MIC2142 Micrel MIC2142 Micropower Boost Converter Preliminary Information General Description Features The MIC2142 is a micropower boost switching regulator housed in a SOT23-5 package. The input voltage range is between 2.2V to 16V, making the device suitable for one-cell Li Ion and 3 to 4-cell alkaline/NiCad/NiMH applications. The output voltage of the MIC2142 can be adjusted up to 22V. The MIC2142 is well suited for portable, space-sensitive applications. It features a low quiescent current of 85µA, and a typical shutdown current of 0.1µA. It’s 330kHz operation allows small surface mount external components to be used. The MIC2142 is capable of efficiences over 85% in a small board area. The MIC2142 can be configured to efficiently power a variety of loads. It is capable of providing a few mA output for supplying low power bias voltages; it is also capable of providing the 80mA needed to drive 4 white LEDs. The MIC2142 is available in a SOT23-5 package with an ambient operating temperature range from –40°C to +85°C • • • • • • • 2.2V to 16V input voltage Up to 22V output voltage 330kHz switching frequency 0.1µA shutdown current 85µA quiescent current Implements low-power boost, SEPIC, or flyback SOT23-5 package Applications • • • • LCD bias supply White LED driver 12V Flash memory supply Local 3V to 5V conversion Typical Application Efficiency vs. Output Current 2.8V to 4.7V VIN L1 33µH 1 CIN 10µF 5 D1 MIC2142 VCC SW 3 FB 4 EN GND 2 EFFICIENCY (%) 0.90 0.85 +5V @60mA R2 365k R1 124k 0.80 0.75 0.70 0.65 0.60 0.55 VIN = 4.2V VIN = 3.0V 0.50 0.45 COUT 22µF 0.40 0 Typical Configuration 10 20 30 40 50 60 70 OUTPUT CURRENT (mA) Efficiency vs. Output Current Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com December 2000 1 MIC2142 MIC2142 Micrel Ordering Information Part Number Voltage Ambient Temp. Range Package MIC2142BM5 Adj –40°C to +85°C SOT23-5 Pin Configuration SW GND VCC 3 2 1 SBAA 4 Part Identification 5 FB EN SOT23-5 (BM5) Pin Description Pin Number Pin Name 1 VCC Chip Supply: +2.2V to +16V 2 GND Ground: Return for internal circuitry and internal MOSFET (switch) source. 3 SW Switch Node (Input): Internal MOSFET drain; 22V maximum. 4 FB Feedback (Input): Output voltage sense node. 5 EN Shutdown: Device shuts down to 0.1µA typical supply current. MIC2142 Pin Function 2 December 2000 MIC2142 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply voltage (VCC) ..................................................... 18V Switch voltage (VSW) .................................................... 24V Enable pin voltage (VEN) Note 3 ................................... 18V Feedback Voltage (VFB) Adjustable version ....................................................... 8V Ambient Storage Temperature (TS) ......... –65°C to +150°C Supply Voltage (VCC) ....................................... 2.2V to 16V Enable pin voltage (VEN) Note 3 ......................... 0V to 16V Switch Voltage (VSW) .................................................... 22V Ambient Temperature (TA) ......................... –40°C to +85°C Junction Temperature Range (TJ) ........... –40°C to +125°C Package Thermal Impedance θJA SOT23-5 ..................................................... 220°C/W Electrical Characteristics VCC =3.6V, VOUT = 5V, IOUT = 20mA, TA=25°C; unless otherwise specified. Bold values indicate 25°C ≤ TJ ≤ 125°C. Parameter Condition Min Input Voltage Quiescent Current Feedback Voltage (VFB) Typ 2.2 Max Units 16 V VEN = ON , VFB = 2.2V 85 125 µA VEN = OFF (shutdown) 0.1 2 µA 1.28 1.306 V 1.312 V (±2%) 1.254 (±3%) 1.241 Comparator Hysteresis 18 mV Feedback Input Bias Current Note 4 30 nA Enable Input Voltage VIH (turn on) 0.6VCC 0.55VCC 1.1 VIL (turn off) Enable Input Current –1 0.01 V 0.8 V 1 µA Load Regulation 200µA ≤ IOUT ≤ 20mA 0.2 %VOUT Line Regulation 2.2V ≤ VCC ≤ 16V; IOUT = 4mA 0.25 %/V SW on Resistance ISW = 100mA, VCC = 2.5V 5 Ω ISW = 100mA, VCC = 12V 2 Ω Switch Leakage Current VEN = OFF, VSW = 12V 0.05 1 µA Oscillator Frequency 295 330 365 kHz Duty Cycle 50 57 65 % Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(Max), the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The θJA of the power SOT23-5 is 220°C/W mounted on a PC board. Note 2: The device is not guaranteed to function outside its operating rating. Note 3: VEN must be ≤ VIN Note 4: The maximum suggested value of the programming resistor, whose series resistance is measured from feedback to ground, is 124kΩ. Use of larger resistor values can cause errors in the output voltage due to the feedback input bias current. Note 5: Devices are ESD sensitive, handling precautions required. December 2000 3 MIC2142 MIC2142 Micrel Typical Characteristics Quiescent Current vs. Input Voltage 600 VOUT = 5V 400 4 300 3 200 2 100 100 50 2 0 0 4 6 8 10 12 14 16 INPUT VOLTAGE (V) 1 ISW = 100mA 2 4 6 8 10 12 INPUT VOLTAGE (V) IL = 2mA L = 220µH 200 65 4 6 8 10 12 INPUT VOLTAGE (V) 14 60 2 350 100 V = 15V O 50 IO = 100µA L= 220µH 0 0 2 4 6 8 10 12 INPUT VOLTAGE (V) 0.45 0.40 14 tON vs. Temperature tON (µsec) 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) MIC2142 10 L = 22µH 8 VIN = 5V 6 4 0 0 80 78 76 74 72 VIN = 3.6V 70 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) VIN = 3.6V 15.15 IO = 100µA L = 22µH 15.10 15.00 330 325 320 315 310 305 300 295 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) 4 1.290 1.285 15.05 1.280 VOUT 1.275 14.95 VREF 14.90 1.270 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) Frequency vs. Temperature 335 5 10 15 20 25 30 OUTPUT CURRENT (mA) VOUT and VREF Over Temperature 15.20 82 VREF 2 14 340 FREQUENCY (kHz) 2 0.50 QUIESCENT CURRENT (µA) Duty Cycle DUTY CYCLE 0.55 150 12 VOUT = 15V 84 0.60 250 200 IL = 7mA L = 22µH 6 8 10 12 INPUT VOLTAGE (V) 14 VOUT 14 Quiescent Current vs. Temperature 0.65 Frequency IL = 2mA L = 220µH 4 6 8 10 12 INPUT VOLTAGE (V) 16 OUTPUT VOLTAGE (V) 2 4 MIC2142 Load Regulation 70 Oscillator Characteristics vs. Input Voltage 300 14 2 Timing Characteristics Over Temperature OSCILLATOR CHARACTERISTICS 400 0 0 14.5 OUTPUT VOLTAGE (V) EFFICIENCY (%) VOUT = 15V IL = 2mA L = 220µH 15 0 14 80 75 L = 22µH 15.5 85 IL = 7mA L = 22µH 800 600 16 Efficiency vs. Input Voltage 1200 1000 I = 7mA REFERENCE VOLTAGE (V) 150 5 OUTPUT VOLTAGE (V) 200 500 Output Ripple vs. Input Voltage OUTPUT RIPPLE (mV) 16.5 RDS(ON) 250 0 0 FREQUENCY (kHz) Line Regulation 6 L VDS (V) QUIESCENT CURENT (µA) 350 300 VDS and RDS(ON) vs. Input Voltage 3.5 3.0 T (µsec) 2.5 2.0 1.5 t (µsec) ON 1.0 0.5 Duty Cycle 0 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) December 2000 MIC2142 Micrel 6 Timing Characteristics Over Temperature RDS(ON) vs. Temperature 0.6 VCC=3.3V DUTY CYCLE (%) 7 RDS(ON) (Ω) 5 4 3 VCC = 4.5V 2 1 0.54 0.52 0.5 0.48 0.46 0.44 0.42 0.4 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) 0 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (°C) December 2000 0.58 0.56 5 MIC2142 MIC2142 Micrel Functional Diagram VCC Bandgap Reference SW Oscillator 330kHz FIXED DUTY CYCLE EN Shutdown FB MIC2142 GND Functional Description output. Once the feedback input to the comparator exceeds the control voltage by 18mV, the high frequency oscillator drive is removed from the output switch. As the feedback input to the comparator returns to the reference voltage level, the comparator is reset and the high frequency oscillator is again gated to the output switch. The 18mV of hysteresis seen at the comparator will be multiplied by the ratio of the output voltage to the reference voltage. For a five volt output this ratio would be 4, corresponding to a ripple voltage of 72mV at the output. The maximum output voltage is limited by the voltage capability of the output switch. Output voltages up to 22V can be achieved with a standard boost circuit. Higher output voltages can be realized with a flyback configuration. This MIC2142 is a fixed duty cycle, constant frequency, gated oscillator, micropower, switch-mode power supply controller. Quiescent current for the MIC2142 is only 85µA in the switch off state, and since a MOSFET output switch is used, additional switch drive current is minimized. Efficiencies above 85% throughout most operating conditions can be realized. A functional block diagram is shown above and typical schematic is shown on page 1. Regulation is performed by a hysteretic comparator, which regulates the output voltage by gating the internal oscillator. The internal oscillator operates at a fixed 57% duty cycle and 330kHz frequency. For the fixed output versions, the output is divided down internally and then compared to the internal VREF input. An external resistive divider is use for the adjustable version. The comparator has hysteresis built into it, which determines the amount of low frequency ripple that will be present on the MIC2142 6 December 2000 MIC2142 Micrel recommmended. Table 6 lists minimum inductor sizes versus input and output voltage. In low-cost, low-peak-current applications, RF-type leaded inductors may sufficient. All inductors listed in Table 5 can be found within the selection of CR32- or LQH4C-series inductors from either Sumida or muRata. Application Information Predesigned circuit information is at the end of this section. Component Selection Resistive Divider (Adjustable Version) The external resistive divider should divide the output voltage down to the nominal reference voltage. Current drawn through this resistor string should be limited in order to limit the effect on the overall efficiency. The maximum value of the resistor string is limited by the feedback input bias current and the potential for noise being coupled into the feedback pin. A resistor string on the order of 2MΩ limits the additional load on the output to 20µA for a 20V output. In addition, the feedback input bias current error would add a nominal 60mV error to the expected output. Equation 1 can be used for determining the values for R2 and R1. (1) (2) 2LMAX TS eff (3) IPK = − VIN(min) t ON(max ) VIN(max ) LMIN Table 1 lists common inductors suitable for most applications. Due to the internal transistor peak current limitation at low input voltages, inductor values less than 10µH are not December 2000 LQH1C/3C/4C surface mount Sumida CR32 surface mount J.W. Miller 78F axial leaded Coilcraft 90 axial leaded Diode 75°C VFWD at 100mA 25°C Room 75°C VFWD Temp. Leakage Package at Leakage at 15V 100mA at 15V MBR0530 0.275V 0.325V 2.5µA 90µA SOD123 SMT 1N4148 0.6V (175°C) 0.95V 25nA (20V) 0.2µA (20V) leaded and SMT BAT54 0.4V (85°C) 0.45V 10nA (25V) 1µA (20V) SMT BAT85 0.54 (85°C) 0.56V 0.4µA 2µA (85°C) DO-34 leaded Output Capacitor Due to the limited availability of tantalum capacitors, ceramic capacitors and inexpensive electrolyics may be preferred. Selection of the capacitor value will depend upon the peak inductor current and inductor size. MuRata offers the GRM series with up to 10uF @ 25V with a Y5V temperature coefficient in a 1210 surface mount package. Low cost applications can use the M series leaded electrolytic capacitor from Panasonic. In general, ceramic, electrolytic, or tantalum values ranging from 1µF to 22µF can be used for the output capacitor. 1 VO MuRata Table 2. Diode Examples 2 × Device Type Boost Output Diode Speed, forward voltage, and reverse current are very important in selecting the output diode. In the boost configuration the average diode current is the same as the average load current and the peak is the same as the inductor and switch current. The peak current is the same as the peak inductor current and can be derived from Equation 3 or the graph in Figure 13. Care must be taken to make sure that the peak current is evaluated at the maximum input voltage. The BAT54 and BAT85 series are low current Shottky diodes available from “On Semiconductor” and “Phillips” respectively. They are suitable for peak repetitive currents of 300mA or less with good reverse current characteristics. For applications that are cost driven, the 1N4148 or equivalent will provide sufficient switching speed with greater forward drop and reduced cost. Other acceptable diodes are On Semiconductor’s MBR0530 or Vishay’s B0530, although they can have reverse currents that exceed 1 mA at very high junction temperatures. Table 2 summarizes some typical performance characteristics of various suitable diodes. Boost Inductor Maximum power is delivered to the load when the oscillator is gated on 100% of the time. Total output power and circuit efficiency must be considered when determining the maximum inductor value. The largest inductor possible is preferable in order to minimize the peak current and output ripple. Efficiency can vary from 80% to 90% depending upon input voltage, output voltage, load current, inductor, and output diode. Equation 2 solves for the output current capability for a given inductor value and expected efficiency. Figures 7 through 12 show estimates for maximum output current assuming the minimum duty and maximum frequency and 80% efficiency. To determine the necessary inductance, find the intersection between the output voltage and current, and then select the value of the inductor curve just above the intersection. If the efficiency is expected to be different than the 85% used for the graph, Equation 2 can then be used to better determine the maximum output capability. The peak inductor/switch current can be calculated from Equation 3 or read from the graph in Figure 13. The peak current shown in the graph in Figure 13 is derived assuming a max duty cycle and a minimum frequency. The selected inductor and diode peak current capability must be greater than this. The peak current seen by the inductor is calculated at the maximum input voltage. A wide ranging input voltage will result in a higher worst case peak current in the inductor than a narrow input range. (VIN(min) tON ) Series Table 1. Inductor Examples R1 + R2 VOUT = V R1 REF IO(max) = Manufacturer 7 MIC2142 MIC2142 Micrel Manufacturer Series Type Package MuRata GRM ceramic Y5V surface mount Vishay 594 tantalum surface mount Panasonic M-series electrolytic leaded Bootstrap Configuration For input voltages below 4.5V the bootstrap configuration can increase the output power capability of the MIC2142. Figure 2 shows the bootstrap configuration where the output voltage is used to bias the MIC2142. This impoves the power capability of the MIC2142 by increasing the gate drive voltage hence the peak current capability of the internal switch. This allows the use of a smaller inductor which increases the output power capability. Table 4 also summarizes the various configurations and power capabilities using the booststrap configuration. This bootstrap configuration is limited to output voltage of 16V or less. Figure 1 shows how a resistor (R3) can be added to reduce the ripple seen at the VCC pin when in the bootstrap configuration. Reducing the ripple at the VCC pin can improve output ripple in some applications. Table 3. Capacitor Examples Design Example Given a design requirement of 12V output and 1mA load with an miniumum input voltage of 2.5V, Equation 2 can be used to calculate to maximum inductance or it can be read from the graph in Figure 7. Once the maximum inductance has been determined the peak current can be determined using Equation 3 or the graph in Figure 13. VOUT = 12V IOUT = 5mA VIN = 2.5V to 4.7V Fmax = 360kHz η = 0.8 = efficiency Dnom = 0.55 L1 33µH CR1 MBR0530 R3 100 1 = 2.78µsec Fmax 360kHz D 0.55 t ON(min)= nom = 1.53µsec fmax 360kHz TS(min)= 1 +3.0V to +4.2V VIN +5V @80mA R2 36.5k C3 270pF = C2 10µF VIN(min) × t ON(min) 1 Lmax = × V IO(max) × 2 × TS(min) O − VIN(min) η 2.5 2 × 1.53µsec 2 1 Lmax = × = 42µH 5mA × 2 × 2.78µsec 12 − 2.5 0.8 2 U1 MIC2142 FB SW 3 R1 12.4k 4 GND 2 EN VCC 1 C1 22µF 2 5 C4 1µF GND GND Figure 1. Bootstrap VCC with VCC Low Pass Filter Select 39µH ±10%. 1.1× Dnom 1.1× 0.55 = = 2µsec Fmin 300kHz t ON(max) × VIN(max) 2.0µsec × 4.7V = = 270mA Ipeak = Lmin 35µH t ON(max)= MIC2142 8 December 2000 MIC2142 Micrel L1 47µH VIN CR1 MBR0530 +5V @16mA R2 36.5k R1 12.4k U1 MIC2142 SW 3 4 FB C2 10µF 5 GND 2 EN VCC 1 C3 270pF C1 22µF GND GND Figure 2. Booststrap Configuration For additional predesigned circuits, see Table 4. L1 10µH CR1 MBR0530 VIN +15V @15mA CR5 LWT673 CR7 LWT673 U1 MIC2142 FB SW 3 CR6 LWT673 4 (from µcontroller) PWM GND 2 EN VCC 1 C2 10µF 5 C1 1µF 25V Rprogram 82Ω GND GND Figure 3. Series White LED Driver with PWM Dimming Control L1 10µH CR1 MBR0530 VIN +15V @15mA CR5 LWT673 CR7 LWT673 U1 MIC2142 FB SW 3 CR6 LWT673 4 C2 10µF SHTDWN 5 GND 2 EN VCC 1 C1 1µF 25V Rprogram 82Ω GND GND DAC R4 R3 Figure 4. Series White LED Driver with Analog Dimming Control December 2000 9 MIC2142 MIC2142 Micrel L1 10µH CR3 MBR0530 VIN +5.0V @50mA U1 MIC2142 FB SW 3 CR1 LWT673 4 GND C2 10µF EN 5 EN VCC CR2 LWT673 CR3 LWT673 C1 1µF 25V 2 1 R1 120Ω R2 120Ω R3 120Ω GND GND DAC R4 R3 Figure 5. Parallel White LED Driver with Analog Dimming Control VIN L1 10µH CR1 BAT54HT1 +20V @0.5mA R2 1.8M C2 10µF U1 MIC2142 FB SW 3 R1 120k 4 5 GND 2 EN VCC 1 C1 1µF 25V C1 1µF 25V VINRTN GND Figure 6. Handheld LCD Supply MIC2142 10 December 2000 MIC2142 Micrel Predesigned Circuit Values VIN(min) VIN(max) VOUT IOUT(max) L1 IPK @ VIN(max) CR1 2.5V 3.0V 3.3V 40mA 23mA 10mA 47µH 85µH 180µH 129mA 74mA 34VmA BAT54 BAT54 BAT54 2.5V 4.5V 5V 16.5mA 7.8mA 51 77 47µH 100µH 15 10 193mA 91mA 605 908 BAT54 BAT54 MBR0530 MBR 4.8 2.25 15 22 47 100 15 10 493 232 632 950 MBR BAT MBR MBR 47 100 10 22 622 292 950 430 MBR BAT MBR MBR boot strapped boot strapped 2.5 11.5 12 4.7 boot strapped boot strapped 14.5 15 4.7 boot strapped boot strapped 3.7 1.7 17.4 8 2.5 2.5 4.7 4.7 20 20 2.7 1.5 47 82 202 110 BAT BAT 3.0 4.7 5 boot strapped boot strapped 40 70 100 33 18 12 287 525 800 BAT MBR MBR 3.0 8.5 4.7 4.7 9 boot strapped boot strapped 15 28 40 33 18 12 520 525 800 MBR MBR MBR 3.0 3.0 3.0 14.5 4.7 4.7 15 boot strapped boot strapped 7.8 14 21 33 18 12 886 525 800 MBR MBR MBR 3.0 4.7 20 5.6 33 287 BAT 5.0 8.5 9 70 23 10 27 82 180 635 209 95 MBR BAT BAT 5.0 11.5 12 43 14 6 27 82 180 860 283 129 MBR BAT BAT 5.0 14.5 15 30 10 30 27 82 27 1083 357 672 MBR MBR MBR 2.5 9 5.0 8.0 20 8 68 237 BAT 9 11.5 12 118 66 30 56 100 220 414 232 105 MBR BAT BAT 9 14 15 70 40 18 56 100 220 504 282 128 MBR BAT BAT 9 14 20 20 10 6 120 220 390 235 128 72 BAT BAT BAT 12 14 15 156 71 27 68 150 390 415 182 72 MBR BAT BAT 12 14 20 35 150 188 BAT Table 4. Typical Maximum Power Configuration December 2000 11 MIC2142 MIC2142 Micrel VIN VOUT IOUT L1 CR1 IPEAK 3.3V±5% 5V 9V 12V 15V 20V 70mA 30mA 20mA 15mA 6mA 18µ H 18µH 18µH 18µ H 33µH MBR0530 MBR0530 MBR0530 MBR0530 BAT54 5V±5% 9V 12V 15V 20V 70mA 40mA 30mA 8.0mA 27µH 27µ H 27µH 68µ H MBR0530 370 MBR0530 370 MBR0530 370 BAT54 148 12V±5% 15V 20V 158 35 68 150 MBR0350 350 BAT54 160 15V±5% 20V 50 220 BAT54 400 400 400 400 214 Configuration Bootstrap Bootstrap Bootstrap Bootstrap 1140 Table 5. Typical Maximum Power Configurations for Regulated Inputs VOUT = 16V to 22V VOUT < 16V (boostraped) VOUT < 16 (boostraped) 85C 85C 40C VIN (V) LMIN (µH) LMIN (µH) LMIN (µH) 2.5 47 47 (15) 47 (10) 3 33 33 (18) 33 (12) 3.5 47 27 (22) 27 (15) 4 56 27 (22) 22 (18) 5 68 27 22 6 82 33 22 7 100 39 27 8 100 47 33 9 120 56 33 10 150 56 39 11 150 68 47 12 150 68 47 13 180 82 56 14 180 82 56 15 220 82 56 16 220 100 68 Table 6. Minimum Inductance Manufacturer Web Address MuRata www.MuRata.com Sumida www.sumida.com Coilcraft www.coilcraft.com J. W. Miller www.jwmiller.com Micrel www.micrel.com Vishay www.vishay.com Panasonic www.panasonic.com Table 7. Component Supplier Websites MIC2142 12 December 2000 MIC2142 Micrel Inductor Selection Guides 1000 1000 VIN = 2.5V VIN = 3.0V 12µH 15µH 18µH 22µH 10µH 12µH 27µH 33µH 15µH 100 18µH 100 MAX. OUTPUT CURRENT (mA) MAX. OUTPUT CURRENT (mA) 22µH 33µH 39µH 47µH 56µH 68µH 82µH 100µH 120µH 10 150µ H 180µH 39µH 47µH 56µH 68µH 82µH 100µH 120µH 150µH 180µH 220µH 10 220µH 1 0 2 4 6 8 10 12 14 16 OUTPUT VOLTAGE (V) 18 20 1 0 22 Figure 7. Inductor Selection for VIN = 2.5V December 2000 2 4 6 8 10 12 14 16 OUTPUT VOLTAGE (V) 18 20 22 24 Figure 8. Inductor Selection for VIN = 3.0V 13 MIC2142 MIC2142 Micrel 1000 1000 VIN = 5.0V 18µH VIN = 9.0V 22µH 27µH 33µH 39µH 39µH 47µH 47µH 56µH 56µH 68µH 68µH 100 120µH 100 120µH 150µH 150µH MAX. OUTPUT CURRENT (mA) 82µH 100µH MAX. OUTPUT CURRENT (mA) 82µH 100µH 180µH 220µH 10 1 2 220µH 270µH 330µH 390µH 470µH 10 4 6 8 10 12 14 16 18 OUTPUT VOLTAGE (V) 20 22 1 8 24 Figure 9. Inductor Selection for VIN = 5V MIC2142 180µH 10 12 14 16 18 OUTPUT VOLTAGE (V) 20 22 24 Figure 10. Inductor Selection for VIN = 9V 14 December 2000 MIC2142 Micrel 1000 1000 VIN = 15V VIN = 12.0V 47µH 56µH 68µH 82µH 100µH 120µH 150µH 180µH 220µH 100 270µH MAX. OUTPUT CURRENT (mA) MAX. OUTPUT CURRENT (mA) 330µH 390µH 470µH 56µH 100 68µH 82µH 100µH 120µH 10 150µH 180µH 220µH 270µH 330µH 390µH 470µH 1 10 12 14 16 18 20 OUTPUT VOLTAGE (V) 22 10 14 24 Figure 11. Inductor Selection for VIN = 12V December 2000 16 18 20 OUTPUT VOLTAGE (V) 22 24 Figure 12. Inductor Selection for VIN = 15V 15 MIC2142 68µH 56µH 47µH 39µH 33µH 27µH 22µH 15µH 600 18µH Micrel 10µH 12µH MIC2142 82µH 4.5V to 15VCC Limit 500 100µH 400 PEAK CURRENT (mA) 120µH 300 150µH 3.5VCC Limit 180µH 220µH 200 16V to 20VOUT Limit 8.2µH 2.5VCC Limit 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 INPUT VOLTAGE (V) Figure 13. Peak Inductor Current vs. Input Voltage MIC2142 16 December 2000 MIC2142 Micrel Package Information 1.90 (0.075) REF 0.95 (0.037) REF 1.75 (0.069) 1.50 (0.059) 3.00 (0.118) 2.60 (0.102) DIMENSIONS: MM (INCH) 1.30 (0.051) 0.90 (0.035) 3.02 (0.119) 2.80 (0.110) 0.20 (0.008) 0.09 (0.004) 10° 0° 0.15 (0.006) 0.00 (0.000) 0.50 (0.020) 0.35 (0.014) 0.60 (0.024) 0.10 (0.004) SOT23-5 (M3) MICREL INC. TEL 1849 FORTUNE DRIVE SAN JOSE, CA 95131 + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated December 2000 17 MIC2142