参数资料
| 型号： | MC33470DW |
| 厂商： | ON Semiconductor |
| 文件页数： | 8/15页 |
| 文件大小： | 0K |
| 描述： | IC CONV DC/DC SYNC RECT 20-SOIC |
| 产品变化通告： | Product Obsolescence 11/Feb/2009 |
| 标准包装： | 38 |
| 应用： | 控制器，Intel Pentium? II |
| 输入电压： | 4.5 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 1.8 V ~ 3.5 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 20-SOIC |
| 包装： | 管件 |
MC33470
UVL Threshold
12 V
UVL Threshold
5.0 V
Internal
V ref
Timing Capacitor
2.5 V
1.5 V
Compensation
G1
G2
Figure 15. Timing Diagram
OPERATING DESCRIPTION
V CC and PV
PV
The MC33470 is a monolithic, fixed frequency power
switching regulator specifically designed for dc?to?dc
converter applications which provide a precise supply voltage
for state of the art processors. The MC33470 operates as fixed
frequency, voltage mode regulator containing all the active
functions required to directly implement digitally
programmable step?down synchronous rectification with a
minimum number of external components.
Oscillator
The oscillator frequency is internally programmed to
300 kHz. The charge to discharge ratio is controlled to yield
a 95% maximum duty cycle at the switch outputs. During the
fall time of the internal sawtooth waveform, the oscillator
generates an internal blanking pulse that disables the G1 output
switching MOSFET. The internal sawtooth waveform has a
nominal peak voltage of 2.5 V and a valley voltage of 1.5 V.
Pulse Width Modulator
The pulse width modulator consists of a comparator with
the oscillator ramp voltage applied to the noninverting input,
while the error amplifier output is applied to the inverting
input. Output switch conduction is initiated when the ramp
waveform is discharged to the valley voltage. As the ramp
voltage increases to a voltage that exceeds the error
amplifier output, the latch resets, terminating output G1
MOSFET conduction, and turning on output G2 MOSFET,
combination prevents multiple output pulses during a given
oscillator cycle.
The sense voltage input at Pin 6 is applied to the
noninverting inputs of a pair of high speed comparators. The
high speed comparators’ inverting inputs are tied 0.96 x V ref
and 1.04 x V ref , respectively, to provide an optimum response
to load changes. When load transients which cause the output
voltage to fall outside a " 4% regulation window occur, the
high speed comparators override the PWM comparator to
force a zero or maximum duty cycle operating condition until
the output voltage is once again within the linear window.
When voltages are initially provided to the supply pins,
, undervoltage lockout circuits monitor each
CC
of the supply voltage levels. Both G1 and G2 output pins are
held low until the V CC pin voltage exceeds 4.0 V and the
pin voltage exceeds 9.0 V.
CC
Error Amplifier and Voltage Reference
The error amplifier is a transconductance type amplifier,
having a nominal transconductance of 800 m mho. The
transconductance has a negative temperature coefficient.
Typical transconductance is 868 m mho at 0 ° C and 620 m mho
at 125 ° C junction temperature. The amplifier has a cascode
output stage which provides a typical 3.0 Mega?Ohms of
impedance. The typical error amplifier dc voltage gain is
67 dB.
for the duration of the oscillator ramp. This PWM/latch
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MC33470DWG | 功能描述:直流/直流开关调节器 5-Bit Synchronous Rectification Buck 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 |
| MC33470DWR2 | 功能描述:直流/直流开关调节器 5-Bit Synchronous 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 |
| MC33470DWR2G | 功能描述:直流/直流开关调节器 5-Bit Synchronous Rectification Buck 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 |
| MC33486ADH | 功能描述:电源开关 IC - 配电 DUALHIGH-SIDE BRIDGE RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| MC33486ADHR2 | 功能描述:电源开关 IC - 配电 DUALHIGH-SIDE BRIDGE RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
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