参数资料
| 型号： | MC33363ADW |
| 厂商： | ON Semiconductor |
| 文件页数： | 9/13页 |
| 文件大小： | 0K |
| 描述： | IC SWIT PROG OVP UVLO HV 16SOIC |
| 产品变化通告： | LTB Notification 03/Jan/2008 |
| 标准包装： | 47 |
| 输出隔离： | 隔离 |
| 频率范围： | 59kHz ~ 315kHz |
| 输入电压： | 11.5 V ~ 40 V |
| 输出电压： | 700V |
| 工作温度： | -25°C ~ 125°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： | 管件 |
MC33363A
OPERATING DESCRIPTION
Introduction
The MC33363A 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
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.
= R
T
from a rectified 240 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
I
chg ∕ dscg
5.4
T
f ≈
I
chg ∕ dscg
4C
Regulator Output
2.25 I
RC 6 Current
R T
Blanking
C T
Pulse
? ?
RT -- 1.14
1000
pk
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%
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 .
Current
Mirror
1.0 8
I
Limit
Reference
4I
Oscillator
7
RD
PWM
Comparator
Figure 21. Maximum Duty Cycle Modification
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 MC33363A 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 2819 cells, of which 65 are
connected to a 6.0 Ω 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
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 Ω 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 peak drain current versus R T is shown in Figure 3
with the related formula below.
I = 15.95
The Power Switch is designed to directly drive the
converter transformer and is capable of switching a
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相关代理商/技术参数 |
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| 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 |
| MC33363ADWR2G | 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 |
| MC33363AP | 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 |
| MC33363APG | 功能描述:DC/DC 开关控制器 ANA HI VOLT OFFLN SW REG RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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