Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
TC1240
Positive Doubling Charge Pump with Shutdown
in SOT Package
FEATURES
GENERAL DESCRIPTION
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The TC1240 is a doubling CMOS charge-pump voltage
converter in a small 6-Pin SOT-23A package. TC1240
doubles an input voltage which can range from +2.5V to
+4.0V. Conversion efficiency is typically >99%. Internal
oscillator frequency is 160kHz for the TC1240. The TC1240
has an active high shutdown which limits the current consumption of the device to less than 1µA.
External component requirement is only two capacitors
for standard voltage doubler applications. All other circuitry,
including control, oscillator, power MOSFETs are integrated
on-chip. Typical supply current is 180µA and the device is
available in a 6-Pin SOT-23A surface mount package.
Space Saving 6-Pin SOT-23A Package
>99% Typical Voltage Conversion Efficiency
Voltage Doubling
Operates from +2.5V to +4.0V
Low Output Resistance (17Ω Typical)
Only Two External Capacitors Required
Consumes 180µA (Typical) in Active Mode
Power-Saving Shutdown Mode (1µA Maximum)
Fully Compliant with 1.8V Logic Sytems
APPLICATIONS
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Cellular Phones
Pagers
PDAs, Portable Data Loggers
Battery-Powered Devices
Handheld Instruments
ORDERING INFORMATION
TYPICAL OPERATING CIRCUIT
Part
Number
Package
TC1240ECH
6-Pin SOT-23A
6-Pin SOT-23A
VIN
INPUT
VIN
C1
C–
1
OFF
SHDN
TC1240
–40°C to +85°C
PIN CONFIGURATION
Positive Voltage Doubler
C+
Temp. Range
GND 2
ON
C–
2 x INPUT
OUT
3
TC1240ECH
6
C+
5
OUT
4
SHDN
GND
C2
NOTE: *6-Pin SOT-23A is equivalent to EIAJ SC-74
TC1240-1 7/7/00 DS21333A
1
© 2001 Microchip Technology Inc.
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
ABSOLUTE MAXIMUM RATINGS*
*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 operational sections of the specifications is not implied.
Exposure to Absolute Maximum Rating Conditions for extended periods
may affect device reliability.
Input Voltage (VIN to GND) .......................... +4.5V, –0.3V
Output Voltage (OUT to GND) .............. +9.0V, VIN – 0.3V
Current at OUT Pin ................................................. 50 mA
Short-Circuit Duration –OUT to GND ................ Indefinite
Operating Temperature Range ...............–40 °C to +85°C
Power Dissipation (TA ≤ 70°C)
6-Pin SOT-23A ..........................................240 mW
Storage Temperature (Unbiased) ......... –65 °C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
ELECTRICAL CHARACTERISTICS: TA = –40 to +85 °C, VIN = +2.8V, C1 = C2 = 3.3µF , SHDN = GND,
unless otherwise noted. Typical values are at TA = +25°C.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
IDD
Supply Current
RLOAD = ∞
—
180
300
µA
ISHDN
Shutdown Supply Current
SHDN = VIN
—
0.1
1.0
µA
VMIN
Minimum Supply Voltage
RLOAD = 1.0KΩ
2.5
—
—
V
VMAX
Maximum Supply Voltage
RLOAD = 1.0KΩ
—
—
4.0
V
FOSC
Oscillator Frequency
TA = –40 °C to +85°C
—
160
—
kHz
FSW
Switching Frequency
TA = –40 °C to +85°C
40
80
125
kHz
VIH
Shutdown Input Logic High
VIN = VMIN to VMAX
1.4
—
—
V
VIL
Shutdown Input Logic Low
VIN = VMIN to VMAX
—
—
0.4
V
PEFF
Power Efficiency
RLOAD = 1.0KΩ
VEFF
Voltage Conversion
Efficiency
RLOAD = ∞
ROUT
Output Resistance
(Note 1)
RLOAD = 1.0KΩ
TA = –40°C to +85°C
86
93
—
%
97.5
99.96
—
%
—
—
17
—
—
30
Ω
NOTE: 1. Capacitor contribution is approximately 26% of the output impedance [ESR = 1 / pump frequency x capacitance)].
2. Switching frequency is one-half internal oscillator frequency.
PIN DESCRIPTION
Pin No.
(6-Pin SOT-23A)
1
2
3
4
5
6
TC1240-1 7/7/00 DS21333A
Symbol
VIN
GND
C–
SHDN
OUT
C+
Description
Power Supply Input.
Ground.
Commutation Capacitor Negative Terminal.
Shutdown Input (Active High).
Doubled Output Voltage.
Commutation Capacitor Positive Terminal.
2
© 2001 Microchip Technology Inc.
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
(2) I2R losses due to the on-resistance of the MOSFET
switches on-board the charge pump.
(3) Charge pump capacitor losses due to effective
series resistance (ESR).
(4) Losses that occur during charge transfer (from
commutation capacitor to the output capacitor) when a
voltage difference between the two capacitors exists.
DETAILED DESCRIPTION
The TC1240 charge pump converter doubles the voltage applied to the VIN pin. Conversion consists of a twophase operation (Figure 1). During the first phase, switches
S2 and S4 are open and S1 and S3 are closed. During this
time, C1 charges to the voltage on VIN and load current is
supplied from C2. During the second phase, S2 and S4 are
closed, and S1 and S3 are open.
During this second phase, C1 is level shifted upward by
VIN volts. This connects C1 to the reservoir capacitor C2,
allowing energy to be delivered to the output as needed. The
actual voltage is slightly lower than 2 x VIN since the four
switches (S1 - S4) have an on-resistance and the load drains
charge from reservoir capacitor C2.
Most of the conversion losses are due to factors (2) and
(3) above. These losses are given by Equation 1(b).
(a) PLOSS (2, 3) = IOUT 2 x ROUT
(b)
[(f
1
PUMP)
+8RSWITCH + 4ESRC1 + ESRC2
C1
]
Equation 1.
S2
S1
VIN
The pump frequency in Equation 1(b) is defined as onehalf the oscillator frequency (i.e. fPUMP = fOSC/2). The
1/(fPUMP)(C1) term in Equation 1(b) is the effective output
resistance of an ideal switched capacitor circuit (Figures 2a,
2b). The value of RSWITCH can be approximated at 1.4Ω for
the TC1240.
The remaining losses in the circuit are due to factor (4)
above, and are shown in Equation 2. The output voltage
ripple is given by Equation 3.
TC1240
C1
OUT = 2 x VIN
C2
S3
≅ IOUT2 x
S4
VIN
PLOSS(4) = [(0.5)(C1) (4VIN2– VOUT2 ) + (0.5)(C2)(2VOUT
VRIPPLE – VRIPPLE2 )] x fOSC
OSC
Equation 2.
Figure 1. Ideal Swiched Capacitor Charge Pump Doubler
VRIPPLE = IOUT +2(IOUT)(ESRC2)
(fOSC)(C2)
APPLICATIONS INFORMATION
Output Voltage Considerations
Equation 3.
f
TheTC1240 performs voltage doubling but does not
provide regulation. The output voltage will droop in a linear
manner with respect to load current. The value of this
equivalent output resistance is approximately 17Ω nominal
at +25°C and VIN = +2.8V. VOUT is approximately +5.6V at
light loads, and droops according to the equation below:
V+
C2
C1
VDROOP = IOUT x ROUT
VOUT = 2 x VIN – VDROOP
RL
Figure 2a. Ideal Swiched Capacitor Model
REQUIV
V+
Charge Pump Efficiency
REQUIV =
VOUT
1
f x C1
The overall power efficiency of the charge pump is
affected by four factors:
(1) Losses from power consumed by the internal oscillator, switch drive, etc. (which vary with input voltage,
temperature and oscillator frequency).
TC1240-1 7/7/00 DS21333A
VOUT
C2
RL
Figure 2b. Equivalent Output Resistance
3
© 2001 Microchip Technology Inc.
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
CAPACITOR SELECTION
VIN
C3
In order to maintain the lowest output resistance and
output ripple voltage, it is recommended that low ESR
capacitors be used. Additionally, larger values of C1 will
lower the output resistance and larger values of C2 will
reduce output ripple. (See Equation 1(b)).
Table 1 shows various values of C1 and the corresponding output resistance values @ +25°C. It assumes a 0.1Ω
ESRC1 and 1.2Ω RSW. Table 2 shows the output voltage
ripple for various values of C2. The VRIPPLE values assume
5 mA output load current and 0.1Ω ESRC2.
VOUT
5
C1 (µF)
0.47
1
2.2
3.3
4.7
10
47
100
47
28.5
19.5
17
15.5
13.6
12.5
12.2
C2
3 ––
C
C1
4 SHDN
C1
GND
Device
TC1240
2
C1
3.3µF
C2
3.3µF
C3
3.3µF
Figure 3. Test Circuit
VOLTAGE DOUBLER
The most common application for charge pump
devices is the doubler (Figure 3). This application uses
two external capacitors - C1 and C2 (plus a power supply
bypass capacitor, if necessary). The output is equal to 2 x
VIN minus any voltage drops due to loading. Refer to Table
1 and Table 2 for capacitor selection.
V
0.47
1
2.2
3.3
4.7
10
47
100
RL
Voltage Doubler
Table 2. Output Voltage Ripple vs. C2 (ESR = 0.1Ω) IOUT 5mA
C1 (µF)
6
TC1240
1
VIN
Table 1. Output Resistance vs. C1 (ESR = 0.1Ω)
TC1240
ROUT(Ω)
C1
C+
OUT
TC1240
VRIPPLE (mV)
IN
VIN 1
VIN
6
6 C+
142
67
30
20
14
6.7
2.5
1.6
C+
C1B
C1A
2
TC1240
TC1240
2
GND
3 C–
4
SHDN
"1"
OUT
5
3
4
C2A
1
GND
"n"
C–
OUT
VOUT
5
SHDN
C2B
VOUT = (n + 1)VIN
Figure 4. Cascading Multiple Devies to Increase Output Voltage
INPUT SUPPLY BYPASSING
CASCADING DEVICES
The VIN input should be capacitively bypassed to reduce
AC impedance and minimize noise effects due to the switching internal to the device. The recommended capacitor
should be a large value (at least equal to C1) connected from
the input to GND.
Two or more TC1240s can be cascaded to increase
output voltage (Figure 4). If the output is lightly loaded, it will
be close to ((n + 1) x VIN) but will droop at least by ROUT of
the first device multiplied by the IQ of the second. It can be
seen that the output resistance rises rapidly for multiple
cascaded devices. For the case of the two-stage ‘tripler’output
resistance can be approximated as ROUT = 2 x ROUT1 +
ROUT2, where ROUT1 is the output resistance of the first
stage, and ROUT2 is the output resistance of the second
stage.
SHUTDOWN INPUT
TheTC1240 is disabled when SHDN is high, and
enabled when SHDN is low. This input cannot be allowed
to float.
TC1240-1 7/7/00 DS21333A
4
© 2001 Microchip Technology Inc.
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
However, to preserve ripple performance the value of C2
should be scaled according to the number of paralleled
TC1240s.
ROUT = ROUT OF SINGLE DEVICE
NUMBER OF DEVICES
VIN
...
VIN
1
1
C1A
2
6
4
LAYOUT CONSIDERATIONS
3
3
TC1240
"1"
TC1240
C1B
As with any switching power supply circuit good layout
practice is recommended. Mount components as close
together as possible to minimize stray inductance and
capacitance. Also use a large ground plane to minimize
noise leakage into other circuitry.
2
"n"
6
4 SHDN
5
SHDN
5
VOUT
...
C2
Shutdown
Control
TC1240 DEMO CARD
VOUT = 2 x VIN
The TC1240 Demo Card is a 1.25” x 1.0” card containing a TC1240 and all of the necessary external components
that allow the user to evaluate the device’s ability to generate a 2X non-regulated output voltage. The demo card is
fully assembled with the required external capacitors along
with a variable load resistor that allows the user to vary the
output load current of the output stage. For convenience,
several test points and jumpers are available for measuring
various voltages and currents on the circuit board.
Figure 5. Paralleling Multiple Devices to Reduce Output Resistance
PARALLELING DEVICES
To reduce the value of ROUT, multiple TC1240s can be
connected in parallel (Figure 5). The output resistance will
be reduced by a factor of N where N is the number of
TC1240s. Each device will require its own pump capacitor
(C1x), but all devices may share one resevoir capacitor (C2).
Figure 6. TC1240 Demo Card Schematic
TC1240-1 7/7/00 DS21333A
5
© 2001 Microchip Technology Inc.
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
Figure 7. TC1240 Demo Card Assembly Drawing and Artwork
Figure 6 is a schematic of the TC1240 Demo Card, and
Figure 7 shows the assembly drawing and artwork for the
board. Table 3 lists the voltages that are monitored by the
test points and Table 4 lists the currents that can be
measured using the jumpers or the specific jumper function.
Table 4. TC1240 Demo Card Jumpers
JUMPER
J1
J2
J3
J4
Table 3. TC1240 Demo Card Test Points
TEST POINT
TP1
TP2
TP3
TP4
TP5
TP6
TP7
VOLTAGE MEASUREMENT
CURRENT MEASUREMENT / JUMPER
FUNCTION
TC1240 QUIESCENT CURRENT
TC1240 LOAD CURRENT
TC1240 SHDN INPUT CURRENT
CONNECT EXTERNAL SHDN INPUT TO
VIN (i.e. SHDN ENABLE)
DEMO CARD POWER SUPPLY
INPUT[+2.5V to +4.0V]
GROUND
GROUND
TC1240 OUTPUT (2 x VIN)
TC1240 SHDN INPUT
TC1240 VIN SUPPLY VOLTAGE
EXTERNAL SHDN INPUT
© 2001 Microchip Technology Inc.
6
TC1240-1 7/7/00 DS21333A
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
TYPICAL CHARACTERISTICS
Supply Current vs. Supply Voltage
(No Load)
700
450
400
350
300
250
200
150
100
50
0
-50
600
500
400
300
200
100
0
2.00
3.00
4.00
5.00
Supply Current vs. Temperature
(No Load)
6.00
Supply Voltage (V)
VIN = 4.0V
VIN = 2.8V
-25
0
25
50
75
Temperature (°C)
100
125
Output Source Resistance vs. Temperature
(with Rload = 1K)
Output Source Resistance vs. Supply Voltage
(with Rload = 1K)
25
20
20
15
VIN = 2.8V
15
10
VIN = 4.0V
10
5
5
0
2.00
3.00
4.00
5.00
6.00
0
-50
Supply Voltage (V)
-25
0
25
50
75
Temperature (°C)
100
Power Efficiency Vs Load Current
Output Voltage Drop Vs Load Current
100%
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
125
VIN = 4.0V
90%
VIN = 3.5V
VIN = 2.5V
80%
70%
VIN = 2.8V
60%
50%
VIN = 4.0V
\
40%
30%
20%
10%
0
5
10
15
20
25
30
35
40
45
0%
50
0
Load Current (mA)
5
10
15
20
25
30
35
40
45
50
Load Current (mA)
TC1240-1 7/7/00 DS21333A
7
© 2001 Microchip Technology Inc.
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
MARKING
SWITCHING FREQUENCY (KHz)
TYPICAL CHARACTERISTICS (Cont.)
6-Pin SOT-23A
Switching Frequency vs. Temperature
100
80
V IN = 4.0V
3
V IN = 2.8V
60
40
& represent part number code + temperature range
(two-digit code)
20
0
-50
-25
0
25
50
75
100
125
TC1240
TEMPERATURE (°C)
Code
1240ECH
DN
Ex: 1240ECH =
D
N
represents year and 2-month code
represents lot ID number
TAPING FORM
Component Taping Orientation for 6-Pin SOT-23A (EIAJ SC-74) Devices
PIN 1
User Direction of Feed
User Direction of Feed
Device
Marking
Device
Marking
W
P
PIN 1
Standard Reel Component Orientation
For TR Suffix Device
(Mark Right Side Up)
Reverse Reel Component Orientation
For RT Suffix Device
(Mark Upside Down)
Carrier Tape, Number of Components Per Reel and Reel Size
Package
6-Pin SOT-23A
© 2001 Microchip Technology Inc.
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
8 mm
4 mm
3000
7 in
8
TC1240-1 7/7/00 DS21333A
Positive Doubling Charge Pump with
Shutdown in SOT Package
TC1240
PACKAGE DIMENSIONS
6-Pin SOT-23A (EIAJ SC-74)
.075 (1.90)
REF.
.069 (1.75)
.059 (1.50)
.122 (3.10)
.098 (2.50)
.020 (0.50)
.014 (0.35)
.037 (0.95)
REF.
.118 (3.00)
.110 (2.80)
.057 (1.45)
.035 (0.90)
.008 (0.20)
.004 (0.09)
10° MAX.
.006 (0.15)
.000 (0.00)
.024 (0.60)
.004 (0.10)
Dimensions: inches (mm)
TC1240-1 7/7/00 DS21333A
9
© 2001 Microchip Technology Inc.
TC1240
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with
express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, PIC, PICmicro,
PICMASTER, PICSTART, PRO MATE, KEELOQ, SEEVAL,
MPLAB and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
Total Endurance, ICSP, In-Circuit Serial Programming, FilterLab, MXDEV, microID, FlexROM, fuzzyLAB, MPASM,
MPLINK, MPLIB, PICC, PICDEM, PICDEM.net, ICEPIC,
Migratable Memory, FanSense, ECONOMONITOR, Select
Mode and microPort are trademarks of Microchip Technology
Incorporated in the U.S.A.
Serialized Quick Term Programming (SQTP) is a service mark
of Microchip Technology Incorporated in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2001, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received QS-9000 quality system
certification for its worldwide headquarters,
design and wafer fabrication facilities in
Chandler and Tempe, Arizona in July 1999. The
Company’s quality system processes and
procedures are QS-9000 compliant for its
PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs and microperipheral
products. In addition, Microchip’s quality
system for the design and manufacture of
development systems is ISO 9001 certified.
DS21333A-page 10
2001 Microchip Technology Inc
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DS21333A - page 11