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TC7660S - TC7660S
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
TC7660S TC7660S
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER
FEATURES
Oscillator boost from 10kHz 45kHz Converts Logic Supply System Wide Input Voltage Range 1.5V Efficient Voltage Conversion 99.9% Excellent Power Efficiency Power Supply 80µA Cost Easy Only External Capacitors Required Available Small Outline (SOIC) Package Improved Protection 10kV External Diode Required High Voltage Operation
GENERAL DESCRIPTION
TC7660S pin-compatible upgrade Industry standard TC7660 charge pump voltage converter. converts +1.5V +12V input corresponding -1.5V -12V output using only low-cost capacitors, eliminating inductors their associated cost, size EMI. Added features include extended supply range 12V, frequency boost higher operating frequency, allowing smaller external capacitors. on-board oscillator operates nominal frequency 10kHz. Frequency increased 45kHz when connected Operation below 10kHz (for lower supply current applications) possible connecting external capacitor from ground (with open). TC7660S available both 8-pin 8-pin small outline (SOIC) packages commercial extended temperature ranges.
ORDERING INFORMATION
Part
TC7660SCOA TC7660SCPA TC7660SEJA TC7660SEOA TC7660SEPA TC7660SMJA
Package
8-Pin SOIC 8-Pin Plastic 8-Pin CerDIP 8-Pin SOIC 8-Pin Plastic 8-Pin CerDIP
Temperature Range
+70°C +70°C 40°C +85°C 40°C +85°C 40°C +85°C 55°C +125°C
CONFIGURATION (DIP SOIC)
TC7660SCOA VOLTAGE (LV) TC7660SEOA VOUT
Boost
Boost
TC7660SCPA VOLTAGE (LV) TC7660SEJA TC7660SEPA VOUT
TC7660EV
Evaluation Charge Pump Family
FUNCTIONAL BLOCK DIAGRAM
BOOST
OSCILLATOR
VOLTAGE- LEVEL TRANSLATOR
INTERNAL VOLTAGE REGULATOR LOGIC NETWORK VOUT
TC7660S
TC7660S-14 9/16/96 TelCom Semiconductor reserves right make changes circuitry specifications devices.
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage +13V Boost, Inputs Voltage (Note 0.3V +0.3V) 5.5V 5.5V) +0.3V) 5.5V Current Into (Note 20µA 3.5V Output Short Duration (VSUPPLY 5.5V) Continuous Power Dissipation 70°C) (Note CerDIP .800mW Plastic .730mW SOIC .470mW Operating Temperature Range Suffix +70°C Suffix 40°C +85°C Suffix 55°C +125°C Storage Temperature Range 65°C +150°C Lead Temperature (Soldering, sec) +300°C
*Static-sensitive device. Unused devices must stored conductive material. Protect devices from static discharge static fields. Stresses above those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only functional operation device these other conditions above those indicated operation sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS: +25°C, COSC Test Circuit (Figure unless otherwise
indicated. Symbol
Parameter
Supply Current (Boost OPEN GND)
Test Conditions
+70°C 40°C +85°C 55°C +125°C +70°C 40°C +85°C 55°C +125°C Max, 10k, Open Max, 10k, IOUT 20mA IOUT 20mA, +70°C IOUT 20mA, 40°C +85°C IOUT 20mA, 55°C +125°C IOUT 3mA, +70°C 55°C +125°C open; open Boost Boost Open TMIN TMAX; Boost Open Boost
99.9
Unit
Supply Current (Boost Supply Voltage Range, High Supply Voltage Range, Output Source Resistance
ROUT
FOSC PEFF
Oscillator Frequency Power Efficiency
VOUT ZOSC
Voltage Conversion Efficiency Oscillator Impedance
NOTES: Connecting input terminal voltages greater than less than cause destructive latch-up. recommended that inputs from sources operating from external supplies applied prior "power TC7660S. Derate linearly above 50°C 5.5mW/°C.
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
Detailed Description
TC7660S contains necessary circuitry implement voltage inverter, with exception external capacitors, which inexpensive polarized electrolytic capacitors. Operation best understood considering Figure which shows idealized voltage inverter. Capacitor charged voltage half cycle when switches closed. (Note: Switches open during this half cycle.) During second half cycle operation, switches closed, with open, thereby shifting capacitor negatively volts. Charge then transferred from negatively volts. Charge then transferred from such that voltage exactly assuming ideal switches load four switches Figure power switches; P-channel device, N-channel devices. main difficulty with this approach that integrating switches, substrates must always remain reverse-biased with respect their sources, much degrade their resistances. addition, circuit start-up, under output short circuit conditions (VOUT V+), output voltage must sensed substrate bias adjusted accordingly. Failure accomplish this will result high power losses probable device latch-up. This problem eliminated TC7660S logic network which senses output voltage (VOUT) together with level translators, switches substrates correct level maintain necessary reverse bias.
VOUT
Figure Idealized Charge Pump Inverter
voltage regulator portion TC7660S integral part anti-latch-up circuitry. inherent voltage drop can, however, degrade operation voltages. improve low-voltage operation, "LV" should connected GND, disabling regulator. supply voltages greater than 3.5V, terminal must left open ensure latch-up-proof operation prevent device damage.
Theoretical Power Efficiency Considerations
theory, capacitive charge pump approach 100% efficiency certain conditions met: drive circuitry consumes minimal power. output switches have extremely resistance virtually offset.
10µF
(+5V)
impedances pump reservoir capacitors negligible pump frequency. TC7660S approaches these conditions negative voltage multiplication large values used. Energy lost only transfer charge between capacitors change voltage occurs. energy lost defined (V12 V22) voltages during pump transfer cycles. impedances relatively high pump frequency (refer Figure compared value there will substantial difference voltages Therefore, desirable only make large possible eliminate output voltage ripple, also employ correspondingly large value order achieve maximum efficiency operation.
TC7660S
COSC*
10µF
NOTE: large values COSC (>1000pF), values should increased 100µF.
Figure TC7660S Test Circuit
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
Don'ts
exceed maximum supply voltages. connect terminal supply voltages greater than 3.5V. short circuit output supply voltages above 5.5V extended periods; however, transient conditions including start-up okay. When using polarized capacitors inverting mode, terminal must connected TC7660S terminal must connected GND. output characteristics circuit Figure those nearly ideal voltage source series with Thus, load current -10mA supply voltage +5V, output voltage would 4.3V. dynamic output impedance TC7660S due, primarily, capacitive reactance charge transfer capacitor (C1). Since this capacitor connected output only cycle, equation 3.18, where 10kHz 10µF.
Paralleling Devices Simple Negative Voltage Converter
Figure shows typical connections provide negative supply where positive supply available. similar scheme employed supply voltages anywhere operating range +1.5V +12V, keeping mind that (LV) tied supply negative (GND) only supply voltages below 3.5V.
10µF VOUT* 10µF
number TC7660S voltage converters paralleled reduce output resistance (Figure reservoir capacitor, serves devices, while each device requires pump capacitor, resultant output resistance would approximately: ROUT TC7660S) (number devices)
ROUT
TC7660S
NOTES:
Figure Simple Negative Converter
TC7660S
TC7660S
Figure Paralleling Devices Lowers Output Impedance
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
10µF TC7660S 10µF TC7660S VOUT* 10µF
NOTES:
VOUT -n(V+) 1.5V
10µF
Figure Increased Output Voltage Cascading Devices
Cascading Devices
TC7660S cascaded shown (Figure produce larger negative multiplication initial supply voltage. However, finite efficiency each device, practical limit devices light loads. output voltage defined VOUT (VIN) where integer representing number devices cascaded. resulting output resistance would approximately weighted individual TC7660S ROUT values.
Changing TC7660S Oscillator Frequency
desirable some applications (due noise other considerations) increase oscillator frequency. frequency boost connected increase oscillator frequency 45kHz from nominal 10kHz input supply voltage volts. oscillator also synchronized external clock shown Figure order prevent possible device latch-up, resistor must used series with clock output.
10µF TC7660S 10µF VOUT CMOS GATE
situation where designer generated external clock frequency using logic, addition pullup resistor supply required. Note that pump frequency with external clocking, with internal clocking, will clock frequency. Output transitions occur positive-going edge clock. also possible increase conversion efficiency TC7660S load levels lowering oscillator frequency. This reduces switching losses, achieved connecting additional capacitor, COSC, shown Figure Lowering oscillator frequency will cause undesirable increase impedance pump (C1) reservoir (C2) capacitors. overcome this, increase values same factor that frequency been reduced. example, addition 100pF capacitor between (OSC) (V+) will lower oscillator frequency 1kHz from nominal frequency 10kHz multiple 10), necessitate corresponding increase values (from 10µF 100µF).
Positive Voltage Multiplication
TC7660S employed achieve positive voltage multiplication using circuit shown Figure this application, pump inverter switches TC7660S used charge voltage level V+-VF (where supply voltage forward voltage drop diode D1). transfer cycle, voltage plus supply voltage (V+) applied through diode capacitor voltage thus created becomes (2V+) (2VF), twice supply voltage minus combined forward voltage drops diodes source impedance output (VOUT) will depend output current, output current 10mA, will approximately
Figure External Clocking
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
COSC
will bypass other Figure would never turn on), else diode resistor shown dotted Figure used "force" internal regulator
TC7660S
VOUT
Voltage Splitting
same bidirectional characteristics used Figure also used split higher supply half, shown Figure combined load will evenly shared between sides. Once again, high value resistor ensures start-up. Because switches share load parallel, output impedance much lower than standard circuits, higher currents drawn from device. using this circuit, then circuit Figure +15V converted (via +7.5V 7.5V) nominal -15V, though with rather high series resistance (~250).
Figure Lowering Oscillator Frequency
Combined Negative Voltage Conversion Positive Supply Multiplication
Figure combines functions shown Figures provide negative voltage conversion positive voltage multiplication simultaneously. This approach would example, suitable generating from existing supply. this instance, capacitors perform pump reservoir functions, respectively, generation negative voltage, while capacitors pump reservoir, respectively, multiplied positive voltage. There penalty this configuration which combines both functions, however, that source impedances generated supplies will somewhat higher finite impedance common charge pump driver device.
VOUT
TC7660S
VOUT
Efficient Positive Voltage Multiplication/Conversion
Since switches that allow charge pumping operation bidirectional, charge transfer performed backwards easily forwards. Figure shows TC7660S transforming +10V, etc.). only problem here that internal clock switchdrive section will operate until some positive voltage been generated. initial inefficient pump, shown Figure could used start this circuit after which
VOUT
Figure Combined Negative Converter Positive Multiplier
Negative Voltage Generation Display ADCs
TC7106 designed work from battery. With fixed power supply system, TC7106 will perform conversions with input signal referenced power supply ground.
Negative Supply Generation Digit Data Acquisition System
TC7135 digit operating from supplies. TC7660S provides inexpensive source. (See AN16 AN17 TC7135 interface details software routines.)
TC7660S
Figure Positive Voltage Multiplier
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
VOUT
50µF
10µF
10µF
TC7660S
50µF
TC7660S
INPUT
50µF
Figure Positive Voltage Multiplier
Figure Splitting Supply Half
TYPICAL CHARACTERISTICS
Unloaded Freq Temperature
OSCILLATOR FREQUENCY (kHz)
OSCILLATOR FREQUENCY (kHz)
Unloaded Freq Temperature with Boost
TEMPERATURE (°C)
TEMPERATURE (°C)
1000
(µA)
VOLTAGE CONVERSION EFFICIENCY
Supply Current Temperature (with Boost VIN)
Voltage Conversion
101.0 100.5 100.0 99.5 99.0 98.5 25°C 98.0
INPUT VOLTAGE
Without Load
Load
TEMPERATURE (°C)
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
TYPICAL CHARACTERISTICS (Cont.)
Output Source Resistance Supply Voltage
OUTPUT SOURCE RESISTANCE OUTPUT SOURCE RESISTANCE
Output Source Resistance Temperature
2.5V
5.5V
IOUT 20mA 25°C 10.5 11.5
SUPPLY VOLTAGE
TEMPERATURE (°C)
Output Voltage Output Current
OUTPUT VOLTAGE VOUT
Power Conversion Efficiency Load
Boost Open Boost
POWER EFFICIENCY
OUTPUT CURRENT (mA)
Supply Current Temperature
SUPPLY CURRENT (µA)
12.5V
5.5V
TEMPERATURE (°C)
10.0 15.0 20.0 25.0 30.0 35.0 40.0 50.0 55.0 60.0
LOAD CURRENT (mA)
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
TYPICAL CHARACTERISTICS (Cont.)
Supply Current Temperature
SUPPLY CURRENT (µA)
5.5V 12.5V
TEMPERATURE (°C)
PACKAGE DIMENSIONS 8-Pin Plastic
.260 (6.60) .240 (6.10)
.045 (1.14) .030 (0.76) .400 (10.16) .348 (8.84) .200 (5.08) .140 (3.56) .150 (3.81) .115 (2.92)
.070 (1.78) .045 (1.14)
.310 (7.87) .290 (7.37)
.040 (1.02) .020 (0.51)
.015 (0.38) .008 (0.20) .400 (10.16) .310 (7.87)
3°MIN.
.110 (2.79) .090 (2.29)
.022 (0.56) .015 (0.38)
Dimensions: inches (mm)
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
PACKAGE DIMENSIONS (Cont.) 8-Pin CerDIP
.110 (2.79) .090 (2.29)
.300 (7.62) .230 (5.84)
.055 (1.40) MAX. .400 (10.16) .370 (9.40) .200 (5.08) .160 (4.06) .200 (5.08) .125 (3.18)
.020 (0.51) MIN. .320 (8.13) .290 (7.37) .040 (1.02) .020 (0.51) .015 (0.38) .008 (0.20) .400 (10.16) .320 (8.13) .065 (1.65) .020 (0.51) .045 (1.14) .016 (0.41)
.150 (3.81) MIN.
3°MIN.
8-Pin Plastic SOIC
indicated beveled edge
.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) .018 (0.46) .010 (0.25) .014 (0.36) .004 (0.10) .010 (0.25) .007 (0.18) .050 (1.27) .016 (0.40)
8°MAX.
Dimensions: inches (mm)
SUPER CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER TC7660S
Sales Offices
TelCom Semiconductor 1300 Terra Bella Avenue P.O. 7267 Mountain View, 94039-7267 TEL: 650-968-9241 FAX: 650-967-1590 E-Mail: liter@c2smtp.telcom-semi.com TelCom Semiconductor Austin Product Center 9101 Burnet Suite Austin, 78758 TEL: 512-873-7100 FAX: 512-873-8236 TelCom Semiconductor H.K. Ltd. Chuk Street, Ground Floor Kong, Kowloon Hong Kong TEL: 852-2324-0122 FAX: 852-2354-9957
Printed U.S.A.
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