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參數(shù)資料
| 型號： | MC33023DWG |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High Speed Single−Ended PWM Controller |
| 中文描述： | 2 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | LEAD FREE, SOIC-16 |
| 文件頁數(shù)： | 10/18頁 |
| 文件大?。?/td> | 450K |
| 代理商： | MC33023DWG |
MC34023, MC33023
http://onsemi.com
10
In certain applications, it may be desirable to disable the
current limit comparator. This can be accomplished by
biasing pin 11 to a level greater than 1.4 V but less than 3.0 V.
Under these conditions, the shutdown comparator and
softstart latch are activated during an overcurrent event
causing the converter to enter an hiccup mode.
Undervoltage Lockout
There are two undervoltage lockout circuits within the IC.
The first senses V
CC
and the second V
ref
. During powerup,
V
CC
must exceed 9.2 V and V
ref
must exceed 4.2 V before
the outputs can be enabled and the SoftStart latch released.
If V
CC
falls below 8.4 V or V
ref
falls below 3.6 V, the outputs
are disabled and the SoftStart latch is activated. When the
UVLO is active, the part is in a low current standby mode
allowing the IC to have an offline bootstrap startup circuit.
Typical startup current is 500 A.
Output
The MC34023 has a high current totem pole output
specifically designed for direct drive of power MOSFETs.
It is capable of up to
±
2.0 A peak drive current with a typical
rise and fall time of 30 ns driving a 1.0 nF load.
Separate pins for V
C
and Power Ground are provided.
With proper implementation, a significant reduction of
switching transient noise imposed on the control circuitry is
possible. The separate V
C
supply input also allows the
designer added flexibility in tailoring the drive voltage
independent of V
CC
.
Reference
A 5.1 V bandgap reference is pinned out and is trimmed
to an initial accuracy of
±
1.0% at 25
°
C. This reference has
short circuit protection and can source in excess of 10 mA
for powering additional control system circuitry.
Design Considerations
Do not attempt to construct the converter on
wirewrap or plugin prototype boards.
With high
frequency, high power, switching power supplies it is
imperative to have separate current loops for the signal paths
and for the power paths. The printed circuit layout should
contain a ground plane with low current signal and high
current switch and output grounds returning on separate
paths back to the input filter capacitor. Shown in Figure 36
is a printed circuit layout of the application circuit. Note how
the power and ground traces are run. All bypass capacitors
and snubbers should be connected as close as possible to the
specific part in question. The PC board lead lengths must be
less than 0.5 inches for effective bypassing for snubbing.
Instabilities
In current mode control, an instability can be encountered
at any given duty cycle. The instability is caused by the
current feedback loop. It has been shown that the instability
is caused by a double pole at half the switching frequency.
If an external ramp (S
e
) is added to the ontime ramp (S
n
)
of the currentsense waveform, stability can be achieved.
One must be careful not to add too much ramp
compensation. If too much is added the system will start to
perform like a voltage mode regulator. All benefits of
current mode control will be lost. Figure 26 is an example of
one way in which external ramp compensation can be
implemented.
1.25 V
Figure 21. Ramp Compensation
Current
Signal S
n
Ramp Compensation
Ramp Input
Ramp
Compensation S
e
A simple equation can be used to calculate the amount of
external ramp slope necessary to add that will achieve
stability in the current loop. For the following equations, the
calculated values for the application circuit in Figure 35 are
also shown.
Se
VO
L
NS
NP
(RS)A
i
where:
= DC output voltage
= number of power transformer primary
=
or secondary turns
= gain of the current sense network
=
(see Figures 24 and 25)
= output inductor
= current sense resistance
V
O
N
P
, N
S
A
i
L
R
S
= 0.115 V/ms
For the application circuit: Se
5
1.8
μ
2
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| MC33023DWR2 | High Speed Single−Ended PWM Controller |
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| MC33025DWG | High Speed Double−Ended PWM Controller |
| MC33025DWR2 | High Speed Double−Ended PWM Controller |
| MC33025DWR2G | High Speed Double−Ended PWM Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MC33023DWR2 | 功能描述:電流型 PWM 控制器 Single Ended Voltage RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC33023DWR2G | 功能描述:電流型 PWM 控制器 Single Ended Voltage or Current Mode PWM RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC33023P | 制造商:Motorola 功能描述:MOTOROLA S1I2F |
| MC33024 | 制造商:SPC Multicomp 功能描述:FINGER GUARD 制造商:SPC Multicomp 功能描述:FINGER GUARD; For Use With:127mm Axial Fans; Fan Size:127mm; Fixing Centers:113.3mm; Guard Material:Steel; Accessory Type:Finger Guard; Color:Chrome; External Depth:5.5mm; External Height:115.6mm; External Width:115.6mm ;RoHS Compliant: Yes |
| MC33025 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:High Speed Double-Ended PWM Controller |
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