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參數(shù)資料
| 型號： | MC33067DWR2 |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High Performance Resonant Mode Controllers |
| 中文描述： | 1.5 A SWITCHING CONTROLLER, 2200 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | PLASTIC, SOIC-16 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大?。?/td> | 544K |
| 代理商： | MC33067DWR2 |
MC34067, MC33067
http://onsemi.com
11
Fault
Latch
S
R
Q
Figure 20. Fault Detector and SoftStart
C
SoftStart
Fault
Input
10
9.0 A
1.0 V
11
6
Ground
SoftStart
Buffer
Error Amp
Clamp
UVLO + Fault
UVLO
Fault
Comparator
Fault
SoftStart Circuit
The SoftStart circuit shown in Figure 20 forces the
variable frequency Oscillator to start at the maximum
frequency and ramp downward until regulated by the
feedback control loop. The external capacitor at the
C
SoftStart
terminal is initially discharged by the
UVLO+Fault signal. The low voltage on the capacitor
passes through the SoftStart Buffer to hold the Error
Amplifier output low. After UVLO+Fault switches to a
logic zero, the softstart capacitor is charged by a 9.0 A
current source. The buffer allows the Error Amplifier output
to follow the softstart capacitor until it is regulated by the
Error Amplifier inputs. The softstart function is generally
applicable to controllers operating below resonance and can
be disabled by simply opening the C
SoftStart
terminal.
APPLICATIONS INFORMATION
The MC34067 is specifically designed for zero voltage
switching (ZVS) quasiresonant converter (QRC)
applications. The IC is optimized for doubleended
pushpull or bridge type converters operating in continuous
conduction mode. Operation of this type of ZVS with
resonant properties is similar to standard pushpull or bridge
circuits in that the energy is transferred during the transistor
ontime. The difference is that a series resonant tank is
usually introduced to shape the voltage across the power
transistor prior to turnon. The resonant tank in this
topology is not used to deliver energy to the output as is the
case with zero current switch topologies. When the power
transistor is enabled the voltage across it should already be
zero, yielding minimal switching loss. Figure 21 shows a
timing diagram for a halfbridge ZVS QRC. An application
circuit is shown in Figure 22. The circuit built is a dc to dc
halfbridge converter delivering 75 W to the output from a
48 V source.
When building a zero voltage switch (ZVS) circuit, the
objective is to waveshape the power transistor’s voltage
waveform so that the voltage across the transistor is zero
when the device is turned on. The purpose of the control IC
is to allow a resonant tank to waveshape the voltage across
the power transistor while still maintaining regulation. This
is accomplished by maintaining a fixed deadtime and by
varying the frequency; thus the effective duty cycle is
changed.
Primary side resonance can be used with ZVS circuits. In
the application circuit, the elements that make the resonant
tank are the primary leakage inductance of the transformer
(L
L
) and the average output capacitance (C
OSS
) of a power
MOSFET (C
R
).
The desired resonant frequency for the application circuit
is calculated by Equation 6:
LL2CR
1
=
π
2
r
(eq. 6)
In the application circuit, the operating voltage is low and
the value of C
OSS
versus Drain Voltage is known. Because
the C
OSS
of a MOSFET changes with drain voltage, the
value of the C
R
is approximated as the average C
OSS
of the
MOSFET. For the application circuit the average C
OSS
can
be calculated by Equation 7:
measured at
CR
1
2
2 * COSS
=
in
V
(eq. 7)
The MOSFET chosen fixes C
R
and that L
L
is adjusted to
achieve the desired resonant frequency.
However, the desired resonant frequency is less critical
than the leakage inductance. Figure 21 shows the primary
current ramping toward its peak value during the resonant
transition. During this time, there is circulating current
flowing through the secondary inductance, which
effectively makes the primary inductance appear shorted.
Therefore, the current through the primary will ramp to its
peak value at a rate controlled by the leakage inductance and
the applied voltage. Energy is not transferred to the
secondary during this stage, because the primary current has
not overcome the circulating current in the secondary. The
larger the leakage inductance, the longer it takes for the
primary current to slew. The practical effect of this is to
lower the duty cycle, thus reducing the operating range.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MC33067DWR2G | 功能描述:DC/DC 開關(guān)控制器 High Performance Resonant Mode RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MC33067P | 功能描述:DC/DC 開關(guān)控制器 High Performance RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MC33067PG | 功能描述:DC/DC 開關(guān)控制器 High Performance Resonant Mode RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MC3306D5R2 | 制造商:MOT 功能描述:_ |
| MC3306D-5R2 | 制造商:MOT 功能描述:_ |
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