View MIC214207_4350089.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

MIC2142
Micropower Boost Converter
General Description
Features
The MIC2142 is a micropower boost switching regulator * 2.2V to 16V input voltage housed in a SOT23-5 package. The input voltage range is * Up to 22V output voltage between 2.2V to 16V, making the device suitable for one* 330kHz switching frequency cell Li Ion and 3 to 4-cell alkaline/NiCad/NiMH applica* 0.1A shutdown current tions. The output voltage of the MIC2142 can be adjusted * 85A quiescent current up to 22V. * Implements low-power boost, SEPIC, or flyback The MIC2142 is well suited for portable, space-sensitive applications. It features a low quiescent current of 85A, * SOT23-5 package and a typical shutdown current of 0.1A. It's 330kHz operation allows small surface mount external components Applications to be used. The MIC2142 is capable of efficiencies over 85% in a small board area. * LCD bias supply The MIC2142 can be configured to efficiently power a * White LED driver variety of loads. It is capable of providing a few mA output * 12V Flash memory supply for supplying low power bias voltages; it is also capable of * Local 3V to 5V conversion 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. Data sheets and support documentation can be found on Micrel's web site at www.micrel.com. ___________________________________________________________________________________________________________
Typical Application
2.8V to 4.7V VIN L1 33H MIC2142 VCC SW FB
5
D1
+5V @60mA
EFFICIENCY (%)
1
3
CIN 10F
R2 365k R1 124k COUT 22F
4 2
EN GND
0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0
Efficiency vs. Output Current
VIN = 4.2V VIN = 3.0V
10 20 30 40 50 60 70 OUTPUT CURRENT (mA)
Typical Configuration
Efficiency vs. Output Current
Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com
October 2007
M9999-102507
Micrel, Inc.
MIC2142
Ordering Information
Part Number Standard MIC2142BM5 Pb-Free MIC2142YM5 Marking* Standard SBAA Pb-Free SBAA Voltage Adj. Ambient Temperature Range -40 to +85C Package 5-Pin SOT23
* Under bar symbol (_) may not be to scale.
Pin Configuration
5-Pin SOT23 (BM5)
5-Pin SOT23 (YM5)
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.
October 2007
2
M9999-102507
Micrel, Inc.
MIC2142
Absolute Maximum Ratings(1)
Supply Voltage (VCC)......................................................18V Switch Voltage (VSW)......................................................24V Enable Pin Voltage (VEN)(3) .............................................18V Feedback Voltage (VFB) Adjustable Version.....................................................8V Ambient Storage Temperature (Ts) ...........-65C to +150C ESD Rating(4)
Operating Ratings(2)
Supply Voltage (VCC)......................................... 2.2V to 16V Enable Pin Voltage (VEN)(3)................................... 0V to 16V Switch Voltage (VSW)......................................................22V Ambient Temperature (TA) .......................... -40C to +85C Junction Temperature Range (TJ)............. -40C to +125C Package Thermal Impedance SOT23-5 (JA) ..................................................220C/W
Electrical Characteristics
VCC = 3.6V; VOUT = 5V; IOUT = 200mA; TA = 25C, bold values indicate -40C< TJ < +125C, unless noted.
Parameter Input Voltage Quiescent Current VEN = ON , VFB = 2.2V (adjustable) VEN = ON , VOUT(NOMINAL) + 1V (MIC2142-5.0) VEN = OFF (shutdown) Feedback Voltage (VFB) Comparator Hysteresis Feedback Input Bias Current, Note 5 Enable Input Voltage Enable Input Current Load Regulation Line Regulation SW on Resistance Switch Leakage Current Oscillator Frequency Duty Cycle
Notes: 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, 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. 2. The device is not guaranteed to function outside its operating rating. 3. VEN must be VIN. 4. Devices are ESD sensitive. Handling precautions recommended. 5. 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.
Condition
Min 2.2
Typ 85 85 0.1
Max 16 125 125 2 1.306 1.312
Units V A A A V V mV nA A V
(2%) (3%) adjustable fixed VIH (turn on) VIL (turn off)
1.254 1.241
1.28 18 30 20
0.6VCC -1
0.55VCC 1.1 0.01 0.2 0.25 0.25 5 0.05 1 365 65 0.8 1
V A %VOUT %/V %/V A kHz %
200A IOUT 20mA 2.2V VCC 16V; IOUT = 4mA (adjustable) 2.2V VCC 4.5V; IOUT = 4mA (MIC2142-5.0) ISW = 100mA, VCC = 2.5V VEN = OFF, VSW = 12V 295 50
330 57
October 2007
3
M9999-102507
Micrel, Inc.
MIC2142
Typical Characteristics
350 QUIESCENT CURENT (A) 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 16 INPUT VOLTAGE (V)
Quiescent Current vs. Input Voltage
OUTPUT VOLTAGE (V) VOUT = 5V
16.5 16 15.5 15 14.5 14 2
Line Regulation
IL = 7mA L = 22 H IL = 2mA L = 220H
4
6 8 10 12 INPUT VOLTAGE (V)
14
1200 OUTPUT RIPPLE (mV) 1000 800 600 400 200 0 0 2
Output Ripple vs. Input Voltage
OUTPUT VOLTAGE (V) IL = 7mA L = 22 H
16 14 12 10 6 4 2 0 0
MIC2142 Load Regulation
VOUT
VOUT = 15V
IL = 2mA L = 220H
L = 22H 8 VIN = 5V
VREF 5 10 15 20 25 30 OUTPUT CURRENT (mA)
4 6 8 10 12 14 INPUT VOLTAGE (V)
350 300 FREQUENCY (kHz) 250 200 150
Oscillator Characteristics vs. Input Voltage
Frequency
0.65 QUIESCENT CURRENT (A) 0.60 0.55 DUTY CYCLE
84 82 80 78 76 74 72
Quiescent Current vs. Temperature
Duty Cycle
0.50
100 V = 15V O 0.45 50 IO = 100A L= 220H 0 0.40 0 2 4 6 8 10 12 14 INPUT VOLTAGE (V)
VIN = 3.6V 70 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE C) (
335 FREQUENCY (kHz) 330 325 320 315 310 305 300 295 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE C) (
OSCILLATOR CHARACTERISTICS
340
Frequency vs. Temperature
3.5
Timing Characteristics Over Temperature
3.0 T (sec) 2.5 2.0 1.5 t 1.0 0.5 Duty Cycle 0 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE C) (
ON
(sec)
October 2007
4
M9999-102507
Micrel, Inc.
MIC2142
Typical Characteristics (cont.)
7 6 5 RDS(O N) () 4 3 2 1 0 -50 -30 -10 10 30 50 70 90 110 TEMPERATURE C) ( VCC = 4.5V
RDS(ON) vs. Temperature
VCC=3.3V DUTY CYCLE (%)
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) (
Timing Characteristics Over Temperature
October 2007
5
M9999-102507
Micrel, Inc.
MIC2142
Functional Diagram
VCC SW
Bandgap Reference
1.265V
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.
October 2007
6
M9999-102507
Micrel, Inc.
MIC2142
(VIN(min) t ON ) 2 2L MAX TS 1 VO - VIN(min) eff
Application Information
Pre-designed circuit information is at the end of this section. Component Selection Resistive Divider (Adjustable Version) The external resistive divider should divide the output volt-age 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)
VOUT R1 + R2 = VREF R1
(2)
IO(max) =
x
(3)
IPK =
t ON(max)VIN(max) L MIN
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 recommended. Table 6 lists minimum inductor sizes versus input and output voltage. In lowcost, 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 LQH4Cseries inductors from either Sumida or MuRata.
Manufacturer MuRata Sumida J.W. Miller Coilcraft Series LC4/C3/C1HQ CR32 78F 90 Table 1. Inductor Examples Device Type surface mount surface mount axial leaded axial 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.
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.
October 2007
7
M9999-102507
Micrel, Inc.
MIC2142
Diode
75C VFWD at 100mA 0.275V 0.6V (175C) 0.4V (85C) 0.54V (85C)
25C VFWD at 100mA 0.325V 0.95V 0.45V 0.56V
Room Temp. Leakage at 15V 2.5A 25nA (20V) 10nA (25V) 0.4A
75C Leakage at 15V 90A 0.2A (20V) 1A (20V) 2A (85C)
t ON(min) =
Package
D nom 0.55 = = 1.53 sec fmax 360kHz x 1 VO - VIN(min)
L max =
SOD123 SMT leaded and SMT SMT DO-34 leaded
VIN(min) 2 x t ON(min) 2 IO(max) x 2 x TS(min)
MBR0530 1N4148 BAT54 BAT85
2.5 2 x 1.53 sec 2 1 x = 42 H 5mA x 2 x 2.78 sec 12 - 2.5 0.8 Select 39H 10%. L max = t ON(max) = 1.1 x D nom 1.1 x 0.55 = = 2sec Fmin 300kHz
= 2.0 sec x 4.7V = 270mA 35 H
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 10F @ 25V with a Y5V temperature coefficient in a 1210 surface mount package. Low cost applications can use the Mseries leaded electrolytic capacitor from Panasonic. In general, ceramic, electrolytic, or tantalum values ranging from 1F to 22F can be used for the output capacitor.
Manufacturer MuRata Vishay Panasonic Series GRM 594 M-series Type ceramic Y5V tantalum Electrolytic Package surface mount surface mount leaded
Ipeak =
t ON(max) x VIN(max) L min
Table 3. Capacitor Examples
Design Example Given a design requirement of 12V output and 1mA load with a minimum 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 Fmax 1 = = 2.78 sec 360kHz
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 improves the power capability of the MIC2142 by increasing the gate drive volt-age 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.
+3.0V to +4.2V VIN L1 33H CR1 MBR0530 +5V @80mA R2 36.5k
R3 100
C3 270pF
C2 10F
4
U1 MIC2142 FB SW 3 GND
2 1
R1 12.4k C1 22F C4 1F
5
EN VCC
GND
GND
Figure 1. Bootstrap VCC with VCC Low Pass Filter
October 2007
8
M9999-102507
Micrel, Inc.
MIC2142
VIN
L1 47H
CR1 MBR0530 R2 36.5k
+5V @16mA
C3 270pF
C2 10F
U1 MIC2142 SW 3 4 FB GND
5 2 1
R1 12.4k
C1 22F
EN VCC
GND
GND
Figure 2. Bootstrap Configuration
For additional pre-designed circuits, see Table 4.
L1 10H VIN CR1 MBR0530 +15V @15mA CR5 LWT673 CR7 LWT673 U1 MIC2142 FB SW 3 GND
5 2
4
CR6 LWT673 C1 1F 25V Rprogram 82
(from controller) PWM
C2 10F
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 U1 MIC2142 FB SW 3 GND
5 2
4
CR6 LWT673 C1 1F 25V Rprogram 82
C2 10F SHTDWN
EN VCC
1
GND DAC
GND
R4
R3
Figure 4. Series White LED Driver with Analog Dimming Control
October 2007
9
M9999-102507
Micrel, Inc.
MIC2142
Figure 5. Parallel White LED Driver with Analog Dimming Control
L1 10H CR1 BAT54HT1
VIN
+20V @0.5mA
R2 1.8M
C1 1F 25V
C2 10F
4
U1 MIC2142 FB SW 3 GND
2 1
R1 120k C1 1F 25V
5
EN VCC
VINRTN
GND
Figure 6. Handheld LCD Supply
October 2007
10
M9999-102507
Micrel, Inc.
MIC2142
VIN(min) 2.5V
VIN(max) 3.0V
VOUT 3.3V
2.5V
4.5V
5V boot strapped boot strapped 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
11.5 4.7
2.5
14.5 4.7
2.5 2.5 3.0
4.7 4.7 4.7
3.0
3.0 3.0 3.0 3.0 5.0
8.5 4.7 4.7 14.5 4.7 4.7 4.7 8.5
5.0
11.5
12
5.0
14.5 9 8.0 11.5
15
5.0 9
20 12
9
14
15
9
14
20
12
14
15
12
14
20
IOUT(max) 40mA 23mA 10mA 16.5mA 7.8mA 51 77 1.8 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
Table 4. Typical Maximum Power Configuration
October 2007
11
M9999-102507
Micrel, Inc.
MIC2142
VIN 3.3V5%
5V5%
12V5% 15V5%
VOUT 5V 9V 12V 15 20 9V 12V 15V 20 15V 20V 20V
IOUT 70mA 30mA 20mA 15mA 6mA 70mA 40mA 30mA 8mA 158 35 50
L1 18H 18H 18H 18H 33H 27H 27H 27H 68H 68 150 220
CR1 MBR0530 MBR0530 MBR0530 MBR0530 BAT54 MBR0530 MBR0530 MBR0530 BAT54 MBR0530 BAT54 BAT54
IPEAK 400 400 400 400 214 370 370 370 148 350 160 1140
Configuration Bootstrap Bootstrap Bootstrap Bootstrap
Table 5. Typical Maximum Power Configurations for Regulated Inputs
VIN (V) 2.5 3 3.5 4 5 6 7 8 9 10 11 12 13 14 15 16
VOUT = 16V to 22V 85C LMIN (H) 47 33 47 56 68 82 100 100 120 150 150 150 180 180 220 220
VOUT < 16V (bootstapped) 85C LMIN (H) 47 (15) 33 (18) 27 (22) 27 (22) 27 33 39 47 56 56 68 68 82 82 82 100
VOUT < 16V (bootstapped) 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.micre.com www.vishay.com www.panasonic.com
Table 7. Component Supplier Websites
October 2007
12
M9999-102507
Micrel, Inc.
MIC2142
Inductor Selection Guides
Figure 7. Inductor Selection for VIN = 2.5V
Figure 8. Inductor Selection for VIN = 3.0V
October 2007
13
M9999-102507
Micrel, Inc.
MIC2142
Figure 9. Inductor Selection for VIN = 5V
Figure 10. Inductor Selection for VIN = 9V
October 2007
14
M9999-102507
Micrel, Inc.
MIC2142
IN
Figure 11. Inductor Selection for VIN = 12V
Figure 8. Inductor Selection for VIN = 15V
October 2007
15
M9999-102507
Micrel, Inc.
MIC2142
Figure 13. Peak Inductor Current vs. Input Voltage
October 2007
16
M9999-102507
Micrel, Inc.
MIC2142
Package Information
5-Pin SOT23 (M5)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2000 Micrel, Incorporated.
October 2007
17
M9999-102507

▲Up To Search▲

Price & Availability of MIC214207

	To Download MIC214207 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .