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MIC2142
Micrel
MIC2142
Micropower Boost Converter Preliminary Information General Description
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 85A, and a typical shutdown current of 0.1A. 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 -40C to +85C
Features
* * * * * * * 2.2V to 16V input voltage Up to 22V output voltage 330kHz switching frequency 0.1A shutdown current 85A 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
0.90 0.85
2.8V to 4.7V VIN
L1 33H MIC2142 VCC SW FB
5
D1
EFFICIENCY (%)
0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0 10 20 30 40 50 60 70 OUTPUT CURRENT (mA) VIN = 4.2V VIN = 3.0V
+5V @60mA
1
3
R2 365k R1 124k COUT 22F
CIN 10F
4
EN GND
2
Typical Configuration
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
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MIC2142
MIC2142
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Ordering Information
Part Number MIC2142BM5 Voltage Adj Ambient Temp. Range -40C to +85C Package SOT23-5
Pin Configuration
SW GND VCC
3 2 1
SBAA
4 5
Part Identification
FB
EN
SOT23-5 (BM5)
Pin Description
Pin Number 1 2 3 4 5 Pin Name VCC GND SW FB EN Pin Function Chip Supply: +2.2V to +16V Ground: Return for internal circuitry and internal MOSFET (switch) source. Switch Node (Input): Internal MOSFET drain; 22V maximum. Feedback (Input): Output voltage sense node. Shutdown: Device shuts down to 0.1A typical supply current.
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Absolute Maximum Ratings (Note 1)
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) ......... -65C to +150C
Operating Ratings (Note 2)
Supply Voltage (VCC) ....................................... 2.2V to 16V Enable pin voltage (VEN) Note 3 ......................... 0V to 16V Switch Voltage (VSW) .................................................... 22V Ambient Temperature (TA) ......................... -40C to +85C Junction Temperature Range (TJ) ........... -40C to +125C Package Thermal Impedance JA SOT23-5 ..................................................... 220C/W
Electrical Characteristics
VCC =3.6V, VOUT = 5V, IOUT = 20mA, TA=25C; unless otherwise specified. Bold values indicate 25C TJ 125C. Parameter Input Voltage Quiescent Current VEN = ON , VFB = 2.2V VEN = OFF (shutdown) Feedback Voltage (VFB) Comparator Hysteresis Feedback Input Bias Current Note 4 Enable Input Voltage VIH (turn on) VIL (turn off) Enable Input Current Load Regulation Line Regulation SW on Resistance 200A IOUT 20mA 2.2V VCC 16V; IOUT = 4mA ISW = 100mA, VCC = 2.5V ISW = 100mA, VCC = 12V Switch Leakage Current Oscillator Frequency Duty Cycle
Note 1:
Condition
Min 2.2
Typ
Max 16
Units V A A V V mV nA V
85 0.1 1.254 1.241 18 30 0.6VCC 0.55VCC 1.1 -1 0.01 0.2 0.25 5 2 0.05 295 50 330 57 1.28
125 2 1.306 1.312
(2%) (3%)
0.8 1
V A %VOUT %/V A kHz %
VEN = OFF, VSW = 12V
1 365 65
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, JA, 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 JA of the power SOT23-5 is 220C/W mounted on a PC board. The device is not guaranteed to function outside its operating rating. VEN must be VIN The maximum suggested value of the programming resistor, whose series resistance is measured from feedback to ground, is 124k. Use of larger resistor values can cause errors in the output voltage due to the feedback input bias current. Devices are ESD sensitive, handling precautions required.
Note 2: Note 3: Note 4: Note 5:
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Typical Characteristics
Quiescent Current vs. Input Voltage
350 QUIESCENT CURENT (A) 300 250 VOUT = 5V
600 500 400
VDS (V)
VDS and RDS(ON) vs. Input Voltage
6
OUTPUT VOLTAGE (V)
Line Regulation
16.5 16 15.5 15 14.5 14 2 I = 7mA
L
5 4 3 2 1 ISW = 100mA 2 4 6 8 10 12 INPUT VOLTAGE (V) 0 14
RDS(ON)
L = 22H IL = 2mA L = 220H
200 150 100 50 0 0 2 4 6 8 10 12 14 16 INPUT VOLTAGE (V)
300 200 100 0 0
4
6 8 10 12 INPUT VOLTAGE (V)
14
Output Ripple vs. Input Voltage
1200 OUTPUT RIPPLE (mV) 1000 800 600 400 200 0 0 2 4 6 8 10 12 INPUT VOLTAGE (V) 14 VOUT = 15V IL = 7mA L = 22H
Efficiency vs. Input Voltage
85 80
EFFICIENCY (%)
OUTPUT VOLTAGE (V)
MIC2142 Load Regulation
16 14 12 10 L = 22H 8 VIN = 5V 6 4 2 0 0 VREF 5 10 15 20 25 30 OUTPUT CURRENT (mA) VOUT
75 70 65 60 2
IL = 2mA L = 220H IL = 7mA L = 22H
IL = 2mA L = 220H
VOUT = 15V 4 6 8 10 12 INPUT VOLTAGE (V) 14
Oscillator Characteristics vs. Input Voltage
350 300 FREQUENCY (kHz) 250 200 150 Duty Cycle 0.55 0.50 0.45 0.40 14 Frequency 0.65 QUIESCENT CURRENT (A) 0.60 DUTY CYCLE 84 82 80 78 76 74 72
Quiescent Current vs. Temperature
15.20
OUTPUT VOLTAGE (V)
VOUT and VREF Over Temperature
1.285
15.05 15.00 14.95 VOUT
1.280
100 V = 15V O 50 IO = 100A L= 220H 0 0 2 4 6 8 10 12 INPUT VOLTAGE (V)
1.275 VREF
VIN = 3.6V 70 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (C)
14.90 1.270 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (C)
2 1.9 1.8
340 335 FREQUENCY (kHz) 330 325 320 315 310 305 300 295 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (C)
OSCILLATOR CHARACTERISTICS
tON vs. Temperature
Frequency vs. Temperature
3.5
Timing Characteristics Over Temperature
3.0 T (sec) 2.5 2.0 1.5 t (sec) ON 1.0 0.5 Duty Cycle 0 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (C)
tON (sec)
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)
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REFERENCE VOLTAGE (V)
VIN = 3.6V 15.15 IO = 100A L = 22H 15.10
1.290
MIC2142
Micrel
7 6 5 RDS(ON) () 4 3 2 1
RDS(ON) vs. Temperature
VCC=3.3V DUTY CYCLE (%)
Timing Characteristics Over Temperature
0.6 0.58 0.56 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)
VCC = 4.5V
0 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE (C)
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MIC2142
Micrel
Functional Diagram
VCC SW
Bandgap Reference
Oscillator 330kHz
FIXED DUTY CYCLE
EN FB
Shutdown
MIC2142 GND
Functional Description
This MIC2142 is a fixed duty cycle, constant frequency, gated oscillator, micropower, switch-mode power supply controller. Quiescent current for the MIC2142 is only 85A 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 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.
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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.
Manufacturer MuRata Sumida J.W. Miller Coilcraft Series LQH1C/3C/4C CR32 78F 90 Device Type surface mount surface mount axial leaded axial leaded
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 2M limits the additional load on the output to 20A 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) R1 + R2 VOUT = V R1 REF
Table 1. Inductor Examples 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.
Diode 75C VFWD at 100mA 0.275V 0.6V (175C) 0.4V (85C) 0.54 (85C) 25C Room 75C VFWD Temp. Leakage Package at Leakage at 15V 100mA at 15V 0.325V 0.95V 0.45V 0.56V 2.5A 25nA (20V) 10nA (25V) 0.4A 90A 0.2A (20V) 1A (20V) 2A (85C) SOD123 SMT leaded and SMT SMT DO-34 leaded
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.
IO(max) =
MBR0530 1N4148 BAT54 BAT85
Table 2. Diode Examples 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 1F to 22F can be used for the output capacitor. 7 MIC2142
(VIN(min) tON )
2LMAX TS
2
(2)
x
1 VO eff - VIN(min)
(3)
IPK =
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 10H are not December 2000
MIC2142
Manufacturer MuRata Vishay Panasonic Series GRM 594 M-series Type ceramic Y5V tantalum electrolytic Package surface mount surface mount leaded
Micrel
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.
L1 33H
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 = 0.8 = efficiency Dnom = 0.55
TS(min)= 1 = 2.78sec Fmax 360kHz D 0.55 t ON(min)= nom = 1.53sec fmax 360kHz =
2 2
+3.0V to +4.2V VIN
CR1 MBR0530
+5V @80mA
R3 100
R2 36.5k
C3 270pF
1
C2 10F
4
U1 MIC2142 FB SW 3 GND
2
R1 12.4k C1 22F C4 1F
VIN(min) x t ON(min) 1 Lmax = x VO IO(max) x 2 x TS(min) - VIN(min) 2.5 2 x 1.53sec 2 1 Lmax = x = 42H 5mA x 2 x 2.78sec 12 - 2.5 0.8
5
EN VCC
1
GND
GND
Figure 1. Bootstrap VCC with VCC Low Pass Filter
Select 39H 10%.
1.1x Dnom 1.1x 0.55 = = 2sec Fmin 300kHz t ON(max) x VIN(max) 2.0sec x 4.7V = = 270mA Ipeak = Lmin 35H t ON(max)=
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VIN L1 47H CR1 MBR0530 +5V @16mA R2 36.5k
Micrel
C3 270pF
C2 10F
U1 MIC2142 SW 3 4 FB GND
5 2
R1 12.4k
C1 22F
EN VCC
1
GND
GND
Figure 2. Booststrap Configuration
For additional predesigned circuits, see Table 4.
L1 10H VIN
CR1 MBR0530 +15V @15mA CR5 LWT673 CR7 LWT673
4
U1 MIC2142 FB SW 3 GND
2
CR6 LWT673 C1 1F 25V Rprogram 82
(from controller) PWM
C2 10F
5
EN VCC
1
GND
GND
Figure 3. Series White LED Driver with PWM Dimming Control
L1 10H VIN
CR1 MBR0530 +15V @15mA CR5 LWT673 CR7 LWT673
4
U1 MIC2142 FB SW 3 GND
2
CR6 LWT673 C1 1F 25V Rprogram 82
C2 10F SHTDWN
5
EN VCC
1
GND DAC R4 R3
GND
Figure 4. Series White LED Driver with Analog Dimming Control
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MIC2142
L1 10H VIN CR3 MBR0530
Micrel
+5.0V @50mA
4
U1 MIC2142 FB SW 3 GND
2
CR1 LWT673 C1 1F 25V R1 120
CR2 LWT673
CR3 LWT673
C2 10F EN
5
EN VCC
1
R2 120
R3 120 GND
GND DAC R4 R3
Figure 5. Parallel White LED Driver with Analog Dimming Control
VIN
L1 10H
CR1 BAT54HT1
+20V @0.5mA
R2 1.8M
C1 1F 25V
C2 10F
4
U1 MIC2142 FB SW 3 GND
2
R1 120k C1 1F 25V
5
EN VCC
1
VINRTN
GND
Figure 6. Handheld LCD Supply
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Predesigned Circuit Values
VIN(min) 2.5V VIN(max) 3.0V VOUT 3.3V IOUT(max) 40mA 23mA 10mA 16.5mA 7.8mA 51 77 4.8 2.25 15 22 3.7 1.7 17.4 8 2.7 1.5 40 70 100 15 28 40 7.8 14 21 5.6 70 23 10 43 14 6 30 10 30 8 118 66 30 70 40 18 20 10 6 156 71 27 35 L1 47H 85H 180H 47H 100H 15 10 47 100 15 10 47 100 10 22 47 82 33 18 12 33 18 12 33 18 12 33 27 82 180 27 82 180 27 82 27 68 56 100 220 56 100 220 120 220 390 68 150 390 150 IPK @ VIN(max) 129mA 74mA 34VmA 193mA 91mA 605 908 493 232 632 950 622 292 950 430 202 110 287 525 800 520 525 800 886 525 800 287 635 209 95 860 283 129 1083 357 672 237 414 232 105 504 282 128 235 128 72 415 182 72 188 CR1 BAT54 BAT54 BAT54 BAT54 BAT54 MBR0530 MBR MBR BAT MBR MBR MBR BAT MBR MBR BAT BAT BAT MBR MBR MBR MBR MBR MBR MBR MBR BAT MBR BAT BAT MBR BAT BAT MBR MBR MBR BAT MBR BAT BAT MBR BAT BAT BAT BAT BAT MBR BAT BAT BAT
Micrel
2.5V
4.5V
5V boot strapped boot strapped
2.5
11.5 4.7
12 boot strapped boot strapped 15 boot strapped boot strapped 20 20 5 boot strapped boot strapped 9 boot strapped boot strapped 15 boot strapped boot strapped 20 9
2.5
14.5 4.7
2.5 2.5 3.0
4.7 4.7 4.7
3.0
8.5 4.7 4.7 14.5 4.7 4.7 4.7 8.5
3.0 3.0 3.0 3.0 5.0
5.0
11.5
12
5.0
14.5 9
15
5.0 9
8.0 11.5
20 12
9
14
15
9
14
20
12
14
15
12
14
20
Table 4. Typical Maximum Power Configuration
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VIN 3.3V5% VOUT 5V 9V 12V 15V 20V 9V 12V 15V 20V 15V 20V 20V IOUT 70mA 30mA 20mA 15mA 6mA 70mA 40mA 30mA 8.0mA 158 35 50 L1 18 H 18H 18H 18 H 33H 27H 27 H 27H 68 H 68 150 220 CR1 MBR0530 MBR0530 MBR0530 MBR0530 BAT54 IPEAK 400 400 400 400 214 Configuration Bootstrap Bootstrap Bootstrap Bootstrap
Micrel
5V5%
MBR0530 370 MBR0530 370 MBR0530 370 BAT54 148 MBR0350 350 BAT54 160 BAT54 1140
12V5% 15V5%
Table 5. Typical Maximum Power Configurations for Regulated Inputs
VOUT = 16V to 22V 85C VIN (V) 2.5 3 3.5 4 5 6 7 8 9 10 11 12 13 14 15 16 LMIN (H) 47 33 47 56 68 82 100 100 120 150 150 150 180 180 220 220
VOUT < 16V (boostraped) 85C LMIN (H) 47 (15) 33 (18) 27 (22) 27 (22) 27 33 39 47 56 56 68 68 82 82 82 100
VOUT < 16 (boostraped) 40C LMIN (H) 47 (10) 33 (12) 27 (15) 22 (18) 22 22 27 33 33 39 47 47 56 56 56 68
Table 6. Minimum Inductance
Manufacturer MuRata Sumida Coilcraft J. W. Miller Micrel Vishay Panasonic Web Address www.MuRata.com www.sumida.com www.coilcraft.com www.jwmiller.com www.micrel.com www.vishay.com www.panasonic.com
Table 7. Component Supplier Websites MIC2142 12 December 2000
MIC2142
Inductor Selection Guides
Micrel
1000 VIN = 2.5V
1000 VIN = 3.0V
12H 15H 18H 10H 12H 15H 100
MAX. OUTPUT CURRENT (mA)
22H 27H 33H 100
MAX. OUTPUT CURRENT (mA)
18H 22H 33H 39H 47H 56H 68H 82H 100H 120H 150 H 180H 220H
39H 47H 56H 68H 82H 100H 120H 150H 180H 220H
10
10
1 0
2
4
6
8 10 12 14 16 OUTPUT VOLTAGE (V)
18
20
22
1 0
2
4
6
8 10 12 14 16 OUTPUT VOLTAGE (V)
18
20
22
24
Figure 7. Inductor Selection for VIN = 2.5V
Figure 8. Inductor Selection for VIN = 3.0V
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1000 VIN = 5.0V
1000 VIN = 9.0V
18H 22H 27H 33H 39H 47H 56H 68H 82H 100H 100 120H 150H
MAX. OUTPUT CURRENT (mA)
39H 47H 56H 68H 82H 100H 100 120H 150H
MAX. OUTPUT CURRENT (mA)
180H 220H
180H 220H 270H 330H 390H 470H
10
10
1 2
4
6
8
10 12 14 16 18 OUTPUT VOLTAGE (V)
20
22
24
1 8
10
12
14 16 18 OUTPUT VOLTAGE (V)
20
22
24
Figure 9. Inductor Selection for VIN = 5V
Figure 10. Inductor Selection for VIN = 9V
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1000 VIN = 12.0V 47H 56H 68H 82H 100H 120H 150H 180H 220H 100
MAX. OUTPUT CURRENT (mA)
1000 VIN = 15V
270H 330H 390H 470H
MAX. OUTPUT CURRENT (mA)
100
56H 68H 82H 100H 120H 150H 180H 220H 270H 330H 390H 470H
10
1 10
12
14
16 18 20 OUTPUT VOLTAGE (V)
22
24
10 14
16
18 20 OUTPUT VOLTAGE (V)
22
24
Figure 11. Inductor Selection for VIN = 12V
Figure 12. Inductor Selection for VIN = 15V
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10H 12H
56H
33H
39H
15H
18H
600
22H
27H
47H
68H
82H 4.5V to 15VCC Limit 500
100H
400 120H
PEAK CURRENT (mA)
300
150H 3.5VCC Limit 180H
200
220H
16V to 20VOUT Limit 8.2H 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
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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) 3.02 (0.119) 2.80 (0.110) 1.30 (0.051) 0.90 (0.035) 10 0 0.15 (0.006) 0.00 (0.000) 0.20 (0.008) 0.09 (0.004)
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
FAX
USA
+ 1 (408) 944-0800
+ 1 (408) 944-0970
WEB
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. (c) 2000 Micrel Incorporated
December 2000
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MIC2142

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