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| Global Mixed-mode Technology Inc. G5111 Micro-power Step-Up DC/DC Converters in SOT23-5 Features Configurable Output Voltage Up to 14V 20A Quiescent Current <1A Shutdown Current <1A Shutdown Pin Current Supply Range from 2.5V to 6.5V Low VCESAT: 250mV (ISW=300mA) Tiny SOT23-5 Package General Description The G5111 boost converter is designed for small/ medium size LCD panel of high bias voltage. Due to a typical 20A quiescent current and 2.5V~6.5V supply voltage range, it is suitable for battery powered portable applications. Such as PDAs and Handheld Computers. When the IC sets to shutdown mode, it only consumes less than 1A. Furthermore, the 350mA current limit, 500ns fixed minimum off-time and tiny SOT23-5 package facilitates the use of smaller inductor and other surface-mount components to minimize the PCB size in those space-conscious applications. To control the IC, no other external current is needed for the shutdown pin. It typically consumes less than 1A of full supply range. Applications STN/TFT LCD Bias Personal Digital Assistants (PDAs) Handheld Computers Digital Still Cameras Cellular Phones WebPad White LED Driver Local 3V to 5V Conversion Ordering Information PART G5111 TEMP. RANGE -40C ~ +85C PIN-PACKAGE SOT23-5 Pin Configuration Typical Application Circuit 10H VIN 2.5V to 4.2V 12V 10mA SW 1M SW 1 5 VCC VCC 10pF GND 2 G5111 G963 4.7F G5111 SHDN FB 110k 1F GND FB 3 SOT23-5 4 SHDN Ver 0.2 Preliminary Jan 09, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 1 Global Mixed-mode Technology Inc. Absolute Maximum Ratings SW to GND.........................................-0.3V to +15V FB to GND............... .............................-0.3V to VCC VCC, SHDN to GND.....................................-0.3V to +7V Operating Temperature Range (Note 1) ..-40C to +85C G5111 Junction Temperature ........................................+125C Storage Temperature......................... -65C to +150C Lead Temperature (Soldering, 10 sec)...............+300C Stress beyond those listed under "Absolute Maximum Rating" may cause permanent damage to the device. Electrical Characteristics (VCC = 2.5V, V SHDN = 2.5V, TA = 25C) PARAMETER Input Voltage Range Quiescent Current FB Comparator Trip Point Output Voltage Line Regulation FB Pin Bias Current (Note 2) Switch Off Time Switch VCESAT Switch Current Limit SHDN Pin Current SHDN Input Voltage High SHDN Input Voltage Low CONDITIONS Not Switching V SHDN = 0V TA = 0C ~ 85C 2.5V MIN 2.5 TYP 20 0.1 1.2 0.05 30 500 1.6 250 350 0.1 MAX 6.5 30 1 1.22 80 UNITS V A A V %/V nA ns s mV mA A V V A 1.18 300 0.9 350 400 1 0.25 Switch Leakage Current Switch Off, VSW = 5V 0.01 5 Note 1: The G5111 are guaranteed to meet performance specifications from 0C to 85C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 2: Bias current flows into the FB pin. Block Diagram L1 VIN C1 5 VCC 4 SHDN 1 SW C2 V OUT BIAS VOUT SHUTDOWN LOGIC PUMP CONTROL OC NPN COMP DRIVER en_sw + TOFF PULSE CONTROL R1 3 R2 + ERROR COMP FB 1.2V VREF 2 GND Ver 0.2 Preliminary Jan 09, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 2 Global Mixed-mode Technology Inc. Pin Description PIN 1 2 3 4 5 G5111 NAME SW GND FB SHDN FUNCTION Switch Pin. The collector of the internal NPN power switch. Connect this pin to inductor. Ground. Feedback Pin. Set the output voltage by selecting values for R1 and R2 (see Block Diagram): R1 = R2 VOUT -1 1 .2 VCC Active-Low Shutdown Pin. Tie this pin to logic-high to enable the device or tied it to logic-low to turn this device off. Input Supply Pin. Bypass this pin with a capacitor as close to the device as possible. Function Description The G5111 is a boost converter with a NPN switch embedded (refer to Block Diagram). The boost cycle is getting started when FB pin voltage drop below 1.2V as the NPN switch turns on. During the switch on period, the inductor current ramps up until 350mA current limit is reached. Then turns the switch off, while the inductor current flows through external schottky diode, and ramps down to zero. During the switch off period, the inductor current charges output capacitor and the output voltage is boosted up. This pumping mechanism continues cycle by cycle until the FB pin voltage exceed 1.2V and entering the none switching mode. In this mode, the G5111 consumes as low as 20uA typically to save battery power. Where VD = 0.4V (Schottky diode voltage), ILIM = 350mA and tOFF = 500ns. A larger value can be used to lightly increase the available output current, but limit it to about twice the calculating value. When too large of an inductor will increase the output voltage ripple without providing much additional output current. In varying VIN condition such as battery power applications, use the minimum VIN value in the above equation. A smaller value can be used to give smaller physical size, but the inductor current overshoot will be occurs (see Current Limit Overshoot section). Inductor Selection--SEPIC Regulator For a SEPIC regulator using the G5111, the approximate inductance value can be calculated by below formula. As for the boost inductor selection, a larger or smaller value can be used. L=2 VOUT + VD ILIM x tOFF Applications Information Choosing an Inductor There are several recommended inductors that work well with the G5111 in Table 1. Use the equations and recommendations in the next few sections to find the proper inductance value for your design. Table 1. Recommended Inductors PART LQH3C4R7 LQH3C100 LQH3C220 CD43-4R7 CD43-100 CDRH4D18-4R7 CDRH4D18-100 DO1608-472 DO1608-103 DO1608-223 VALUE(H) MAX DCR () ( 4.7 10 22 4.7 10 4.7 10 4.7 10 22 0.26 0.30 0.92 0.11 0.18 0.16 0.20 0.09 0.16 0.37 VENDOR Murata www.murata.com Sumida www.sumida.com Current Limit Overshoot The G5111 use a constant off-time control scheme, the power switch is turned off after the 350mA current limit is reached. When the current limit is reached and when the switch actually turns off, there is a 100ns delay time. During this time, the inductor current exceeds the current limit by a small amount. The formula below can calculate the peak inductor current. IPEAK = ILIM + VIN(MAX) - VSAT x 100ns L Coilcraft www.coilcraft.com Inductor Selection--Boost Regulator The appropriate inductance value for the boost regulator application may be calculated from the following equation. Select a standard inductor close to this value. L= VOUT-VIN(MIN)+VD x tOFF ILIM Where VSAT = 0.25V (switch saturation voltage). When the systems with high input voltages and uses smaller inductance value, the current overshoot will be most apparent. This overshoot can be useful as it helps increase the amount of available output current. To use small inductance value for systems design, the current limit overshoot can be quite high. Even if it is internally current limited to 350mA, the power switch of the G5111 can operate larger currents without any problem, but the total efficiency will suffer. The IPEAK is keep below 500mA for the G5111 will be obtained best performance. Ver 0.2 Preliminary Jan 09, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 3 Global Mixed-mode Technology Inc. Capacitor Selection Low ESR (Equivalent Series Resistance) capacitors should be used at the output to minimize the output ripple voltage and the peak-to-peak transient voltage. Multilayer ceramic capacitors (MLCC) are the best choice, as they have a very low ESR and are available in very small packages. Their small size makes them a good match with the G5111's SOT-23 package. If solid tantalum capacitors (like the AVX TPS, Sprague 593D families) or OS-CON capacitors are used, they will occupy more volume than a ceramic ones and the higher ESR increases the output ripple voltage. Notice that use a capacitor with a sufficient voltage rating. A low ESR surface-mount ceramic capacitors also make a good selection for the input bypass capacitor, which should be placed as close as possible to the G5111. A 4.7F input capacitor is sufficient for most applications. Diode Selection For most G5111 applications, the high switching frequency requires a high-speed rectifier Schottky diodes, such as the Motorola MBR0520 (0.5A, 20V) with their low forward voltage drop and fast switching speed, are G5111 recommended. Many different manufacturers make equivalent parts, but make sure that the component is rated to operate at least 0.35A. To achieve high efficiency, the average current rating of the Schottky diodes should be greater than the peak switching current. Choose a reverse breakdown voltage greater than the output voltage. Lowering Output Voltage Ripple The G5111 supplies energy to the load in bursts by ramping up the inductor current, then delivering that current to the load. To use low ESR capacitors will help minimize the output ripple voltage, but proper selection of the inductor and the output capacitor also plays a big role. If a larger inductance value or a smaller capacitance value is used, the output ripple voltage will increase because the capacitor will be slightly overcharged each burst cycle. To reduce the output ripple, increase the output capacitance value or add a 10pF feed-forward capacitor in the feedback network of the G5111 (see the circuits in the Typical Applications section). To add this small, inexpensive 10pF capacitor will greatly reduce the output voltage ripple. Typical Applications Boost Converter SEPIC Converter L1 4.7H VIN 2.5V to 4.2V 5 VCC 1 SW D1 5V 50mA 10pF R1 390k VIN 2.5V to 4.2V 5 L1 10H 1 SW C3 1F D1 3.3V 60mA 10pF L2 10H R1 470k C2 22F VCC G5111 4 C1 4.7F SHDN GND 2 FB 3 R2 120k C2 22F C1 4.7F G5111 4 SHDN GND 2 FB 3 R2 270k L1:MURATA LQH3C4R7M24 D1:MOTOROLA MBR0520 (814) 237-1431 (800) 441-2447 L1,L2:MURATA LQH3C100K24 D1:MOTOROLA MBR0520 (814) 237-1431 (800) 441-2447 Ver 0.2 Preliminary Jan 09, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 4 Global Mixed-mode Technology Inc. Package Information G5111 C L D E H e1 e 1 A A2 A1 b Note: 1. 2. 3. 4. Package body sizes exclude mold flash protrusions or gate burrs Tolerance 0.1000 mm (4mil) unless otherwise specified Coplanarity: 0.1000mm Dimension L is measured in gage plane DIMENSIONS IN MILLIMETERS NOM 1.00 0.00 0.70 0.35 0.10 2.70 1.40 --------2.60 0.37 1 1.10 ----0.80 0.40 0.15 2.90 1.60 1.90(TYP) 0.95 2.80 -----5 SYMBOLS MIN A A1 A2 b C D E e e1 H L 1 MAX 1.30 0.10 0.90 0.50 0.25 3.10 1.80 --------3.00 ----9 Taping Specification Feed Direction SOT23-5 Package Orientation Ver 0.2 Preliminary Jan 09, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 5 |
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