- 您现在的位置：买卖IC网 > PDF目录15113 > MIC2193BM (Micrel Inc)IC REG CTRLR BUCK PWM CM 8-SOIC PDF资料下载
参数资料
| 型号： | MIC2193BM |
| 厂商： | Micrel Inc |
| 文件页数： | 8/10页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 8-SOIC |
| 标准包装： | 95 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 100% |
| 电源电压： | 2.9 V ~ 14 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： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
MIC2193
Micrel
MOSFET Selection
The P-channel MOSFET must have a V GS threshold voltage
equal to or lower than the input voltage when used in a buck
converter topology. There is a limit to the maximum gate
charge the MIC2193 will drive. MOSFETs with higher gate
charge will have slower turn-on and turn-off times. Slower
transition times will cause higher power dissipation in the
MIC2193
Voltage
Amplifier
Pin 3
V OUT
R1
R2
MOSFETs due to higher switching transition losses. The
MOSFETs must be able to completely turn on and off within
the driver non-overlap time If both MOSFETs are conducting
at the same time, shoot-through will occur, which greatly
increases power dissipation in the MOSFETs and reduces
V REF
1.245V
Figure 4
The output voltage is determined by the equation below.
converter efficiency.
The MOSFET gate charge is also limited by power dissipation
in the MIC2193. The power dissipated by the gate drive
V OUT = V REF × 1 +
R1
R 2
circuitry is calculated below:
P GATE_DRIVE = Q GATE × V IN × f S
where:
Q GATE is the total gate charge of both the N and P-
channel MOSFETs.
f S is the switching frequency
Where: V REF for the MIC2193 is typically 1.245V.
Lower values of R1 are preferred to prevent noise from
appearing on the FB pin. A typically recommended value is
10k ? . If R1 is too small in value it will decrease the efficiency
of the power supply, especially at low output loads.
Once R1 is selected, R2 can be calculated with the following
formula.
V IN is the gate drive voltage
The graph in Figure 3 shows the total gate charge that can be
driven by the MIC2193 over the input voltage range, for
R 2 =
V REF × R 1
V OUT – V REF
different values of switching frequency.
Efficiency Considerations
100
90
80
70
60
50
40
30
Max. Gate Charge
Efficiency is the ratio of output power to input power. The
difference is dissipated as heat in the buck converter. Under
light output load, the significant contributors are:
? The V IN supply current
To maximize efficiency at light loads:
? Use a low gate charge MOSFET or use the smallest
MOSFET, which is still adequate for maximum output
current.
20
10
0
0
2
4 6 8 10 12 14
INPUT VOLTAGE (V)
? Use a ferrite material for the inductor core, which has
less core loss than an MPP or iron power core.
Under heavy output loads the significant contributors to
power loss are (in approximate order of magnitude):
Figure 3. MIC2193 Frequency vs Max. Gate Charge
Oscillator
The internal oscillator is free running and requires no external
components. The maximum duty cycle is 100%. This is
another advantage of using a P-channel MOSFET for the
high-side drive: it can continuously turned on.
A frequency foldback mode is enabled if the voltage on the
feedback pin (pin 3) is less than 0.3V. In frequency foldback,
the oscillator frequency is reduced by approximately a factor
of 4. Frequency foldback is used to limit the energy delivered
to the output during a short circuit fault condition.
Voltage Setting Components
The MIC2193 requires two resistors to set the output voltage
as shown in Figure 4.
? Resistive on time losses in the MOSFETs
? Switching transition losses in the high side MOSFET
? Inductor resistive losses
? Current sense resistor losses
? Input capacitor resistive losses (due to the capacitors
ESR)
To minimize power loss under heavy loads:
? Use low on resistance MOSFETs. Use low threshold
logic level MOSFETs when the input voltage is below
5V. Multiplying the gate charge by the on resistance
gives a figure of merit, providing a good balance
between low load and high load efficiency.
? Slow transition times and oscillations on the voltage
and current waveforms dissipate more power during
the turn on and turn off of the MOSFETs. A clean
layout will minimize parasitic inductance and capaci-
tance in the gate drive and high current paths. This
will allow the fastest transition times and waveforms
without oscillations. Low gate charge MOSFETs will
M9999-042704
8
April 2004
相关PDF资料 |
PDF描述 |
|---|---|
| RBM36DCSS | CONN EDGECARD 72POS DIP .156 SLD |
| ISL88708IB829Z | IC SUPERVISOR 2.92V 8-SOIC |
| VE-24W-EW-F4 | CONVERTER MOD DC/DC 5.5V 100W |
| ISL88708IB826Z | IC SUPERVISOR 2.63V 8-SOIC |
| HBC10DRTI-S734 | CONN EDGECARD 20POS DIP .100 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2193BM TR | 功能描述:IC REG CTRLR BUCK PWM CM 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| MIC2193PM | 制造商:Micrel Inc 功能描述: |
| MIC2193YM | 功能描述:DC/DC 开关控制器 SO-8 3V Synchronous Buck Contoller (Lead Free) 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 |
| MIC2193YM TR | 功能描述:DC/DC 开关控制器 SO-8 3V Synchronous Buck Contoller (Lead Free) 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 |
| MIC2193YM-TR | 功能描述:Buck Regulator Positive Output Step-Down DC-DC Controller IC 8-SOIC 制造商:microchip technology 系列:- 包装:剪切带（CT） 零件状态:停产 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:1 输出阶段:1 电压 - 电源（Vcc/Vdd）:2.9 V ~ 14 V 频率 - 开关:400kHz 占空比（最大）:1 同步整流器:是 时钟同步:无 串行接口:- 控制特性:- 工作温度:-40°C ~ 125°C （TJ） 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商器件封装:8-SOIC 标准包装:1 |
发布紧急采购，3分钟左右您将得到回复。