TK11811 DC-DC CONVERTER FEATURES APPLICATIONS ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Miniature Package (SOT-23L) Low Start-up Voltage [0.6 V (typ.)] Few External Components Selectable Output Voltage (1.9 V or 2.8 V) High and Low Current Optimized Designs Pagers Cassette Recorders Cordless Telephones Portable Instrumentation Radio Control Systems Mobile Radios Battery Operated Equipment Local Area Network (LAN) Receivers DESCRIPTION The TK11811 is a low power, low input voltage DC-DC converter. TK11811 This device can be optimized for use in high or low current applications through component selection. The output voltage is selectable for 1.9 or 2.8 V operation and can be trimmed to any voltage in between. VIN T FB 20 P The frequency of the built-in relaxation oscillator is set by external components. The internal voltage regulator provides a stable output voltage. Optimized Toko inductor components are available. GND OSC VOUT The TK11811 is available in a miniature SOT-23L surface mount package. BLOCK DIAGRAM VIN FB OSC VOUT ORDERING INFORMATION TK11811M Tape/Reel Code T Vref OSCILLATOR + TAPE/REEL CODE TL: Tape Left GND January 1999 TOKO, Inc. Page 1 TK11811 ABSOLUTE MAXIMUM RATINGS Input Voltage ............................................................ 16 V Power Dissipation (Note 1) ................................ 200 mW Junction Temperature ........................................... 150 °C Storage Temperature Range ................... -55 to +150 °C Operating Temperature Range ...................-10 to +65 °C Lead Soldering Temperature (10 s) ...................... 235 °C TK11811 ELECTRICAL CHARACTERISTICS Test Conditions: TA = 25 °C, VOUT = 2.9 V (VOUT to T open), unless otherwise specified. SYMBOL PARAMETER VIN Supply Voltage Range VSTART Start-up Voltage IIN Input Current VOUT Output Voltage VOUT(LOW) Output Voltage (LOW) IOUT Output Current Line Reg Line Regulation Load Reg TEST CONDITIONS MIN TYP MAX UNITS 0.6 14 V IOUT = 0 mA 0.6 0.75 V VIN = 1.1 V, IOUT = 3 mA 11.0 mA VIN = 1.4 V, IOUT = 3 mA 8.3 mA VIN = 1.1 V, IOUT = 3 mA 2.85 V VIN = 1.4 V, IOUT = 3 mA 2.70 2.85 3.0 V VIN = 1.1 V, IOUT = 3 mA, T to VOUT connected 1.75 1.90 2.05 V VIN = 1.1 V 4.0 4.5 mA VIN = 1.4 V 6.0 6.8 mA IOUT = 3 mA, 1.1 V ≤ VIN ≤ 2.0 V 10 mV Load Regulation VIN = 1.1 V, 0.5 mA ≤ IOUT ≤ 3 mA 45 mV EFF Efficiency VIN = 1.4 V, IOUT = 3 mA 72 % FOSC Oscillator Frequency VIN = 1.4 V, IOUT = 3 mA, (Note 2) 300 kHz ∆VOUT /∆T Temperature Coefficient VIN = 1.4 V, IOUT = 3 mA 0.7 mV/° C 63 Note 1: Power dissipation is 400 mW when mounted as recommended. Derate at 3.2 mW/°C for operation above 25 °C. Power dissipation is 200 mW when in Free Air. Derate at 1.6 mW/°C for operation above 25 °C. Note 2: This IC is a frequency-controlled DC-DC converter; thus the value is varied by condition. Page 2 January 1999 TOKO, Inc. TK11811 TEST CIRCUIT R1 10 KΩ VIN C1 10 µF 3 + VIN C2 3300 pF 1 R2 22 KΩ L 4 Di T (See “Voltage Adjustment Circuit”) FB GND OSC VOUT VOUT 6 + C3 10 µF Note: Di: IS2837,38 (NEC) L: Toko 395KN-0369AQ Toko PS5CDL-1639X TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise specified. EFFICIENCY VS. OUTPUT CURRENT (VOUT = 1.9 V) OUTPUT VOLTAGE VS. OUTPUT CURRENT (VOUT = 1.9 V) 1.6 V 1.5 1.4 V 1.2 V 50 1.0 V .5 0.8 V VIN = 0.6 V 0.8 V VIN = 0.6 V 0 2 4 0 6 1.4 V 1.0 V 1.2 V 1.0 4 1.6 V VOUT (V) 2.0 EFF (%) VOUT (V) 5 100 2.5 0 OUTPUT VOLTAGE VS. OUTPUT CURRENT (VOUT = 2.8 V, ILOAD = 0 mA) 8 10 0 3 1.6 V 2 1.0 V 1 5 0 10 IOUT (mA) IOUT (mA) EFFICIENCY VS. OUTPUT CURRENT (VOUT = 2.8 V) INPUT CURRENT VS. INPUT VOLTAGE (IOUT = 0 mA) 0.8 V 1.4 V 1.2 V VIN = 0.6 V .5 5 10 IOUT (mA) OUTPUT VOLTAGE DRIFT VS. TEMPERATURE +50 100 ∆VOUT (mV) 1.2 V 50 VOUT = 2.8 V 200 IIN (µA) EFF (%) 1.6 V 1.4 V 1.0 V 100 0.8 V 0 VOUT = 1.9 V VIN = 0.6 V 0 5 IOUT (mA) January 1999 TOKO, Inc. 10 0 0 10 VIN (V) 20 -50 -50 0 50 100 TA (°C) Page 3 TK11811 TEST CIRCUIT R1 10 KΩ VIN 3 + C1 10 µF VIN C2 3300 pF 1 R2 22 KΩ L 4 Di T FB GND OSC VOUT (See “Voltage Adjustment Circuit”) VOUT 6 + C3 10 µF Note: L: Toko 395KN-0370UG Note: This test circuit is effective at low load current. TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise specified. EFFICIENCY VS. OUTPUT CURRENT OUTPUT VOLTAGE VS. OUTPUT CURRENT INPUT CURRENT VS. INPUT VOLTAGE (IOUT = 0 mA) 100 3 200 VOUT = 2.8 V EFF (%) VOUT (V) 1.6 V 1.4 V 2 1.4 V 50 1.2 V 1.0 V 0.8 V 1 2 3 IOUT (mA) Page 4 1.2 V VIN = 0.8 V VIN = 0.6 V 0 100 VOUT = 1.9 V 1.0 V 1 IIN (µA) 1.6 V 4 5 0 0 0 1 2 3 IOUT (mA) 4 5 0 10 20 VIN (V) January 1999 TOKO, Inc. TK11811 TEST CIRCUIT R1 10 KΩ VIN VIN C2 0.1 µF 3 + C1 10 µF 1 R2 22 KΩ L 4 Di T FB GND OSC VOUT RIPPLE FILTER VOUT Rf 6 + + L: Toko 395KN-0369AQ C3 10 µF Cf Note: This test circuit is effective at high load currents. By changing C2 from 3300pF to 0.1 µF, the converter operates in the burst mode. The apparent frequency of operation drops (70 to 100 kHz) and a larger output ripple occurs during burst mode operation. A ripple filter consisting of Cf and Rf can be added to the output to reduce noise. The values of Cf and Rf should be determined experimentally based on the design parameters. The output voltage will drop slightly due to Rf. TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise specified. OUTPUT VOLTAGE VS. OUTPUT CURRENT EFFICIENCY VS. OUTPUT CURRENT 5 100 1.4 V EFF (%) VOUT (V) 4 1.4 V 3 50 2 1.2 V 0.8 V VIN = 0.6 V 1 0 0 2 4 1.2 V 1.0 V VIN = 0.6 V 0.8 V 6 IOUT (mA) January 1999 TOKO, Inc. 1.0 V 8 10 0 0 5 10 IOUT (mA) Page 5 TK11811 VOLTAGE ADJUSTMENT CIRCUIT T R VOUT VOUT 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 R 0 12 k 22 k 33 k 56 k 82 k 150 k 330 k 560 k * Note: The output voltage can be set between 1.9 V and 2.8 V with an external resistor connected between pins 4 and 6. ADDITIONAL INFORMATION APPLICATION INFORMATION Maximize copper foil area connecting to all IC pins for optimum performance. Place input and output bypass capacitors close to the GND pin. For best transient behavior and lowest output impedance use as large a capacitor value as possible. The temperature coefficient of the capacitance and Equivalent Series Resistant (ESR) should be taken into account. These parameters can influence power supply noise and ripple rejection. In extreme cases, oscillation may occur. In order to maintain stability, the output bypass capacitor value should be minimum 10 µF in case of tantalum electrolytic or 15 µF in case of aluminum electrolytic. HANDLING MOLDED RESIN PACKAGES All plastic molded packages absorb some moisture from the air. If moisture absorption occurs prior to soldering the device into the printed circuit board, increased separation of the lead from the plastic molding may occur, degrading the moisture barrier characteristics of the device. This property of plastic molding compounds should not be overlooked, particularly in the case of very small packages where the plastic is very thin. In order to preserve the original moisture barrier properties of the package, devices are stored and shipped in moisture proof bags filled with dry air. The bags should not be opened or damaged prior Page 6 to actual use of the devices. If this is unavoidable, the devices should be stored in a low relative humidity environment (40 to 65 %) or in an enclosed environment with desiccant. INDUCTOR NOTES The output current and efficiency are largely dependant upon the coil used. A coil with lower DC resistance is generally better in efficiency than one with a higher DCR (DC Resistance). The recommended TOKO 395KN-0369 AQ is 1:1 turns ratio transformer with an inductance of 110 µH and Toko 395KN-0370UG is 1:3 turns ratio transformer with inductance of 60 µH:600 µH. These coils, or equivalent, should be used. Smaller coils with higher DCR will not perform as well as the above coil, and the oscillator will not be stable. FEEDBACK RC TIME CONSTANT If a different coil is used other than the one mentioned, the RC time constant of the feedback loop will need to be adjusted for optimum performance. Generally, a lower resistance will give more output current. In fact, R can be zero; however, lower resistance will sacrifice efficiency at low output currents as the quiescent current increases. If the capacitance is increased beyond or below a certain value, the oscillator will become unstable. The optimum January 1999 TOKO, Inc. TK11811 ADDITIONAL INFORMATION (CONT.) RC values depend upon the operating current, and should be chosen experimentally using the given values of 3300 pF and 22 kΩ as a starting point. INPUT/OUTPUT DECOUPLING CAPACITORS DC-DC converters generate a large ripple current on both the input and the output of the circuit. The capacitors used should be as large as possible and have low impedance in the 300 kHz range. Since low temperatures cause capacitors to decrease capacitance and increase Equivalent Series Resistance (ESR), care should be taken to choose capacitors that have acceptable characteristics over the temperature range you intend to use. This should be done experimentally to verify results, as capacitor performance varies widely from manufacturer to manufacturer. Tantalum capacitors are generally the best choice and 10 µF should be adequate for most applications. LOAD CHARACTERISTICS The TK11811 should not be allowed to start-up under full load conditions. If this occurs, the output may not stabilize to the correct output voltage. This can be compensated for, somewhat, by adjusting the RC of the feedback loop or by decreasing the output decoupling capacitor. Maximum current can be drawn after the oscillator has started and the output has reached nominal output voltage. This is more critical with input voltages under 1.3 V as the converter needs to generate sufficient output to ensure correct internal bandgap and bias voltages. January 1999 TOKO, Inc. Page 7 TK11811 PACKAGE OUTLINE Marking Information SOT-23L (SOT-23L-6) TK11811 Marking D1 0.6 6 5 4 e1 3.0 1.0 Marking 1 2 3 0.32 e +0.15 - 0.05 0.1 e 0.95 M e 0.95 e 0.95 3.5 0.95 Recommended Mount Pad +0.3 - 0.1 2.2 max 15 1.2 0.15 0.1 +0.15 - 0.05 0 - 0.1 1.4 max 0.3 (3.4) 0.4 + 0.3 3.3 Dimensions are shown in millimeters Tolerance: x.x = ± 0.2 mm (unless otherwise specified) Toko America, Inc. Headquarters 1250 Feehanville Drive, Mount Prospect, Illinois 60056 Tel: (847) 297-0070 Fax: (847) 699-7864 TOKO AMERICA REGIONAL OFFICES Midwest Regional Office Toko America, Inc. 1250 Feehanville Drive Mount Prospect, IL 60056 Tel: (847) 297-0070 Fax: (847) 699-7864 Western Regional Office Toko America, Inc. 2480 North First Street , Suite 260 San Jose, CA 95131 Tel: (408) 432-8281 Fax: (408) 943-9790 Eastern Regional Office Toko America, Inc. 107 Mill Plain Road Danbury, CT 06811 Tel: (203) 748-6871 Fax: (203) 797-1223 Semiconductor Technical Support Toko Design Center 4755 Forge Road Colorado Springs, CO 80907 Tel: (719) 528-2200 Fax: (719) 528-2375 Visit our Internet site at http://www.tokoam.com The information furnished by TOKO, Inc. is believed to be accurate and reliable. However, TOKO reserves the right to make changes or improvements in the design, specification or manufacture of its products without further notice. TOKO does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. No license is granted by implication or otherwise under any patent or patent rights of TOKO, Inc. Page 8 © 1999 Toko, Inc. All Rights Reserved January 1999 TOKO, Inc. IC-134-TK11811 0798O0.0K Printed in the USA