MIC2145 High Efficiency 2.5W Boost Converter Final Information
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MIC2145
MIC2145
High Efficiency 2.5W Boost Converter Final Information
General Description
MIC2145 MSOP-8 boost switching regulator that provide over 2.5W output power. input voltage range between 2.4V 16V, making device suitable one-cell Li-Ion 4-cell alkaline/NiCad/NiMH applications. output voltage MIC2145 adjusted 16V. MIC2145 well suited portable, space-sensitive applications. typical 450KHz operation allows small surface mount external components used. MIC2145 quiescent current 200µA, typical shutdown current 0.5µA. MIC2145 capable high efficiencies small board area. MIC2145 features low-on resistance internal switch that allows provide over 2.5W output power. peak switch current programmed through external resistor. This allows user peak switch current level where maximum efficiency occurs. also allows user further optimize efficiency inductor size setting peak current below level inductor saturation. MIC2145 available MSOP-8 package with ambient operating temperature range from -40°C +85°C.
Features
2.4V input voltage Output adjustable Programable peak current limit Soft Start 450KHz switching frequency 0.5µA shutdown current 200µA quiescent current Capable 500mA output with 3.3V input Achieves over efficiency Implements power BOOST, SEPIC, FLYBACK topologies MSOP-8 package
Applications
bias supply White driver bias supply Local conversion
Ordering Information
Part Number MIC2145BMM Voltage Ambient Temp. Range -40°C +85°C Package 8-lead MSOP
Typical Application
3.0V 5.0V 10µF/6.3V
10µH PGND SGND
Output Efficiency
VOUT 10V/150mA
EFFICIENCY
3.0V 1000 OUTPUT CURRENT (mA)
MIC2145
COUT 10µF/16V
RSET
Limit
Adjstable Output Boost Converter with Programmable Peak Switch Current
Micrel, Inc. 1849 Fortune Drive Jose, 95131 (408) 944-0800 (408) 944-0970 http://www.micrel.com
September 2001
MIC2145
MIC2145
Configuration
RSET PGND SGND
8-Lead MSOP (MM)
Description
Number Adjustable Voltage Name RSET PGND SGND Function Enable (Input): Logic high (1.5V) enables regulator. Logic (0.7V) shuts down regulator. float. Soft-Start Capacitor (External Component): Connect external capacitor ground control rise time output voltage. Current Limit (External Component): Sets peak current limit internal power MOSFET using external resistor. Power Ground (Return): Internal power MOSFET source. Switch Node (Input): Internal power MOSFET drain. Supply (Input): +2.4V +16V internal circuitry. Feedback (Input): Output voltage sense node. Small Signal Ground (Return): Ground
MIC2145
September 2001
MIC2145
Absolute Maximum Ratings (Note
Supply Voltage (VDD) Switch Voltage (VSW) Feedback Voltage (VFB) Switch Current (ISW) Enable Voltage(VEN), Note RSET Voltage (VRSET) Rating, Note Ambient Storage Temperature(TS) -65°C +150°C
Operating Ratings (Note
Supply Voltage (VDD) 2.4V Switch Voltage (VSW) Ambient Temperature (TA) -40°C +85°C Junction Temperature (TJ) -40°C +125°C Package Thermal Resistance MSOP (JA) 206°C/W
Electrical Characteristics
10V,VOUT 10V, IOUT 100mA; =25°C, unless otherwise noted, bold values indicate -40°C 125°C; Parameter Supply Voltage Shutdown Current Quiescent Current Feedback Voltage Reference 0.3V, 10V, VFB=1.35V VDD, 10V, 1.35V (±2%) (±3%) Comparator Hysterisis Feedback Input Current Peak Current Limit VFB=1.35V RSET=200, 3.6V, Note RSET=1K, 10V, Note Current Limit Comparator Propagation Delay Switch On-Resistance 150mA, 3.0V 1.2A, Maximum Time Enable Input Voltage Logic (turn-off) Logic High (turn-on) Enable Input Current Soft Start Current
Note Note Note Note Note
Condition
Units
1.058 1.048 1000 0.01 0.01 1.08
1.102 1.112
2V,VDD=3.0V
Exceeding absolute maximum rating damage device. device guaranteed function outside operating rating. Devices sensitive. Handling precautions recommended. Human body model, 1.5K series with 100pF. current measured mode. Actual peak switching current will higher internal propagation delay circuit. VDD.
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MIC2145
MIC2145
Typical Characteristics
Efficiency-Basic Configuration
EFFICIENCY
EFFICIENCY
Efficiency-Bootstrapped Configuration
3.3V VOUT 10µH
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 VOUT
Load Regulation
10.2 10.0 3.6V 10µH
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09
3.3V VOUT 10µH
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
OUTPUT CURRENT
OUTPUT CURRENT
OUTPUT CURRENT
Line Regulation
SWITCH ON-RESISTANCE
15.8 15.6
VOUT
15.4 15.2 15.0 14.8 14.6 14.4 14.2 14.0
SWITCH ON-RESISTANCE
16.0
Switch On-Resistance
Switch On-Resistance Temperature
TEMPERATURE (°C)
IOUT 10mA
10µH
0.50
QUIESCENT CURRENT
Quiescent Current
FEEDBACK VOLTAGE
Feedback Voltage Temperature
1.09 1.08 1.07 1.06 1.05 TEMPERATURE (°C) FEEDBACK CURRENT (µA) 0.10 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01
Feedback Current Temperature
0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00
0.00 TEMPERATURE (°C)
Time Temperature
SHUTDOWN CURRENT (µA) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05
Shutdown Current Temperature
0.50 QUIESCENT CURRENT (mA) 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05
Quiescent Current Temperature
TIME (µs)
TEMPERATURE (°C)
3.6V
0.00 TEMPERATURE (°C)
0.00 TEMPERATURE (°C)
MIC2145
September 2001
MIC2145
Soft Start Current Temperature
SOFT START CURRENT (µA)
PEAK CURRENT LIMIT
Peak Current Limit Temperature
RSET RSET 3.6V RSET VOUT 10µH TEMPERATURE (°C) 2000
PEAK CURRENT LIMIT (mA)
Peak Current Limit RSET
1800 1600 1400 1200 1000
10µH 5.0V 4.2V 3.6V 3.3V 3.0V 2.4V 8.0V
3.6V
TEMPERATURE (°C)
VOUT/VIN 1.25 1000 10000 RSET()
100000
September 2001
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MIC2145
Functional Diagram
RSET
10µH
VOUT
COUT
RSET
Current Limit Comparator
Thermal Shutdown
Shot 800nS
Soft Start POWER MOSFET SGND
PGND Feedback Comparator
VREF
On(/Off)
VOUT 1.08
Figure Block Diagram
MIC2145
September 2001
MIC2145
Output maximum output voltage limited voltage capability output switch. Output voltages achieved with boost circuit. Higher output voltages require flyback configuration. Peak Current Limit peak current limit externally with resistor. peak current range from 420mA There minimum resistor value RSET lower voltages. resistor value selections, "Typical Characteristics: Peak Current Limit RSET". Soft Start MIC2145 built soft start that controls rise time output voltage peak current-limit threshold during start
Functional Description
"Application Information" component selection predesigned circuits. Overview MIC2145 2.5W boost regulator with programmable peak current limit constant time. Quiescent current MIC2145 typically 200µA when switch state. Efficiencies above throughout most operating conditions realized. Regulation Regulation achieved both comparators, which regulate inductor current output voltage gating power MOSFET. Initially, power applied pins. When part enabled, power MOSFET turns current flows. When current exceeds peak current limit threshold, current-limit comparator fires one-shot turn power MOSFET 1000ns resets flip-fop. current-limit comparator continues cycle power MOSFET until output voltage trips upper threshold feedback comparator, which terminates cycle. cycle will begin again when output voltage drops below lower hysteresis threshold feedback comparator. feedback comparator typical hysteresis 18mV. gain feedback resistor divider, voltage VOUT experiences typical 167mV hysteresis output 2.4V VDD. This reduced adding feed-forward capacitor, (See Output Voltage section).
(2V/div) VOUT RSET 0.01µF
VOUT (5V/div)
(5V/div)
IINDUCTOR (500mA/div)
Time 200µs
Figure Typical Soft-Start Waveforms
VOUT Couple (100mV/div)
Thermal Shutdown Built-in thermal protection circuitry turns power MOSFET when junction temperature exceeds about 150°C.
(5V/div)
IINDUCTOR (500mA/div)
Time 20µs
Figure Typical Regulator Waveforms
September 2001
MIC2145
MIC2145
value recommended minimize quiescent current when part off. Then, solved using above equation. feed-forward capacitor, CFF, ranging from 100pF used parallel with reduce peak-to-peak output voltage ripple, which shown Figures
Application Information
Pre-designed circuit information this section. Output Voltage output voltage regulator between 2.4V connecting resistor divider pin. resistor values selected following equations:
1.08V VOUT 1.08V
VOUT Couple (100mV/div)
VOUT Couple (100mV/div)
(5V/div)
(5V/div)
Time 20µs
Time
Figure Without Feed-Forward Capacitor
Figure With Feed-Forward Capacitor (100pF)
MIC2145
September 2001
MIC2145
Bootstrap bootstrapped configuration recommended applications that require high efficiency heavy loads (>70mA). This achieved connecting VOUT (see
Figure applications that require high efficiency light loads(<70mA), connected input voltage (VIN); this referred basic configuration (see Figure
3.6V 10µF/6.3V Murata GRM42-6 106K
10µH Sumida CR43-100 Semiconductor MBR0530T1
VOUT 5V/250mA 10µF/6.3V Murata GRM42-6 106K
PGND MIC2145 SGND
100pF
RSET 100k 0.01µF
274k
Figure Basic Configuration
3.6V 10µF/6.3V Murata GRM42-6 106K
10µH Sumida CR43-100 Semiconductor MBR0530T1 PGND
VOUT 5V/350mA 10µF/6.3V Murata GRM42-6 106K
SGND MIC2145 RSET 0.01µF 100k 274k
100pF
Figure Bootstrap Configuration
September 2001
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MIC2145
Inductor MIC2145 programmable peak current allow usage small surface mount inductors. 10µH 4.7µH inductor recommended most portable applications such powering white LEDs biasing panels.
inductor should have saturation current rating higher than peak current during circuit operation. (Equivalent Series Resistance) inductor also desirable high efficiency. Below tables that list maximum output current minimum input voltage with efficiencies greater than 80%.
VIN(min)
VIN(max)
RSET
IOUT(max) (mA)
VOUT
VIN(min)
VIN(max)
RSET
IOUT(max) (mA)
VOUT
11.5 14.5 11.5 14.5 11.5 14.5 11.5 14.5
11.5 14.5 11.5 14.5 11.5 14.5 11.5 14.5
Table Typical Application 10µH inductor Basic Configuration
Table Typical application 10µH inductor Bootstrap Configuration
VIN(min)
VIN(max)
RSET
IOUT(max) (mA)
VOUT
VIN(min)
VIN(max)
RSET
IOUT(max) (mA)
VOUT
Table Typical Application 4.7µH inductor Basic Configuration
Table Typical Application 4.7µH inductor Bootstrap Configuration
MIC2145
September 2001
MIC2145
Diode Schottky diode should used output diode. Most application circuits this data sheet specify Motorola MBR0530 surface mount Schottky diode. forward current 0.5A forward voltage drop. applications that cost driven, 1N4148 equivalent used efficiency will suffer higher forward voltage drop. Output Capacitor capacitors should used output MIC2145 minimize switching output ripple voltage. Selection capacitor value will depend upon peak inductor current, inductor size, load. MuRata offers GRM43-2 series with 10µF 25V, with temperature coefficient 1812 surface-mount package. lower output voltage applications, GRM42-2 (1210 package/10µF/16V) GRM42-6 (1206 package/10µF/ 6.3V) series used. Typically, values ranging from 10µF 47µF used output capacitor.
Reducing Peak Current lower than 400mA peak current required then soft start shorted ground. This changes reference current limit comparator. With soft start shorted ground, maximum current will approximatly reduce half. peak current should always least higher than maximum load curent.
September 2001
MIC2145
MIC2145
Pre-designed Application Circuits
3.0V-4.2V 10µF/6.3V Murata GRM42-6 106K
4.7µH Murata LQH3C4R7M24 Semiconductor MBR0530T1 100pF 274k
VOUT 10µF/6.3V Murata GRM42-6 106K LED1 LED2 LEDn
PGND MIC2145 SGND
RSET 100k 0.01µF
VOUT
Load
Ripple Voltage mV(peak-peak) <100
Output Efficiency
Efficiency
EFFICIENCY 3.6V 1000 OUTPUT CURRENT (mA)
Figure White Driver Application (Drives LEDs Parallel)
MIC2145
September 2001
MIC2145
3.0V-5.0V 10µF/6.3V Murata GRM42-6 106K
10µH Sumida CR32-100 Semiconductor MBR0530T1 PGND 100pF
VOUT 10.0V 10µF/16V Murata GRM42-2 106K
MIC2145 SGND
RSET 100k 0.01µF
121k
VOUT 10.0
Load
Ripple Voltage mV(peak-peak) <200
Output Efficiency
Efficiency
EFFICIENCY
3.0V 1000 OUTPUT CURRENT (mA)
Figure Application Bootstrap Configuration
September 2001
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MIC2145
3.0V-5.0V F/6.3V Murata GRM42-6 106K
Sumida CR32-100 Semiconductor MBR0530T1 PGND 100pF
VOUT 15.0V
LED1 LED2 LED3 LED4
MIC2145 SGND
F/16V Murata GRM42-2 106K
RSET 100k 0.01
78.7k
VOUT 15.0
Load
Ripple Voltage mV(peak-peak) <100
Efficiency
Output Efficiency
EFFICIENCY
3.6V OUTPUT CURRENT (mA)
Figure Series White Driver Application
MIC2145
September 2001
MIC2145
Package Information
0.122 (3.10) 0.112 (2.84)
0.199 (5.05) 0.187 (4.74)
DIMENSIONS: INCH (MM)
0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.032 (0.81) 0.043 (1.09) 0.038 (0.97) 0.012 (0.30)
0.007 (0.18) 0.005 (0.13)
0.012 (0.3) 0.0256 (0.65)
0.008 (0.20) 0.004 (0.10)
0.012 (0.03) 0.039 (0.99) 0.035 (0.89) 0.021 (0.53)
8-Pin MSOP (MM)
MICREL INC. 1849 FORTUNE DRIVE JOSE, 95131
(408) 944-0800
(408) 944-0970
http://www.micrel.com
This information believed accurate reliable, however responsibility assumed Micrel infringement patents other rights third parties resulting from use. license granted implication otherwise under patent patent right Micrel Inc. 2001 Micrel Incorporated
September 2001
MIC2145
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