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参数资料
| 型号： | LM2760M5/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHED CAPACITOR REGULATOR, 750 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | SOT-23, 5 PIN |
| 文件页数： | 9/10页 |
| 文件大小： | 242K |
| 代理商： | LM2760M5/NOPB |
Application Information (Continued)
is illustrated in Figure 1, which graphs of output voltage
ripple versus input voltage for a few different output capaci-
tor values.
In addition to the amount of output capacitance present, the
ESR of the output capacitor also affects output voltage
ripple. A low-ESR ceramic capacitor is recommended on the
output to keep output voltage ripple low. Placing multiple
capacitors is parallel can reduce ripple significantly, both by
increasing capacitance and reducing ESR. When capacitors
are in parallel, ESR is in parallel as well. The effective net
ESR is determined according to the properties of parallel
resistance. Two identical capacitors in parallel have twice the
capacitance and half the ESR as compared to a single
capacitor of the same make. On a similar note, if a large-
value, high-ESR capacitor (tantalum, for example) is to be
used as the primary output capacitor, the net output ESR can
be significantly reduced by placing a low-ESR ceramic ca-
pacitor in parallel with this primary output capacitor.
CAPACITORS
The LM2760 requires 3 external capacitors for proper opera-
tion. Surface-mount multi-layer ceramic capacitors are rec-
ommended. These capacitors are small, inexpensive and
have very low equivalent series resistance (
≤10m typ.).
Tantalum capacitors, OS-CON capacitors, and aluminum
electrolytic capacitors generally are not recommended for
use with the LM2760 due to their high ESR, as compared to
ceramic capacitors.
For most applications, ceramic capacitors with X7R or X5R
temperature characteristic are preferred for use with the
LM2760. These capacitors have tight capacitance tolerance
(as good as +/-10%), hold their value over temperature
(X7R: +/-15% over -55oC to +125oC; X5R: +/-15% over
-55oCto+85oC), and typically have little voltage coefficient.
Capacitors with Y5V and/or Z5U temperature characteristic
are generally not recommended. These types of capacitors
typically have wide capacitance tolerance (+80%, -20%),
vary significantly over temperature (Y5V: +22%, -82% over
-35oCto+85oC; Z5U: +22%, -56% over -10oCto+85oC), and
have poor voltage coefficients. Under some conditions, a
nominally 1F Y5V or Z5U capacitor could have a capaci-
tance of only 0.1F. Such detrimental deviation is likely to
cause these Y5V and Z5U of capacitors to fail to meet the
minimum capacitance requirements of the LM2760.
The table below lists some leading ceramic capacitor manu-
facturers.
Manufacturer
Contact Information
TDK
www.component.tdk.com
AVX
www.avx.com
Murata
www.murata.com
Taiyo-Yuden
www.t-yuden.com
Vishay-Vitramon
www.vishay.com
INPUT CAPACITORS
The input capacitor (C
IN) is used as a reservoir of charge,
helping to quickly transfer charge to the flying capacitor
during the charge phase (1) of operation. The input capaci-
tor helps to keep the input voltage from drooping at the start
of the charge phase, when the flying capacitor is first con-
nected to the input, and helps to filter noise on the input pin
that could adversely affect sensitive internal analog circuitry
biased off the input line. As mentioned above, an X7R/X5R
ceramic capacitor is recommended for use. An input capaci-
tance of 4.7F is recommended. It may be possible to re-
duce this value in applications where the maximum output
current is significantly less than 20mA. A smaller input ca-
pacitance typically results in higher input voltage ripple,
which may also show up as higher output voltage ripple as
well.
FLYING CAPACITORS
The flying capacitor (C
FLY) transfers charge from the input to
the output, providing the voltage boost of the doubler. A
polarized capacitor (tantalum, aluminum electrolytic, etc.)
must not be used here, as the capacitor will be reverse-
biased upon start-up of the LM2760. For most applications, a
0.1F X7R/X5R ceramic capacitor is recommended for C
FLY.
Smaller flying capacitance typically will reduce the output
current capability of the part. The ESR also affects the output
current capability of the LM2760. For optimal performance, a
low-ESR ceramic capacitor (< 10m
typ.) should be used.
Larger flying capacitance may increase output current capa-
bility, but it comes with the drawback of typically increasing
the magnitude of the output voltage ripple.
OUTPUT CAPACITOR
Both output capacitance and ESR of the LM2760 output
capacitor affect output voltage ripple. A low-ESR X7R/X5R
ceramic capacitor is the capacitor of choice for the LM2760
output. An output capacitance of 10F is recommended for
most applications. Reducing output capacitance typically in-
creases output voltage ripple. In applications where the
maximum output current is significantly less than 20mA,
output voltage ripple is less of a concern and it may be
desirable to reduce the output capacitance.
POWER EFFICIENCY
Efficiency of the LM2760 mirrors that of an unregulated
switched capacitor converter cascaded with a linear regula-
tor when more-than nominal output current is present (
≥
20044306
FIGURE 1. Output Voltage Ripple vs. Input Voltage
(T
A =25
oC)
I
OUT = 10mA, TA =25
oC
Top: C
OUT = 4.7F
Mid: C
OUT = 10F
Bottom: C
OUT = 22F
LM2760
www.national.com
8
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相关代理商/技术参数 |
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|---|---|
| LM2760M5X | 制造商:NSC 制造商全称:National Semiconductor 功能描述:3.3V Regulated Switched Capacitor Voltage Converter |
| LM2760M5X/NOPB | 功能描述:IC REG BST SWITCHED CAP SOT23-5 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 |
| LM2765 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Switched Capacitor Voltage Converter |
| LM2765M6 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM2765M6/NOPB | 功能描述:IC REG SWITCHED CAP DBL SOT23-6 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 |
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