参数资料
| 型号： | MIC2169BYMME |
| 厂商： | Micrel Inc |
| 文件页数： | 13/25页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-MSOP |
| 特色产品： | MIC2169B Buck Control IC |
| 标准包装： | 100 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 550kHz |
| 占空比： | 92% |
| 电源电压： | 3 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 ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1092 (CN2011-ZH PDF) |
| 其它名称： | 576-3545-5 |
I C OUT ( rms ) =
V O = V REF × ? 1 +
?
V REF × R 1
Micrel, Inc.
The voltage rating of capacitor should be twice the
voltage for a tantalum and 20% greater for aluminum
electrolytic.
The output capacitor RMS current is calculated below:
I PP
12
The power dissipated in the output capacitor is:
I
P DISS ( C OUT ) = ( C OUT ( rms ) ) 2 × R ESR ( C OUT )
Input Capacitor Selection
The input capacitor should be selected for ripple current
rating and voltage rating. Tantalum input capacitors may
fail when subjected to high inrush currents, caused by
turning the input supply on. A tantalum input capacitor’s
voltage rating should be at least 2 times the maximum
input voltage to maximize reliability. Aluminum
electrolytic, OS-CON, and multilayer polymer film
capacitors can handle the higher inrush currents without
voltage derating. The input voltage ripple will primarily
depend on the input capacitor’s ESR. The peak input
current is equal to the peak inductor current, so:
Δ V IN = I INDUCTOR ( peak ) × R ESR ( C IN )
The input capacitor must be rated for the input current
ripple. The RMS value of input capacitor current is
determined at the maximum output current. Assuming
the peak-to-peak inductor ripple current is low:
I C IN ( rms ) ≈ I OUT (max) × D × ( 1 ? D )
The power dissipated in the input capacitor is:
I
P DISS ( C IN ) = ( CIN ( rms ) ) 2 × R ESR ( C IN )
Voltage Setting Components
The MIC2169B requires two resistors to set the output
voltage as shown in Figure 6.
MIC2169B
The output voltage is determined by the equation:
? R1 ?
? R 2 ?
where
V REF for the MIC2169B is typically 0.8V
A typical value of R1 can be between 3k Ω and 10k Ω . If
R1 is too large, it may allow noise to be introduced into
the voltage feedback loop. If R1 is too small, in value, it
will decrease the efficiency of the power supply,
especially at light loads. Once R1 is selected, R2 can be
calculated using:
R 2 =
V O ? V REF
External Schottky Diode
An external freewheeling diode is used to keep the
inductor current flow continuous while both MOSFETs
are turned off. This dead time prevents current from
flowing unimpeded through both MOSFETs and is
typically 50ns. The diode conducts twice during each
switching cycle. Although the average current through
this diode is small, the diode must be able to handle the
peak current.
I D(avg) = I OUT × 2 × 50ns × f S
The reverse voltage requirement of the diode is:
V DIODE(rrm) = V IN
The power dissipated by the Schottky diode is:
P DIODE = I D(avg) × V F
where:
V F = forward voltage at the peak diode current
The external Schottky diode, D1, is not necessary for
circuit operation since the low-side MOSFET contains a
parasitic body diode. The external diode will improve
efficiency and decrease high frequency noise. If the
MOSFET body diode is used, it must be rated to handle
Error
Amp
MIC2169B
V REF
0.8V
FB
5
R1
R2
the peak and average current. The body diode has a
relatively slow reverse recovery time and a relatively
high forward voltage drop. The power lost in the diode is
proportional to the forward voltage drop of the diode. As
the high-side MOSFET starts to turn on, the body diode
becomes a short circuit for the reverse recovery period,
dissipating additional power. The diode recovery and the
circuit inductance will cause ringing during the high-side
MOSFET turn-on. An external Schottky diode conducts
Figure 6. Voltage-Divider Configuration
at a lower forward voltage preventing the body diode in
the MOSFET from turning on. The lower forward voltage
drop dissipates less power than the body diode. The lack
of a reverse recovery mechanism in a Schottky diode
causes less ringing and less power loss.
April 2010
13
M9999-041210-B
相关PDF资料 |
PDF描述 |
|---|---|
| MIC2171BU TR | IC REG MULTI CONFIG 2.5A TO263-5 |
| MIC2174-1YMM TR | IC REG CTRLR BUCK PWM 10-MSOP |
| MIC2176-3YMM TR | IC REG CTRLR BUCK PWM 10-MSOP |
| MIC2177BWM TR | IC REG BUCK SYNC ADJ 2.5A 20SOIC |
| MIC2178BWM TR | IC REG BUCK SYNC ADJ 2.5A 20SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2169BYMME TR | 功能描述:直流/直流开关转换器 Synchronous Step Down Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MIC2169MM | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500 KHZ PWM SYNCHRONOUS BUCK CONTROL IC |
| MIC2169YMM | 功能描述:直流/直流开关调节器 Replaced by MIC2169AYMM (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 |
| MIC2169YMM TR | 功能描述:直流/直流开关调节器 Replaced by MIC2169AYMM TR (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 |
| MIC2171 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:100kHz 2.5A Switching Regulator Preliminary Information |
发布紧急采购，3分钟左右您将得到回复。