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参数资料
| 型号： | MIC2172YM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 18/20页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG 1.25A 8SOIC |
| 标准包装： | 1 |
| 类型： | 降压（降压），升压（升压），反相，Cuk |
| 输出数： | 1 |
| 输入电压： | 3 V ~ 40 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz |
| 电流 - 输出： | 1.25A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 供应商设备封装： | 8-SOIC |
| 产品目录页面： | 1092 (CN2011-ZH PDF) |
| 其它名称： | 576-1064-6 |
Micrel
Figure 13. Step-Down or Buck Regulator
MIC2172/3172
mutual coupling to the feedback winding further reduces
primary current eventually turning Q1 off. The primary
windings now change state with the feedback winding
forcing Q2 on repeating the alternate half cycle exactly
as with Q1. This action produces a sinusoidal voltage
wave form; whose amplitude is proportional to the input
voltage, across T1’s primary winding which is stepped
up and capacitively coupled to the lamp.
Lamp Current Regulation
Initial ionization (lighting) of the fluorescent lamp
requires several times the ac voltage across it than is
required to sustain current through the device. The
current through the lamp is sampled and regulated by
the MIC3172 to achieve a given intensity. The MIC3172
uses L1 to maintain a constant average current through
the transistor emitters. This current controls the voltage
amplitude of the Royer oscillator and maintains the lamp
current. During the negative half cycle, lamp current is
rectified by D3. During the positive half cycle, lamp
current is rectified by D2 through R4 and R5. R3 and C5
filter the voltage dropped across R4 and R5 to the
MIC3172’s feedback pin. The MIC3172 maintains a
constant lamp current by adjusting its duty cycle to keep
the feedback voltage at 1.24V. The intensity of the lamp
is adjusted using potentiometer R5. The MIC3172
adjusts its duty cycle accordingly to bring the average
voltage across R4 and R5 back to 1.24V.
On/Off Control
Especially important for battery powered applications,
the lamp can be remotely or automatically turned off
using the MIC3172’s EN pin. The entire circuit draws
less than 1μA while shutdown.
Efficiency
To obtain maximum circuit efficiency careful selection of
Q1 and Q2 for low collector to emitter saturation voltage
is a must. Inductor L1 should be chosen for minimal core
and copper losses at the switching frequency of the
MIC3172, and T1 should be carefully constructed from
magnetic materials optimized for the output power
required at the Royer oscillator frequency. Suitable
inductors may be obtained from Coiltronics, Inc., tel:
(407) 241-7876.
April 2006
18
M9999-041806
(408) 955-1690
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2172YN | 功能描述:直流/直流开关调节器 2.5A 100kHz Switching Regulator (Lead Free) 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 |
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| MIC2174_10 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Synchronous Buck Controller Featuring Adaptive On-Time Control 40V Input, 300kHz |
| MIC2174-1YMM | 功能描述:DC/DC 开关控制器 300kHz Synch Current Mode PWM Controller 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 |
| MIC2174-1YMM 3A EV | 功能描述:电源管理IC开发工具 300kHz Synch Current Mode PWM Controller - Evaluation Board RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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