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参数资料
| 型号： | TC7662AMJAG |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHED CAPACITOR CONVERTER, 12 kHz SWITCHING FREQ-MAX, CDIP8 |
| 封装： | CERDIP-8 |
| 文件页数： | 11/14页 |
| 文件大小： | 458K |
| 代理商： | TC7662AMJAG |
TC7662A
DS21468B-page 6
2002 Microchip Technology Inc.
4.0
TYPICAL APPLICATIONS
4.1
Simple Negative Voltage
Converter
The majority of applications will undoubtedly utilize the
TC7662A for generation of negative supply voltages.
Figure 4-1 shows typical connections to provide a
negative supply where a positive supply of +3V to +18V
is available.
FIGURE 4-1:
SIMPLE NEGATIVE
CONVERTER AND ITS
OUTPUT EQUIVALENT
The output characteristics of the circuit in Figure 4-1
are those of a nearly ideal voltage source in series with
a resistance as shown in Figure 4-1b. The voltage
source has a value of -(VDD). The output impedance
(RO) is a function of the ON resistance of the internal
MOS switches (shown in the Functional Block
Diagram), the switching frequency, the value of CP and
CR, and the ESR (equivalent series resistance) of CP
and CR. A good first order approximation for RO is:
Combining the four RSWX terms as RSW, we see that:
RSW, the total switch resistance, is a function of supply
voltage and temperature (See Section 5.0, Typical
Characteristics “Output Source Resistance” graphs),
typically 23
at +25°C and 5V. Careful selection of CP
and CR will reduce the remaining terms, minimizing the
output impedance.
High
value
capacitors
will
reduce the 1/(fPUMP x CP) component, and low ESR
capacitors will lower the ESR term. Increasing the
oscillator frequency will reduce the 1/(fPUMP x CP) term,
but may have the side effect of a net increase in output
impedance when CP > 10F and there is not enough
time to fully charge the capacitors every cycle. In a typ-
ical application when fOSC = 12kHz and C = CP = CR =
10
F:
Since the ESRs of the capacitors are reflected in the
output impedance multiplied by a factor of 5, a high
value could potentially swamp out a low 1/(fPUMP x CP)
term, rendering an increase in switching frequency
or filter capacitance ineffective. Typical electrolytic
capacitors may have ESRs as high as 10
.
1
2
3
4
8
7
6
5
TC7662A
10
F
+
VDD
+
10
F
VOUT = -V+
–
VOUT
RO
VDD
+
–
AB
RO 2(RSW1 + RSW2 + ESRCP) + 2(RSW3 + RSW4 +
ESRCP) +
+ ESRCR
1
fPUMP x CP
(fPUMP =
, RSWX = MOSFET switch resistance)
fOSC
2
RO 2 x RSW +
+ 4 x ESRCP + ESRCR
1
fPUMP x CP
RO 2 x 23 +
+ 4 x ESRCP + ESRCR
1
(5 x 123 x 10 x 10-6)
RO (46 + 20 + 5 x ESRC)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC7662B | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| TC7662BC0A | 制造商:Texas Instruments 功能描述: |
| TC7662BCOA | 功能描述:电荷泵 High Voltage RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| TC7662BCOA | 制造商:Microchip Technology Inc 功能描述:DC/DC CONVERTER SMD 7662 SOIC8 |
| TC7662BCOA713 | 功能描述:电荷泵 High Voltage RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
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