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MAX1044ESA 参数 Datasheet PDF下载

MAX1044ESA图片预览
型号: MAX1044ESA
PDF下载: 下载PDF文件 查看货源
内容描述: 开关电容电压转换器 [Switched-Capacitor Voltage Converters]
分类和应用: 转换器稳压器开关式稳压器或控制器电源电路开关式控制器光电二极管
文件页数/大小: 12 页 / 118 K
品牌: MAXIM [ MAXIM INTEGRATED PRODUCTS ]
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S w it c h e d -Ca p a c it o r Vo lt a g e Co n ve rt e rs  
MAX14/ICL760  
_____________________________________________________________ P in De s c rip t io n  
PIN  
NAME  
FUNCTION  
BOOST  
(MAX1044)  
Frequency Boost. Connecting BOOST to V+ increases the oscillator frequency by a factor of six. When the  
oscillator is driven externally, BOOST has no effect and should be left open.  
1
N.C.  
(ICL7660)  
No Connection  
2
3
4
CAP+  
GND  
CAP-  
Connection to positive terminal of Charge-Pump Capacitor  
Ground. For most applications, the positive terminal of the reservoir capacitor is connected to this pin.  
Connection to negative terminal of Charge-Pump Capacitor  
Negative Voltage Output. For most applications, the negative terminal of the reservoir capacitor is  
connected to this pin.  
5
6
V
OUT  
Low-Voltage Operation. Connect to ground for supply voltages below 3.5V.  
ICL7660: Leave open for supply voltages above 5V.  
LV  
Oscillator Control Input. Connecting an external capacitor reduces the oscillator frequency. Minimize stray  
capacitance at this pin.  
7
8
OSC  
V+  
Power-Supply Positive Voltage Input. (1.5V to 10V). V+ is also the substrate connection.  
During the first half of each cycle, switches S1 & S3  
close and switches S2 & S4 open, which connects the  
V+  
b uc ke t c a p a c itor C1 a c ros s V+ a nd c ha rg e s C1.  
C
BYPASS  
During the second half of each cycle, switches S2 & S4  
close and switches S1 & S3 open, which connects the  
positive terminal of C1 to ground and shifts the nega-  
BOOST  
V+  
= 0.1µF  
EXTERNAL  
OSCILLATOR  
MAX1044  
CAP+ ICL7660 OSC  
tive terminal to V  
. This connects C1 in parallel with  
OUT  
the reservoir capacitor C2. If the voltage across C2 is  
smaller than the voltage across C1, then charge flows  
from C1 to C2 until the voltages across them are equal.  
During successive cycles, C1 will continue pouring  
charge into C2 until the voltage across C2 reaches  
- (V+). In an actual voltage inverter, the output is less  
than - (V+) since the switches S1–S4 have resistance  
and the load drains charge from C2.  
R
L
C
C1  
10µF  
OSC  
GND  
CAP-  
LV  
V
V
OUT  
OUT  
C2  
10µF  
Additional qualities of the MAX1044/ICL7660 can be  
und e rs tood b y us ing a s witc he d -c a p a c itor c irc uit  
model. Switching the bucket capacitor, C1, between  
the input and output of the circuit synthesizes a resis-  
tance (Figures 3a and 3b.)  
Figure 1. Maxim MAX1044/ICL7660 Test Circuit  
_______________De t a ile d De s c rip t io n  
When the switch in Figure 3a is in the left position,  
capacitor C1 charges to V+. When the switch moves to  
The MAX1044/ICL7660 are charge-pump voltage con-  
verters. They work by first accumulating charge in a  
bucket capacitor and then transfer it into a reservoir  
capacitor. The ideal voltage inverter circuit in Figure 2  
illustrates this operation.  
the rig ht p os ition, C1 is d is c ha rg e d to V  
. The  
OUT  
charge transferred per cycle is: Q = C1(V+ - V  
). If  
OUT  
the switch is cycled at frequency f, then the resulting  
_______________________________________________________________________________________  
5