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参数资料
| 型号： | MIC4685BR |
| 厂商： | Micrel Inc |
| 文件页数： | 3/17页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 3A SPAK-7 |
| 标准包装： | 48 |
| 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： | 3A |
| 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： | SPak（7 引线 + 接片） |
| 包装： | 散装 |
| 供应商设备封装： | S-PAK-7 |
Micrel, Inc.
Detailed Pin Description
Switch (SW, Pin 6)
The switch pin is tied to the emitter of the main internal
NPN transistor. This pin is biased up to the input voltage,
minus the V SAT , of the main NPN pass element. The
emitter is also driven negative when the output inductor’s
magnetic ? eld collapses at turn-off. During the OFF time,
the SW pin is clamped by the output Schottky diode
typically to a –0.5V.
Ground (GND, Pin 4, Tab)
There are two main areas of concern when it comes to the
ground pin, EMI and ground current. In a buck regulator or
any other non-isolated switching regulator, the output
capacitor(s) and diode(s) ground is referenced back to the
switching regulator’s or controller’s ground pin. Any
resistance between these reference points causes an
offset voltage/IR drop proportional to load current and poor
load regulation. This is why it’s important to keep the
output grounds placed as close as possible to the
switching regulator’s ground pin. To keep radiated EMI to
a minimum, it is necessary to place the input capacitor
ground lead as close as possible to the switching
regulator’s ground pin.
Input Voltage (V IN , Pin 2)
The V IN pin is the collector of the main NPN pass element.
This pin is also connected to the internal regulator. The
output diode or clamping diode should have its cathode as
close as possible to this point to avoid voltage spikes
adding to the voltage across the collector.
MIC4685
Bootstrap (BS, Pin 1)
The bootstrap pin, in conjunction with the external
bootstrap capacitor, provides a bias voltage higher than
the input voltage to the MIC4685’s main NPN pass
element. The bootstrap capacitor sees the dv/dt of the
switching action at the SW pin as an AC voltage. The
bootstrap capacitor then couples the AC voltage back to
the BS pin, plus the dc offset of V IN where it is recti ? ed and
used to provide additional drive to the main switch; in this
case, a NPN transistor.
This additional drive reduces the NPN’s saturation voltage
and increases ef ? ciency, from a V SAT of 1.8V, and 75%
ef ? ciency to a V SAT of 0.5V and 88% ef ? ciency
respectively.
Feedback (FB, Pin 3)
The feedback pin is tied to the inverting side of an error
ampli ? er. The noninverting side is tied to a 1.235V
bandgap reference. An external resistor voltage divider is
required from the output-to-ground, with the center tied to
the feedback pin. See Tables 1 and 2 for recommended
resistor values.
Enable (EN, Pin 5)
The enable (EN) input is used to turn on the regulator and
is TTL compatible. Note: connect the enable pin to the
input if unused. A logic-high enables the regulator. A logic-
low shuts down the regulator and reduces the stand-by
quiescent input current to typically 150μA. The enable pin
has an up-per threshold of 2.0V minimum and lower
threshold of 0.8V maximum. The hysterisis provided by the
upper and lower thresholds acts as an UVLO and prevents
unwanted turn on of the regulator due to noise.
January 2010
3
M9999-012610
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| MIC4685BR TR | 功能描述:IC REG BUCK ADJ 3A SPAK-7 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 |
| MIC4685BRTR | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| MIC4685WR | 功能描述:直流/直流开关调节器 3A Buck Regulator in SPAK-7 (ROHS Compliant) 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 |
| MIC4685WR TR | 功能描述:直流/直流开关调节器 3A Buck Regulator in SPAK-7 (ROHS Compliant) 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 |
| MIC4685WREV | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:3A SPAK SuperSwitcher Buck Regulator |
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