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參數(shù)資料
| 型號： | TC7662BCPA |
| 廠商： | TelCom Semiconductor, Inc. |
| 英文描述： | CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| 中文描述： | 電荷泵型DC - DC電壓轉(zhuǎn)換器 |
| 文件頁數(shù)： | 5/9頁 |
| 文件大?。?/td> | 133K |
| 代理商： | TC7662BCPA |
4-87
TELCOM SEMICONDUCTOR, INC.
7
6
5
4
3
1
2
8
Paralleling Devices
Any number of TC7662B voltage converters may be
paralleled to reduce output resistance (Figure 5). The reser-
voir capacitor, C
2
, serves all devices, while each device
requires its own pump capacitor, C
1
. The resultant output
resistance would be approximately:
R
OUT
(of TC7662B)
n (number of devices)
R
OUT
=
Changing the TC7662B Oscillator Frequency
It may be desirable in some applications (due to noise or
other considerations) to increase the oscillator frequency.
This is achieved by one of several methods described
below:
By connecting the BOOST Pin (Pin 1) to V
+
, the oscilla-
tor charge and discharge current is increased and, hence
the oscillator frequency is increased by approximately 3-1/
2 times. The result is a decrease in the output impedance
and ripple. This is of major importance for surface mount
applications where capacitor size and cost are critical.
Smaller capacitors, e.g., 0.1
μ
F, can be used in conjunction
with the Boost Pin in order to achieve similar output currents
compared to the device free running with C
1
= C
2
= 1
μ
F or
10
μ
F. (Refer to graph of Output Source Resistance as a
Function of Oscillator Frequency).
Increasing the oscillator frequency can also be achieved
by overdriving the oscillator from an external clock as shown
in Figure 7. In order to prevent device latchup, a 1k
resistor
must be used in series with the clock output. In a situation
where the designer has generated the external clock fre-
quency using TTL logic, the addition of a 10k
pull-up-
resistor to V
+
supply is required. Note that the pump fre-
quency with external clocking, as with internal clocking, will
be 1/2 of the clock frequency. Output transitions occur on the
positive-going edge of the clock.
Figure 6. Cascading Devices for Increased Output Voltage
1
2
3
4
8
7
6
5
V+
1
2
3
4
8
7
6
5
10
μ
F
10
μ
F
"n"
"1"
10
μ
F
VOUT
*VOUT = –nV+
+
+
+
TC7662B
TC7662B
10
μ
F
Cascading Devices
The TC7662B may be cascaded as shown 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:
V
OUT
= –n(V
IN
)
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 TC7662B
R
OUT
values.
Figure 5. Paralleling Devices
1
2
3
4
8
7
6
5
TC7662B
+
V+
+
CMOS
GATE
10
μ
F
VOUT
10
μ
F
1 k
V+
Figure 7. External Clocking
It is also possible to increase the conversion efficiency
of the TC7662B at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is shown
in Figure 8. However, lowering the oscillator frequency will
cause an undesirable increase in the impedance of the
pump (C
1
) and reservoir (C
2
) capacitors; this is overcome by
increasing the values of C
1
and C
2
by the same factor that
the frequency has been reduced. For example, the addition
of a 100pF capacitor between pin 7 (Osc) and V
+
will lower
the oscillator frequency to 1kHz from its nominal frequency
of 10kHz (multiple of 10), and thereby necessitate a corre-
sponding increase in the value of C
1
and C
2
(from 10
μ
F to
100
μ
F).
1
2
3
4
8
7
6
5
TC7662B
V+
1
2
3
4
8
7
6
5
TC7662B
C1
RL
C2
C1
"n"
"1"
+
TC7662B
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TC7662BEPA | CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| TC7662BCOA | CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| TC7662BEOA | CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| TC811 | 3-1/2 DIGIT A/D CONVERTER WITH HOLD AND DIFFERENTIAL REFERENCE INPUTS |
| TC811 | 3-1/2 Digit Analog-To-Digital Converter with Hold and Differential Reference Inputs |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TC7662BCPA | 制造商:Microchip Technology Inc 功能描述:DC/DC Charge Pump Converter (DC-DC) IC |
| TC7662BEOA | 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 |
| TC7662BEOA | 制造商:Microchip Technology Inc 功能描述:DC/DC Charge Pump Converter (DC-DC) IC |
| TC7662BEOA713 | 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 |
| TC7662BEPA | 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 |
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