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| 型号： | MC33362DWR2 |
| 厂商： | ON Semiconductor |
| 文件页数： | 9/14页 |
| 文件大小： | 0K |
| 描述： | IC SWIT PWM OVP UVLO HV 16SOIC |
| 产品变化通告： | LTB Notification 03/Jan/2008 |
| 标准包装： | 1 |
| 输出隔离： | 隔离 |
| 频率范围： | 59kHz ~ 315kHz |
| 输入电压： | 9.5 V ~ 40 V |
| 输出电压： | 500V |
| 工作温度： | -25°C ~ 150°C |
| 封装/外壳： | 16-SOIC（0.295"，7.50mm 宽）13 引线 |
| 供应商设备封装： | 16-SOIC W |
| 包装： | 标准包装 |
| 其它名称： | MC33362DWR2OSDKR |
MC33362
OPERATING DESCRIPTION
5.4
chg dscg
chg dscg
4C
T
Introduction
The MC33362 represents a new higher level of integration
by providing all the active high voltage power, control, and
protection circuitry required for implementation of a
flyback or forward converter on a single monolithic chip.
This device is designed for direct operation from a rectified
120 VAC line source and requires a minimum number of
external components to implement a complete converter. A
description of each of the functional blocks is given below,
and the representative block and timing diagrams are shown
in Figures 19 and 20.
Oscillator and Current Mirror
The oscillator frequency is controlled by the values
selected for the timing components R T and C T . Resistor R T
programs the oscillator charge/discharge current via the
Current Mirror 4 I output, Figure 4. Capacitor C T is charged
and discharged by an equal magnitude internal current
source and sink. This generates a symmetrical 50 percent
duty cycle waveform at Pin 7, with a peak and valley
threshold of 2.6 V and 0.6 V respectively. During the
discharge of C T , the oscillator generates an internal blanking
pulse that holds the inverting input of the AND gate Driver
high. This causes the Power Switch gate drive to be held in
a low state, thus producing a well controlled amount of
output deadtime. The amount of deadtime is relatively
constant with respect to the oscillator frequency when
operating below 1.0 MHz. The maximum Power Switch
duty cycle at Pin 16 can be modified from the internal 50%
limit by providing an additional charge or discharge current
path to C T , Figure 21. In order to increase the maximum duty
cycle, a discharge current resistor R D is connected from
Pin 7 to ground. To decrease the maximum duty cycle, a
charge current resistor R C is connected from Pin 7 to the
Regulator Output. Figure 5 shows an obtainable range of
maximum output duty cycle versus the ratio of either R C or
R D with respect to R T .
The formula for the charge/discharge current along with
the oscillator frequency are given below. The frequency
formula is a first order approximation and is accurate for C T
values greater than 500 pF. For smaller values of C T , refer to
Figure 2. Note that resistor R T also programs the Current
Limit Comparator threshold.
I
I + R f [
T
PWM Comparator and Latch
The pulse width modulator consists of a comparator with
the oscillator ramp voltage applied to the non ? inverting
input, while the error amplifier output is applied into the
inverting input. The Oscillator applies a set pulse to the
PWM Latch while C T is discharging, and upon reaching the
valley voltage, Power Switch conduction is initiated. When
C T charges to a voltage that exceeds the error amplifier
output, the PWM Latch is reset, thus terminating Power
Switch conduction for the duration of the oscillator ramp ? up
period. This PWM Comparator/Latch combination
prevents multiple output pulses during a given oscillator
clock cycle. The timing diagram shown in Figure 20
illustrates the Power Switch duty cycle behavior versus the
Compensation voltage.
Current Limit Comparator and Power Switch
The MC33362 uses cycle ? by ? cycle current limiting as a
means of protecting the output switch transistor from
overstress. Each on ? cycle is treated as a separate situation.
Current limiting is implemented by monitoring the output
switch current buildup during conduction, and upon sensing
an overcurrent condition, immediately turning off the switch
for the duration of the oscillator ramp ? up period.
The Power Switch is constructed as a SENSEFET
allowing a virtually lossless method of monitoring the drain
current. It consists of a total of 3770 cells, of which 50 are
Regulator Output
Current
Mirror
connected to a 9.0 W ground ? referenced sense resistor. The
Current Sense Comparator detects if the voltage across the
sense resistor exceeds the reference level that is present at
the inverting input. If exceeded, the comparator quickly
Blanking
RC
RD
1.0
R T
C T
8
6
7
I
2.25 I
Current
Limit
Reference
4I
Oscillator
Pulse
resets the PWM Latch, thus protecting the Power Switch.
The current limit reference level is generated by the 2.25 I
output of the Current Mirror. This current causes a reference
voltage to appear across the 450 W resistor. This voltage
level, as well as the Oscillator charge/discharge current are
both set by resistor R T . Therefore when selecting the values
for R T and C T , R T must be chosen first to set the Power Switch
peak drain current, while C T is chosen second to set the
desired Oscillator frequency. A graph of the Power Switch
PWM
peak drain current versus R T is shown in Figure 3 with the
related formula below.
T
Comparator
Figure 21. Maximum Duty Cycle Modification
I
pk
+ 12.3
R
1000
? 1.115
http://onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MC33362DWR2G | 功能描述:直流/直流开关调节器 ANA HI VOLT OFFLN SW REG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MC33362XDWR2G | 功能描述:直流/直流开关调节器 ANA HI VOLT OFFLN SW REG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MC33363ADW | 功能描述:交流/直流开关转换器 700V 1.5A Switching RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
| MC33363ADWG | 功能描述:交流/直流开关转换器 700V 1.5A Switching RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
| MC33363ADWR2 | 功能描述:交流/直流开关转换器 700V 1.5A Switching RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
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