- 您现在的位置：买卖IC网 > PDF目录13484 > MIC4684BM (Micrel Inc)IC REG BUCK ADJ 2A 8SOIC PDF资料下载
参数资料
| 型号： | MIC4684BM |
| 厂商： | Micrel Inc |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2A 8SOIC |
| 标准包装： | 95 |
| 系列： | SuperSwitcher™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调至 1.235V |
| 输入电压： | 4 V ~ 30 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 200kHz |
| 电流 - 输出： | 2A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SOIC |
V OUT = V REF ?
+ 1 ?
R1 = R2 ? OUT ? 1 ?
Constant-Frequency Switchin g
Micrel, Inc.
Applications Information
Adjustable Regulators
Adjustable regulators require a 1.23V feedback signal. Rec -
ommended voltage-divider resistor values for common output
voltages are included in Table 1.
For other voltages, the resistor values can be determined
using the following formulas:
? R1 ?
? R2 ?
? V ?
? V REF ?
V REF = 1.235V
Minimum Pulse Width
The minimum duty cycle of the MIC4684 is approximately
10%. See Minimum Duty Cycle Graph . If this input-to-output
voltage characteristic is exceeded, the MIC4684 will skip
cycles to maintain a regulated V OUT .
Max. V IN for a Given V OUT for
40
35
30
25
20
15
10
MIC4684
Examining θ JA in more detail:
θ JA = ( θ JC + θ CA )
where:
θ JC = junction-to-case thermal resistance
θ CA = case-to-ambient thermal resistance
θ JC is a relatively constant 25°C/W for a power SOP-8.
θ CA is dependent on layout and is primarily governed by the
connection of pins 2, 6, and 7 to the ground plane. The pur -
pose of the ground plane is to function as a heat sink.
θ JA is ideally 75°C/W, but will vary depending on the size of
the ground plane to which the power SOP-8 is attached.
Determining Ground-Plane Heat-Sink Area
Make sure that MIC4684 pins 2, 6, and 7 are connected to
a ground plane with a minimum area of 6cm 2 . This ground
plane should be as close to the MIC4684 as possible. The
area may be distributed in any shape around the package
or on any pcb layer as long as there is good thermal contact
to pins 2, 6, and 7 . This ground plane area is more than suf -
ficient for most designs.
SOP-8
0
1
2
3 4
5
6
BIE
5
0
OUTPUT VOLTAGE (V)
Figure 1. Minimum Pulse Width Characteristic
θ JC
θ JA
θ CA
AM
NT
ground plane
heat sink area
P D = OUT ? P OUT
Thermal Considerations
The MIC4684 SuperSwitcher? features the power-SOP-8.
This package has a standard 8-lead small-outline package
profile, but with much higher power dissipation than a standard
SOP-8. Micrel’s MIC4684 SuperSwitcher? family are the first
dc-to-dc converters to take full advantage of this package.
The reason that the power SOP-8 has higher power dissipa -
tion (lower thermal resistance) is that pins 2, 6, and 7 and
the die-attach paddle are a single piece of metal. The die is
attached to the paddle with thermally conductive adhesive.
This provides a low thermal resistance path from the junction
of the die to the ground pins. This design significantly improves
package power dissipation by allowing excellent heat transfer
through the ground leads to the printed circuit board.
One limitation of the maximum output current on any MIC4684
design is the junction-to-ambient thermal resistance ( θ JA ) of
the design (package and ground plane).
printed circuit board
Figure 2. Power SOP-8 Cross Section
When designing with the MIC4684, it is a good practice to
connect pins 2, 6, and 7 to the largest ground plane that is
practical for the specific design.
Checking the Maximum Junction Temperature:
For this example, with an output power (P OUT ) of 5W, (5V
output at 1A with V IN = 12V) and 60°C maximum ambient
temperature, what is the junction temperature?
Referring to the “Typical Characteristics: 5V Output Efficiency”
graph, read the efficiency ( η ) for 1A output current at V IN =
12V or perform you own measurement.
η = 84%
The efficiency is used to determine how much of the output
power (P OUT ) is dissipated in the regulator circuit (P D ).
P
η
P D =
5W
0.84
? 5W
P D = 0.95W
January 2010
10
M9999-012610
相关PDF资料 |
PDF描述 |
|---|---|
| FK26X5R1C685K | CAP CER 6.8UF 16V 10% RADIAL |
| VI-J3J-EY-F2 | CONVERTER MOD DC/DC 36V 50W |
| MIC4680BM TR | IC REG BUCK ADJ 1.3A 8SOIC |
| RCC49DRYI-S734 | CONN EDGECARD 98POS DIP .100 SLD |
| MIC4680BM | IC REG BUCK ADJ 1.3A 8SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC4684BM TR | 功能描述:IC REG BUCK ADJ 2A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:SuperSwitcher™ 标准包装:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
| MIC4684YM | 功能描述:直流/直流开关调节器 SO-8 Efficient Simple Buck 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 |
| MIC4684YM TR | 功能描述:直流/直流开关调节器 SO-8 Efficient Simple Buck 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 |
| MIC4684YM | 制造商:Micrel Inc 功能描述:IC VOLTAGE REGULATOR SOIC |
| MIC4684YM | 制造商:Micrel Inc 功能描述:Voltage Regulator IC |
发布紧急采购，3分钟左右您将得到回复。