- 您现在的位置：买卖IC网 > PDF目录15113 > MIC2194BM (Micrel Inc)IC REG CTRLR BST PWM CM 8-SOIC PDF资料下载
参数资料
| 型号： | MIC2194BM |
| 厂商： | Micrel Inc |
| 文件页数： | 8/10页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST 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： | 是 |
| 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 |
MIC2194
MIC2194
MOSFET Selection
Micrel
V IN
R1
1.5V
Typical
Bias
Circuitry
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 MIC2194 will drive. MOSFETs with high gate
charge will have slower turn-on and turn-off times. Slower
R2
EN/UVLO
(3)
140mV
Hysteresis
(typical)
transition times will cause higher power dissipation in the
MOSFET due to higher switching transition losses.
The MOSFET gate charge is also limited by power dissipation
V INPUT _ ENABLE = V THRESHOLD ×
Figure 3. UVLO Circuitry
The line voltage turn on trip point is:
R 2
R 1 + R 2
where:
V THRESHOLD is the voltage level of the internal
comparator reference, typically 1.5V.
The input voltage hysteresis is equal to:
in the MIC2194. The power dissipated by the gate drive
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
V IN is the gate drive voltage
The graph in Figure 4 shows the total gate charge that can be
driven by the MIC2194 over the input voltage range, for
V INPUT _ HYST = V HYST ×
R1 + R 2
R 2
different values of switching frequency.
Max Gate Charge
(V THRESHOLD – V HYST ) ×
where:
V HYST is the internal comparator hysteresis level,
typically 140mV.
V INPUT_HYST is the hysteresis at the input voltage
The MIC2194 will be disabled when the input voltage drops
back down to:
V INPUT_OFF =
V INPUT_ENABLE – V INPUT_HYST =
R 2
R 1 + R 2
Either of 2 UVLO conditions will pull the soft start capacitor
low:
? When the V DD voltage drops below its
undervoltage lockout level.
? When the enable pin drops below the its enable
threshold
The internal bias circuit generates an internal 1.245V band-
gap reference voltage for the voltage error amplifier and a 3V
VDD voltage for the internal control circuitry. The VDD pin
must be decoupled with a 1 μ F ceramic capacitor. The capaci-
tor must be placed close to the VDD pin. The other end of the
capacitor must be connected directly to the ground plane.
MOSFET Gate Drive
The MIC2194 is designed to drive a high-side P-channel
MOSFET. The source pin of the P-channel MOSFET is
connected to the input of the power supply. It is turned on
when OUTP pulls the gate of the MOSFET low. The advan-
tage of using a P-channel MOSFET is that it does not require
a bootstrap circuit to boost the gate voltage higher than the
input, as would be required for an N-channel MOSFET. The
VIN pin (pin 8) supplies the drive voltage to the gate drive pin,
OUTP.
250
200
150
100
50
0
0 5 10 15
INPUT VOLTAGE (V)
Figure 4. MIC2194 V IN vs Max. Gate Charge
Oscillator
The internal oscillator is free running and requires no external
components. The maximum duty cycle for both frequencies
is 100%. This is another advantage of using a P-channel
MOSFET for the high-side drive; it can be continuously turned
on.
A frequency foldback mode is enabled if the voltage on the
feedback pin (pin 2) 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 MIC2194 requires two resistors to set the output voltage
as shown in Figure 5.
MIC2194
8
April 2005
相关PDF资料 |
PDF描述 |
|---|---|
| RCC13DRTI-S734 | CONN EDGECARD 26POS .100 EXTEND |
| UCD2A221MNQ1MS | CAP ALUM 220UF 100V 20% SMD |
| ISL88708IB831Z | IC SUPERVISOR 3.09V 8-SOIC |
| UVP0J682MHD | CAP ALUM 6800UF 6.3V 20% RADIAL |
| RSM11DRYF | CONN EDGECARD 22POS DIP .156 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2194BM TR | 功能描述:IC REG CTRLR BST 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) |
| MIC2194YM | 功能描述:DC/DC 开关控制器 SO-8 3V 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 |
| MIC2194YM TR | 功能描述:DC/DC 开关控制器 SO-8 3V 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 |
| MIC2196 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:400kHz SO-8 Boost Control IC |
| MIC2196_08 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:400kHz SO-8 Boost Control IC |
发布紧急采购，3分钟左右您将得到回复。