MIC5209 500mA Low-Noise LDO Regulator General Description Features The MIC5209 is an efficient linear voltage regulator with very low dropout voltage, typically 10mV at light loads and less than 500mV at full load, with better than 1% output voltage accuracy. • Meets Intel® Slot 1 and Slot 2 requirements • Guaranteed 500mA output over the full operating temperature range • Low 500mV maximum dropout voltage at full load • Extremely tight load and line regulation • Thermally-efficient surface-mount package • Low temperature coefficient • Current and thermal limiting • Reversed-battery protection • No-load stability • 1% output accuracy • Ultra-low-noise capability in SO-8 and TO-263-5 • Ultra-small 3mm x 3mm MLF™ package Designed especially for hand-held, battery-powered devices, the MIC5209 features low ground current to help prolong battery life. An enable/shutdown pin on SO-8 and TO-2635 versions can further improve battery life with near-zero shutdown current. Key features include reversed-battery protection, current limiting, overtemperature shutdown, ultra-low-noise capability (SO-8 and TO-263-5 versions), and availability in thermally efficient packaging. The MIC5209 is available in adjustable or fixed output voltages. Applications • • • • • • For space-critical applications where peak currents do not exceed 500mA, see the MIC5219. Pentium II Slot 1 and Slot 2 support circuits Laptop, notebook, and palmtop computers Cellular telephones Consumer and personal electronics SMPS post-regulator/dc-to-dc modules High-efficiency linear power supplies Typical Applications MIC5209-2.5BS VIN ≥ 3.0V 1 2 3 0.1µF VOUT 2.5V ±1% 22µF tantalum 3.3V Nominal-Input Slot-1 Power Supply ENABLE SHUTDOWN VIN 6V VOUT 5V 2.2µF tantalum 1 MIC5209-5.0BM 8 2 7 3 6 4 5 470pF (OPTIONAL) Ultra-Low-Noise 5V Regulator Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com June 2006 1 M9999-060906 MIC5209 Micrel, Inc. Ordering Information Part Number Voltage Junction Temp. Range Package Pb-Free MIC5209-2.5BS 2.5V -40°C to +125°C SOT-223 MIC5209-2.5YS 2.5V -40°C to +125°C SOT-223 MIC5209-3.0BS 3.0V -40°C to +125°C SOT-223 MIC5209-3.0YS 3.0V -40°C to +125°C SOT-223 MIC5209-3.3BS 3.3V -40°C to +125°C SOT-223 MIC5209-3.3YS 3.3V -40°C to +125°C SOT-223 MIC5209-3.6BS 3.6V -40°C to +125°C SOT-223 MIC5209-3.6YS 3.6V -40°C to +125°C SOT-223 MIC5209-4.2BS 4.2V -40°C to +125°C SOT-223 MIC5209-4.2YS 4.2V -40°C to +125°C SOT-223 MIC5209-5.0BS 5.0V -40°C to +125°C SOT-223 MIC5209-5.0YS 5.0V -40°C to +125°C SOT-223 MIC5209-1.8BM* 1.8V -0°C to +125°C SOIC-8 MIC5209-1.8YM* 1.8V -0°C to +125°C SOIC-8 MIC5209-2.5BM 2.5V -40°C to +125°C SOIC-8 MIC5209-2.5YM 2.5V -40°C to +125°C SOIC-8 MIC5209-3.0BM 3.0V -40°C to +125°C SOIC-8 MIC5209-3.0YM 3.0V -40°C to +125°C SOIC-8 MIC5209-3.3BM 3.3V -40°C to +125°C SOIC-8 MIC5209-3.3YM 3.3V -40°C to +125°C SOIC-8 MIC5209-3.6BM 3.6V -40°C to +125°C SOIC-8 MIC5209-3.6YM 3.6V -40°C to +125°C SOIC-8 MIC5209-5.0BM 5.0V -40°C to +125°C SOIC-8 MIC5209-5.0YM 5.0V -40°C to +125°C SOIC-8 MIC5209BM Adj. -40°C to +125°C SOIC-8 MIC5209YM Adj. -40°C to +125°C SOIC-8 X MIC5209-1.8YU* 1.8V -0°C to +125°C TO-263-5 X MIC5209-2.5BU 2.5V -40°C to +125°C TO-263-5 MIC5209-2.5YU 2.5V -40°C to +125°C TO-263-5 MIC5209-3.0BU 3.0V -40°C to +125°C TO-263-5 MIC5209-3.0YU 3.0V -40°C to +125°C TO-263-5 MIC5209-3.3BU 3.3V -40°C to +125°C TO-263-5 MIC5209-3.3YU 3.3V -40°C to +125°C TO-263-5 MIC5209-3.6BU 3.6V -40°C to +125°C TO-263-5 MIC5209-3.6YU 3.6V -40°C to +125°C TO-263-5 MIC5209-5.0BU 5.0V -40°C to +125°C TO-263-5 MIC5209-5.0YU 5.0V -40°C to +125°C TO-263-5 MIC5209BU Adj. -40°C to +125°C TO-263-5 MIC5209YU Adj. -40°C to +125°C TO-263-5 X MIC5209YML Adj. -40°C to +125°C 8-pin MLF™ X X X X X X X X X X X X X X X X X X * Contact marketing for availability. M9999-060906 2 June 2006 MIC5209 Micrel, Inc. Pin Configuration GND TAB VIN 1 VIN 2 VOUT 3 1 IN 2 VOUT 4 3 Y 5209 YWW 8 EN 7 GND 6 ADJ 5 NC Part Identification GND OUT MIC5209-x.xBS SOT-223 Fixed Voltages 8 GND IN 2 7 GND OUT 3 6 GND BYP 4 5 GND TAB EN 1 GND MIC5209YML 8-Pin 3x3 MLF Adjustable Voltages 5 4 3 2 1 BYP OUT GND IN EN 5 4 3 2 1 ADJ OUT GND IN EN MIC5209-x.xBU TO-263-5 Fixed Voltages 8 GND IN 2 7 GND OUT 3 6 GND ADJ 4 5 GND TA AB EN 1 GND MIC5209-x.xBM SO-8 Fixed Voltages MIC5209BU TO-263-5 Adjustable Voltage MIC5209BM SO-8 Adjustable Voltage Pin Description Pin No. 8-pin MLF Pin No. SOT-223 Pin No. SO-8 Pin No. TO-263-5 Pin Name Pin Function 1, 2 1 2 2 IN Supply Input. 7 2, TAB 5–8 3 GND Ground: SOT-223 pin 2 and TAB are internally connected. SO-8 pins 5 through 8 are internally connected. 3, 4 3 3 4 OUT Regulator Output. Pins 3 and 4 must be tied together. 1 1 EN Enable (Input): CMOS compatible control input. Logic high = enable; logic low = shutdown. 4 (fixed) 5 (fixed) BYP Reference Bypass: Connect external 470pF capacitor to GND to reduce output noise. May be left open. For 1.8V or 2.5V operation, see “Applications Information.” 4 (adj.) 5 (adj.) ADJ Adjust (Input): Feedback input. Connect to resistive voltage-divider network. 8 6 June 2006 3 M9999-060906 MIC5209 Micrel, Inc. Absolute Maximum Ratings(1) Operating Ratings(2) Supply Input Voltage (VIN) ..............................–20V to +20V Power Dissipation (PD) ..........................Internally Limited(3) Junction Temperature (TJ) all except 1.8V ...................................... –40°C to +125°C 1.8V only................................................... 0°C to +125°C Lead Temperature (soldering, 5 sec.) ........................ 260°C Storage Temperature (TS) ........................ –65°C to +150°C Supply Input Voltage (VIN) ............................ +2.5V to +16V Enable Input Voltage (VEN) ...................................0V to VIN Junction Temperature (TJ) all except 1.8V ...................................... –40°C to +125°C 1.8V only................................................... 0°C to +125°C Package Thermal Resistance................................... Note 3 Electrical Characteristics (Note 11) VIN = VOUT + 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C except 0°C ≤ TJ ≤ +125°C for 1.8V version; unless noted. Symbol Parameter Conditions VOUT Output Voltage Accuracy variation from nominal VOUT ΔVOUT/ΔT Output Voltage Temperature Coefficient Note 4 ΔVOUT/VOUT Line Regulation VIN = VOUT + 1V to 16V 0.009 0.05 0.1 %/V %/V ΔVOUT/VOUT Load Regulation IOUT = 100µA to 500mA(5) 0.05 0.5 0.7 % % VIN – VOUT Dropout Voltage(6) IOUT = 100µA 10 60 80 mV mV IOUT = 50mA 115 175 250 mV mV IOUT = 150mA 165 300 400 mV mV IOUT = 500mA 350 500 600 mV mV VEN ≥ 3.0V, IOUT = 100µA 80 130 170 µA µA VEN ≥ 3.0V, IOUT = 50mA 350 650 900 µA µA VEN ≥ 3.0V, IOUT = 150mA 1.8 2.5 3.0 mA mA VEN ≥ 3.0V, IOUT = 500mA 8 20 25 mA mA IGND IGND Ground Pin Current(7, 8) Ground Pin Quiescent Current(8) Min Typical –1 –2 Max Units 1 2 % % 40 ppm/°C 0.05 3 µA VEN ≤ 0.18V (shutdown) 0.10 8 µA 900 1000 mA mA VEN ≤ 0.4V (shutdown) PSRR Ripple Rejection f = 120Hz 75 ILIMIT Current Limit VOUT = 0V 700 ΔVOUT/ΔPD Thermal Regulation Note 9 0.05 %/W VOUT = 2.5V, IOUT = 50mA, COUT = 2.2µF, CBYP = 0 500 nV √Hz 300 nV √Hz eno Output Noise(10) IOUT = 50mA, COUT = 2.2µF, CBYP = 470pF M9999-060906 4 dB June 2006 MIC5209 Micrel, Inc. ENABLE Input VENL Enable Input Logic-Low Voltage VEN = logic low (regulator shutdown) IENL Enable Input Current VENL ≤ 0.4V IENH VEN = logic high (regulator enabled) VENL ≤ 0.18V 0.4 0.18 V V 0.01 –1 µA 0.01 –2 µA 5 20 25 µA µA 30 50 µA µA 2.0 V VENH = 2.0V VENH = 16V Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. The maximum allowable power dissipation at any TA (ambient temperature) is calculated using: PD(max) = (TJ(max) – TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. See Table 1 and the “Thermal Considerations” section for details. 4. Output voltage temperature coefficient is the worst case voltage change divided by the total temperature range. 5. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 100µA to 500mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 6. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differential. 7. Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of the load current plus the ground pin current. 8. VEN is the voltage externally applied to devices with the EN (enable) input pin. [SO-8 (M) and TO-263-5 (U) packages only.] 9. Thermal regulation is the change in output voltage at a time “t” after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a 500mA load pulse at VIN = 16V for t = 10ms. 10. CBYP is an optional, external bypass capacitor connected to devices with a BYP (bypass) or ADJ (adjust) pin. [SO-8 (M) and TO-263-5 (U) packages only]. June 2006 5 M9999-060906 MIC5209 Micrel, Inc. Block Diagrams OUT IN VIN VOUT COUT Bandgap Ref. Current Limit Thermal Shutdown MIC5209-x.xBS GND Low-Noise Fixed Regulator (SOT-223 version only) VIN OUT IN VOUT COUT BYP CBYP (optional) Bandgap Ref. V REF EN Current Limit Thermal Shutdown MIC5209-x.xBM/U GND Ultra-Low-Noise Fixed Regulator VIN OUT IN VOUT COUT ADJ Bandgap Ref. V REF R1 R2 CBYP (optional) EN Current Limit Thermal Shutdown MIC5209BM/U [adj.] GND Ultra-Low-Noise Adjustable Regulator M9999-060906 6 June 2006 MIC5209 Micrel, Inc. Typical Characteristics Power Supply Rejection Ratio -80 -20 PSRR (dB) -20 PSRR (dB) 0 VIN = 6V VOUT = 5V -40 -60 IOUT = 100µA COUT = 2.2µF CBYP = 0.01µF -80 30 IOUT = 100mA 20 10 0 10 1 NOISE (µV/√Hz) 1mA 10mA 0.1 COUT = 1µF 0.1 0.2 0.3 VOLTAGE DROP (V) PSRR (dB) -60 RIPPLE REJECTION (dB) 40 0.4 Noise Performance 10 IOUT = 1mA COUT = 2.2µF CBYP = 0.01µF 10mA 0.01 VOUT = 5V 1mA 0.001 C OUT = 10µF electrolytic 0.0001 1k 10k 1E+51E+6 10 1E+2 100k 1M 1E+7 10M 100 1E+31E+4 1E+1 FREQUENCY (Hz) -40 -60 IOUT = 100mA COUT = 2.2µF CBYP = 0.01µF -80 -100 10k 100k1E+61E+7 1M 10M 1E+1 10 1E+21E+3 100 1k 1E+41E+5 FREQUENCY (Hz) 10 1 1mA 10mA IOUT = 100mA COUT = 2.2µF CBYP = 0.01µF 0.1 0.2 0.3 VOLTAGE DROP (V) Noise Performance 10mA, COUT = 1µF 0.1 0.01 0.001 0.4 Noise Performance 1 100mA NOISE (µV/√Hz) RIPPLE REJECTION (dB) 50 VIN = 6V VOUT = 5V -20 -40 100 90 80 70 60 50 40 30 20 10 0 0 Power Supply Rejection Ratio 0 VIN = 6V VOUT = 5V Power Supply Ripple Rejection vs. Voltage Drop 60 IOUT = 100mA COUT = 1µF -100 10k 100k1E+61E+7 1M 10M 1E+1 10 1E+21E+3 100 1k 1E+41E+5 FREQUENCY (Hz) -100 10k 100k1E+61E+7 1M 10M 1E+1 10 1E+21E+3 100 1k 1E+41E+5 FREQUENCY (Hz) Power Supply Ripple Rejection vs. Voltage Drop -60 Power Supply Rejection Ratio -80 -100 10k 100k1E+61E+7 1M 10M 1E+1 10 1E+21E+3 100 1k 1E+41E+5 FREQUENCY (Hz) -40 -80 IOUT = 1mA COUT = 1µF -100 10k 100k1E+61E+7 1M 10M 1E+1 10 1E+21E+3 100 1k 1E+41E+5 FREQUENCY (Hz) Power Supply Rejection Ratio 0 June 2006 -60 -80 IOUT = 100µA COUT = 1µF -100 10k 100k1E+61E+7 1M 10M 1E+1 10 1E+21E+3 100 1k 1E+41E+5 FREQUENCY (Hz) 0 -40 PSRR (dB) -60 VIN = 6V VOUT = 5V -20 NOISE (µV/√Hz) -40 0 VIN = 6V VOUT = 5V -20 PSRR (dB) -20 PSRR (dB) 0 VIN = 6V VOUT = 5V Power Supply Rejection Ratio 100mA 0.1 VOUT = 5V 0.0001 10 100 1E+31E+4 1k 10k 1E+51E+6 100k 1M 1E+7 10M 1E+11E+2 FREQUENCY (Hz) 400 Dropout Voltage vs. Output Current DROPOUT VOLTAGE (mV) 0 Power Supply Rejection Ratio 300 200 0.01 V OUT = 5V COUT = 10µF 0.001 electrolytic CBYP = 100pF 1mA 10mA 0.0001 10 1E+21E+3 1M 10M 10k 100k 1E+61E+7 100 1k 1E+41E+5 1E+1 FREQUENCY (Hz) 7 100 0 0 100 200 300 400 500 OUTPUT CURRENT (mA) M9999-060906 MIC5209 Micrel, Inc. Dropout Characteristics OUTPUT VOLTAGE (V) 3.0 12 IL =100µA GROUND CURRENT (mA) 3.5 10 2.5 2.0 1.5 IL=100mA 1.0 IL=500mA 0.5 GROUND CURRENT (mA) 25 1 2 3 4 5 6 7 8 INPUT VOLTAGE (V) 6 4 2 0 0 9 Ground Current vs. Supply Voltage 3.0 100 200 300 400 500 OUTPUT CURRENT (mA) Ground Current vs. Supply Voltage 2.5 20 2.0 15 1.5 10 1.0 5 0 0 M9999-060906 8 GROUND CURRENT (mA) 0 0 Ground Current vs. Output Current IL=500mA 1 2 3 4 5 6 7 8 INPUT VOLTAGE (V) 0.5 0 0 9 8 IL=100 mA IL=100µ A8 4 6 2 INPUT VOLTAGE (V) June 2006 MIC5209 Micrel, Inc. Applications Information Thermal Considerations The SOT-223 has a ground tab which allows it to dissipate more power than the SO-8. Refer to “Slot-1 Power Supply” for details. At 25°C ambient, it will operate reliably at 2W dissipation with “worst-case” mounting (no ground plane, minimum trace widths, and FR4 printed circuit board). Enable/Shutdown Enable is available only on devices in the SO-8 (M) and TO-263-5 (U) packages. Forcing EN (enable/shutdown) high (> 2V) enables the regulator. EN is compatible with CMOS logic. If the enable/shutdown feature is not required, connect EN to IN (supply input). Thermal resistance values for the SO-8 represent typical mounting on a 1”-square, copper-clad, FR4 circuit board. For greater power dissipation, SO-8 versions of the MIC5209 feature a fused internal lead frame and die bonding arrangement that reduces thermal resistance when compared to standard SO-8 packages. Input Capacitor A 1µF capacitor should be placed from IN to GND if there is more than 10 inches of wire between the input and the ac filter capacitor or if a battery is used as the input. Output Capacitor Package An output capacitor is required between OUT and GND to prevent oscillation. The minimum size of the output capacitor is dependent upon whether a reference bypass capacitor is used. 1µF minimum is recommended when CBYP is not used (see Figure 1). 2.2µF minimum is recommended when CBYP is 470pF (see Figure 2). Larger values improve the regulator’s transient response. θJA θJC SOT-223 (S) 50°C/W 8°C/W SO-8 (M) 50°C/W 20°C/W TO-263-5 (U) — 2°C/W 3x3 MLF (ML) 63°C/W 2°C/W Table 1. MIC5209 Thermal Resistance The output capacitor should have an ESR (equivalent series resistance) of about 1Ω and a resonant frequency above 1MHz. Ultra-low-ESR capacitors can cause a low amplitude oscillation on the output and/or underdamped transient response. Most tantalum or aluminum electrolytic capacitors are adequate; film types will work, but are more expensive. Since many aluminum electrolytics have electrolytes that freeze at about –30°C, solid tantalums are recommended for operation below –25°C. Multilayer boards with a ground plane, wide traces near the pads, and large supply-bus lines will have better thermal conductivity and will also allow additional power dissipation. At lower values of output current, less output capacitance is needed for output stability. The capacitor can be reduced to 0.47µF for current below 10mA or 0.33µF for currents below 1mA. Low-Voltage Operation For additional heat sink characteristics, please refer to Micrel Application Hint 17, “Designing P.C. Board Heat Sinks”, included in Micrel’s Databook. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to Regulator Thermals section of Micrel’s Designing with LowDropout Voltage Regulators handbook. The MIC5209-1.8 and MIC5209-2.5 require special consideration when used in voltage-sensitive systems. They may momentarily overshoot their nominal output voltages unless appropriate output and bypass capacitor values are chosen. No-Load Stability The MIC5209 will remain stable and in regulation with no load (other than the internal voltage divider) unlike many other voltage regulators. This is especially important in CMOS RAM keep-alive applications. During regulator power up, the pass transistor is fully saturated for a short time, while the error amplifier and voltage reference are being powered up more slowly from the output (see “Block Diagram”). Selecting larger output and bypass capacitors allows additional time for the error amplifier and reference to turn on and prevent overshoot. Reference Bypass Capacitor BYP (reference bypass) is available only on devices in SO-8 and TO-263-5 packages. To ensure that no overshoot is present when starting up into a light load (100µA), use a 4.7µF output capacitance and 470pF bypass capacitance. This slows the turn-on enough to allow the regulator to react and keep the output voltage from exceeding its nominal value. At heavier loads, use a 10µF output capacitance and 470pF bypass capacitance. Lower values of output and bypass capacitance can be used, depending on the sensitivity of the system. BYP is connected to the internal voltage reference. A 470pF capacitor (CBYP) connected from BYP to GND quiets this reference, providing a significant reduction in output noise (ultra-low-noise performance). Because CBYP reduces the phase margin, the output capacitor should be increased to at least 2.2µF to maintain stability. The start-up speed of the MIC5209 is inversely proportional to the size of the reference bypass capacitor. Applications requiring a slow ramp-up of output voltage should consider larger values of CBYP. Likewise, if rapid turn-on is necessary, consider omitting CBYP. Applications that can withstand some overshoot on the output of the regulator can reduce the output capacitor and/or reduce or eliminate the bypass capacitor. Applications that are not sensitive to overshoot due to power-on reset delays can use normal output and bypass capacitor configurations. If output noise is not critical, omit CBYP and leave BYP open. June 2006 Please note the junction temperature range of the regulator at 1.8V output (fixed and adjustable) is 0˚C to +125˚C. 9 M9999-060906 MIC5209 Micrel, Inc. Fixed Regulator Circuits MIC5209-x.xBM VIN 2 3 IN OUT 1 4 EN BYP GND 5–8 VIN VOUT MIC5209BM 2 1 IN EN OUT ADJ GND VOUT 3 4 R1 5–8 1µF 470pF 2.2µF R2 Figure 1. Low-Noise Fixed Voltage Regulator Figure 4. Ultra-Low-Noise Adjustable Application. Figure 1 shows a basic MIC5209-x.xBM (SO-8) fixed-voltage regulator circuit. See Figure 5 for a similar configuration using the more thermally-efficient MIC5209-x.xBS (SOT-223). A 1µF minimum output capacitor is required for basic fixedvoltage applications. Figure 4 includes the optional 470pF bypass capacitor from ADJ to GND to reduce output noise. MIC5209-x.xBM VIN 2 1 IN OUT EN BYP GND 5–8 Slot-1 Power Supply Intel’s Pentium II processors have a requirement for a 2.5V ±5% power supply for a clock synthesizer and its associated loads. The current requirement for the 2.5V supply is dependant upon the clock synthesizer used, the number of clock outputs, and the type of level shifter (from core logic levels to 2.5V levels). Intel estimates a worst-case load of 320mA. VOUT 3 4 2.2µF The MIC5209 was designed to provide the 2.5V power requirement for Slot-1 applications. Its guaranteed performance of 2.5V ±3% at 500mA allows adequate margin for all systems, and its dropout voltage of 500mV means that it operates from a worst-case 3.3V supply where the voltage can be as low as 3.0V. 470pF Figure 2. Ultra-Low-Noise Fixed Voltage Regulator Figure 2 includes the optional 470pF noise bypass capacitor between BYP and GND to reduce output noise. Note that the minimum value of COUT must be increased when the bypass capacitor is used. VIN Adjustable Regulator Circuits VIN MIC5209BM 2 1 IN EN OUT ADJ GND 5–8 3 4 CIN 0.1µF VOUT R1 IN OUT GND 2,TAB 3 VOUT COUT 22µF Figure 5. Slot-1 Power Supply 1µF A Slot-1 power supply (Figure 5) is easy to implement. Only two capacitors are necessary, and their values are not critical. CIN bypasses the internal circuitry and should be at least 0.1µF. COUT provides output filtering, improves transient response, and compensates the internal regulator control loop. Its value should be at least 22µF. CIN and COUT may be increased as much as desired. R2 Figure 3. Low-Noise Adjustable Voltage Regulator The MIC5209BM/U can be adjusted to a specific output voltage by using two external resistors (Figure 3). The resistors set the output voltage based on the equation: R2 VOUT = 1.242V 1 + R1 Slot-1 Power Supply Power Dissipation Powered from a 3.3V supply, the Slot-1 power supply of Figure 5 has a nominal efficiency of 75%. At the maximum anticipated Slot 1 load (320mA), the nominal power dissipation is only 256mW. This equation is correct due to the configuration of the bandgap reference. The bandgap voltage is relative to the output, as seen in the block diagram. Traditional regulators normally have the reference voltage relative to ground; therefore, their equations are different from the equation for the MIC5209BM/U. The SOT-223 package has sufficient thermal characteristics for wide design margins when mounted on a single layer copper-clad printed circuit board. The power dissipation of the MIC5209 is calculated using the voltage drop across the device × output current plus supply voltage × ground current. Although ADJ is a high-impedance input, for best performance, R2 should not exceed 470kΩ. M9999-060906 MIC5209-x.xBS 1 10 June 2006 MIC5209 Micrel, Inc. Considering worst case tolerances, the power dissipation could be as high as: Figure 6 shows the necessary copper pad area to obtain specific heat sink thermal resistance (θSA) values. The θSA values in Table 2 require much less than 500mm2 of copper, according to Figure 6, and can easily be accomplished with the minimum footprint. (VIN(max) – VOUT(max)) × IOUT + VIN(max) × IGND [(3.6V – 2.375V) × 320mA] + (3.6V × 4mA) PD = 407mW Using the maximum junction temperature of 125°C and a θJC of 8°C/W for the SOT-223, 25°C/W for the SO-8, or 2°C/W for the TO-263 package, the following worst-case heat-sink thermal resistance (θSA) requirements are: TJ(max J(max) − TA θJA = PD 70 60 50 40 30 θSA = θJA = θJC TA 20 40°C 50°C 60°C 75°C θJA (limit) 209°C/W 184°C/W 160°C/W 123°C/W θSA SOT-223 201°C/W 176°C/W 152°C/W 115°C/W θSA SO-8 184°C/W 159°C/W 135°C/W 98°C/W θSA TO-263-5 207°C/W 182°C/W 158°C/W 121°C/W 10 0 0 2000 4000 6000 COPPER HEAT SINK AREA (mm2) Figure 6. PCB Heat Sink Thermal Resistance Table 2. Maximum Allowable Thermal Resistance Table 2 and Figure 6 show that the Slot-1 power supply application can be implemented with a minimum footprint layout. June 2006 11 M9999-060906 MIC5209 Micrel, Inc. Package Information SOT-223 (S) 8-Pin SOIC (M) M9999-060906 12 June 2006 MIC5209 Micrel, Inc. θ4 θ1 θ2 θ1 θ1 θ2 θ3 θ4 θ1 θ3 TO-263-5 (U) 8-Pin 3mm x 3mm MLF (ML) MICREL INC. TEL 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com This 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. © 2004 Micrel Incorporated June 2006 13 M9999-060906