Datasheet TC1044SCPA, TC1044SCOA, TC1044SMJA, TC1044SIJA, TC1044SEPA Datasheet (TelCom Semiconductor)
...
EVALUATION
KIT
AVAILABLE
CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
FEATURES
GENERAL DESCRIPTION
1
TC1044S
2
■ 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 Consumption ............ 80µA @ VIN = 5V
■ Low Cost and Easy to Use
— Only Two External Capacitors Required
■ RS-232 Negative Power Supply
■ Available in 8-Pin Small Outline (SOIC) and 8-Pin
Plastic DIP Packages
■ Improved ESD Protection ..................... Up to 10kV
■ No External Diode Required for High Voltage
Operation
■ Frequency Boost Raises F
to 45kHz
OSC
PIN CONFIGURATION (DIP and SOIC)
BOOST
CAP
GND
CAP
1
+
2
3
–
4
TC1044SCPA
TC1044SEPA
TC1044SIJA
TC1044SMJA
+
8
V
7
OSC
LOW
6
VOLTAGE (LV)
5
V
OUT
BOOST
CAP
GND
CAP
1
+
2
3
–
4
TC1044SCOA
TC1044SEOA
+
8
V
7
OSC
LOW
6
VOLTAGE (LV)
5
V
OUT
The TC1044S is a pin-compatible upgrade to the Industry 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 frequency boost pin for higher operating frequency,
allowing the use of smaller external capacitors.
The on-board oscillator operates at a nominal frequency
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 TC1044S is available in both 8-pin DIP and
8-pin small outline (SOIC) packages in commercial and
extended temperature ranges.
ORDERING INFORMATION
Part No. Package Temp. Range
TC1044SCOA 8-Pin SOIC 0°C to +70°C
TC1044SCPA 8-Pin Plastic DIP 0°C to +70°C
TC1044SEOA 8-Pin SOIC – 40°C to +85°C
TC1044SEPA 8-Pin Plastic DIP – 40°C to +85°C
TC1044SIJA 8-Pin CerDIP – 25°C to +85°C
TC1044SMJA 8-Pin CerDIP – 55°C to +125°C
TC7660EV Charge Pump Family Evaluation Kit
3
4
5
FUNCTIONAL BLOCK DIAGRAM
OSC
LV
1
7
OSCILLATOR
6
TC1044S
BOOST
TELCOM SEMICONDUCTOR, INC.
RC
INTERNAL
VOLTAGE
REGULATOR
2
VOLTAGE–
LEVEL
TRANSLATOR
+
V
82
3
GND
CAP
+
LOGIC
NETWORK
6
4
5
CAP
V
OUT
–
7
8
TC1044S-12 9/16/96
4-43
TC1044S
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage ......................................................... +13V
LV, Boost and 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
Current Into LV (Note 1)......................20µA for V+ > 3.5V
Output Short Duration (V
Lead Temperature (Soldering, 10 sec) .................+300°C
*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 permanent 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: T
≤ 5.5V) .........Continuous
SUPPLY
= +25°C, V+ = 5V, C
A
Package Power Dissipation (TA ≤ 70°C) (Note 2)
8-Pin CerDIP ..................................................800mW
8-Pin Plastic DIP.............................................730mW
8-Pin SOIC .....................................................470mW
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
= 0, Test Circuit (Figure 1), unless otherwise
OSC
indicated.
Symbol Parameter Test Conditions Min Typ Max Unit
+
I
+
I
+
V
H2
+
V
L2
R
OUT
F
OSC
P
EFF
V
OUT EFF
Z
OSC
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
Supply Current RL = ∞ — 80 160 µA
0°C < T
– 40°C < T
< +70°C — — 180
A
< +85°C — — 180
A
– 55°C < TA < +125°C — — 200
Supply Current 0°C < TA < +70°C — — 300 µA
+
(Boost Pin = V
)– 40°C < TA < +85°C — — 350
– 55°C < TA < +125°C — — 400
Supply Voltage Range, High Min ≤ TA ≤ Max, 3 — 12 V
RL = 10 kΩ, LV Open
Supply Voltage Range, Low Min ≤ TA ≤ Max, 1.5 — 3.5 V
RL = 10 kΩ, LV to GND
Output Source Resistance I
= 20mA — 60 100 Ω
OUT
I
= 20mA, 0°C ≤ TA ≤ +70°C — 70 120
OUT
= 20mA, –40°C ≤ TA ≤ +85°C — 70 120
I
OUT
I
= 20mA, –55°C ≤ TA ≤ +125°C — 105 150
OUT
V+ = 2V, I
0°C ≤ T
= 3 mA, LV to GND
OUT
≤ +70°C — — 250 Ω
A
– 55°C ≤ TA ≤ +125°C — — 400
Oscillator Frequency Pin 7 open; Pin 1 open or GND — 10 — kHz
Boost Pin = V
+
—45—
Power Efficiency RL = 5 kΩ; Boost Pin Open 96 98 — %
< TA < T
T
MIN
Boost Pin = V
; Boost Pin Open 95 97 —
MAX
+
—88—
Voltage Conversion Efficiency RL = ∞ 99 99.9 — %
Oscillator Impedance V+ = 2V — 1 — MΩ
V+ = 5V — 100 — kΩ
inputs from sources operating from external supplies be applied prior to "power up" of the TC1044S.
2. Derate linearly above 50°C by 5.5mW/°C.
4-44
TELCOM SEMICONDUCTOR, INC.
V
+
GND
S
3
S
1
S
2
S
4
C
2
V
OUT
= – V
IN
C
1
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
Circuit Description
1
TC1044S
The TC1044S contains all the necessary circuitry to
implement a voltage inverter, with the exception of two
external capacitors, which may be inexpensive 10 µF polarized 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 (V
and the substrate bias adjusted accordingly. Failure to
accomplish this will result in high power losses and probable
device latch-up.
This problem is eliminated in the TC1044S by a logic
network which senses the output voltage (V
with the level translators, and switches the substrates of S
and S4 to the correct level to maintain necessary reverse
bias.
+
V
+
C
1
1µF
NOTE: For large values of C
= V+), the output voltage must be sensed
OUT
1
2
TC1044S
3
4
of C
and C2 should be increased to 100µF.
1
Figure 1. TC1044S Test Circuit
8
7
C
OSC
+
6
5
(>1000pF), the values
OSC
OUT
*
C
2
10µF
I
I
R
) together
S
+
V
(+5V)
L
L
V
OUT
Figure 2. Idealized Charge Pump Inverter
The voltage regulator portion of the TC1044S 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
3
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.
The TC1044S 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 (V
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.
1
– V
2
)
2
2
3
4
5
6
7
8
TELCOM SEMICONDUCTOR, INC.
4-45
TC1044S
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
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.
• When using polarized capacitors in the inverting mode,
the + terminal of C1 must be connected to pin 2 of the
TC1044S and the + terminal of C2 must be connected
to GND.
Simple Negative Voltage Converter
Figure 3 shows typical connections to provide a negative 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
pin 6 (LV) is tied to the supply negative (GND) only for supply
voltages below 3.5V.
+
V
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 TC1044S 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,
2πf C
1
where f = 10 kHz and C1 = 10µF.
Paralleling Devices
Any number of TC1044S voltage converters may be
paralleled to reduce output resistance (Figure 4). The reservoir capacitor, C2, serves all devices, while each device
requires its own pump capacitor, C1. The resultant output
resistance would be approximately:
R
(of TC1044S)
R
OUT
=
OUT
n (number of devices)
C
10µF
1
NOTES:
*
1
2
+
TC1044S
3
4
Figure 3. Simple Negative Converter
C
1
1
2
3
4
8
7
6
5
TC1044S
"1"
*
V
OUT
C
2
10µF
+
+
V
8
7
6
5
C
1
1
2
3
4
TC1044S
"n"
8
R
7
6
5
L
C
2
+
4-46
Figure 4. Paralleling Devices Lowers Output Impedance
TELCOM SEMICONDUCTOR, INC.
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
1
TC1044S
+
V
10µF
*
NOTES:
1. V
1
2
+
OUT
TC1044S
3
"1"
4
= –n(V+) for 1.5V ≤ V+ ≤ 12V
8
7
6
5
Figure 5. Increased Output Voltage by Cascading Devices
10µF
Cascading Devices
The TC1044S 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:
V
= –n(VIN)
OUT
where n is an integer representing the number of devices
cascaded. The resulting output resistance would be approximately the weighted sum of the individual TC1044S
R
values.
OUT
Changing the TC1044S Oscillator Frequency
It may be desirable in some applications (due to noise or
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
Figure 6. In order to prevent possible device latch-up, a 1kΩ
resistor must be used in series with the clock output. In a
10µF
+
V
1
2
+
3
TC1044S
4
Figure 6. External Clocking
8
1kΩ
7
6
5
+
V
CMOS
GATE
V
OUT
10µF
+
1
2
+
10µF
+
situation where the designer has generated the external
clock frequency using TTL logic, the addition of a 10kΩ pullup 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 TC1044S at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is achieved
by connecting an additional capacitor, C
Figure 7. Lowering the oscillator frequency will cause an
undesirable increase in the impedance of the pump (C1) and
the reservoir (C2) capacitors. To overcome this, increase
the 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).
3
4
TC1044S
"n"
8
7
6
5
+
V
OUT
10µF
, as shown in
OSC
Positive Voltage Multiplication
The TC1044S may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 8. In
this application, the pump inverter switches of the TC1044S
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.
The source impedance of the output (V
on the output current, but for V+ = 5V and an output current
of 10mA, it will be approximately 60Ω.
) will depend
OUT
2
*
3
4
5
6
+
7
8
TELCOM SEMICONDUCTOR, INC.
4-47
TC1044S
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
+
V
1
2
+
C
1
TC1044S
3
4
Figure 7. Lowering Oscillator Frequency
8
7
6
5
C
OSC
V
OUT
C
2
+
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 voltage 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 C
perform the pump and reservoir functions, respectively, for
the generation of the negative voltage, while capacitors C
and C4 are pump and reservoir, respectively, for the multiplied positive voltage. There is a penalty in this configuration
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.
Efficient Positive Voltage
Multiplication/Conversion
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.
Voltage Splitting
The same bidirectional characteristics used in Figure 10
can also be used to split a higher supply in half, as shown in
Figure 11. The combined load will be evenly shared between 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
the standard circuits, and higher currents can be drawn from
the device. By using this circuit, and then the circuit of Figure
5, +15V can be converted (via +7.5V and –7.5V) to a nominal
–15V, though with rather high series resistance (~250Ω).
+
3
2
1
2
TC1044S
3
4
+
C
1
+
C
2
V
V
8
7
6
5
D
1
V
(2 V+) – (2 VF)
D
2
+
OUT
+
OUT
C
=
C
= –V
3
4
+
Since the switches that allow the charge pumping operation are bidirectional, the charge transfer can be performed backwards as easily as forwards. Figure 10 shows
a TC1044S transforming –5V to +5V (or +5V to +10V, etc.).
The only problem here is that the internal clock and switchdrive section will not operate until some positive voltage has
been generated. An initial inefficient pump, as shown in
+
V
4-48
1
2
TC1044S
3
4
Figure 8. Positive Voltage Multiplier
8
D
7
6
5
1
D
+
C
1
2
+
V
=
OUT
(2 V+) – (2 VF)
C
2
Figure 9. Combined Negative Converter and Positive Multiplier
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.
Negative Supply Generation for
4¹⁄₂ Digit Data Acquisition System
The TC7135 is a 4¹⁄₂ digit ADC operating from ±5V
supplies. The TC1044S provides an inexpensive –5V source.
(See AN16 and AN17 for TC7135 interface details and
software routines.)
TELCOM SEMICONDUCTOR, INC.
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
V
= –V
OUT
C
10µF
1
2
+
1
3
4
TC1044S
8
7
1 MΩ
6
5
–
V
–
INPUT
1
TC1044S
+
V
R
L1
V
+
10µF
OUT
V+–V
2
R
L2
=
+
–
50
µF
50 µF
50
µF
100
kΩ
+
1
2
TC1044S
3
100
4
kΩ
+
8
7
1 MΩ
6
5
V
2
–
3
Figure 10. Positive Voltage Conversion
TYPICAL CHARACTERISTICS
Unloaded Osc Freq vs. Temperature
12
10
8
6
4
2
OSCILLATOR FREQUENCY (kHz)
0
-40 -20 0 20 40 10060 80
TEMPERATURE (°C)
Supply Current vs. Temperature
(with Boost Pin = V
1000
IN
VIN = 5V
VIN = 12V
)
Figure 11. Splitting a Supply in Half
Unloaded Osc Freq vs. Temperature
60
with Boost Pin = V
50
40
30
20
10
OSCILLATOR FREQUENCY (kHz)
0
-40 -20 0 20 40 10060 80
TEMPERATURE (°C)
IN
VIN = 12V
Voltage Conversion
101.0
4
VIN = 5V
5
6
800
600
(µA)
DD
400
I
200
0
-40 -20 0 20 40 10060 80
TEMPERATURE (°C)
TELCOM SEMICONDUCTOR, INC.
VIN = 12V
VIN = 5V
100.5
100.0
99.5
99.0
98.5
VOLTAGE CONVERSION EFFICIENCY (%)
98.0
112111098756423
INPUT VOLTAGE VIN (V)
Without Load
7
10K Load
TA = 25°C
8
4-49
TC1044S
TYPICAL CHARACTERISTICS (Cont.)
CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER
Output Source Resistance vs. Supply Voltage
100
70
50
30
I
= 20mA
OUT
T
= 25°C
A
OUTPUT SOURCE RESISTANCE (Ω)
10
1.5 1211.510.59.58.57.55.5 6.54.52.5 3.5
SUPPLY VOLTAGE (V)
Output Voltage vs. Output Current
0
-2
(V)
-4
OUT
-6
-8
-10
OUTPUT VOLTAGE V
-12
0 1009080706040 503010 20
OUTPUT CURRENT (mA)
Output Source Resistance vs. Temperature
100
80
60
40
20
OUTPUT SOURCE RESISTANCE (Ω)
0
-40 -20 0 20 40 10060 80
TEMPERATURE (°C)
VIN = 2.5V
VIN = 5.5V
Power Conversion Efficiency vs. Load
100
90
80
Boost Pin = V
70
60
50
40
30
20
POWER EFFICIENCY (%)
10
0
4.5
3.0
2.0
1.5
1.0
LOAD CURRENT (mA)
6.0
7.5
Boost Pin = Open
+
9.0
15.0
10.0
20.0
25.0
30.0
35.0
40.0
50.0
55.0
60.0
4-50
200
Supply Current vs. Temperature
175
150
(µA)
DD
125
100
75
50
SUPPLY CURRENT I
25
0
-40 -20 0 20 40 10060 80
TEMPERATURE (°C)
VIN = 12.5V
VIN = 5.5V
TELCOM SEMICONDUCTOR, INC.
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