- 您现在的位置：买卖IC网 > PDF目录15517 > MIC2155YML TR (Micrel Inc)IC REG CTRLR BUCK PWM VM 32MLF PDF资料下载
参数资料
| 型号： | MIC2155YML TR |
| 厂商： | Micrel Inc |
| 文件页数： | 25/35页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 32MLF |
| 特色产品： | MIC2155/6 Buck Control IC |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 550kHz |
| 占空比： | 80% |
| 电源电压： | 4.5 V ~ 14.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 32-VFQFN 裸露焊盘，32-MLF? |
| 包装： | 标准包装 |
| 产品目录页面： | 1091 (CN2011-ZH PDF) |
| 其它名称： | 576-3527-6 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页当前第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页
I
I SW _ RMS ( HIGH _ SIDE ) = D ( I OUT (max) 2 + PP )
I
I SW _ RMS ( LOW _ SIDE ) = ( 1 ? D ) ( I OUT (max) 2 + PP )
V OUT
Micrel, Inc.
The average current required to drive the MOSFETs is:
I DD = Qg × fs
Where:
Qg is the total gate charge for all high and low side
MOSFETs. This information should be obtained from
the manufacturer’s data sheet with a 5V V GS .
Since the current from the gate drive comes from the
input voltage, the power dissipated in the MIC2155 due
to gate drive is:
P GATE _ DRIVE = Qg × f S × V IN
A convenient figure of merit for switching MOSFETs is
the on-resistance times the total gate charge (R DSON ×
Qg). Lower numbers translate into higher efficiency. Low
gate charge, logic level MOSFETs are a good choice for
use with the MIC2155. The internal LDO that supplies
V DD is rated for 75mA. Exceeding this value could
damage the regulator or cause excessive power
dissipation in the IC. Refer to the “Supply Voltages and
Internal Regulator” section of this specification for
additional information.
Parameters that are important to MOSFET switch
selection are:
? Voltage rating
? On resistance
? Total Gate Charge
The V DS voltage rating of the MOSFETs is essentially
equal to the input voltage. A safety factor of 20% should
be added to the V DS(max) of the MOSFETs to account for
voltage spikes due to circuit parasitics.
The power dissipated in the switching transistor is the
sum of the conduction losses during the on-time
(P CONDUCTION ) and the switching losses that occur during
the period of time when the MOSFETs turn on and off
(P AC ).
P SW = P CONDUCTION + P AC
Where:
P CONDUCTION = I SWITCH ( rms ) 2 × R SWITCH
P AC = P AC ( off ) + P AC ( on )
R SWITCH is the on resistance of the MOSFET switch.
MIC2155/2156
Making the assumption the turn-on and turn-off transition
times are equal, the total AC switching loss is:
P AC = ( V IN + V D ) × I SW _ PEAK × T t × f S
Where:
T t is the switching transition time (typically 15ns to
30ns)
f S it the switching frequency of each phase
RMS Current and MOSFET Power Dissipation
Calculation
Under normal operation, the high side MOSFET’s RMS
current is greatest when V IN is low (maximum duty
cycle). The low side MOSFET’s RMS current is greatest
when V IN is high (minimum duty cycle). However, the
MOSFET sees maximum stress during short circuit
conditions, where the output current is equal to the
maximum overcurrent level. The calculations below are
for normal operation. To calculate the stress under short
circuit conditions, substitute the maximum overcurrent
level for I OUT(max) .
The RMS value of the high side switch current is:
2
12
2
12
Where:
D is the duty cycle of the converter
I PP is the individual inductor ripple current
D =
η × V IN
and η is the efficiency of the converter.
Converter efficiency also depends on other component
parameters that have not yet been selected. For design
purposes, an efficiency estimate of 85% – 90% can be
used. The efficiency can be more accurately calculated
once the design is complete. If the assumed efficiency is
grossly inaccurate, a second iteration through the design
procedure should be made.
For the high-side switch, the maximum DC power
dissipation is:
I
P SWITCH 1 ( DC ) = R DSON 1 × ( SW 1 ( rms ) ) 2
November 2009
25
M9999-111209-B
相关PDF资料 |
PDF描述 |
|---|---|
| 4590-394K | INDUCTOR HIGH CURRENT 390.0UH |
| 4590-334K | INDUCTOR HIGH CURRENT 330.0UH |
| 4590-274K | INDUCTOR HIGH CURRENT 270.0UH |
| 4590R-184K | INDUCTOR HIGH CURRENT 180.0UH |
| 4590-184K | INDUCTOR HIGH CURRENT 180.0UH |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2156 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Two-Phase, Single-Output, PWM Synchronous Buck Control IC |
| MIC2156YML | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:2-Phase, Single Output, PWM Synchronous Buck Control IC |
| MIC2156YML TR | 功能描述:DC/DC 开关控制器 Single Output, PWM Sync Buck 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 |
| MIC2156YML-TR | 功能描述:Buck Regulator Positive Output Step-Down DC-DC Controller IC 32-MLF? (5x5) 制造商:microchip technology 系列:- 包装:剪切带（CT） 零件状态:过期 输出类型:晶体管驱动器 功能:降压 输出配置:正 拓扑:降压 输出数:2 输出阶段:2 电压 - 电源（Vcc/Vdd）:4.5 V ~ 14.5 V 频率 - 开关:300kHz 占空比（最大）:0.8 同步整流器:是 时钟同步:是 串行接口:- 控制特性:限流，使能，电源良好，软启动 工作温度:-40°C ~ 125°C （TJ） 封装/外壳:32-VFQFN 裸露焊盘，32-MLF? 供应商器件封装:32-MLF?（5x5） 标准包装:1 |
| MIC2159 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:SYNCHRONOUS-itty⑩ Step-Down Converter IC |
发布紧急采购，3分钟左右您将得到回复。