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参数资料
| 型号： | LM2686MTCX/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHED CAPACITOR REGULATOR, 180 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封装： | TSSOP-14 |
| 文件页数： | 7/8页 |
| 文件大小： | 243K |
| 代理商： | LM2686MTCX/NOPB |
Application Information
CAPACITOR SELECTION
The output resistance and ripple voltage are dependent on
the capacitance and ESR values of the external capacitors.
VOLTAGE DOUBLER EXTERNAL CAPACITORS
The selection of capacitors are based on the specifications
of the dropout voltage (which equals I
OUT ROUT), the output
voltage ripple, and the converter efficiency.
where R
SW is the sum of the ON resistance of the internal
MOSFET switches as shown in Figure 2.
The peak-to-peak output voltage ripple is determined by the
oscillator frequency, the capacitance and ESR of the capaci-
tor C3.
High capacitance (2.2F to higher), low ESR capacitors can
reduce the output resistance and the voltage ripple.
where I
Q(V+) is the quiescent power loss of the IC device,
and I
2
LR is the conversion loss associated with the switch
on-resistance, the two external capacitors and their ESRs.
Low ESR capacitors (table to be referenced) are recom-
mended to maximize efficiency, reduce the output voltage
drop and voltage ripple.
+5 LDO REGULATOR EXTERNAL CAPACITORS
The voltage doubler output capacitor, C3, serves as the input
capacitor of the 5 LDO regulator. The output capacitor C4,
must meet the requirement for minimum amount of capaci-
tance and appropriate ESR (Equivalent Serving Resistance)
for proper operations. The ESR value must remain within the
regions of stability as shown in Figure 3, Figure 4 and Figure
5 to ensure output’s stability. A minimum capacitance of 1F
is required at the output. This can be increased without limit,
but a 4.7F tantalum capacitor is recommended for loads
ranging upto the maximum specification. In lighter loads of
less or equal to 10mA, ceramic capacitor of at least 1F and
ESR in the milliohms can be used. This has to be connected
to V
PSW pin instead of the V05 pin.
Any output capacitor used should have a good tolerance
over temperature for capacitance and ESR values. The
larger the capacitor, with ESR within the stable region, the
better the stability and noise performance.
10114125
FIGURE 3. ESR Curve for C
OUT = 2.2F
10114126
FIGURE 4. ESR Curve for C
OUT = 4.7F
10114127
FIGURE 5. ESR Curve for C
OUT =10F
LM2686
www.national.com
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相关代理商/技术参数 |
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| LM2687LD | 制造商:Texas Instruments 功能描述: |
| LM2687LD/NOPB | 功能描述:IC REG SWITCHD CAP INV ADJ 8-LLP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:3.3V 输入电压:4.5 V ~ 24 V PWM 型:- 频率 - 开关:- 电流 - 输出:125mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 包装:Digi-Reel® 供应商设备封装:SOT-6 其它名称:MAX1836EUT33#TG16DKR |
| LM2687LDX | 功能描述:电荷泵 RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| LM2687LDX/NOPB | 功能描述:电荷泵 RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| LM2687MM | 功能描述:电荷泵 RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
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