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PDF TC7662BCOA Data sheet ( Hoja de datos )
| Número de pieza | TC7662BCOA | |
| 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 TC7662BCOA (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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EVALUATION
KIT
AVAILABLE
1
TC7662B
CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
FEATURES
s Wide Operating Voltage Range: 1.5V to 15V
s Boost Pin (Pin 1) for Higher Switching Frequency
s High Power Efficiency is 96%
s Easy to Use – Requires Only 2 External Non-Critical
Passive Components
s Improved Direct Replacement for Industry Stan-
dard ICL7660 and Other Second Source Devices
APPLICATIONS
s Simple Conversion of +5V to ±5V Supplies
s Voltage Multiplication VOUT = ±nVIN
s Negative Supplies for Data Acquisition Systems
and Instrumentation
s RS232 Power Supplies
s Supply Splitter, VOUT = ±VS/2
PIN CONFIGURATION (DIP and SOIC)
BOOST 1
8 V+
BOOST 1
8 V+
CAP + 2
7 OSC
CAP + 2
7 OSC
GND
3
TC7662BCPA
TC7662BEPA
6
LOW
VOLTAGE (LV)
CAP – 4
5 VOUT
GND
3
TC7662BCOA
TC7662BEOA
6
LOW
VOLTAGE (LV)
CAP – 4
5 VOUT
GENERAL DESCRIPTION
The TC7662B is a pin-compatible upgrade to the Indus-
try standard TC7660 charge pump voltage converter. It
converts a +1.5V to +15V input to a corresponding – 1.5 to
– 15V output using only two low-cost capacitors, eliminating
inductors and their associated cost, size and EMI.
The on-board oscillator operates at a nominal fre-
quency of 10kHz. Frequency is increased to 35kHz when
pin 1 is connected to V+, allowing the use of smaller external
capacitors. Operation below 10kHz (for lower supply current
applications) is also possible by connecting an external
capacitor from OSC to ground (with pin 1 open).
The TC7662B is available in both 8-pin DIP and 8-pin
small outline (SO) packages in commercial and extended
temperature ranges.
ORDERING INFORMATION
Part No.
Package
Temperature
Range
TC7662BCOA
TC7662BCPA
TC7662BEOA
TC7662BEPA
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
Evaluation Kit for
Charge Pump Family
2
3
4
5
FUNCTIONAL BLOCK DIAGRAM
BOOST
1
V + CAP +
82
6
OSC
LV
7 RC
OSCILLATOR
6
÷2
INTERNAL
VOLTAGE
REGULATOR
TC7662B
VOLTAGE–
LEVEL
TRANSLATOR
4 CAP –
5 VOUT
LOGIC
NETWORK
7
TELCOM SEMICONDUCTOR, INC.
3
GND
8
TC7662B-8 9/11/96
4-83
1 page  
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
1
TC7662B
Paralleling Devices
Any number of TC7662B voltage converters may be
paralleled to reduce output resistance (Figure 5). The reser-
voir capacitor, C2, serves all devices, while each device
requires its own pump capacitor, C1. The resultant output
resistance would be approximately:
ROUT =
ROUT (of TC7662B)
n (number of devices)
V+
18
27
C1
TC7662B
36
4 "1" 5
18
27
C1 3 TC7662B 6
4 "n" 5
RL
+ C2
Figure 5. Paralleling Devices
Cascading Devices
The TC7662B may be cascaded as shown 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 TC7662B
ROUT values.
Changing the TC7662B Oscillator Frequency
It may be desirable in some applications (due to noise or
other considerations) to increase the oscillator frequency.
This is achieved by one of several methods described
below:
By connecting the BOOST Pin (Pin 1) to V+, the oscilla-
tor charge and discharge current is increased and, hence
the oscillator frequency is increased by approximately 3-1/
2 times. The result is a decrease in the output impedance
and ripple. This is of major importance for surface mount
applications where capacitor size and cost are critical.
Smaller capacitors, e.g., 0.1µF, can be used in conjunction
with the Boost Pin in order to achieve similar output currents
compared to the device free running with C1 = C2 = 1µF or
10µF. (Refer to graph of Output Source Resistance as a
Function of Oscillator Frequency).
Increasing the oscillator frequency can also be achieved
by overdriving the oscillator from an external clock as shown
in Figure 7. In order to prevent device latchup, a 1kΩ resistor
must be used in series with the clock output. In a situation
where the designer has generated the external clock fre-
quency using TTL logic, the addition of a 10kΩ pull-up-
resistor to V+ supply is required. Note that the pump fre-
quency 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.
+
10µF
18
27
3 TC7662B 6
45
V+
1 kΩ
V+
CMOS
GATE
VOUT
10µF
+
2
3
4
5
6
+
10µF
V+
18
27
3 TC7662B 6
4 "1" 5
+
10µF
*VOUT = –nV+
10µF
18
27
3 TC7662B 6
4 "n" 5
VOUT
+ 10µF
Figure 6. Cascading Devices for Increased Output Voltage
TELCOM SEMICONDUCTOR, INC.
Figure 7. External Clocking
It is also possible to increase the conversion efficiency
of the TC7662B at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is shown
in Figure 8. However, lowering the oscillator frequency will
cause an undesirable increase in the impedance of the
pump (C1) and reservoir (C2) capacitors; this is overcome by
increasing 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 V+ will lower
the oscillator frequency to 1kHz from its nominal frequency
of 10kHz (multiple of 10), and thereby necessitate a corre-
sponding increase in the value of C1 and C2 (from 10µF to
100µF).
7
8
4-87
5 Page | ||
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| PDF Descargar | [ Datasheet TC7662BCOA.PDF ] | |
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