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參數(shù)資料
| 型號(hào)： | LM828M5X |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Banana Plug; Current Rating:15A; Body Material:Brass; Color:Black; Spring Material:Beryllium Copper; Operating Temperature Range :? F; Voltage Rating:5000V RoHS Compliant: Yes |
| 中文描述： | SWITCHED CAPACITOR CONVERTER, 56 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封裝： | SOT-23, 5 PIN |
| 文件頁(yè)數(shù)： | 5/8頁(yè) |
| 文件大?。?/td> | 186K |
| 代理商： | LM828M5X |
Pin Description
Pin
1
2
3
4
5
Name
OUT
V+
CAP
GND
CAP+
Function
Negative voltage output.
Power supply positive input.
Connect this pin to the negative terminal of the charge-pump capacitor.
Power supply ground input.
Connect this pin to the positive terminal of the charge-pump capacitor.
Circuit Description
The LM828 contains four large CMOS switches which are
switched in a sequence to invert the input supply voltage.
Energy transfer and storage are provided by external capaci-
tors. Figure 2 illustrates the voltage conversion scheme.
When S
and S
are closed, C
charges to the supply volt-
age V+. During this time interval, switches S
and S
are
open. In the second time interval, S
1
and S
are open; at the
same time, S
and S
are closed, C
is charging C
. After a
number of cycles, the voltage across C
will be pumped to
V+. Since the anode of C
is connected to ground, the output
at the cathode of C
equals (V+) when there is no load cur-
rent. The output voltage drop when a load is added is deter-
mined by the parasitic resistance (R
of the MOSFET
switches and the ESR of the capacitors) and the charge
transfer loss between capacitors.
Application Information
Simple Negative Voltage Converter
The main application of LM828 is to generate a negative
supply voltage. The voltage inverter circuit uses only two ex-
ternal capacitors as shown in the Basic Application Circuits.
The range of the input supply voltage is 1.8V to 5.5V.
The output characteristics of this circuit can be approximated
by an ideal voltage source in series with a resistance. The
voltage source equals (V+). The output resistance, R
out
, is
a function of the ON resistance of the internal MOSFET
switches, the oscillator frequency, the capacitance and the
ESR of both C
and C
. Since the switching current charging
and discharging C
is approximately twice as the output cur-
rent, the effect of the ESR of the pumping capacitor C
will
be multiplied by four in the output resistance. The output ca-
pacitor C
is charging and discharging at a current approxi-
mately equal to the output current, therefore, this ESR term
only counts once in the output resistance. A good approxi-
mation of R
out
is:
where R
is the sum of the ON resistance of the internal
MOSFET switches shown in Figure 2
High capacitance, low ESR capacitors will reduce the output
resistance.
The peak-to-peak output voltage ripple is determined by the
oscillator frequency, the capacitance and ESR of the output
capacitor C
2
:
Again, using a low ESR capacitor will result in lower ripple.
Capacitor Selection
The output resistance and ripple voltage are dependent on
the capacitance and ESR values of the external capacitors.
The output voltage drop is the load current times the output
resistance, and the power efficiency is
Where I
Q
(V+) is the quiescent power loss of the IC device,
and I
L2
R
is the conversion loss associated with the switch
on-resistance, the two external capacitors and their ESRs.
The selection of capacitors is based on the specifications of
the dropout voltage (which equals I
R
), the output volt-
age ripple, and the converter efficiency. Low ESR capacitors
(following table) are recommended to maximize efficiency,
reduce the output voltage drop and voltage ripple.
Low ESR Capacitor Manufacturers
Manufacturer
Nichicon Corp.
AVX Corp.
Sprague
Sanyo
Phone
Capacitor Type
(708)-843-7500
(803)-448-9411
(207)-324-4140
(619)-661-6835
PL & PF series, through-hole aluminum electrolytic
TPS series, surface-mount tantalum
593D, 594D, 595D series, surface-mount tantalum
OS-CON series, through-hole aluminum electrolytic
DS100137-26
FIGURE 2. Voltage Inverting Principle
www.national.com
5
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM828M5X/NOPB | 功能描述:電荷泵 RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| LM828M5X-NOPB | 制造商:TI 制造商全稱:Texas Instruments 功能描述:LM828 Switched Capacitor Voltage Converter |
| LM82CIMQA | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| LM82CIMQA/NOPB | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| LM82CIMQA/NOPB | 制造商:Texas Instruments 功能描述:Temperature Sensor IC |
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