ICL7660ESA Datasheet Download

Part No.:
ICL7660ESA
Download:
Download Datasheet
Description:
[Switched-Capacitor Voltage Converters]
File Size:
118 K
Page:
12 Pages
Logo:
Manufacturer:
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
PCB Prototype
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Switched-Capacitor Voltage Converters
MAX1044/ICL7660
current is: I = f x
∆Q
= f x C1(V+ - V
OUT
). Rewriting this
equation in Ohm’s law form defines an equivalent resis-
tance synthesized by the switched-capacitor circuit
where:
I
=
(V+ - V
OUT
)
1 / (f x C1)
and
1
R
EQUIV
=
f x C1
S1
V+
C1
S2
S3
S4
C2
V
OUT
= -(V+)
where f is one-half the oscillator frequency. This resis-
tance is a major component of the output impedance of
switched-capacitor circuits like the MAX1044/ICL7660.
As shown in Figure 4, the MAX1044/ICL7660 contain
MOSFET switches, the necessary transistor drive cir-
cuitry, and a timing oscillator.
Figure 2. Ideal Voltage Inverter
________________Design Information
f
V+
V
OUT
The MAX1044/ICL7660 are designed to provide a
simple, compact, low-cost solution where negative or
doubled supply voltages are needed for a few low-
power components. Figure 5 shows the basic negative
voltage converter circuit. For many applications, only
two external capacitors are needed. The type of
capacitor used is not critical.
C1
C2
R
LOAD
Proper Use of the Low-Voltage (LV) Pin
Figure 4 shows an internal voltage regulator inside the
MAX1044/ICL7660. Use the LV pin to bypass this
regulator, in order to improve low-voltage performance
Figure 3a. Switched Capacitor Model
V+
pin 8
S1
CAP+
pin 2
S2
R
EQUIV
V+
1
R
EQUIV
=
f
×
C1
C2
R
LOAD
V
OUT
1M
OSCILLATOR
BOOST
pin 1
OSC
pin 7
Q
÷2
Q
S3
INTERNAL
REGULATOR
S4
CAP-
pin 4
V
OUT
pin 5
LV
pin 6
GND
pin 3
Figure 3b. Equivalent Circuit
6
Figure 4. MAX1044 and ICL7660 Functional Diagram
_______________________________________________________________________________________