TC125 MICROCHIP | Alldatasheet
Document overview
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Technical content
Features
- Assured Start-up at 0.9V PFM (100kHz Max Operating Frequency) 4 0 µA Maximum Supply Current OUT = 3V @ 30mA) 0 . 5µA Shutdown Mode (TC125) Voltage Sense Input (TC126) Requires Only Three External Components 80mA Maximum Output Current Small Package: 5-Pin SOT-23A
Applications
Palmtops/PDAs Battery-Operated Systems Cameras Portable Communicators Device Selection Table *Other output voltages are available. Please contact Microchip Technology Inc. for details. Package Type General Description The TC125/126 step-up (Boost) switching regulators furnish output currents to a maximum of 80mA (VIN =2 V ,VOUT = 3V) with typical efficiencies above 80%. These devices employ pulse frequency modula- tion (PFM) for minimum supply current at low loads. They are ideal for battery-operated applications powered from one or more cells. Maximum supply current is less than 70 µA at full output load, and less than 5µA in standby (V OUT = 3V). Both devices require only an external inductor, diode, and capacitor to implement a complete DC/DC regulator. The TC126 has separate output voltage sensing and chip power inputs for greater application flexibility. The TC125 combines the output voltage sensing and chip power inputs onto a single package pin, but adds a power-saving shutdown mode that suspends regulator operation and reduces supply current to less than 0.5µA when the shutdown control input (SHDN )i sl o w . The TC125/TC126 are available in a small 5-Pin SOT-23A package, occupy minimum board space and use small external components. The TC125 accepts input voltages from 2V to 10V. The TC126 accepts input voltages from 2.2V to 10V. Both the TC125 and TC126 have a start-up voltage of 0.9V at light load. Typical Application Part Number Output Voltage (V)* Package Operating Temp. Range TC125501ECT 5.0 5-Pin SOT-23A -40 °Ct o+ 8 5°C TC125331ECT 3.3 5-Pin SOT-23A -40 °Ct o+ 8 5°C TC125301ECT 3.0 5-Pin SOT-23A -40 °Ct o+ 8 5°C TC126503ECT 5.0 5-Pin SOT-23A -40 °Ct o+ 8 5°C TC126333ECT 3.3 5-Pin SOT-23A -40 °Ct o+ 8 5°C TC126303ECT 3.0 5-Pin SOT-23A -40 °Ct o+ 8 5°C 5-Pin SOT-23A NOTE: 5-Pin SOT-23A is equivalent to the EIAJ SC-74A VDDSENSE TC125 1 23 5 4 PS LX GND NCSHDN TC126 1 23 5 4 LX GND NC 3V2 x "AA" Cell Two Cell to 5V Boost Regulator 1 2 3 5 4 TC125 LX SHDN NCPS GND MA735 VIN Sumida 100µH CD54 VOUT 5V @80mA 47µF/16V Tantalum PFM Step-Up DC/DC Regulators
DS21372B-page 2 2002 Microchip Technology Inc.
1.0 ELECTRICAL
Absolute Maximum Ratings* Voltage on VDD, SENSE/VDD, LX, SHDN Pins *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. TC125/TC126 ELECTRICAL SPECIFICATIONS Symbol Parameter Min Typ Max Units Test Conditions VOUT Output Voltage V R –2 . 5 % V R ±0 . 5 % V R +2 . 5 % V VDD Operating Supply Voltage 0.70 — 10.0 V Note 4 VSTART Start-Up Supply Voltage — 0.80 0.90 V I OUT =1 m A IDD Operating Supply Current TC125 TC125/126 TC125/126 µA( N o t e 2 ) V OUT =2 V , IOUT =1 0 m A VOUT =3 V , IOUT =3 0 m A VOUT =5 V , IOUT =5 0 m A INL No Load Supply Current — µAI OUT =0 ,V OUT =2 V VOUT =3 V VOUT =5 V ISTBY Standby Supply Current — µAV IN =V OUT +0 . 5 V ,VIN =2 V VIN =3 V VIN =5 V ISHDN Shutdown Supply Current — — 0.5 µA SHDN =V IL,( N o t e2 ) RLX(ON) LX Pin ON Resistance — Ω VLX =0 . 4 V ,VOUT =2 V VOUT =3 V VOUT =5 V (Note 2), (Note 3) ILX LX Pin Leakage Current — — 1 µA No external components, VOUT =V LX =1 0 V DCYCLE Duty Cycle 70 75 80 % Measured at LX pin (Note 2) fMAX Maximum Oscillator Frequency 85 100 115 kHz Note 2 VLXLIM LX Pin Limit Voltage 0.7 — 1.1 V Note 2 η Efficiency — OUT =2 V VOUT =3 V VOUT =5 V VIH SHDN Input Logic High 0.75 — — V VIL SHDN Input Logic Low — — 0.20 V IINH SHDN Input Current (High) — — 0.25 µA IINL SHDN Pin Input Current (Low) -0.25 — — µA Note 1: VR is the factory output voltage setting. 2: VIN =V OUT x 0.95. 3: VDD input tied to SENSE input for TC126, as shown in Figure 3-2. 4: The VPS input of the TC125 must be operated between 2.0V and 10.0V for spec compliance. The VDD input of the TC126 must be operated between 2.2V and 10.0V for spec compliance.
2002 Microchip Technology Inc. DS21372B-page 3 TC125/TC126
2.0 PIN DESCRIPTIONS
T h ed e s c r i p t i o n so ft h ep i n sa r el i s t e di nT a b l e2 - 1 . TABLE 2-1: PIN FUNCTION TABLE TC125 Pin No. (5-Pin SOT-23A) TC126 Pin No. (5-Pin SOT-23A) Symbol Description 1 — SHDN Shutdown input. A logic low on this input suspends device operation and supply current is reduced to less than 0.5 µA. The device resumes normal operation when SHDN is again brought high. — 1 SENSE Voltage sense input. This input provides feedback voltage sensing to the internal error amplifier. It must be connected to the output voltage node, preferably the single point in the system where tight voltage regulation is most beneficial. 2 — PS Power and voltage sense input. This dual function input provides both feedback voltage sensing and internal chip power. It should be connected to the regulator output. (See Figure 3-1). —2 V DD Power supply voltage input. 3 3 NC Not connected. 4 4 GND Ground terminal. 5 5 LX Inductor switch output. LX is the drain of an internal N-channel switching transistor. This terminal drives the external inductor, which ultimately provides current to the load.
DS21372B-page 4 2002 Microchip Technology Inc.
3.0 DETAILED DESCRIPTION
The TC125/126 are PFM step-up DC/DC regulators for use in systems operating from two or more cells or in low voltage, line powered applications. Because Pulse Frequency Modulation (PFM) is used, the TC125/126 switching frequency (and therefore supply current) is minimized at low output loads. This is especially important in battery operated applications (such as pagers) that operate in standby mode most of the time. For example, a TC125/126 with a 3V output and no load will consume a maximum supply current of only 10µA versus a supply current of 40 µA maximum when I OUT = 30mA. Both devices require only an external inductor, diode and capacitor to implement a complete DC/DC converter. The TC125 is recommended for applications requiring shutdown mode as a means of reducing system supply current. The TC125 is powered from the PS input, which must be connected to the regulated output as shown in Figure 3-1. PS also senses output voltage for closed-loop regulation. Start-up current is furnished through the inductor when input voltage is initially applied. This action starts the oscillator, causing the voltage at the PS input to rise, bootstrapping the regulator into full operation. The TC126 (Figure 3-2) is recommended for all appli- cations not requiring shutdown mode. It has separate V DD and SENSE inputs, allowing it to be powered from any source of 2.2V to 10V in the system. The VDD input of the TC126 may be connected to the VIN,V OUT,o ra n external DC voltage. Lower values of V DD result in lower supply current, but lower efficiency due to higher switch ON resistance. Higher V DD values increase supply current, but drive the internal switching transistor harder (lowering RDS ON), thereby increasing efficiency.
3.1 Low Power Shutdown Mode
The TC125 enters a low power shutdown mode when SHDN is brought low. While in shutdown, the oscillator is disabled and the internal switch is shut off. Normal regulator operation resumes when SHDN is brought high. Because the TC125 uses an external diode, a leakage path between the input voltage and the output node (through the inductor and diode) exists while the regulator is in shutdown. Care must be taken in system design to assure the input supply is isolated from the load during shutdown.
3.2 Behavior When V IN is Greater
Than the Factory-Programmed OUT Setting The TC125 and TC126 are designed to operate as step-up regulators only. As such, V IN is assumed to always be less than the factory-programmed output voltage setting (V R). Operating the TC125/126 with VIN >V R causes regulating action to be suspended (and corresponding supply current reduction) until V IN is again less than V R. While regulating action is suspended, VIN is connected to the output voltage node through the series combination of the inductor and Schottky diode. Again, care must be taken to add the appropriate isolation (MOSFET series switch or post LDO with shutdown) during system design if this V IN/ VOUT leakage path is problematic. FIGURE 3-1: TYPICAL TC125 CIRCUIT FIGURE 3-2: TYPICAL TC126 CIRCUIT 100µH Sumida CD54 D1 MA735 Shutdown Control 1 2 3 5 4 TC125 LX SHDN NCPS GND 1.5V ON OFF VOUT 3.3V @40mA 47µF/16V Tantalum 1 2 3 TC126 LX SENSE NCVDD GND 3.3V Line Supply 100µH Sumida CD54 MA735 VOUT 5V @80mA 47µF/16V Tantalum
2002 Microchip Technology Inc. DS21372B-page 5 TC125/TC126
4.0 APPLICATIONS
4.1 Input Bypass Capacitors
Adding an input bypass capacitor reduces peak current transients drawn from the input supply and reduces the switching noise generated by the regulator. The source impedance of the input supply determines the size of the capacitor that should be used.
4.2 Inductor Selection
Selecting the proper inductor value is a trade-off between physical size and power conversion require- ments. Lower value inductors cost less, but result in higher ripple current and core losses. They are also more prone to saturate since the coil current ramps to a higher value. Larger inductor values reduce both ripple current and core losses, but are larger in physical size and tend to increase the start-up time slightly. The recommended inductor value for use with the TC125/ 126 is 100 µH. Inductors with a ferrite core (or equiva- lent) are recommended. For highest efficiency, use an inductor with a series resistance less than 20m Ω.
4.3 Internal Transistor Switch Current
The peak switch current is equal to the input voltage divided by the RDS ON of the internal switch. The internal transistor has absolute maximum current rating of 400mA with a design limit of 350mA. A built-in oscillator fre quency doubling circuit guards against high switching currents. Should the voltage on the LX pin rise above 1.1V, max while the internal N-channel switch is ON, the oscillator frequency automatically doubles to minimize ON time. Although reduced, switch current still flows because the regulator remains in operation. Therefore, the LX input is not internally current limited and care must be taken never to exceed the 350mA maximum limit. Failure to observe this will result in damage to the regulator.
4.4 Output Diode
For best results, use a Schottky diode such as the MA735, 1N5817, MBR0520L or equivalent. Connect the diode between the PS and LX pins (TC125) or SENSE and LX pins (TC126) as close to the IC as possible. (Do not use ordinary rectifier diodes since the higher threshold voltages reduce efficiency.)
4.5 Output Capacitor
The effective series resistance of the output capacitor directly affects the amplitude of the output voltage ripple. (The product of the peak inductor current and the ESR determines output ripple amplitude.) There- fore, a capacitor with the lowest possible ESR should be selected. Smaller capacitors are acceptable for light loads or in applications where ripple is not a concern. The Sprague 595D series of tantalum capacitors are among the smallest of all low ESR surface mount capacitors available. Table 4-1 lists suggested components and suppliers.
4.6 Board Layout Guidelines
As with all inductive switching regulators, the TC125/ 126 generate fast switching waveforms that radiate noise. Interconnecting lead lengths should be minimized to keep stray capacitance, trace resistance, and radiated noise as low as possible. In addition, the GND pin, input bypass capacitor, and output filter capacitor ground leads should be connected to a single point. The input capacitor should be placed as close to power and ground pins of the TC125/126 as possible. TABLE 4-1: SUGGESTED COMPONENTS AND SUPPLIERS Type Inductors Capacitors Diodes Surface Mount Sumida CD54 Series CDR125 Series Coiltronics CTX Series Murata LQN6C Series Matsuo
267 Series
DS21372B-page 6 2002 Microchip Technology Inc.
5.0 TYPICAL CHARACTERISTICS
(Unless Otherwise Specified, All Parts Are Measured At Temperature = 25°C) Note: The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. 0 20 40 60 80 100 OUTPUT CURRENT IOUT (mA) 3.5 OUTPUT VOLTAGE VOUT (V) Output Voltage vs. Output Current TC125/126 1.0 2.0 2.5 L = 100µH, C = 47µF (Tantalum) 3.0 1.5 0.5 0 20 40 60 80 100 OUTPUT CURRENT IOUT (mA) OUT (V) L = 100µ µF (Tantalum) VVININ V = 0.9V VV1.2V 1.5V 1.8V 3.0V3.0V 2.0V 1.5V 1.2V VVIN V = 0.9V Output Voltage vs. Output Current TC125/126 0 20 40 60 80 100 OUTPUT CURRENT IOUT (mA) EFFICIENCY EFFI (%) Efficiency vs. Output Current TC125/126 L = 100µH, C = 47µF (Tantalum) 100 0 20 40 60 80 100 OUTPUT CURRENT IOUT (mA) EFFICIENCY EFFI (%) L = 100µ µF (Tantalum) 100 VIN = 1.8V = 1.8V 1.5V1.2VV1.2V0.9V VVIN = 3.0V = 3.0V 1.5V1.2V0.9V 2.0V2.0V Efficiency vs. Output Current TC125/126
2002 Microchip Technology Inc. DS21372B-page 7 TC125/TC126
6.0 PACKAGING INFORMATION
6.1 Package Marking Information
(100kHz) Voltage 1 represents product classification; TC125 = L TC126 = N 2 represents first integer of voltage Symbol (100kHz) Voltage 0. 0 1. 1 2. 2 3. 3 4. 4 5. 5 6. 6 7. 7 8. 8 9. 9 3 represents first decimal of voltage 4 represents production lot ID code
DS21372B-page 8 2002 Microchip Technology Inc.
6.2 Taping Form
6.3 Package Dimensions
Component Taping Orientation for 5-Pin SOT-23A (EIAJ SC-74A) Devices Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 5-Pin SOT-23A 8 mm 4 mm 3000 7 in Carrier Tape, Number of Components Per Reel and Reel Size User Direction of Feed Device Marking PIN 1 Standard Reel Component Orientation TR Suffix Device (Mark Right Side Up) W P .071 (1.80) .059 (1.50) .122 (3.10) .098 (2.50) .075 (1.90) REF. .020 (0.50) .012 (0.30) PIN 1 .037 (0.95) REF. .122 (3.10) .106 (2.70) .057 (1.45) .035 (0.90) .006 (0.15) .000 (0.00) .024 (0.60) .004 (0.10) .004 (0.09) SOT-23A-5 Dimensions: inches (mm)
2002 Microchip Technology Inc. DS21372B-page9 TC125/TC126 Sales and Support Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom- mended workarounds. T o determine if an errata sheet exists for a particular device, please contact one of the following: 1. Your local Microchip sales office 2. The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277 3. The Microchip Worldwide Site (www.microchip.com) Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
DS21372B-page10 2002 Microchip Technology Inc. NOTES:
2002 Microchip Technology Inc. DS2372B-page 11 TC125/TC126 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 T echnology 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 com- ponents in life support systems is not authorized except with express written approval by Microchip. No licenses are con- veyed, implicitly or otherwise, under any intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, FilterLab, K EELOQ,m i c r o I D ,M P L A B ,P I C ,P I C m i c r o ,P I C M A S T E R , PICSTART, PRO MATE, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Tech- nology Incorporated in the U.S.A. and other countries. dsPIC, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, microPort, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, MXDEV, MXLAB, PICC, PICDEM, PICDEM.net, rfPIC, Select Mode and T otal Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. Serialized Quick Turn 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. © 2002, 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 and Mountain View, California in March 2002. The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro ® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, non-volatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified.
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