TC7660SEOA713 Microchip Technology, TC7660SEOA713 Datasheet - Page 5
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TC7660SEOA713
Manufacturer Part Number
TC7660SEOA713
Description
HIGH VOLTAGE DC-DC CONVERTER,
Manufacturer
Microchip Technology
Type
Switched Capacitor (Charge Pump), Invertingr
Specifications of TC7660SEOA713
Rohs Compliant
YES
Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
-1.5 ~ -12 V
Current - Output
20mA
Frequency - Switching
10kHz ~ 45kHz
Voltage - Input
1.5 ~ 12 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
8-SOIC (3.9mm Width)
Power - Output
470mW
Function
Inverting, Step Up
Output Voltage
- 12 V to - 1.5 V, 3 V to 24 V
Output Current
20 mA
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Mounting Style
SMD/SMT
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
TC7660SEOA713RTR
TC7660SEOA713RTR
TC7660SEOA713TR
TC7660SEOA713RTR
TC7660SEOA713TR
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
TC7660SEOA713
Manufacturer:
Microchip Technology
Quantity:
75 225
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
Cascading Devices
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:
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 TC7660S
R
Changing the TC7660S Oscillator Frequency
other considerations) to increase the oscillator frequency.
Pin 1, frequency boost pin may be connected to V
increase oscillator frequency to 45kHz from a nominal of
10kHz for an input supply voltage of 5.0 volts. The oscillator
may also be synchronized to an external clock as shown in
Figure 6. In order to prevent possible device latch-up, a 1k
resistor must be used in series with the clock output. In a
© 2001 Microchip Technology Inc.
10 F
OUT
The TC7660S may be cascaded as shown (Figure 5) to
It may be desirable in some applications (due to noise or
values.
+
10 F
1
2
3
4
Figure 6. External Clocking
TC7660S
*
+
NOTES:
1. V
V
DS21467A
OUT
OUT
1
2
3
4
= –n(V
= – n (V
8
7
6
5
TC7660S
"1"
+
) for 1.5V
V +
1 k
IN
Figure 5. Increased Output Voltage by Cascading Devices
)
8
7
6
5
+
V
V
+
+
10 F
12V
V +
V OUT
CMOS
GATE
10 F
+
to
+
5
10 F
+
situation where the designer has generated the external
clock frequency using TTL logic, the addition of a 10k pull-
up resistor to V
frequency with external clocking, as with internal clocking,
will be
the positive-going edge of the clock.
of the TC7660S at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is achieved
by connecting an additional capacitor, C
Figure 7. Lowering the oscillator frequency will cause an
undesirable increase in the impedance of the pump (C
the reservoir (C
values of C
has been reduced. For example, the addition of a 100pF
capacitor between pin 7 (OSC) and pin 8 (V
oscillator frequency to 1kHz from its nominal frequency of
10kHz (a multiple of 10), and necessitate a corresponding
increase in the values of C
Positive Voltage Multiplication
voltage multiplication using the circuit shown in Figure 8. In
this application, the pump inverter switches of the TC7660S
are used to charge C
is the supply voltage and V
diode D
supply voltage (V
C
or twice the supply voltage minus the combined forward
voltage drops of diodes D
on the output current, but for V
of 10mA, it will be approximately 60 .
2
. The voltage thus created on C
It is also possible to increase the conversion efficiency
The TC7660S may be employed to achieve positive
The source impedance of the output (V
1
1
2
3
4
). On the transfer cycle, the voltage on C
of the clock frequency. Output transitions occur on
1
TC7660S
and C
"n"
2
) capacitors. To overcome this, increase the
+
+
supply is required. Note that the pump
) is applied through diode D
2
by the same factor that the frequency
1
to a voltage level of V
8
7
6
5
1
1
F
and D
and C
is the forward voltage drop of
+
= 5V and an output current
2
2
2
.
becomes (2V
(from 10 F to 100 F).
+
OSC
10 F
OUT
+
+
–V
) will lower the
TC7660S
V OUT
, as shown in
2
) will depend
TC7660S-14 9/16/96
to capacitor
F
(where V
+
1
) – (2V
*
plus the
1
) and
F
),
+