TC7660SCOA [TELCOM]
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER; SUPER充电泵DC- TO- DC电压转换器
| 型号： | TC7660SCOA |
| 厂家： | 
TELCOM SEMICONDUCTOR, INC |
| 描述： | SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| 文件： | 总8页 (文件大小：138K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
4
EVALUATION
KIT
AVAILABLE
TC7660S
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
FEATURES
GENERAL DESCRIPTION
■ Oscillator boost from 10kHz to 45kHz
■ Converts +5V Logic Supply to ±5V System
■ Wide Input Voltage Range .................... 1.5V to 12V
■ Efficient Voltage Conversion......................... 99.9%
■ Excellent Power Efficiency ............................... 98%
■ Low Power Supply..............................80µA @ 5 VIN
■ Low Cost and Easy to Use
— Only Two External Capacitors Required
■ Available in Small Outline (SOIC) Package
■ Improved ESD Protection ..................... Up to 10kV
■ No External Diode Required for High Voltage
Operation
The TC7660S 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, eliminating
inductors and their associated cost, size and EMI. Added
features include an extended supply range to 12V, and a
frequencyboostpinforhigheroperatingfrequency, allowing
the use of smaller external capacitors.
Theon-boardoscillatoroperatesatanominalfrequency
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 TC7660S is available in both 8-pin DIP and 8-pin
small outline (SOIC) packages in commercial and extended
temperature ranges.
ORDERING INFORMATION
Temperature
Part No.
Package
Range
TC7660SCOA
TC7660SCPA
TC7660SEJA
TC7660SEOA
TC7660SEPA
TC7660SMJA
TC7660EV
8-Pin SOIC
0°C to +70°C
0°C to +70°C
PIN CONFIGURATION (DIP and SOIC)
8-Pin Plastic DIP
8-Pin CerDIP
8-Pin SOIC
– 40°C to +85°C
– 40°C to +85°C
– 40°C to +85°C
– 55°C to +125°C
+
V
+
Boost
8
7
6
5
Boost
1
2
3
4
8
7
6
5
1
2
3
4
V
+
+
OSC
CAP
CAP
OSC
LOW
VOLTAGE (LV)
8-Pin Plastic DIP
8-Pin CerDIP
Evaluation Kit for
LOW
VOLTAGE (LV)
GND
TC7660SCPA
TC7660SEJA
TC7660SEPA
GND
TC7660SCOA
TC7660SEOA
–
CAP
–
V
CAP
V
OUT
OUT
Charge Pump Family
FUNCTIONAL BLOCK DIAGRAM
+
+
V
CAP
2
8
1
BOOST
VOLTAGE–
LEVEL
TRANSLATOR
7
6
RC
4
÷ 2
–
OSC
LV
CAP
V
OSCILLATOR
5
OUT
INTERNAL
VOLTAGE
REGULATOR
LOGIC
NETWORK
TC7660S
3
GND
TC7660S-14 9/16/96
TELCOM SEMICONDUCTOR, INC.
4-69
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660S
Operating Temperature Range
ABSOLUTE MAXIMUM RATINGS*
C Suffix .................................................. 0°C to +70°C
E Suffix ............................................. – 40°C to +85°C
M Suffix........................................... – 55°C to +125°C
Storage Temperature Range ................ – 65°C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
Supply Voltage ......................................................... +13V
LV, Boost, OSC Inputs
Voltage (Note 1) ......................... – 0.3V to (V+ +0.3V)
for V+ <5.5V
(V+ – 5.5V) to (V+ +0.3V)
for V+ >5.5V
*Static-sensitive device. Unused devices must be stored in conductive
material. Protect devices from static discharge and static fields. Stresses
above those listed under "Absolute Maximum Ratings" may cause perma-
nent damage to the device. These are stress ratings only and functional
operation of the device at these or any other conditions above those
indicated in the operation sections of the specifications is not implied.
Exposuretoabsolutemaximumratingconditionsforextendedperiodsmay
affect device reliability.
Current Into LV (Note 1) ....................... 20µA for V+ >3.5V
Output Short Duration (VSUPPLY ≤ 5.5V) ......... Continuous
Power Dissipation (TA ≤ 70°C) (Note 2)
CerDIP ............................................................800mW
Plastic DIP ......................................................730mW
SOIC ...............................................................470mW
ELECTRICAL CHARACTERISTICS: TA = +25°C, V+ = 5V, COSC = 0, Test Circuit (Figure 1), unless otherwise
indicated.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
I+
Supply Current
(Boost pin OPEN or GND)
RL = ∞
—
—
—
—
80
—
—
—
160
180
180
200
µA
0°C ≤ TA ≤ +70°C
– 40°C ≤ TA ≤ +85°C
– 55°C ≤ TA ≤ +125°C
I+
Supply Current
(Boost pin = V+)
0°C ≤ TA ≤ +70°C
– 40°C ≤ TA ≤ +85°C
– 55°C ≤ TA ≤ +125°C
—
—
—
—
—
—
300
350
400
µA
+
VH
Supply Voltage Range, High
Supply Voltage Range, Low
Output Source Resistance
Min ≤ TA ≤ Max,
RL = 10 kΩ, LV Open
3
—
12
V
V
Ω
V+L
Min ≤ TA ≤ Max,
RL = 10 kΩ, LV to GND
1.5
—
3.5
ROUT
IOUT = 20mA
—
—
—
—
60
70
100
120
120
150
IOUT = 20mA, 0°C ≤ TA ≤ +70°C
I
OUT = 20mA, – 40°C ≤ TA ≤ +85°C
70
IOUT = 20mA, – 55°C ≤ TA ≤ +125°C
105
V+ = 2V, IOUT = 3 mA, LV to GND
0°C ≤ TA ≤ +70°C
—
—
—
—
250
400
Ω
– 55°C ≤ TA ≤ +125°C
FOSC
PEFF
Oscillator Frequency
Power Efficiency
Pin 7 open; Pin 1 open or GND
Boost Pin = V+
—
—
10
45
—
—
kHz
%
RL = 5 kΩ; Boost Pin Open
96
95
—
98
98
88
—
—
—
T
MIN ≤ TA ≤ TMAX; Boost Pin Open
Boost Pin = V+
VOUT EFF
ZOSC
Voltage Conversion Efficiency
Oscillator Impedance
RL = ∞
99
99.9
—
%
V+ = 2V
—
—
1
100
—
—
MΩ
kΩ
V+ = 5V
NOTES: 1. Connecting any input terminal to voltages greater than V+ or less than GND may cause destructive latch-up. It is recommended that no
inputs from sources operating from external supplies be applied prior to "power up" of the TC7660S.
2. Derate linearly above 50°C by 5.5mW/°C.
4-70
TELCOM SEMICONDUCTOR, INC.
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660S
Detailed Description
S
S
1
2
+
V
The TC7660S contains all the necessary circuitry to
implement a voltage inverter, with the exception of two
external capacitors, which may be inexpensive 10 µF 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 andS4 areopenduringthishalfcycle.)Duringthesecond
half cycle of operation, switches S2 and S4 are closed, with
S1 and S3 open, thereby shifting capacitor C1 negatively by
V+ volts.ChargeisthentransferredfromC1 negativelybyV+
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.
C
1
C
2
GND
S
S
3
4
V
= – V
OUT
IN
Figure 2. Idealized Charge Pump Inverter
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
accomplishthiswillresultinhighpowerlossesandprobable
device latch-up.
This problem is eliminated in the TC7660S 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.
The voltage regulator portion of the TC7660S is an
integral part of the anti-latch-up circuitry. Its inherent voltage
drop can, however, degrade operation at low voltages. To
improve low-voltage operation, the “LV” pin should be
connected to GND, disabling the regulator. For supply
voltages greater than 3.5V, the LV terminal must be left
open to ensure latch-up-proof operation and prevent device
damage.
Theoretical Power Efficiency
Considerations
In theory, a capacitive charge pump 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.
+
V
I
S
1
2
3
4
8
7
6
5
+
The TC7660S approaches these conditions for nega-
tive 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:
V
(+5V)
I
L
+
C
C
*
TC7660S
1
OSC
10µF
R
L
2
E = 1/2 C1 (V12 – V2 )
V
O
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.
C
10µF
2
+
NOTE: For large values of COSC (>1000pF), the values
of C1 and C2 should be increased to 100µF.
Figure 1. TC7660S Test Circuit
TELCOM SEMICONDUCTOR, INC.
4-71
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660S
The output characteristics of the circuit in Figure 3 are
those of a nearly ideal voltage source in series with 70Ω.
Thus, for a load current of –10mA and a supply voltage of
+5V, the output voltage would be –4.3V.
Dos and Don'ts
• Do not exceed maximum supply voltages.
• Do not connect the LV terminal to GND for supply
voltages greater than 3.5V.
• Do not short circuit the output to V+ supply for voltages
above 5.5V for extended periods; however, transient
conditions including start-up are okay.
The dynamic output impedance of the TC7660S is due,
primarily, to capacitive reactance of the charge transfer
capacitor (C1). Since this capacitor is connected to the
output for only 1/2 of the cycle, the equation is:
2
XC =
= 3.18Ω,
• When using polarized capacitors in the inverting mode,
the + terminal of C1 must be connected to pin 2 of the
TC7660S and the + terminal of C2 must be connected
to GND.
2πf C1
where f = 10kHz and C1 = 10µF.
Paralleling Devices
Simple Negative Voltage Converter
Any number of TC7660S voltage converters may be
paralleled to reduce output resistance (Figure 4). The reser-
voir capacitor, C2, serves all devices, while each device
requires its own pump capacitor, C1. The resultant output
resistance would be approximately:
Figure 3 shows typical connections to provide a nega-
tive supply where a positive supply is available. A similar
scheme may be employed for supply voltages anywhere in
the operating range of +1.5V to +12V, keeping in mind that
pin6(LV)istiedtothesupplynegative(GND)onlyforsupply
voltages below 3.5V.
ROUT (of TC7660S)
ROUT
=
n (number of devices)
+
V
1
2
3
4
8
7
6
5
V
*
OUT
C
+
1
C
2
10µF
TC7660S
10µF
+
*NOTES:
Figure 3. Simple Negative Converter
+
V
1
2
3
4
8
7
6
5
1
2
3
4
8
7
TC7660S
"1"
R
L
C
1
TC7660S
"n"
C
6
5
1
C
2
+
Figure 4. Paralleling Devices Lowers Output Impedance
4-72
TELCOM SEMICONDUCTOR, INC.
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660S
+
V
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
+
TC7660S
"1"
10µF
+
TC7660S
"n"
10µF
V
*
OUT
10µF
+
*
NOTES:
1. VOUT = –n(V+) for 1.5V ≤ V+ ≤ 12V
10µF
+
Figure 5. Increased Output Voltage by Cascading Devices
Cascading Devices
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.
The TC7660S 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:
It is also possible to increase the conversion efficiency
of the TC7660S at low load levels by lowering the oscillator
frequency.Thisreducestheswitchinglosses,andisachieved
by connecting an additional capacitor, COSC, as shown in
Figure 7. Lowering the oscillator frequency will cause an
undesirableincreaseintheimpedanceofthepump(C1)and
thereservoir(C2)capacitors.Toovercomethis,increasethe
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).
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 TC7660S
ROUT values.
Changing the TC7660S Oscillator Frequency
Itmaybedesirableinsomeapplications(duetonoiseor
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
Figure6. Inordertopreventpossibledevicelatch-up, a1kΩ
resistor must be used in series with the clock output. In a
Positive Voltage Multiplication
The TC7660S may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 8. In
this application, the pump inverter switches of the TC7660S
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.
+
+
V
V
1
2
3
4
8
7
6
5
1 kΩ
CMOS
GATE
+
TC7660S
10µF
V
OUT
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.
10µF
+
Figure 6. External Clocking
TELCOM SEMICONDUCTOR, INC.
4-73
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660S
will bypass the other (D1 and D2 in Figure 9 would never turn
on), or else the diode and resistor shown dotted in Figure 10
can be used to "force" the internal regulator on.
+
V
1
2
3
4
8
7
6
5
C
OSC
Voltage Splitting
+
TC7660S
C
1
ThesamebidirectionalcharacteristicsusedinFigure10
can also be used to split a higher supply in half, as shown in
Figure 11. The combined load will be evenly shared be-
tween the two sides. Once again, a high value resistor to the
LV pin ensures start-up. Because the switches share the
load in parallel, the output impedance is much lower than in
thestandardcircuits, andhighercurrentscanbedrawnfrom
thedevice. Byusingthiscircuit, andthenthecircuitofFigure
5,+15Vcanbeconverted(via+7.5Vand–7.5V)toanominal
–15V, though with rather high series resistance (~250Ω).
V
OUT
C
2
+
Figure 7. Lowering Oscillator Frequency
Combined Negative Voltage Conversion
and Positive Supply Multiplication
Figure 9 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
and C4 are pump and reservoir, respectively, for the multi-
pliedpositivevoltage. Thereisapenaltyinthisconfiguration
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
+
V
= –V
OUT
1
2
3
4
8
7
6
5
C
3
+
D
D
1
TC7660S
+
V
=
OUT
+
+
C
(2 V ) – (2 V )
F
2
1
+
C
2
C
4
Efficient Positive Voltage
Multiplication/Conversion
Figure 9. Combined Negative Converter and Positive Multiplier
Since the switches that allow the charge pumping op-
eration are bidirectional, the charge transfer can be per-
formed backwards as easily as forwards. Figure 10 shows
a TC7660S transforming –5V to +5V (or +5V to +10V, etc.).
The only problem here is that the internal clock and switch-
drive section will not operate until some positive voltage has
been generated. An initial inefficient pump, as shown in
Figure 9, could be used to start this circuit up, after which it
Negative Voltage Generation for
Display ADCs
The TC7106 is designed to work from a 9V battery. With
a fixed power supply system, the TC7106 will perform
conversions with input signal referenced to power supply
ground.
+
V
Negative Supply Generation for
4¹⁄₂ Digit Data Acquisition System
1
2
3
4
8
7
6
5
The TC7135 is a 4¹⁄₂ digit ADC operating from ±5V
supplies.TheTC7660Sprovidesaninexpensive–5Vsource.
(See AN16 and AN17 for TC7135 interface details and
software routines.)
D
1
V
=
OUT
D
+
2
(2 V ) – (2 V )
TC7660S
F
+
+
C
C
2
1
Figure 8. Positive Voltage Multiplier
4-74
TELCOM SEMICONDUCTOR, INC.
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660S
+
V
–
V
= –V
OUT
+
50µF
R
L1
1
2
3
4
8
1
2
3
4
8
7
6
5
7
+
50µF
V
=
–
OUT
100 kΩ
1 MΩ
10µF
+
–
+
V
–V
2
TC7660S
6
1 MΩ
+
C
1
TC7660S
5
R
10µF
L2
+
–
–
50µF
V
INPUT
–
V
Figure 10. Positive Voltage Multiplier
Figure 11. Splitting a Supply in Half
TYPICAL CHARACTERISTICS
Unloaded Osc Freq vs. Temperature
Unloaded Osc Freq vs. Temperature
with Boost Pin = V
IN
12
10
8
60
50
40
30
20
10
0
VIN = 5V
VIN = 12V
VIN = 5V
6
4
VIN = 12V
2
0
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Voltage Conversion
Supply Current vs. Temperature
(with Boost Pin = V )
IN
1000
800
600
400
200
0
101.0
100.5
100.0
99.5
Without Load
10K Load
VIN = 12V
99.0
98.5
VIN = 5V
80
TA = 25°C
98.0
-40
-20
0
20
40
60
100
1
2
3
4
5
6
7
8
9
10 11 12
TEMPERATURE (°C)
INPUT VOLTAGE VIN (V)
TELCOM SEMICONDUCTOR, INC.
4-75
SUPER CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660S
TYPICAL CHARACTERISTICS (Cont.)
Output Source Resistance vs. Supply Voltage
Output Source Resistance vs. Temperature
100
100
70
50
VIN = 2.5V
80
60
40
20
0
VIN = 5.5V
30
IOUT = 20mA
TA = 25°C
10
1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10.511.5 12
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
Power Conversion Efficiency vs. Load
Output Voltage vs. Output Current
100
90
80
70
60
50
40
30
20
10
0
0
Boost Pin = Open
-2
-4
+
Boost Pin = V
-6
-8
-10
-12
0
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
LOAD CURRENT (mA)
Supply Current vs. Temperature
200
175
150
125
100
75
VIN = 12.5V
VIN = 5.5V
50
25
0
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
4-76
TELCOM SEMICONDUCTOR, INC.
相关型号：
TC7660SCOAG
SWITCHED CAPACITOR REGULATOR, 45 kHz SWITCHING FREQ-MAX, PDSO8, PLASTIC, SOIC-8
MICROCHIP
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