TC7660H View Datasheet(PDF) - TelCom Semiconductor Inc => Microchip
Part Name
Description
Manufacturer
TC7660H Datasheet PDF : 6 Pages
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HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
1
TC7660H
V+
1
8
2
7
C1
TC7660H
3
6
4
"1"
5
1
8
2
7
C1
3 TC7660H 6
4
"n"
5
RL
RL
+ C2
2
3
Figure 5. Paralleling Devices Lowers Output Impedance
+
1.0 µF
1
8
2
7
3 TC7660H 6
4
5
V+
1 kΩ
V+
CMOS
GATE
VOUT
1.0 µF
+
Figure 6. External Clocking
Positive Voltage Multiplication
The TC7660H may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 7. In
this application, the pump inverter switches of the TC7660H
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
C2. The voltage thus created on C2 becomes (2 V+) – (2 VF),
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 60Ω.
V+
1
8
2
7
3 TC7660H 6
4
5
D1
VOUT =
D2
(2 V+) – (2 VF)
+
C1
+
C2
Figure 7. Positive Voltage Multiplier
TELCOM SEMICONDUCTOR, INC.
Combined Negative Voltage Conversion
and Positive Supply Multiplication
4 Figure 8 combines the functions shown in Figures 3 and
8 to provide negative voltage conversion and positive volt-
age multiplication simultaneously. This approach would be,
for example, suitable for generating +9V and –5V from an
existing +5V supply. In this instance, capacitors C1 and C3
perform the pump and reservoir functions, respectively, for
the generation of the negative voltage, while capacitors C2
5 and C4 are pump and reservoir, respectively, for the multi-
plied positive voltage. There is a penalty in this configuration
which combines both functions, however, in that the source
impedances of the generated supplies will be somewhat
higher due to the finite impedance of the common charge
pump driver at pin 2 of the device.
V+
1
8
2
7
3 TC7660H 6
+
4
C1
5
+
C2
VOUT =
– (V+– VF)
6
D1
+ C3
D2
V(2OVU+T)
=
–
(2
VF)
+
C4
7
Figure 8. Combined Negative Converter and Positive Multiplier
8
4-67
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