TCM680EPA [TELCOM]
+5V TO 【10V VOLTAGE CONVERTER; + 5V至± 10V电压转换器
| 型号： | TCM680EPA |
| 厂家： | 
TELCOM SEMICONDUCTOR, INC |
| 描述： | +5V TO 【10V VOLTAGE CONVERTER |
| 文件： | 总7页 (文件大小：98K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
4
EVALUATION
KIT
AVAILABLE
TCM680
+5V TO ±10V VOLTAGE CONVERTER
FEATURES
GENERAL DESCRIPTION
■ 99% Voltage Conversion Efficiency
■ 85% Power Conversion Efficiency
■ Wide Voltage Range .........................+2.0V to +5.5V
■ Only 4 External Capacitors Required
■ Space Saving 8-Pin SOIC Design
The TCM680 is a dual charge pump voltage converter
that develops output voltages of +2VIN and – 2VIN from a
single input voltage of +2.0V to +5.5V. Common applica-
tions include ±10V from a single +5V logic supply, and ±6V
from a +3V lithium battery.
The TCM680 is packaged in a space-saving 8-pin
SOIC package and requires only four inexpensive external
capacitors. The charge pumps are clocked by an on-board
8kHz oscillator. Low output source impedances (typically
150Ω) provides maximum output currents of 10mA for each
output. Typical power conversion efficiency is 85%.
High efficiency, small installed size and low cost make
the TCM680 suitable for a wide variety of applications that
need both positive and negative power supplies derived
from a single input voltage.
APPLICATIONS
■ ±10V From +5V Logic Supply
■ ±6V From a 3V Lithium Cell
■ Handheld Instruments
■ Portable Cellular Phones
■ LCD Display Bias Generator
■ Panel Meters
■ Operational Amplifier Power Supplies
PIN CONFIGURATIONS (DIP AND SOIC)
ORDERING INFORMATION
+
–
8
7
6
5
VOUT
C1
1
2
3
4
Part No.
Package
Temperature
+
+
C1
C2
TCM680COA 8-Pin SOIC
8-Pin Plastic DIP
TCM680EOA 8-Pin SOIC
0°C to +70°C
0°C to +70°C
– 40°C to +85°C
– 40°C to +85°C
TCM680CPA
TCM680EPA
TCM680CPA
–
VIN
C2
–
VOUT
TCM680EPA
8-Pin Plastic DIP
Charge Pump Family
Evaluation Kit
GND
TC7660EV
+
–
C1
VOUT
1
2
3
4
8
7
+
+
C1
C2
TCM680COA
TCM680EOA
–
6
5
VIN
C2
–
GND
VOUT
TYPICAL OPERATING CIRCUIT
2.0V<VIN < +5.5V
+5V
+
VIN
4.7µF
C4
C1
+
+
+
C1
+
VOUT
VOUT = (2xVIN
)
4.7µF
–
C1
+
TCM680
C2
+
C2
–
–
VOUT = (– 2 x VIN
VOUT
)
4.7µF
–
C2
4.7µF
C3
GND
+
GND
GND
TC660-2 9/4/96
TELCOM SEMICONDUCTOR, INC.
4-13
+5V TO ±10V VOLTAGE CONVERTER
TCM680
ABSOLUTE MAXIMUM RATINGS*
Power Dissipation (TA ≤ 70°C)
Plastic DIP ......................................................730mW
Small Outline ..................................................470mW
Storage Temperature ............................ – 65°C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
VIN ..................................................................................................... +6.0V
V+OUT .............................................................................................. +12.0V
VO–UT ............................................................................................. – 12.0V
VO–UT Short-Circuit Duration ............................ Continuous
V+OUT Current ............................................................75mA
VIN dV/dT.............................................................. 1V/µsec
*Stresses above those listed in "Absolute Maximum Ratings" may cause
permanent damage to the device. These are stress ratings only and
functional operation of the device at these or other conditions above those
indicated in the operation section of the specification is not implied.
Exposure to the Absolute Maximum Ratings conditions for extended
periods of time may affect device reliability.
ELECTRICAL CHARACTERISTICS: VIN = +5V, TA = +25°C, test circuit Figure 1, unless otherwise indicated.
Symbol Parameter
Test Conditions
Min
Typ
Max
Unit
Supply Voltage Range
MIN. ≤ TA ≤ MAX., RL = 2kΩ
2.0 1.5 to 5.5 5.5
V
Supply Current
VIN = 3V, RL = ∞
VIN = 5V, RL = ∞
—
—
—
—
0.5
1
—
—
1
2
2.5
3
mA
VIN = 5V, 0°C ≤ TA ≤ +70°C, RL = ∞
VIN = 5V, – 40°C ≤ TA ≤ +85°C, RL = ∞
Negative Charge Pump Output
Source Resistance
IL– = 10mA, IL+ = 0mA, VIN = 5V
IL–= 5mA, IL+ = 0mA, VIN = 2.8V
IL–= 10mA, IL+ = 0mA, VIN = 5V:
0°C ≤ TA ≤ +70°C
—
—
140
180
180
250
Ω
Ω
—
—
—
—
220
250
– 40°C ≤ TA ≤ +85°C
Positive Charge Pump Output
Source Resistance
IL+ = 10mA, IL– = 0mA, VIN = 5V
IL+ = 5mA, IL– = 0mA, VIN = 2.8V
IL+ = 10mA, IL– = 0mA, VIN = 5V:
0°C ≤ TA ≤ +70°C
—
—
140
180
180
250
—
—
—
—
220
250
– 40°C ≤ TA ≤ +85°C
FOSC
PEFF
Oscillator Frequency
Power Efficiency
—
—
21
85
—
—
kHz
%
RL = 2kΩ
VOUT EFF Voltage Conversion Efficiency
V+OUT, RL = ∞
97
97
99
99
—
—
%
VO–UT, RL = ∞
TelCom Semiconductor reserves the right to make changes in the circuitry or specifications detailed in this manual at any time without notice. Minimums
and maximums are guaranteed. All other specifications are intended as guidelines only. TelCom Semiconductor assumes no responsibility for the use of
any circuits described herein and makes no representations that they are free from patent infringement.
PIN DESCRIPTION
VIN
8-Pin
DIP/SOIC Symbol Description
4.7µF
4.7µF
C1
+
+
OUT
8
7
1
2
C1–
Input. Capacitor C1 negative terminal.
Input. Capacitor C2 positive terminal.
Input. Capacitor C2 negative terminal.
Output. Negative output voltage (–2VIN).
Input. Device ground.
–
V
V
OUT
C1
1
2
3
4
5
6
7
8
C2+
+
+
C1
C2
C4
10µF
C2–
C2
+
RL
TCM680
6
5
3
4
–
VO–UT
GND
VIN
VIN
C2
–
V
GND
GND
OUT
Input. Power supply voltage.
C1+
V+OUT
Input. Capacitor C1 positive terminal.
Output. Positive output voltage (+2VIN)
C3
10µF
–
RL
–
OUT
V
Figure 1. Test Circuit
4-14
TELCOM SEMICONDUCTOR, INC.
+5V TO ±10V VOLTAGE CONVERTER
4
TCM680
DETAILED DESCRIPTION
Phase 1
VIN = +5V
–
C
4
+
VDD
VSS
SW1
SW3
VSS charge storage – The positive side of capacitors C1
and C2 are connected to +5V at the start of this phase. C1+ is
then switched to ground and the charge in C1– is transferred
to C2–. Since C2+ is connected to +5V, the voltage potential
across capacitor C2 is now 10V.
+
–
+
–
C
1
C
2
–
C
3
SW2
+
SW4
–5V
VIN = +5V
–
Figure 4. Charge Pump – Phase 3
C
4
Phase 4
+
VDD
SW1
SW3
VDD transfer – The fourth phase of the clock connects
the negative terminal of C2 to ground, and transfers the
generated 10V across C2 to C4, the VDD storage capacitor.
Again, simultaneously with this, the positive side of capaci-
tor C1 is switched to +5V and the negative side is connected
to ground, and the cycle begins again.
VSS
+
–
+
–
C
1
C
2
–
+
C
3
SW2
SW4
–5V
Figure 2. Charge Pump – Phase 1
+5V
–
Phase 2
C
4
+
VDD
VSS
SW1
SW3
VSS transfer – Phase two of the clock connects the
negative terminal of C2 to the VSS storage capacitor C3 and
the positive terminal of C2 to ground, transferring the gener-
ated–10VtoC3. Simultaneously, thepositivesideofcapaci-
tor C1 is switched to +5V and the negative side is connected
to ground.
+
–
+
–
C
C
1
2
–
+
C
3
SW2 SW4
–10V
+5V
–
Figure 5. Charge Pump – Phase 4
C
4
+
VDD
MAXIMUM OPERATING LIMITS
SW1
SW3
VSS
+
–
+
–
The TCM680 has on-chip zener diodes that clamp VIN
to 5.8V, V+OUT to 11.6V, and VO– UT to –11.6V. Never exceed
the maximum supply voltage or excessive current will be
shuntedbythesediodes, potentiallydamagingthechip. The
TCM680 will operate over the entire operating temperature
range with an input voltage of 2V to 5.5V.
C
1
C
2
–
+
C
3
SW2
SW4
–10V
Figure 3. Charge Pump – Phase 2
Phase 3
VDD charge storage – The third phase of the clock is
identical to the first phase – the charge transferred in C1
produces–5VinthenegativeterminalofC1,whichisapplied
to the negative side of capacitor C2. Since C2+ is at +5V, the
voltage potential across C2 is 10V.
TELCOM SEMICONDUCTOR, INC.
4-15
+5V TO ±10V VOLTAGE CONVERTER
TCM680
Capacitor Selection
EFFICIENCY CONSIDERATIONS
The TCM680 requires only 4 external capacitors for
operation. These can be inexpensive polarized aluminum
electrolytic types. For the circuit in Figure 6 the output
characteristics are largely determined by the external
capacitors.AnexpressionforROUT canbederivedasshown
below:
Theoretically a charge pump can approach 100% effi-
ciency under the following conditions:
• The charge Pump switches have virtually no offset
and extremely low on resistance
• Minimal power is consumed by the drive circuitry
• The impedances of the reservoir and pump capaci-
tors are negligible
R+OUT = 4(RSW1 + RSW2 + ESRC1 + RSW3 + RSW4 + ESRC2
)
For the TCM680, efficiency is as shown below:
+4(RSW1 + RSW2 + ESRC1 + RSW3 + RSW4 + ESRC2
+1/(fPUMP x C1) + 1/(fPUMP x C2) + ESRC4
)
Efficiency V+ = VDD /(2VIN)
VDD = 2VIN – V+DROP
R–OUT
=
4(RSW1 + RSW2 + ESRC1 + RSW3 + RSW4 + ESRC2
+4(RSW1 + RSW2 + ESRC1 + RSW3 + RSW4+ ESRC2
+1/(fPUMP x C1) + 1/(fPUMP x C2) + ESRC3
)
)
V+DROP = (I+OUT)(R+OUT
)
Efficiency V– = VSS /(– 2VIN)
VSS = 2VIN – V–DROP
V–DROP = (I–OUT)(R–OUT
Assuming all switch resistances are approximately
equal...
)
Power Loss = (V+DROP)(I+OUT) + (V–DROP)(I–OUT
)
R+OUT = 32RSW + 8ESRC1 + 8ESRC2 + ESRC4
+1/(fPUMP x C1) + 1/(fPUMP x C2)
There will be a substantial voltage difference between
(V+OUT – VIN) and VIN for the positive pump and between
V+OUT andVO– UTiftheimpedancesofthepumpcapacitorsC1
and C2 are high with respect to the output loads.
R–OUT = 32RSW + 8ESRC1 + 8ESRC2 + ESRC3
+1/(fPUMP x C1) + 1/(fPUMP x C2)
Larger values of reservoir capacitors C3 and C4 will
reduce output ripple. Larger values of both pump and
reservoir capacitors improve the efficiency. See "Capacitor
Selection" in Applications Section.
ROUT is typically 140Ω at +25°C with VIN = +5V and C1
and C2 as 4.7µF low ESR capacitors. The fixed term
(32RSW) is about 130Ω. It can be seen easily that increasing
or decreasing values of C1 and C2 will affect efficiency by
changing ROUT. However, be careful about ESR. This term
can quickly become dominant with large electrolytic capaci-
tors. Table 1 shows ROUT for various values of C1 and C2
(assume 0.5Ω ESR). C1 and C4 must be rated at 6VDC or
greater while C2 and C3 must be rated at 12VDC or greater.
OutputvoltagerippleisaffectedbyC3andC4. Typically
the larger the value of C3 and C4 the less the ripple for a
given load current. The formula for VRIPPLE(p-p) is given
below:
APPLICATIONS
Positive and negative Converter
The most common application of the TCM680 is as a
dualchargepumpvoltageconverterwhichprovidespositive
and negative outputs of two times a positive input voltage.
The simple circuit of Figure 6 performs this same function
using the TCM680 and external capacitors, C1, C2, C3 and C4.
V+RIPPLE(p-p) = {1/[2(fPUMP /3) x C4] + 2(ESRC4)}(I+OUT
V–RIPPLE(p-p) = {1/[2(fPUMP /3) x C3] + 2(ESRC3)}(I–OUT
)
C1
22µF
22µF
)
+
+
8
7
1
2
–
VOUT
VOUT
C1
For a 10µF (0.5Ω ESR) capacitor for C3, C4,
fPUMP = 21kHz and IOUT = 10mA the peak-to-peak ripple
voltage at the output will be less than 100mV. In most
applications(IOUT <=10mA)10-20µFoutputcapacitorsand
1-5µF pump capacitors will suffice. Table 2 shows VRIPPLE
for different values of C3 and C4 (assume 1Ω ESR).
+
+
C4
C2
C1
22µF
C2
TCM680
6
5
–
3
4
VIN
VIN
C2
–
VOUT
GND
GND
C3
22µF
–
VOUT
Figure 6. Positive and Negative Converter
4-16
TELCOM SEMICONDUCTOR, INC.
+5V TO ±10V VOLTAGE CONVERTER
4
TCM680
Table 1. ROUT vs. C1 ,C2
Paralleling Devices
C1, C2 (µF)
ROUT (Ω)
Paralleling multiple TCM680s reduces the output resis-
tance of both the positive and negative converters. The
effective output resistance is the output resistance of a
single device divided by the number of devices. As illus-
trated in Figure 7, each requires separate pump capacitors
C1 and C2, but all can share a single set of reservoir
capacitors.
0.1
0.47
1
1089
339
232
165
157
146
141
137
3.3
4.7
10
±5V Regulated Supplies From A Single
22
3V Battery
100
Figure 8 shows a complete ±5V power supply using one
3V battery. The TCM680 provides +6V at V+OUT, which is
regulatedto+5VbytheTC55,and–5VbythenegativeLDO.
The input to the TCM680 can vary from 3V to 6V without
affecting regulation appreciably. With higher input voltage,
more current can be drawn from the outputs of the TCM680.
With 5V at VIN, 10mA can be drawn from both regulated
outputs simultaneously. Assuming 150Ω source resistance
forbothconverters, with(I+L +IL)=20mA, thepositivecharge
pump will droop 3V, providing +7V for the negative charge
pump.
Table 2. VRIPPLE (p-p) vs. C3, C4 (IOUT = 10mA)
C3, C4 (µF)
VRIPPLE (mV)
0.47
1
1540
734
236
172
91
3.3
4.7
10
22
52
100
27
VIN
VIN
+
+
VIN
C1
C1
+
+
–
10µF
10µF
10µF
–
–
–
C1
C1
TCM680
TCM680
GND
+
+
C2
–
C2
VOUT
+
–
+
–
–
NEGATIVE
SUPPLY
10µF
VOUT
–
–
C2
C2
GND
–
+
–
COUT
22µF
GND
Figure 7. Paralleling TCM680 for Lower Output Source Resistance
TELCOM SEMICONDUCTOR, INC.
4-17
+5V TO ±10V VOLTAGE CONVERTER
TCM680
+
–
+
COUT
22µF
TC55RP5002Exx
VOUT
+
+
VIN
C1
VIN
+5 SUPPLY
VOUT
+
–
+6V
+
–
10µF
VSS
1µF
1µF
–
C1
+
–
3V
GROUND
TCM680
+
C2
–
+
+
–
VSS
10µF
–6V
–
–
VOUT
VOUT
VIN
–5 SUPPLY
C
2
GND
–
+
22µF
NEGATIVE LDO
–
COUT
TC54VC2702Exx
VOUT
VIN
LOW BATTERY
VSS
Figure 8. Split Supply Derived from 3V Battery
4-18
TELCOM SEMICONDUCTOR, INC.
+5V TO ±10V VOLTAGE CONVERTER
4
TCM680
TYPICAL CHARACTERISTICS
V+OUT or V–OUT
Output Resistance vs. VIN
+
–
VOUT or VOUT vs. Load Current
10.0
9.0
300
C1 – C4 = 10µF
V
= 5V
IN
250
200
8.0
7.0
150
R
OUT
100
4
5
6
3
2
5
15
1
0
10
V
(V)
LOAD CURRENT (mA)
IN
+
–
Supply Current vs. VIN
Output Voltage vs. Output Current From V
10.0
to V
OUT
V
OUT
1.4
1.2
1.0
= 5V
IN
9.0
0.8
0.6
0.4
0.2
NO LOAD
8.0
7.0
4
5
6
1
3
2
6
8
10
0
4
2
+
OUT
–
OUT
V
(V)
IN
OUTPUT CURRENT (mA) From V
TO V
Output Source Resistance vs. Temperature
180
160
V
I
= 5V
IN
OUT = 10mA
R
OUT
140
120
100
-50
0
50
100
TEMPERATURE (°C)
TELCOM SEMICONDUCTOR, INC.
4-19
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