | 4/26頁 |
| 文件大?。?/td> | 5123K |
| 代理商： | LTM4612IV#PBF |
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LTM4612
4612fa
Figure 4. Conducted Emission Scan with 24VIN to
12VOUT at 5A (3 × 10F Ceramic Capacitors on VIN
Pads and 1 × 10F Ceramic Capacitor on VD Pads).
applicaTions inForMaTion
If lower output ripple is required, the operating frequency
f can be increased by adding a resistor RfSET between fSET
pin and SGND, as shown in Figure 19.
f
V
R
k
OUT
fSET
=
(
)
1 5 10
93 1
10
.
||
.
For output voltages more than 12V, the frequency can be
higherthan1MHz,thusreducingtheefficiencysignificantly.
Additionally, the minimum off time 400ns normally limits
the operation when the input voltage is close to the output
voltage. Therefore, it is recommended to lower the fre-
quencyintheseconditionsbyconnectingaresistor(RfSET)
from the fSET pin to VIN, as shown in Figure 20.
f
V
R
k
R
k
OUT
fSET
=
5 10
3
93 1
2 93 1
11
.
.
Theloadcurrentcanaffectthefrequencyduetoitsconstant
on-time control. If constant frequency is a necessity, the
PLLIN pin can be used to synchronize the frequency of
the LTM4612 to an external clock, as shown in Figures
21 to 23.
Input Capacitors
LTM4612 is designed to achieve the low input conducted
EMI noise due to the fast switching of turn-on and turn-off.
In the LTM4612, a high-frequency inductor is integrated
into the input line for noise attenuation. VD and VIN pins
are available for external input capacitors to form a high
frequency π filter. As shown in Figure 18, the ceramic
capacitor C1 on the VD pins is used to handle most of
the RMS current into the converter, so careful attention
is needed for capacitor C1 selection.
For a buck converter, the switching duty cycle can be
estimated as:
D
V
OUT
IN
=
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
I
D
CIN RMS
OUT MAX
(
)
(
)
–
=
( )
h
1
In this equation,
h is the estimated efficiency of the
power module. Note the capacitor ripple current ratings
are often based on temperature and hours of life. This
makes it advisable to properly derate the input capacitor,
or choose a capacitor rated at a higher temperature than
required. Always contact the capacitor manufacturer for
derating requirements.
In a typical 5A output application, one very low ESR, X5R
or X7R, 10F ceramic capacitor is recommended for C1.
This decoupling capacitor should be placed directly adja-
cent to the module VD pins in the PCB layout to minimize
the trace inductance and high frequency AC noise. Each
10F ceramic is typically good for 2A to 3A of RMS ripple
current. Refer to your ceramics capacitor catalog for the
RMS current ratings.
Toattenuatethehighfrequencynoise,extrainputcapacitors
should be connected to the VIN pads and placed before the
high frequency inductor to form the π filter. One of these
low ESR ceramic input capacitors is recommended to be
close to the connection into the system board. A large
bulk 100F capacitor is only needed if the input source
impedance is compromised by long inductive leads or
traces. Figure 4 shows the conducted EMI testing results
to meet the Level 5 of the CISPR 25 limit. For different
applications, input capacitance may be varied to meet
different conducted EMI limits.
FREQUENCY (MHz)
0.15
0
SIGNAL
AMPLITUDE
(dB
V)
20
40
60
80
10
30
50
70
1
30
10
4612 F04
CIS25QP
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| LTM4612MPV | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Ultralow Noise 36VIN, 15VOUT, 5A, DC/DC μModule |
| LTM4612MPV#PBF | 功能描述:IC BUCK SYNC ADJ 5A 133LGA RoHS:是 類別:電源 - 板載 >> DC DC Converters 系列:µModule® 設(shè)計資源:VI-200, VI-J00 Design Guide, Appl Manual 標準包裝:1 系列:* 類型:隔離 輸出數(shù):1 電壓 - 輸入（最?。?66V 電壓 - 輸入（最大）:160V Voltage - Output 1:12V Voltage - Output 2:- Voltage - Output 3:- 電流 - 輸出（最大）:* 電源（瓦） - 制造商系列:50W 電壓 - 隔離:* 特點:* 安裝類型:通孔 封裝/外殼:9-FinMod 尺寸/尺寸:4.60" L x 1.86" W x 0.79" H（116.8mm x 47.2mm x 20.1mm） 包裝:散裝 工作溫度:-25°C ~ 85°C 效率:* 電源（瓦特）- 最大:* |
| LTM4612MPV-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Ultralow Noise 36VIN, 15VOUT, 5A, DC/DC μModule |
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| LTM4613 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:符合 EN55022B 規(guī)格的36VIN、15VOUT、8A、DC/DC μModule 穩(wěn)壓器,LTM®4613 是一款完整、超低噪聲、8A 開關(guān)模式 DC/DC電源。 |
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