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| 型号： | SP7656EN2-L |
| 厂商： | Exar Corporation |
| 文件页数： | 5/10页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 3A 8HNSOIC |
| 标准包装： | 98 |
| 系列： | Power Blox™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 28 V |
| 输入电压： | 4.5 V ~ 29 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 600kHz |
| 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： | 8-SOIC（0.154"，3.90mm Width）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 8-HSOICN |
| 其它名称： | 1016-1443 SP7656EN2-L-ND |
Overcurrent Protection
Figure 2 – Overcurrent Protection Circuit
The overcurrent protection circuit functions by
monitoring the voltage across the internal P-
Channel FET. When this voltage exceeds
0.3V (nominal), the overcurrent comparator
triggers and the controller enters hiccup mode.
Since the FET has nominal Rds(on) of 0.06 Ω ,
assuming no temperature rise, the overcurrent
will trigger at Iocp = 0.3V/0.06 Ω= 5A. To
program a lower overcurrent use a resistor Rs
between ISET and LX pins. Calculate Rs from:
Rs ?
30 uA
Where:
- 1.15 is a multiplier to calculate peak current
- Iocp is the desired overcurrent protection,
- 0.06 Ω is nominal FET Rsd(on) at 25°C
- Kt is a multiplier that calculates increase in
Rds(on) for a given temperature
Kt is 1.0 and 1.4 for the FET operating at 25°C
and 150°C respectively. This accounts for
40% increase in FET Rds(on) as temperature
is increased from 25°C to 150°C.
Example: Calculate Rs for Iocp of 3.5A. FET
operating temperature is 88°C.
Rs ?
30 uA
Rs=340 Ω
Using the above equation there is good
agreement between calculated and test results
for Rs up to 3k. For Rs larger than 3k test
results are lower than those predicted by the
Rs equation due to circuit parasitics. Therefore
11/07/08 SP7656 PowerBlox
5
the maximum value of Rs should be limited to
3k ? .
Using the ON/OFF Function via VFB
The feedback pin serves a dual role of On/Off
control. The MOSFET driver is disabled when
a voltage greater than 1V is applied at FB pin.
Maximum voltage rating of this pin is 5.5V.
The controlling signal should be applied
through a small signal diode to FB pin. Please
note that an optional 10k bleeding resistor across
the output helps keep the output capacitor
discharged under no load condition.
Programming the Output Voltage
To program the output voltage, calculate R2
using the following equation:
200 k
? Vout ?
? 0 . 6 ?
0.6 is used as it is the reference voltage of the
SP7656. 200k is a fixed-value and is the top
resistor in the output set point resistor pair. In
addition to being part of the voltage divider, it
is part of the compensation network. R1 of the
output voltage divider should always be
200k ? .
Soft Start
Soft Start is preset internally to 5ms (nominal).
Internal Soft Start eliminates the need for the
external capacitor CSS that is commonly used
to program this function.
Input Capacitance Selection
Select the input capacitor for Voltage,
Capacitance, ripple current, ESR and ESL.
Voltage rating is nominally selected to be
approximately twice the input voltage. The
RMS value of input capacitor current,
assuming a low inductor ripple current (I RIP ),
can be calculated from:
Icin ? Iout D ( 1 ? D )
In general total input voltage ripple should be
maintained below 1.5% of V IN (not to exceed
180mV).
Input voltage ripple has three components:
ESR and ESL cause a step voltage drop upon
turn on of the MOSFET. During the on time
? Copyright 2008 EXAR Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7656EN2-L/TR | 功能描述:开关变换器、稳压器与控制器 600KHZ HIGH INPUT NON-SYNC STEP DWN RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| SP7661 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7661_07 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 600kHz, Buck Regulator |
| SP7661_1 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7661EB | 功能描述:电源管理IC开发工具 Eval Board for SP7661 Series RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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