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參數(shù)資料
| 型號： | TC7660SEOA |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHED CAPACITOR REGULATOR, 45 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | PLASTIC, SOIC-8 |
| 文件頁數(shù)： | 7/11頁 |
| 文件大?。?/td> | 95K |
| 代理商： | TC7660SEOA |
5
TC7660S
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
2001 Microchip Technology Inc.
DS21467A
TC7660S-14 9/16/96
Figure 5. Increased Output Voltage by Cascading Devices
situation where the designer has generated the external
clock frequency using TTL logic, the addition of a 10k
pull-
up resistor to V
+ supply is required. Note that the pump
frequency with external clocking, as with internal clocking,
will be
of the clock frequency. Output transitions occur on
the positive-going edge of the clock.
It is also possible to increase the conversion efficiency
of the TC7660S at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is achieved
by connecting an additional capacitor, COSC, as shown in
Figure 7. Lowering the oscillator frequency will cause an
undesirable increase in the impedance of the pump (C1) and
the reservoir (C2) capacitors. To overcome this, increase the
values of C1 and C2 by the same factor that the frequency
has been reduced. For example, the addition of a 100pF
capacitor between pin 7 (OSC) and pin 8 (V
+) will lower the
oscillator frequency to 1kHz from its nominal frequency of
10kHz (a multiple of 10), and necessitate a corresponding
increase in the values of C1 and C2 (from 10F to 100F).
Positive Voltage Multiplication
The TC7660S may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 8. In
this application, the pump inverter switches of the TC7660S
are used to charge C1 to a voltage level of V
+–VF (where V+
is the supply voltage and VF is the forward voltage drop of
diode D1). On the transfer cycle, the voltage on C1 plus the
supply voltage (V
+) is applied through diode D2 to capacitor
+) – (2VF),
or twice the supply voltage minus the combined forward
voltage drops of diodes D1 and D2.
The source impedance of the output (VOUT) will depend
on the output current, but for V
+ = 5V and an output current
of 10mA, it will be approximately 60
.
Cascading Devices
The TC7660S may be cascaded as shown (Figure 5) to
produce larger negative multiplication of the initial supply
voltage. However, due to the finite efficiency of each device,
the practical limit is 10 devices for light loads. The output
voltage is defined by:
VOUT = – n (VIN)
where n is an integer representing the number of devices
cascaded. The resulting output resistance would be ap-
proximately the weighted sum of the individual TC7660S
ROUT values.
Changing the TC7660S Oscillator Frequency
It may be desirable in some applications (due to noise or
other considerations) to increase the oscillator frequency.
Pin 1, frequency boost pin may be connected to V
+ to
increase oscillator frequency to 45kHz from a nominal of
10kHz for an input supply voltage of 5.0 volts. The oscillator
may also be synchronized to an external clock as shown in
Figure 6. In order to prevent possible device latch-up, a 1k
resistor must be used in series with the clock output. In a
Figure 6. External Clocking
1
2
3
4
8
7
6
5
TC7660S
+
V +
+
CMOS
GATE
10
F
VOUT
10
F
1 k
V +
1
2
3
4
8
7
6
5
V
+
1
2
3
4
8
7
6
5
10
F
10
F
"n"
"1"
10
F
VOUT
NOTES:
*
+
TC7660S
1. VOUT = –n(V+) for 1.5V ≤ V+ ≤ 12V
10
F
+
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TC7660SEOA | 制造商:Microchip Technology Inc 功能描述:DC/DC Charge Pump Converter (DC-DC) IC |
| TC7660SEOA713 | 功能描述:電荷泵 High Voltage 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 |
| TC7660SEPA | 功能描述:電荷泵 High Voltage 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 |
| TC7660SMJA | 功能描述:電荷泵 High Voltage 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 |
| TC7662A | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:CHARGE PUMP DC-TO-DC CONVERTER |
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