TC7660MJA [TELCOM]
CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER; 电荷泵DC - DC电压转换器
| 型号： | TC7660MJA |
| 厂家： | 
TELCOM SEMICONDUCTOR, INC |
| 描述： | CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER |
| 文件： | 总9页 (文件大小：130K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
4
EVALUATION
KIT
AVAILABLE
TC7660
CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
GENERAL DESCRIPTION
FEATURES
The TC7660 is a pin-compatible replacement for the
Industry standard TC7660 charge pump voltage converter.
It converts a +1.5V to +10V input to a corresponding – 1.5V
to – 10V output using only two low-cost capacitors, eliminat-
ing inductors and their associated cost, size and EMI.
The on-board oscillator operates at a nominal fre-
quency of 10kHz. Operation below 10kHz (for lower supply
current applications) is possible by connecting an external
capacitor from OSC to ground (with pin 1 open).
The TC7660 is available in both 8-pin DIP and 8-pin
SOIC packages in commercial and extended temperature
ranges.
■ Converts +5V Logic Supply to ±5V System
■ Wide Input Voltage Range .................... 1.5V to 10V
■ Efficient Voltage Conversion......................... 99.9%
■ Excellent Power Efficiency ............................... 98%
■ Low Power Supply...............................80µA @ 5VIN
■ Low Cost and Easy to Use
— Only Two External Capacitors Required
■ RS232 Negative Power Supply
■ Available in Small Outline (SO) Package
■ Improved ESD Protection ....................... Up to 3kV
■ No Dx Diode Required for High Voltage Operation
ORDERING INFORMATION
PIN CONFIGURATION (DIP and SOIC)
Temperature
Part No.
Package
Range
+
V
+
NC
8
7
6
5
NC
1
2
3
4
8
7
6
5
1
2
3
4
V
TC7660COA
TC7660CPA
TC7660EOA
TC7660EPA
TC7660IJA
TC7660MJA
TC7660EV
8-Pin SOIC
0°C to +70°C
0°C to +70°C
+
–
+
–
OSC
CAP
GND
CAP
GND
CAP
OSC
8-Pin Plastic DIP
8-Pin SOIC
LOW
VOLTAGE (LV)
LOW
VOLTAGE (LV)
TC7660COA
TC7660CPA
TC7660CPA
TC7660EPA
TC7660IJA
– 40°C to +85°C
– 40°C to +85°C
– 40°C to +85°C
– 55°C to +125°C
V
V
CAP
OUT
OUT
8-Pin Plastic DIP
8-Pin CerDIP
8-Pin CerDIP
Evaluation Kit for
NC = NO INTERNAL CONNECTION
Charge Pump Family
FUNCTIONAL BLOCK DIAGRAM
+
+
V
CAP
2
8
VOLTAGE–
7
6
RC
OSCILLATOR
4
÷ 2
–
LEVEL
OSC
LV
CAP
TRANSLATOR
5
V
OUT
INTERNAL
VOLTAGE
REGULATOR
LOGIC
NETWORK
TC7660
3
GND
TC7660-7 9/30/96
TELCOM SEMICONDUCTOR, INC.
4-51
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage ...................................................... +10.5V
LV and OSC Inputs
Operating Temperature Range
C Suffix .................................................. 0°C to +70°C
I Suffix............................................... – 25°C to +85°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
Voltage (Note 1) ........................ – 0.3V to (V+ + 0.3V)
for V+ < 5.5V
(V+ – 5.5V) to (V+ + 0.3V)
for V+ > 5.5V
Current Into LV (Note 1)..................... 20 µA 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
*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.
Exposure to absolute maximum rating conditions for extended periods
may affect device reliability.
ELECTRICAL CHARACTERISTICS: Specifications Measured Over Operating Temperature Range With,
V+ = 5V, COSC = 0, Test Circuit (Figure 1), unless otherwise indicated.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
I
V+
Supply Current
RL = ∞
Min ≤ TA ≤ Max,
RL = 10 kΩ, LV Open
—
3
80
—
180
10
µA
+
Supply Voltage Range, High
V
H
L
V+
Supply Voltage Range, Low
Output Source Resistance
Min ≤ TA ≤ Max,
RL = 10 kΩ, LV to GND
1.5
—
3.5
V
ROUT
IOUT = 20mA, TA = 25°C
—
—
70
—
100
120
Ω
Ω
IOUT = 20mA, 0°C ≤ TA ≤ +70°C
(C Device)
IOUT = 20mA, – 40°C ≤ TA ≤ +85°C
(I Device)
IOUT = 20mA, – 55°C ≤ TA ≤ +125°C
(M Device)
—
—
—
130
150
Ω
Ω
104
V+ = 2V, IOUT = 3 mA, LV to GND
0°C ≤ TA ≤ +70°C
V+ = 2V, IOUT = 3 mA, LV to GND
—
—
150
160
300
600
Ω
Ω
– 55°C ≤ TA ≤ +125°C (Note 3)
FOSC
Oscillator Frequency
Power Efficiency
Pin 7 open
RL = 5 kΩ
RL = ∞
V+ = 2V
V+ = 5V
—
95
97
10
98
—
—
—
kHz
%
PEFF
VOUT EFF
ZOSC
Voltage Conversion Efficiency
Oscillator Impedance
99.9
%
—
—
1
100
—
—
MΩ
kΩ
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 TC7660.
2. Derate linearly above 50°C by 5.5 mW/°C.
3. TC7660M only.
4. The TC7660 can be operated without the Dx diode over full temperature and voltage range.
4-52
TELCOM SEMICONDUCTOR, INC.
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 1)
Operating Voltage vs. Temperature
12
Power Conversion Eff. vs. Osc. Freq.
100
98
96
I
I
= 1 mA
10
OUT
OUT
94
92
8
6
= 15 mA
90
88
86
84
82
SUPPLY VOLTAGE RANGE
4
2
T
= +25°C
A
+
V
= +5V
80
100
0
1k
OSCILLATOR FREQUENCY (Hz)
10k
–55 –25
0
+25 +50 +75 +100 +125
TEMPERATURE (°C)
Output Source Resistance vs. Supply Voltage
Output Source Resistance vs. Temperature
10k
500
T
= +25°C
I
= 1 mA
A
OUT
450
400
1k
100Ω
10Ω
200
150
100
50
+
V
V
= +2V
= +5V
+
0
0
1
2
3
4
5
6
7
8
–55 –25
0
+25 +50 +75 +100 +125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
Unloaded Osc. Freq. vs. Temperature
Freq. of Osc. vs. Ext. Osc. Capacitance
20
10k
+
V
= +5V
T
= +25°C
A
+
V
= +5V
18
16
14
1k
100
10
12
10
8
6
–55 –25
0
+25 +50 +75 +100 +125
1
10
100
1000
10k
TEMPERATURE (°C)
OSCILLATOR CAPACITANCE (pF)
TELCOM SEMICONDUCTOR, INC.
4-53
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660
TYPICAL CHARACTERISTICS (Cont.)
Output Voltage vs. Output Current
Output Voltage vs. Load Current
0
5
4
T
= +25°C
A
–1
–2
–3
–4
–5
–6
–7
+
V
= +5V
3
2
1
0
–1
–2
–3
–4
–8
T
= +25°C
SLOPE 55Ω
A
–9
LV OPEN
–10
–5
0
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
0
10 20 30 40 50 60 70
LOAD CURRENT (mA)
80
Supply Current and Power Conversion Efficiency vs. Load Current
100
90
20
18
16
100
90
100
T
= +25°C
A
90
80
+
V
= 2V
80
80
70
60
50
14
12
10
70
60
50
70
60
50
40
30
20
10
8
6
4
2
0
40
30
20
10
40
30
20
10
0
T
= +25°C
A
+
V
= +5V
0
1.5
3.0
4.5
6.0
7.5 9.0
0
10
20
30
40
50
60
LOAD CURRENT (mA)
LOAD CURRENT (mA)
Output Voltage vs. Load Current
2
1
T
= +25°C
A
+
V
= +2V
0
–1
–2
SLOPE 150Ω
0
1
2
3
4
5
6
7
8
LOAD CURRENT (mA)
4-54
TELCOM SEMICONDUCTOR, INC.
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660
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.
I
S
1
2
3
4
8
7
6
5
+
V
(+5V)
I
L
+
C
C
*
TC7660
1
OSC
10µF
R
L
V
O
This problem is eliminated in the TC7660 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 TC7660 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.
C
10µF
2
+
NOTES: * For large values of C
(>1000pF), the values
of C and C should be increased to 100µF.
OSC
1
2
Figure 1. TC7660 Test Circuit
Detailed Description
The TC7660 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. 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.
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.
S
S
2
1
+
V
C
2
GND
S
S
4
3
V
OUT
= – V
IN
Figure 2. Idealized Charge Pump Inverter
TELCOM SEMICONDUCTOR, INC.
4-55
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660
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.
The dynamic output impedance of the TC7660 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:
The TC7660 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:
2
E = 1/2 C1 (V12 – V2 )
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 not only desirable 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.
2
XC =
= 3.18Ω,
2πf C1
where f = 10kHz and C1 = 10µF.
+
V
Dos and Don'ts
1
2
3
4
8
7
6
5
• Do not exceed maximum supply voltages.
V
*
OUT
C
+
• Do not connect 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.
1
C
10µF
2
10µF
TC7660
+
+
+
*
NOTES: 1. V
= –n V for 1.5V ≤ V ≤ 10V
OUT
• When using polarized capacitors in the inverting mode,
the + terminal of C1 must be connected to pin 2 of the
TC7660 and the + terminal of C2 must be connected to
GND Pin 3.
Figure 3. Simple Negative Converter
Simple Negative Voltage Converter
Paralleling Devices
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 +10V, keeping in mind that
pin6(LV)istiedtothesupplynegative(GND)onlyforsupply
voltages below 3.5V.
Any number of TC7660 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:
ROUT (of TC7660)
ROUT
=
n (number of devices)
4-56
TELCOM SEMICONDUCTOR, INC.
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660
+
V
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
TC7660
"1"
R
C
L
1
TC7660
"n"
C
1
C
2
+
Figure 4. Paralleling Devices Lowers Output Impedance
device latch-up, a 1kΩ resistor must be used in series with
the clock output. In a 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 TC7660 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).
Cascading Devices
The TC7660 may be cascaded as shown (Figure 6) 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 TC7660
ROUT values.
Changing the TC7660 Oscillator Frequency
Itmaybedesirableinsomeapplications(duetonoiseor
other considerations) to increase the oscillator frequency.
This is achieved by overdriving the oscillator from an exter-
nal clock, as shown in Figure 6. In order to prevent possible
+
V
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
+
TC7660
"1"
10µF
+
TC7660
"n"
10µF
V
*
OUT
10µF
+
*
1. V
NOTES:
+
+
= –n V for 1.5V ≤ V ≤ 10V
OUT
Figure 5. Increased Output Voltage by Cascading Devices
TELCOM SEMICONDUCTOR, INC.
4-57
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
TC7660
+
+
Combined Negative Voltage Conversion
and Positive Supply Multiplication
V
V
1
2
3
4
8
7
6
5
1 kΩ
CMOS
GATE
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.
+
TC7660
10µF
V
OUT
10µF
+
Figure 6. External Clocking
+
V
1
2
3
4
8
7
C
OSC
+
TC7660
6
C
1
5
V
OUT
+
V
V
=
C
OUT
2
+
+
–(V –V )
F
1
2
3
4
8
7
6
5
Figure 7. Lowering Oscillator Frequency
C
3
+
D
D
1
TC7660
+
Positive Voltage Multiplication
V
=
OUT
+
+
C
(2 V ) – (2 V )
F
The TC7660 may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 8. In
this application, the pump inverter switches of the TC7660
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 (2 V+) – (2 VF),
or twice the supply voltage minus the combined forward
voltage drops of diodes D1 and D2.
2
1
+
C
2
C
4
Figure 9. Combined Negative Converter and Positive Multiplier
Efficient Positive Voltage
Multiplication/Conversion
The source impedance of the output (VOUT) will depend
on the output current, but for V+ = 5V and an output current
of 10 mA, it will be approximately 60Ω.
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 TC7660 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
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
D
1
V
=
OUT
D
+
2
(2 V ) – (2 V )
TC7660
F
+
+
C
C
2
1
Figure 8. Positive Voltage Multiplier
4-58
TELCOM SEMICONDUCTOR, INC.
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
4
TC7660
+
V
–
V
= –V
OUT
+
R
V
50 µF
L1
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
+
50 µF
10µF
=
–
OUT
+
100 kΩ
1 MΩ
+
–
V
–V
2
1 MΩ
TC7660
+
C
1
TC7660
10µF
R
L2
–
+
–
V
INPUT
50 µF
–
V
Figure 11. Splitting a Supply in Half
Figure 10. Positive Voltage Conversion
Voltage Splitting
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).
TELCOM SEMICONDUCTOR, INC.
4-59
相关型号：
TC7660SCOAG
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