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PDF TC660 Data sheet ( Hoja de datos )
| Número de pieza | TC660 | |
| Descripción | 100mA 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 TC660 (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
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EVALUATION
KIT
AVAILABLE
1
TC660
100mA CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
FEATURES
s Pin Compatible with TC7660
s High Output Current ..................................... 100mA
s Converts (+1.5V to 5.5V) to (– 1.5V to – 5.5V)
s Power Efficiency @100mA ......................... 88% typ
s Low Power Consumption ................ 200µA @ 5 VIN
s Low Cost and Easy to Use
— Only Two External Capacitors Required
s Selectable Oscillator Frequency ....... 10kHz/90kHz
s ESD Protection ................................................... 4kV
APPLICATIONS
s Laptop Computers
s µP Based Controllers
s Process Instrumentation
s Automotive Instruments
PIN CONFIGURATION (DIP and SOIC)
GENERAL DESCRIPTION
The TC660 DC-to-DC voltage converter generates a
negative voltage supply, that can support a 100mA maxi-
mum load, from a positive voltage input of 1.5V to 5.5V. Only
two external capacitors are required.
Power supply voltage is stored on an undedicated
capacitor then inverted and transferred to an output reser-
voir capacitor. The on-board oscillator normally runs at a
frequency of 10kHz with V+ at 5V. This frequency can be
lowered by the addition of an external capacitor from OSC
(pin 7) to ground, or raised to 90kHz by connecting the
frequency control pin (FC) to V+, in order to optimize capaci-
tor size, quiescent current, and output voltage ripple
frequency. Operation using input voltage between 1.5V and
3.0V is accommodated by grounding the LV input (pin 6).
Operation at higher input voltages (3.0V to 5.5V) is accom-
plished by leaving LV open.
The TC660 open circuit output voltage is within 0.1% of
the input voltage with the output open-circuited. Power
conversion efficiency is 98% when output load is between
2mA and 5mA.
2
3
4
FC 1
CAP + 2
8 V+
7 OSC
www.DGaNtaDShe3et4TUC.6c6o0mCPA 6 LV
TC660EPA
CAP – 4
5 VOUT
FC 1
CAP + 2
8 V+
7 OSC
GND 3 TC660COA 6 LV
TC660EOA
CAP – 4
5 VOUT
FUNCTIONAL BLOCK DIAGRAM
1
FC
ORDERING INFORMATION
Part No.
Package
TC660COA
TC660CPA
TC660EOA
TC660EPA
TC7660EV
8-Pin SOIC
8-Pin Plastic DIP
8-Pin SOIC
8-Pin Plastic DIP
Evaluation Kit for
Charge Pump Family
V + CAP +
82
Temp. Range
0°C to +70°C
0°C to +70°C
– 40°C to +85°C
– 40°C to +85°C
5
6
OSC
7
RC
OSCILLATOR
6
LV
÷2
INTERNAL
VOLTAGE
REGULATOR
VOLTAGE–
LEVEL
TRANSLATOR
TC660
TELCOM SEMICONDUCTOR, INC.
3
GND
4 CAP –
5 VOUT
LOGIC
NETWORK
7
8
TC660-2 9/10/96
4-5
1 page  
100mA CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
1
TC660
Circuit Description
The TC660 contains all the necessary circuitry to com-
plete a voltage inverter (Figure 1), with the exception of two
external capacitors, which may be inexpensive 150µF polar-
ized electrolytic capacitors. Operation is best understood by
considering Figure 2, which shows an idealized voltage
inverter. Capacitor C1 is charged to a voltage V+ for the half
cycle when switches S1 and S3 are closed. (Note: Switches
S2 and S4 are open during this half cycle.) During the second
half cycle of operation, switches S2 and S4 are closed, with
S1 and S3 open, thereby shifting capacitor C1 negatively by
V+ volts. Charge is then transferred from C1 to C2, such that
the voltage on C2 is exactly V+, assuming ideal switches and
no load on C2.
The four switches in Figure 2 are MOS power switches;
S1 is a P-channel device, and S2, S3 and S4 are N-channel
devices. The main difficulty with this approach is that in
integrating the switches, the substrates of S3 and S4 must
always remain reverse-biased with respect to their sources,
but not so much as to degrade their ON resistances. In
addition, at circuit start-up, and under output short circuit
conditions (VOUT = V+), the output voltage must be sensed
and the substrate bias adjusted accordingly. Failure to
accomplish this would result in high power losses and
possible device latch-up. This problem is eliminated in the
TC660 by a logic network which senses the output voltage
(VOUT) together with the level translators, and switches the
substrates of S3 and S4 to the correct level to maintain
necessary reverse bias.
www.DataTSoheiemt4pUr.ocovme low-voltage operation, the “LV” pin should
be connected to GND, disabling the internal regulator. For
supply voltages greater than 3.0V, the LV terminal should
be left open to ensure latch-up-proof operation and prevent
device damage.
S1
V+
S3
GND
2S2
C1 C2
S4
VOUT = – VIN
3
Figure 2. Idealized Switched Capacitor
Theoretical Power Efficiency
Considerations
4
In theory, a voltage multiplier can approach 100%
efficiency if certain conditions are met:
(1) The drive circuitry consumes minimal power.
(2) The output switches have extremely low ON
resistance and virtually no offset.
(3) The impedances of the pump and reservoir
capacitors are negligible at the pump frequency.
The TC660 approaches these conditions for negative
voltage multiplication if large values of C1 and C2 are used.
Energy is lost only in the transfer of charge between
capacitors if a change in voltage occurs. The energy lost
is defined by:
E = 1/2 C1 (V12 – V22)
5
6
V+
C1 +
150 µF
18
27
3 TC660 6
45
IS
V+
(+5V)
RL
IL VOUT
V1 and V2 are the voltages on C1 during the pump and
transfer cycles. If the impedances of C1 and C2 are relatively
high at the pump frequency (refer to Figure 2) compared to
the value of RL, there will be a substantial difference in
voltages V1 and V2. Therefore, it is desirable not only to
make C2 as large as possible to eliminate output voltage
ripple, but also to employ a correspondingly large value for
C1 in order to achieve maximum efficiency of operation.
7
C2
+ 150 µF
Figure 1. TC660 Test Circuit (Inverter)
8
TELCOM SEMICONDUCTOR, INC.
4-9
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet TC660.PDF ] | |
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