View TC105303ECT_132094.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

TC105
PFM/PWM Step-Down DC/DC Controller
Features
* * * * 57A (Typ) Supply Current 1A Output Current 0.5A Shutdown Mode 300kHz Switching Frequency for Small Inductor Size * Programmable Soft-Start * 92% Typical Efficiency * Small Package: 5-Pin SOT-23A
Package Type
5-Pin SOT-23A
VOUT 5 SHDN 4
TC105
1 EXT 2 VDD 3 GND
Applications
* * * * * * * Palmtops Battery-Operated Systems Portable Instruments Positive LCD Bias Generators Portable Communicators Hand-Held Scanners 5V to 3V Down Converters
NOTE: 5-Pin SOT-23A is equivalent to the EIAJ SC-74A
General Description
The TC105 is a step-down (Buck) switching controller that furnishes output currents of up to 1A (max) while delivering a typical efficiency of 92%. The TC105 normally operates in pulse width modulation mode (PWM), but automatically switches to pulse frequency modulation (PFM) at low output loads for greater efficiency. Oscillator frequency is 300kHz, allowing use of small (22H) inductors. Supply current draw is only 102A (max), and is reduced to less than 0.5A when the SHDN input is brought low. Regulator operation is suspended during shutdown. The TC105 accepts a maximum input voltage of 10V. The TC105 is available in a small 5-Pin SOT-23A package, occupies minimum board space and is ideal for a wide range of applications.
Device Selection Table
Part Number
TC105503ECT TC105333ECT TC105303ECT
Output Voltage (V)*
5.0 3.3 3.0
Package
5-Pin SOT-23A 5-Pin SOT-23A 5-Pin SOT-23A
Osc. Freq. (kHz)
300 300 300
Operating Temp. Range
-40C to +85C -40C to +85C -40C to +85C
*Other output voltages are available. Please contact Microchip Technology Inc. for details.
Functional Block Diagram
L1 22H (Sumida CD54) RSS 470K D1 MA737 CSS 0.033F 3.3V VOUT
OFF ON (From System Control Logic)
5
VOUT
4
SHDN
C2 47F 10V Tantalum
TC105333ECT
EXT VDD GND
1
2
3
Si 9430 P + VBATT 6V - NiMH
C1 10F/16V
3.3V Regulated Supply Using 6V NiMH Battery Pack Input
2002 Microchip Technology Inc.
DS21349B-page 1
(c)
TC105
1.0 ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings*
Voltage on VDD ....................................... -0.3V to +12V EXT Output Current ........................................100mA Voltage on VOUT, EXT, SHDN Pins .....................................-0.3V to VDD +0.3V Power Dissipation.............................................150mW Operating Temperature Range............. -40C to +85C Storage Temperature Range .............. -40C to +125C
*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.
TC105 ELECTRICAL SPECIFICATIONS
Electrical Characteristics: Note 1, fOSC = 300 kHz; TA = 25C, unless otherwise noted. Symbol VDD VDDMIN IDD ISTBY ISHDN fOSC VOUT Parameter Operating Supply Voltage Minimum Input Voltage Operating Supply Current Standby Supply Current Shutdown Supply Current Oscillator Frequency Output Voltage Min 2.2 0.9 -- -- -- -- -- 255 VR x 0.975 100 15 0.65 -- -- -- -- -- -- -- -- Typ -- -- 57 67 15 16 -- 300 VR -- 25 -- -- 17 16 12 15 14 10 92 Max 10.0 2.2 102 122 27 29 0.5 345 VR x 1.025 -- 35 -- 0.20 24 22 17 20 19 14 -- % % V V IOUT = 0mA VOUT = 0V, No external components VOUT = 0V, No external components No external components; VR = 3.0V VR = 3.3V VR = 5.0V VOUT = SHDN = VIN , VEXT = (VIN - 0.4V) No external components; VR = 3.0V VR = 3.3V VR = 5.0V VOUT = 0V, SHDN = VIN, VEXT = 0.4V Units V V A A A kHz EXT = High; No external components; VOUT = 0V, SHDN = VIN No external components; VR = 3.0V, 3.3V VOUT = 0V, SHDN = VIN VR = 5.0V No external components; VR = 3.0V, 3.3V VOUT = SHDN = VIN VR = 5.0V SHDN = GND VIN = VOUT + 0.3V Note 2 Test Conditions
DTYMAX Maximum Duty Cycle (PWM Mode) DTYPFM Duty Cycle (PFM Mode) VIH VIL REXTH SHDN Input Logic High SHDN Input Logic Low EXT ON Resistance to VDD
REXTL
EXT ON Resistance to GND
Note 1:
Efficiency
VR = 3.0V, VIN = 4.5V, IOUT = 200mA VR = 3.3V, VIN = 5.0V, IOUT = 220mA VR = 5.0V, VIN = 7.5V, IOUT = 320mA VR is the factory output voltage setting.
%
2:
(c)
DS21349B-page 2
2002 Microchip Technology Inc.
TC105
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
Pin No. (5-Pin SOT-23A) 1 2 3 4
PIN FUNCTION TABLE
Symbol EXT VDD GND SHDN Description Switch transistor control output. This terminal connects to the gate of an external P-channel MOSFET (or to the base of an external PNP transistor through a current limiting resistor). Power supply voltage input. Ground terminal. Shutdown input (active low). The device enters a low power shutdown state when this input is brought low. During shutdown, regulator action is suspended, and supply current is reduced to less than 0.5A. The device resumes normal operation when SHDN is again brought high. Voltage sense input. This input senses output voltage for regulation and must be connected to the output voltage node as shown in the application schematic in this data sheet.
5
VOUT
2002 Microchip Technology Inc.
DS21349B-page 3
(c)
TC105
3.0 DETAILED DESCRIPTION
3.4 Input Bypass Capacitors
The TC105 is a PFM/PWM step-down DC/DC controller for use in systems operating from two or more cells, or in line-powered applications. It uses PWM as the primary modulation scheme, but automatically converts to PFM at output duty cycles less than approximately 10%. The conversion to PFM provides reduced supply current, and therefore higher operating efficiency at low loads. The TC105 uses an external switching transistor, allowing construction of switching regulators with output currents of up to 1A. The TC105 consumes only 102A, max, of supply current when VIN = 5V and VOUT = 3.3V, and can be placed in a 0.5A shutdown mode by bringing the shutdown input (SHDN) low. The regulator remains disabled while in shutdown mode, and output voltage discharges to zero through the load. Normal operation resumes when SHDN is brought high. Other features include a built-in undervoltage lockout (UVLO) and externally programmable soft start time. Using 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.
3.5
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.) Therefore, 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.
3.1
Low Power Shutdown Mode
3.6
Inductor Selection
The TC105 enters a low power shutdown mode when SHDN is brought low. While in shutdown, the oscillator is disabled and the output switch is shut off. Normal regulator operation resumes when SHDN is again brought high. SHDN may be tied to the input supply if not used.
3.2
Soft Start
Soft start allows the output voltage to gradually ramp from 0 to rated output value during start-up. This action minimizes (or eliminates) overshoot, and in general, reduces stress on circuit components. Figure 4-1 shows the circuit required to implement soft start (values of 470K and 0.033F for R SS and CSS respectively, are adequate for most applications).
Selecting the proper inductor value is a trade-off between physical size and power conversion requirements. 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 faster and could overshoot the desired peak value. This not only reduces efficiency, but could also cause the current rating of the external components to be exceeded. 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. A 22H inductor is recommended as the best overall compromise. For highest efficiency, use inductors with a low DC resistance (less than 20 m). To minimize radiated noise, consider using a toroid, pot core or shielded-bobbin inductor.
3.3
Undervoltage Lockout (UVLO)
3.7
Output Diode
The TC105 is disabled when VIN is below the undervoltage lockout threshold. This threshold is equal to the guaranteed minimum operating voltage for the TC105 (i.e., 2.2V). When UVLO is active, the TC105 is completely disabled.
The high operating frequency of the TC105 requires a high-speed diode. Schottky diodes such as the MA737 or 1N5817 through 1N5823 (and the equivalent surface mount versions) are recommended. Select a diode whose average current rating is greater than the peak inductor current and whose voltage rating is higher than VDDMAX.
(c)
DS21349B-page 4
2002 Microchip Technology Inc.
TC105
3.8 External Switching Transistor Selection
3.8.1 BOARD LAYOUT GUIDELINES
As with all inductive switching regulators, the TC105 generates fast switching waveforms, which 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 TC105 as possible. The length of the EXT trace must also be kept as short as possible.
EXT is a complementary output with a maximum ON resistance of 22 to V DD when high and 19 to ground when low. It is designed to directly drive a P-channel MOSFET or a PNP bipolar transistor through a base current limiting resistor (Figure 4-2). A PNP transistor is recommended in applications where VIN is less than 2.5V. Otherwise, a P-channel MOSFET is preferred as it affords the highest efficiency because it does not draw any gate drive current. However, P-channel MOSFETs are typically more expensive than bipolar transistors. P-channel MOSFET selection is determined mainly by the on-resistance, gate-source threshold, and gate charge requirements. Also, the drain-to-source and gate-to-source breakdown voltage ratings must be greater than VDDMAX. The total gate charge specification should be less than 100nC for best efficiency. The MOSFET must be capable of handling the required peak inductor current, and should have a very low on-resistance at that current. For example, an Si9430 MOSFET has a drain-to-source rating of -20V, and a typical on-resistance rDSON of 0.07 at 2A, with VGS = -4.5V. Table 4-1 lists suppliers of external components recommended for use with the TC105.
2002 Microchip Technology Inc.
DS21349B-page 5
(c)
TC105
4.0
4.1
APPLICATIONS
Circuit Examples
FIGURE 4-1:
SOFT START CIRCUIT
RSS 470K +
4 SHDN/SS
Figure 4-3 shows a TC105 using a PNP switching transistor (Zetex FZT749) that has an hFE of 180 and VCESAT of 100 mV at IC = 1A. Other high beta transistors can be used, but the values of RB and CB may need adjustment if hFE is significantly different from that of the FZT749. The circuit of Figure 4-4 utilizes a P-channel MOSFET switching transistor (Silconix Si9430). This transistor is a member of the LittlefootTM family of small outline MOSFETs.
VIN CSS 0.033F
-
TC105
Shutdown Not Used
RSS 470K SHDN + CSS 0.033F OFF ON (From System Control Logic)
4 SHDN/SS
-
TC105
Shutdown Used
FIGURE 4-2:
VIN P
EXTERNAL TRANSISTOR CONNECTION
L D + - VOUT CL VIN Q + D - CL L VOUT
TC105
EXT 1
RB
+ -
CB
TC105
EXT 1
P-Channel MOSFET
PNP Bipolar Transistor
(c)
DS21349B-page 6
2002 Microchip Technology Inc.
TC105
FIGURE 4-3: REGULATOR USING PNP TRANSISTOR
FZ749 Q1 10F 16V - 22H Sumida CD-54
VIN 2.5V
+
+
MA737
-
47F 10V Tantalum
VOUT 1.8V RSS 470K OFF ON
5 VOUT CB 2200 pF -
4 SHDN/SS
+ -
CSS 0.033F
+
RB 500 EXT 1
TC105
VDD 2 GND 3
FIGURE 4-4:
REGULATOR USING P-CHANNEL MOSFET
Si9430 P VIN 10F 16V - 22H Sumida CD-54
+
+
MA737
-
47F 10V Tantalum
VOUT RSS 470K OFF ON CSS 0.033F
+
5 VOUT 4 SHDN/SS
-
TC105
EXT 1 VDD 2 GND 3
TABLE 4-1:
Type Surface Mount
SUGGESTED COMPONENTS AND SUPPLIERS
Inductors Sumida CD54 Series CDRH Series Coilcraft DO Series Capacitors AVX TPS Series Sprague 595D Series Diodes ON Semiconductor MBRS340T3 Nihon NSQ Series Matsushita MA737 Sanyo OS-CON Series Nichicon PL Series United Chemi-Con LXF Series IRC OAR Series ON Semiconductor TMOS Power MOSFETs (i.e., MTP30P06V) Transistors Silconix Little Foot MOSFET Series Zetex FZT749 PNP Bipolar Transistor Toshiba 2SA1213 PNP Transistor
Miniature Through-Hole Standard Through-Hole
Sumida RCH Series Coilcraft PCH Series Coiltronics CTX Series
2002 Microchip Technology Inc.
DS21349B-page 7
(c)
TC105
5.0
5.1
PACKAGING INFORMATION
Package Marking Information
3
represents first decimal of voltage Symbol (300kHz) A B C D E F H K L M Voltage .0 .1 .2 .3 .4 .5 .6 .7 .8 .9
1
represents product classification; TC105 = M represents first integer of voltage Symbol (300kHz) 1 2 3 4 5 6 Voltage 1. 2. 3. 4. 5. 6.
2
4
represents production lot ID code
(c)
DS21349B-page 8
2002 Microchip Technology Inc.
TC105
5.2 Taping Form
Component Taping Orientation for 5-Pin SOT-23A (EIAJ SC-74A) Devices
User Direction of Feed
Device Marking
W
PIN 1
P Standard Reel Component Orientation TR Suffix Device (Mark Right Side Up)
Carrier Tape, Number of Components Per Reel and Reel Size
Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size
5-Pin SOT-23A
8 mm
4 mm
3000
7 in
5.3
Package Dimensions
SOT-23A-5
.075 (1.90) REF.
.122 (3.10) .098 (2.50) .020 (0.50) .012 (0.30) PIN 1 .122 (3.10) .106 (2.70) .057 (1.45) .035 (0.90) .006 (0.15) .000 (0.00)
.071 (1.80) .059 (1.50)
.037 (0.95) REF.
10 MAX. .024 (0.60) .004 (0.10)
.010 (0.25) .004 (0.09)
Dimensions: inches (mm)
2002 Microchip Technology Inc.
DS21349B-page 9
(c)
TC105
NOTES:
(c)
DS21349B-page 10
2002 Microchip Technology Inc.
TC105
Sales and Support
Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. 2. 3. Your local Microchip sales office The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277 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.
2002 Microchip Technology Inc.
DS21349B-page11
TC105
NOTES:
DS21349B-page12
2002 Microchip Technology Inc.
TC105
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, FilterLab, KEELOQ, microID, MPLAB, PIC, PICmicro, PICMASTER, PICSTART, PRO MATE, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology 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 Total 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. (c) 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 (R) 8-bit MCUs, KEELOQ(R) 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.
2002 Microchip Technology Inc.
DS21349B-page 13
(c)
WORLDWIDE SALES AND SERVICE
AMERICAS
Corporate Office
2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: 480-792-7627 Web Address: http://www.microchip.com
ASIA/PACIFIC
Australia
Microchip Technology Australia Pty Ltd Suite 22, 41 Rawson Street Epping 2121, NSW Australia Tel: 61-2-9868-6733 Fax: 61-2-9868-6755
Japan
Microchip Technology Japan K.K. Benex S-1 6F 3-18-20, Shinyokohama Kohoku-Ku, Yokohama-shi Kanagawa, 222-0033, Japan Tel: 81-45-471- 6166 Fax: 81-45-471-6122
Rocky Mountain
2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7966 Fax: 480-792-7456
China - Beijing
Microchip Technology Consulting (Shanghai) Co., Ltd., Beijing Liaison Office Unit 915 Bei Hai Wan Tai Bldg. No. 6 Chaoyangmen Beidajie Beijing, 100027, No. China Tel: 86-10-85282100 Fax: 86-10-85282104
Korea
Microchip Technology Korea 168-1, Youngbo Bldg. 3 Floor Samsung-Dong, Kangnam-Ku Seoul, Korea 135-882 Tel: 82-2-554-7200 Fax: 82-2-558-5934
Atlanta
500 Sugar Mill Road, Suite 200B Atlanta, GA 30350 Tel: 770-640-0034 Fax: 770-640-0307
Singapore
Microchip Technology Singapore Pte Ltd. 200 Middle Road #07-02 Prime Centre Singapore, 188980 Tel: 65-6334-8870 Fax: 65-6334-8850
Boston
2 Lan Drive, Suite 120 Westford, MA 01886 Tel: 978-692-3848 Fax: 978-692-3821
China - Chengdu
Microchip Technology Consulting (Shanghai) Co., Ltd., Chengdu Liaison Office Rm. 2401, 24th Floor, Ming Xing Financial Tower No. 88 TIDU Street Chengdu 610016, China Tel: 86-28-86766200 Fax: 86-28-86766599
Taiwan
Microchip Technology Taiwan 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
Chicago
333 Pierce Road, Suite 180 Itasca, IL 60143 Tel: 630-285-0071 Fax: 630-285-0075
Dallas
4570 Westgrove Drive, Suite 160 Addison, TX 75001 Tel: 972-818-7423 Fax: 972-818-2924
China - Fuzhou
Microchip Technology Consulting (Shanghai) Co., Ltd., Fuzhou Liaison Office Unit 28F, World Trade Plaza No. 71 Wusi Road Fuzhou 350001, China Tel: 86-591-7503506 Fax: 86-591-7503521
EUROPE
Denmark
Microchip Technology Nordic ApS Regus Business Centre Lautrup hoj 1-3 Ballerup DK-2750 Denmark Tel: 45 4420 9895 Fax: 45 4420 9910
Detroit
Tri-Atria Office Building 32255 Northwestern Highway, Suite 190 Farmington Hills, MI 48334 Tel: 248-538-2250 Fax: 248-538-2260
China - Shanghai
Microchip Technology Consulting (Shanghai) Co., Ltd. Room 701, Bldg. B Far East International Plaza No. 317 Xian Xia Road Shanghai, 200051 Tel: 86-21-6275-5700 Fax: 86-21-6275-5060
Kokomo
2767 S. Albright Road Kokomo, Indiana 46902 Tel: 765-864-8360 Fax: 765-864-8387
France
Microchip Technology SARL Parc d'Activite du Moulin de Massy 43 Rue du Saule Trapu Batiment A - ler Etage 91300 Massy, France Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79
Los Angeles
18201 Von Karman, Suite 1090 Irvine, CA 92612 Tel: 949-263-1888 Fax: 949-263-1338
China - Shenzhen
Microchip Technology Consulting (Shanghai) Co., Ltd., Shenzhen Liaison Office Rm. 1315, 13/F, Shenzhen Kerry Centre, Renminnan Lu Shenzhen 518001, China Tel: 86-755-2350361 Fax: 86-755-2366086
New York
150 Motor Parkway, Suite 202 Hauppauge, NY 11788 Tel: 631-273-5305 Fax: 631-273-5335
Germany
Microchip Technology GmbH Gustav-Heinemann Ring 125 D-81739 Munich, Germany Tel: 49-89-627-144 0 Fax: 49-89-627-144-44
San Jose
Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955
China - Hong Kong SAR
Microchip Technology Hongkong Ltd. Unit 901-6, Tower 2, Metroplaza 223 Hing Fong Road Kwai Fong, N.T., Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431
Italy
Microchip Technology SRL Centro Direzionale Colleoni Palazzo Taurus 1 V. Le Colleoni 1 20041 Agrate Brianza Milan, Italy Tel: 39-039-65791-1 Fax: 39-039-6899883
Toronto
6285 Northam Drive, Suite 108 Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509
India
Microchip Technology Inc. India Liaison Office Divyasree Chambers 1 Floor, Wing A (A3/A4) No. 11, O'Shaugnessey Road Bangalore, 560 025, India Tel: 91-80-2290061 Fax: 91-80-2290062
United Kingdom
Microchip Ltd. 505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44 118 921 5869 Fax: 44-118 921-5820
05/01/02
(c)
DS21349B-page 14
2002 Microchip Technology Inc.

▲Up To Search▲

Price & Availability of TC105303ECT

	To Download TC105303ECT Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .