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PDF TC1044S Data sheet ( Hoja de datos )
| Número de pieza | TC1044S | |
| Descripción | CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER | |
| Fabricantes | TelCom Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TC1044S (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
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EVALUATION
KIT
AVAILABLE
1
TC1044S
CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
FEATURES
s Converts +5V Logic Supply to ±5V System
s Wide Input Voltage Range .................... 1.5V to 12V
s Efficient Voltage Conversion ......................... 99.9%
s Excellent Power Efficiency ............................... 98%
s Low Power Consumption ............ 80µA @ VIN = 5V
s Low Cost and Easy to Use
— Only Two External Capacitors Required
s RS-232 Negative Power Supply
s Available in 8-Pin Small Outline (SOIC) and 8-Pin
Plastic DIP Packages
s Improved ESD Protection ..................... Up to 10kV
s No External Diode Required for High Voltage
Operation
s Frequency Boost Raises FOSC to 45kHz
GENERAL DESCRIPTION
The TC1044S is a pin-compatible upgrade to the Indus-
try standard TC7660 charge pump voltage converter. It
converts a +1.5V to +12V input to a corresponding –1.5V
to –12V output using only two low cost capacitors, eliminat-
ing inductors and their associated cost, size and EMI.
Added features include an extended supply range to 12V,
and a frequency boost pin for higher operating frequency,
allowing the use of smaller external capacitors.
The on-board oscillator operates at a nominal frequency
of 10kHz. Frequency is increased to 45kHz when pin 1 is
connected to V+. Operation below 10kHz (for lower supply
current applications) is possible by connecting an external
capacitor from OSC to ground (with pin 1 open).
The TC1044S is available in both 8-pin DIP and
8-pin small outline (SOIC) packages in commercial and
extended temperature ranges.
2
3
4
PIN CONFIGURATION (DIP and SOIC)
BOOST 1
8 V+
CAP + 2
7 OSC
GND
TC1044SCPA
3 TC1044SEPA 6
LOW
VOLTAGE (LV)
CAP –
4
TC1044SIJA
TC1044SMJA
5
VOUT
BOOST 1
8 V+
CAP + 2
7 OSC
GND
3 TC1044SCOA 6
TC1044SEOA
LOW
VOLTAGE (LV)
CAP – 4
5 VOUT
FUNCTIONAL BLOCK DIAGRAM
1
BOOST
ORDERING INFORMATION
Part No.
Package
Temp. Range
TC1044SCOA
TC1044SCPA
TC1044SEOA
TC1044SEPA
TC1044SIJA
TC1044SMJA
TC7660EV
8-Pin SOIC
0°C to +70°C
8-Pin Plastic DIP
0°C to +70°C
8-Pin SOIC
– 40°C to +85°C
8-Pin Plastic DIP – 40°C to +85°C
8-Pin CerDIP
– 25°C to +85°C
8-Pin CerDIP
– 55°C to +125°C
Charge Pump Family Evaluation Kit
V + CAP +
82
5
6
7
OSC
RC
OSCILLATOR
6
LV
2
INTERNAL
VOLTAGE
REGULATOR
TC1044S
TELCOM SEMICONDUCTOR, INC.
VOLTAGE–
LEVEL
TRANSLATOR
3
GND
4 CAP –
5 VOUT
7
LOGIC
NETWORK
8
TC1044S-12 9/16/96
4-43
1 page  
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
1
TC1044S
+
10µF
V+
18
27
3 TC1044S 6
4 "1" 5
* NOTES:
1. VOUT = –n(V+) for 1.5V ≤ V+ ≤ 12V
+
10µF
18
27
3 TC1044S 6
4 "n" 5
+ 10µF
2
VOUT*
+ 10µF
3
Figure 5. Increased Output Voltage by Cascading Devices
Cascading Devices
The TC1044S may be cascaded as shown (Figure 5) to
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:
VOUT = –n(VIN)
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 TC1044S
ROUT values.
Changing the TC1044S Oscillator Frequency
It may be desirable in some applications (due to noise or
other considerations) to increase the oscillator frequency.
Pin 1, frequency boost pin may be connected to V+ to
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 1kΩ
resistor must be used in series with the clock output. In a
+
10µF
18
27
3 TC1044S 6
45
V+
1kΩ
V+
CMOS
GATE
VOUT
10µF
+
Figure 6. External Clocking
situation where the designer has generated the external
clock frequency using TTL logic, the addition of a 10kΩ pull-
up resistor to V+ supply is required. Note that the pump
frequency with external clocking, as with internal clocking,
will be 1/2 of the clock frequency. Output transitions occur
on the positive-going edge of the clock.
It is also possible to increase the conversion efficiency
of the TC1044S at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is achieved
by connecting an additional capacitor, COSC, as shown in
Figure 7. Lowering the oscillator frequency will cause an
undesirable increase in the impedance of the pump (C1) and
the reservoir (C2) capacitors. To overcome this, increase
the values of C1 and C2 by the same factor that the
frequency has been reduced. For example, the addition of
a 100pF capacitor between pin 7 (OSC) and pin 8 (V+) will
lower the oscillator frequency to 1kHz from its nominal
frequency of 10kHz (a multiple of 10), and necessitate a
corresponding increase in the values of C1 and C2 (from
10µF to 100µF).
Positive Voltage Multiplication
The TC1044S may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 8. In
this application, the pump inverter switches of the TC1044S
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 (2V+) – (2VF),
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.
4
5
6
7
8
TELCOM SEMICONDUCTOR, INC.
4-47
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet TC1044S.PDF ] | |
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