參數(shù)資料
型號(hào)： MC33470DW
廠商： ON SEMICONDUCTOR
元件分類： 穩(wěn)壓器
英文描述： SYNCHRONOUS RECTIFICATION DC/DC CONVERTER PROGRAMMABLE INTEGRATED CONTROLLER
中文描述： SWITCHING CONTROLLER, 390 kHz SWITCHING FREQ-MAX, PDSO20
封裝： PLASTIC, SOIC-20
文件頁(yè)數(shù)： 10/16頁(yè)
文件大小： 311K
代理商： MC33470DW
MC33470
10
MOTOROLA ANALOG IC DEVICE DATA
In this design, choose two parallel MMSF3300 MOSFETs
for both the main switch and the synchronous rectifier to
maximize efficiency.
2. D
≈
VO/Vin = 2.8/5.0 = 0.56
3. Inductor selection
In order to maintain continuous mode operation at 10% of
full load current, the minimum value of the inductor will be:
Lmin = (Vin – VO)(DTs)/(2IO min)
= (5 – 2.8)(0.56 x 3.3
μ
s)/(2 x 1.4 A) = 1.45
μ
H
Coilcraft’s U6904, or an equivalent, provides a surface
mount 1.5
μ
H choke which is rated for for full load current.
4. Output capacitor selection
Vripple
≈
IL x ESR, where ESR is the equivalent series
resistance of the output capacitance. Therefore:
ESRmax = Vripple/
IL = 0.01 x 2.8 V/1.4 A = 0.02
maximum
The AVX TPS series of tantalum chip capacitors may be
chosen. Or OSCON capacitors may be used if leaded parts
are acceptable. In this case, the output capacitance consists
of two parallel 820
μ
F, 4.0 V capacitors. Each capacitor has a
maximum specified ESR of 0.012
.
5. Input Filter
As with all buck converters, input current is drawn in
pulses. In this case, the current pulses may be 14 A peak. If
a 1.5
μ
H choke is used, two parallel OSCON 150
μ
F, 16 V
capacitors will provide a filter cutoff frequency of 7.5 kHz.
6. Feedback Loop Compensation
The corner frequency of the output filter with L = 1.5
μ
H
and Co = 1640
μ
F is 3.2 kHz. In addition, the ESR of each
output capacitor creates a zero at:
fz = 1/(2
π
C ESR) = 1/(2
π
x 820
μ
F x 0.012) = 16.2 kHz
The dc gain of the PWM is: Gain = Vin/Vpp = 5/1 = 5.0.
Where Vpp is the peak–to–peak sawtooth voltage across the
internal timing capacitor. In order to make the feedback loop
as responsive as possible to load changes, choose the
unity gain frequency to be 10% of the switching frequency,
or 30 kHz. Plotting the PWM gain over frequency, at a
frequency of 30 kHz the gain is about –16.5 dB = 0.15.
Therefore, to have a 30 kHz unity gain loop, the error
amplifier gain at 30 kHz should be 1/0.15 = 6.7. Choose a
design phase margin for the loop of 60
°
. Also, choose the
error amp type to be an integrator for best dc regulation
performance. The phase boost needed by the error amplifier
is then 60
°
for the desired phase margin. Then, the following
calculations can be made:
k = tan [Boost/2 + 45
°
] = tan [60/2 + 45] = 3.73
Error Amp zero freq = fc/K = 30 kHz/3.73 = 8.0 kHz
Error Amp pole freq = Kfc = 3.73 x 30 kHz = 112 kHz
R2 = Error Amp Gain/Gm = 6.7/800
μ
= 8.375 k – use an
8.2 k standard value
C16 = 1/(2
π
R2 fz) = 1/(2
π
x 8.2 k x 8.0 kHz) = 2426 pF –
use 2200 pF
C17 = 1/(2
π
R2 fp) = 1/(2
π
x 8.2 k x 112 kHz) = 173 pF –
use 100 pF
The complete design is shown in Figure 13. The PC board
top and bottom views are shown in Figures 17 and 18.
Figure 16. Voltage Coupling Through Miller
Capacitance
相關(guān)PDF資料
PDF描述
MC33493 PLL tuned UHF Transmitter for Data Transfer Applications
MC33493DTB PLL tuned UHF Transmitter for Data Transfer Applications
MC3359 Single Output LDO, 400mA, Fixed(3.3V), Low Noise, Fast Transient Response 5-SOT-23 -40 to 85
MC3359DW Single Output LDO, 400mA, Fixed(5.0V), Low Noise, Fast Transient Response 8-MSOP -40 to 85
MC3359P Single Output LDO, 400mA, Fixed(5.0V), Low Noise, Fast Transient Response 8-MSOP -40 to 85
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MC33470DWG 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 5-Bit Synchronous Rectification Buck RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MC33470DWR2 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 5-Bit Synchronous RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MC33470DWR2G 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 5-Bit Synchronous Rectification Buck RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
MC33486ADH 功能描述:電源開(kāi)關(guān) IC - 配電 DUALHIGH-SIDE BRIDGE RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
MC33486ADHR2 功能描述:電源開(kāi)關(guān) IC - 配電 DUALHIGH-SIDE BRIDGE RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*