TCA7660 [MICROCHIP]
HIGH FREQUENCY 7660 DC-TO-DC VOLTAGE CONVERTER; 高频7660的DC- DC电压转换器
| 型号： | TCA7660 |
| 厂家： | 
MICROCHIP |
| 描述： | HIGH FREQUENCY 7660 DC-TO-DC VOLTAGE CONVERTER |
| 文件： | 总8页 (文件大小：78K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION
KIT
AVAILABLE
TC7660H
HIGH FREQUENCY 7660 DC-TO-DC VOLTAGE CONVERTER
GENERAL DESCRIPTION
FEATURES
The TC7660H is a pin-compatible, high frequency up-
grade to the Industry standard TC7660 charge pump volt-
age converter. It converts a +1.5V to +10V input to a
corresponding – 1.5V to – 10V output using only two low-
cost capacitors, eliminating inductors and their associated
cost, size and EMI.
The TC7660H operates at a frequency of 120kHz
(versus 10kHz for the TC7660), allowing the use of 1.0µF
external capacitors. Oscillator frequency can be reduced
(for lower supply current applications) by connecting an
external capacitor from OSC to ground.
■ Pin Compatible with 7660, High Frequency
Performance DC-to-DC Converter
■ Low Cost, Two Low Value External Capacitors
Required ........................................................ (1.0µF)
■ Converts +5V Logic Supply to ±5V System
■ Wide Input Voltage Range ....................1.5V to 10V
■ Voltage Conversion ........................................ 99.7%
■ Power Efficiency ................................................ 85%
■ Available in 8-Pin SOIC and 8-Pin PDIP Packages
The TC7660H is available in 8-pin DIP and small
outline (SOIC) packages in commercial and extended
temperature ranges.
PIN CONFIGURATION (DIP and SOIC)
+
NC
8
1
2
3
4
V
+
ORDERING INFORMATION
CAP
OSC
7
6
5
TC7660HCPA
TC7660HEPA
Temperature
LOW
VOLTAGE (LV)
V
GND
CAP
Part No.
Package
Range
–
OUT
TC7660HCOA
TC7660HCPA
TC7660HEOA
TC7660HEPA
TC7660EV
8-Pin SOIC
0°C to +70°C
0°C to +70°C
8-Pin Plastic DIP
8-Pin SOIC
+
V
NC
1
2
3
4
8
7
6
5
– 40°C to +85°C
– 40°C to +85°C
OSC
+
8-Pin Plastic DIP
CAP
LOW
VOLTAGE (LV)
V
TC7660HCOA
TC7660HEOA
Evaluation Kit for
Charge Pump Family
GND
–
CAP
OUT
NC = NO INTERNAL CONNECTION
FUNCTIONAL BLOCK DIAGRAM
+
+
V
CAP
2
8
VOLTAGE–
LEVEL
TRANSLATOR
7
RC
OSCILLATOR
4
÷ 2
–
OSC
CAP
6
LV
5
V
OUT
INTERNAL
VOLTAGE
REGULATOR
LOGIC
NETWORK
TC7660H
3
GND
TC7660H-2 10/1/96
© 2001 Microchip Technology Inc. DS21466A
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H
Operating Temperature Range
ABSOLUTE MAXIMUM RATINGS*
C Suffix .................................................. 0°C to +70°C
E Suffix ............................................– 40°C to +85°C
Storage Temperature Range ............... – 65°C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
Supply Voltage ...................................................... +10.5V
LV and OSC Inputs
Voltage (Note 1) ........................ – 0.3V 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.
(V+ – 5.5V) to (V+ + 0.3V)
for V+ > 5.5V
Current Into LV (Note 1) ..................... 20µA for V+ > 3.5V
Output Short Duration (VSUPPLY ≤ 5.5V) .........Continuous
Power Dissipation (TA ≤ 70°C) (Note 2)
SOIC ...............................................................470mW
Plastic DIP ......................................................730mW
ELECTRICAL CHARACTERISTICS: Over Operating Temperature Range with V+= 5V, CI = C2 = 1µF, COSC = 0,
Test Circuit (Figure 1), unless otherwise indicated.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
I+
VH+
Supply Current
RL = ∞
Min ≤ TA ≤ Max,
—
3
0.46
—
1.0
10
mA
V
Supply Voltage Range, High
RL = 5kΩ, LV Open
VL+
Supply Voltage Range, Low
Output Source Resistance
Min ≤ TA ≤ Max,
RL = 5kΩ, LV to GND
1.5
—
3.5
V
ROUT
IOUT = 20mA, TA = 25°C
—
—
55
—
80
95
Ω
Ω
IOUT = 20mA, 0°C ≤ TA ≤ +70°C
(C Device)
I
OUT = 20mA, – 40°C ≤ TA ≤ +85°C
—
—
—
110
250
Ω
Ω
(E Device)
V+ = 2V, IOUT = 3mA, LV to GND
150
0°C ≤ TA ≤ +70°C
FOSC
PEFF
VEFF
Oscillator Frequency
Power Efficiency
—
81
99
120
85
—
—
—
kHz
%
IOUT = 10mA, Min ≤ TA ≤ Max
RL = ∞
Voltage Efficiency
99.7
%
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 TC7660H.
2. Derate linearly above 50°C by 5.5mW/°C.
TC7660H-2 10/1/96
© 2001 Microchip Technology Inc. DS21466A
2
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H
To improve low-voltage operation, the LV pin should be
connected to GND. For supply voltages greater than 3.5V,
the LV terminal must be left open to ensure latch-up-
proof operation and prevent device damage.
I
S
1
2
3
4
8
7
6
5
+
V
(+5V)
Theoretical Power Efficiency Considerations
In theory, a capacitative charge pump can approach
100% efficiency if certain conditions are met:
+
C
TC7660H
1
1.0 µF
(1) The drive circuitry consumes minimal power.
(2) The output switches have extremely low ON
resistance and virtually no offset.
C
1.0 µF
2
(3) The impedances of the pump and reservoir
capacitors are negligible at the pump frequency.
R
L
+
The TC7660H 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:
Figure 1. TC7660H Test Circuit
Detailed Description
2
E = 1/2 C1 (V12 – V2 )
The TC7660H contains all the necessary circuitry to
implement a voltage inverter, with the exception of two
external capacitors, which may be inexpensive 1.0µF
non-polarized 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.
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 1), 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.
Do's and Don'ts
• Do not exceed maximum supply voltages.
• Do not connect LV terminal to GND for supply voltages
greater than 3.5V.
S
S
2
1
+
• 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.
V
• When using polarized capacitors in the inverting mode,
the + terminal of C1 must be connected to pin 2 of the
TC7660H and the + terminal of C2 must be connected
to GND Pin 3.
C
2
GND
S
S
4
3
V
OUT
= – V
IN
Figure 2. Idealized Charge Pump Inverter
© 2001 Microchip Technology Inc. DS21466A
TC7660H-2 10/1/96
3
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H
+
Simple Negative Voltage Converter
V
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.
1
2
3
4
8
7
6
5
V
*
OUT
C
+
1
C
2
1.0 µF
TC7660H
1.0 µF
+
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 – 10 mA and a supply voltage of
+5V, the output voltage would be – 4.3V.
+
+
*
NOTES: 1. V
OUT
= –n V for 1.5V
V
10V
Figure 3. Simple Negative Converter
The dynamic output impedance of the TC7660H 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:
Paralleling Devices
Any number of TC7660H 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:
2
XC =
= 2.12Ω,
2πf C1
where f = 150kHz and C1 = 1.0µF.
R
OUT (of TC7660H)
ROUT
=
n (number of devices)
+
V
1
8
7
6
5
2
1
2
3
4
8
7
6
5
+
TC7660H
"1"
3
4
1.0 µF
+
TC7660H
"n"
1.0 µF
V
*
OUT
1.0 µF
+
*
1. V
NOTES:
+
+
= –n V for 1.5V
V
10V
OUT
Figure 4. Increased Output Voltage by Cascading Devices
Cascading Devices
Changing the TC7660H Oscillator Frequency
The TC7660H may be cascaded as shown in (Figure 4)
to produce larger negative multiplication of the initial supply
voltage. However, due to the finite efficiency of each device,
the practical limit is probably 10 devices for light loads. The
output voltage is defined by:
Itmaybedesirableinsomeapplications(duetonoiseor
other considerations) to increase or decease the oscillator
frequency. This can be achieved by overdriving the oscilla-
tor from 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 situation where the
designer has generated the external clock frequency using
TTLlogic, theadditionofa10kΩ pull-upresistortoV+ 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.
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 TC7660H
ROUT values.
TC7660H-2 10/1/96
© 2001 Microchip Technology Inc. DS21466A
4
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H
+
V
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
TC7660H
"1"
R
C
L
1
TC7660H
"n"
C
1
R
L
C
2
+
Figure 5. Paralleling Devices Lowers Output Impedance
Combined Negative Voltage Conversion
and Positive Supply Multiplication
+
+
V
V
1
2
3
4
8
7
1 kΩ
Figure 8 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.
CMOS
GATE
+
6
5
1.0 µF
TC7660H
V
OUT
1.0 µF
+
Figure 6. External Clocking
Positive Voltage Multiplication
The TC7660H may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 7. In
this application, the pump inverter switches of the TC7660H
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.
+
V
V
=
OUT
+
–(V –V )
F
1
2
3
4
8
7
6
5
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.
C
3
+
D
D
1
TC7660H
+
V
=
OUT
+
+
C
(2 V ) – (2 V )
+
F
V
2
1
+
1
2
3
4
8
7
6
5
C
2
C
4
D
1
V
=
OUT
D
+
2
(2 V ) – (2 V )
TC7660H
F
+
+
C
C
2
1
Figure 8. Combined Negative Converter and Positive Multiplier
Figure 7. Positive Voltage Multiplier
© 2001 Microchip Technology Inc. DS21466A
TC7660H-2 10/1/96
5
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H
Efficient Positive Voltage Multiplication/
Conversion
–
V
= –V
OUT
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 9 shows a
TC7660H 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 diode and resistor shown dotted in
Figure 9.
1
2
3
4
8
7
6
5
+
1.0 µF
1 MΩ
+
C
1
TC7660H
1.0 µF
–
V
INPUT
Figure 9. Positive Voltage Conversion
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 1)
Output Source Resistance vs. Supply Voltage
Output Source Resistance vs. Temperature
500
10k
T
= +25°C
I
= 1 mA
A
OUT
450
400
1k
100Ω
10Ω
200
150
100
50
+
V
V
= +2V
= +5V
+
0
–55 –25
0
+25 +50 +75 +100 +125
0
1
2
3
4
5
6
7
8
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
Output Voltage vs. Output Current
C C =1µF
Output Voltage vs. Load Current
I
2
5
4
0
–1
–2
–3
–4
–5
–6
–7
T
= +25°C
A
+
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
LOAD CURRENT (mA)
80
0
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
TC7660H-2 10/1/96
© 2001 Microchip Technology Inc. DS21466A
6
HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER
TC7660H
PACKAGE DIMENSIONS
8-Pin Plastic DIP
PIN 1
.260 (6.60)
.240 (6.10)
.045 (1.14)
.030 (0.76)
.070 (1.78)
.040 (1.02)
.310 (7.87)
.290 (7.37)
.400 (10.16)
.348 (8.84)
.200 (5.08)
.140 (3.56)
.040 (1.02)
.020 (0.51)
.015 (0.38)
.008 (0.20)
3° MIN.
.150 (3.81)
.115 (2.92)
.400 (10.16)
.310 (7.87)
.110 (2.79)
.090 (2.29)
.022 (0.56)
.015 (0.38)
8-Pin SOIC
.157 (3.99)
.150 (3.81)
.244 (6.20)
.228 (5.79)
.050 (1.27) TYP.
.197 (5.00)
.189 (4.80)
.069 (1.75)
.053 (1.35)
.010 (0.25)
.007 (0.18)
8° MAX.
.020 (0.51)
.013 (0.33)
.010 (0.25)
.004 (0.10)
.050 (1.27)
.016 (0.40)
Dimensions: inches (mm)
© 2001 Microchip Technology Inc. DS21466A
TC7660H-2 10/1/96
7
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01/09/01
All rights reserved.
©
2001 Microchip Technology Incorporated. Printed in the USA. 1/01
Printed on recycled paper.
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TC7660H-2 10/1/96
© 2001 Microchip Technology Inc. DS21466A
8
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