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參數資料
| 型號： | TC1121EOAG |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHED CAPACITOR CONVERTER, 200 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數： | 10/14頁 |
| 文件大?。?/td> | 497K |
| 代理商： | TC1121EOAG |
2006 Microchip Technology Inc.
DS21358C-page 5
TC1121
3.0
APPLICATIONS
3.1
Negative Voltage Converter
The TC1121 is typically used as a charge-pump voltage
inverter. C1 and C2 are the only two external capacitors
used in the operating circuit (Figure 3-1).
FIGURE 3-1:
Charge Pump Inverter
The TC1121 is not sensitive to load current changes,
although its output is not actively regulated. A typical
output source resistance of 11.8
Ω means that an input
of +5V results in -5V output voltage under light load,
and only decreases to -3.8V typ with a 100 mA load.
The supplied output current is from capacitor C2 during
one-half the charge-pump cycle. This results in a
peak-to-peak ripple of:
VRIPPLE = IOUT/2(fPUMP) (C2) + IOUT (ESRC2)
Where fPUMP is 5 kHz (one half the nominal 10 kHz
oscillator frequency), and C2 = 150
μF with an ESR of
0.2
Ω, ripple is about 90 mV with a 100 mA load current.
If C2 is raised to 390
μF, the ripple drops to 45 mV.
3.2
Changing Oscillator Frequency
The TC1121’s clock frequency is controlled by four
modes:
TABLE 3-1:
OSCILLATOR FREQUENCY
MODES
The oscillator runs at 10 kHz (typical) when FC and
OSC are not connected. The oscillator frequency is
lowered by connecting a capacitor between OSC and
GND, but FC can still multiply the frequency by 20
times in this mode.
An external clock source that swings within 100 mV of
V+ and GND may overdrive OSC in the Inverter mode.
OSC can be driven by any CMOS logic output. When
OSC is overdriven, FC has no effect.
Note that the frequency of the signal appearing at
CAP+ and CAP– is half that of the oscillator. In addition,
by lowering the oscillator frequency, the effective
output resistance of the charge-pump increases. To
compensate for this, the value of the charge-pump
capacitors may be increased.
Because the 5 kHz output ripple frequency may be low
enough to interfere with other circuitry, the oscillator
frequency can be increased with the use of the FC pin
or an external oscillator. The output ripple frequency is
half the selected oscillator frequency. Although the
TC1121’s quiescent current will increase if the clock
frequency is increased, it allows smaller capacitance
values to be used for C1 and C2.
3.3
Capacitor Selection
In addition to load current, the following factors affect
the TC1121 output voltage drop from its ideal value 1)
output resistance, 2) pump (C1) and reservoir (C2)
capacitor ESRs and 3) C1 and C2 capacitance.
The voltage drop is the load current times the output
resistance. The loss in C2 is the load current times C2’s
ESR; C1’s loss is larger because it handles currents
greater than the load current during charge-pump
operation. Therefore, the voltage drop due to C1 is
about four times C1’s ESR multiplied by the load
current, and a low (or high) ESR capacitor has a
greater impact on performance for C1 than for C2.
In general, as the TC1121’s pump frequency increases,
capacitance values needed to maintain comparable
ripple and output resistance diminish proportionately.
4
36
7
8
5
2
1
C1
C2
2.4V to 5.5V
VOUT
TC1121
GND
OSC
CAP+
CAP–
FC
VOUT
VIN
SHDN
*SHDN should be tied to VIN if not used.
SHDN*
+
–
+
–
FC
OSC
Oscillator Frequency
Open
10 kHz
FC = V+
Open
200 kHz
Open or
FC = V+
External Capacitor
See Typical Operating
Characteristics
Open
External Clock
External Clock Frequency
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相關代理商/技術參數 |
參數描述 |
|---|---|
| TC1121EPA | 功能描述:電荷泵 w/ Shutdown 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 |
| TC1121EUA | 功能描述:電荷泵 w/ Shutdown 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 |
| TC1121EUA713 | 功能描述:電荷泵 w/ Shutdown 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 |
| TC112A | 制造商:Thomas & Betts 功能描述:Fittings Connector 0.75inch Steel |
| TC112A-RT | 制造商:Thomas & Betts 功能描述:Fittings Connector 0.75inch Steel |
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