MIC5212 Micrel MIC5212 Dual 500mA LDO Regulator Final General Description Features The MIC5212 is a dual linear voltage regulator with very-low dropout voltage (typically 10mV at light loads and 350mV at 500mA), very-low ground current (225µA at 10mA output), and better than 1% initial accuracy. Both regulator outputs can supply up to 500mA at the same time as long as each regulator’s maximum junction temperature is not exceeded. • • • • • • • • Key features include current limiting, overtemperature shutdown, and protection against reversed battery. The MIC5212 is available in a fixed 3.3V/2.5V output voltage configuration. Other voltages are available; contact Micrel for details. Fused lead frame SOIC-8 Up to 500mA per regulator output Low quiescent current Low dropout voltage Tight load and line regulation Low temperature coefficient Current and thermal limiting Reversed input polarity protection Applications • • • • • Hard disk drives CD R/W Bar code scanners SMPS post regulator/DC-to-DC modules High-efficiency linear power supplies Ordering Information Part Number MIC5212-SJBM Voltage Accuracy Junction Temp. Range* Package 3.3V/2.5V 1.0% –40°C to +125°C 8-lead SOIC Other voltages available. Contact Micrel for details. Typical Application MIC5212-SJBM IN = 5V 4.7µF VO1 = 3.3V INA OUTA INB VO2 = 2.5V OUTB GND 4.7µF 4.7µF 3.3V/2.5V Dual LDO Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com April 2003 1 MIC5212 MIC5212 Micrel Pin Configuration OUTA 1 8 GND INA 2 7 GND INB 3 6 GND OUTB 4 5 GND SOIC-8 (M) Pin Description Pin Number Pin Name 1 OUTA 2 INA Regulator A Input 3 INB Regulator B Input 4 OUTB Regulator B Output 5, 6, 7, 8 GND Ground MIC5212 Pin Function Regulator A Output 2 April 2003 MIC5212 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Input Voltage (VIN A or B) ................. –20V to +20V Power Dissipation (PD) ............................ Internally Limited Storage Temperature Range ................... –60°C to +150°C Lead Temperature (soldering, 5 sec.) ....................... 260°C Supply Input Voltage (VIN) ............................... 2.5V to 16V Junction Temperature (TJ) ....................... –40°C to +125°C Thermal Resistance (θJA)......................................... Note 3 Electrical Characteristics Regulator A and B VIN = VOUT + 1V; IL = 100µA; CL = 4.7µF; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted. Symbol Parameter Conditions Min VO Output Voltage Accuracy variation from specified VOUT –1 –2 ∆VO/∆T Output Voltage Temperature Coefficient Note 4 ∆VO/VO Line Regulation VIN = VOUT + 1V to 16V 0.009 0.05 0.1 %/V %/V ∆VO/VO Load Regulation IL = 0.1mA to 500mA, Note 5 0.05 0.7 1.0 % % VIN – VO Dropout Voltage, Note 6 (per regulator) IL = 150mA 175 IL = 500mA 350 275 350 500 600 mV mV mV mV IL = 150mA 1.5 IL = 500mA 12 2.5 3.0 20 25 mA mA mA mA IGND Ground Pin Current, Note 7 (per regulator) Typical Max Units 1 2 % % 40 PSRR Ripple Rejection f = 120Hz, IL = 150mA 75 ILIMIT Current Limit VOUT = 0V 750 Spectral Noise Density VOUT = 2.5V, IOUT = 50mA, COUT = 2.2µF 500 ppm/°C dB5 1000 mA nV/√Hz Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Note 3. 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 at any 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. The θJA of the 8-lead SOIC (M) is 63°C/W mounted on a PC board (see “Thermal Considerations” section for further details). Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 0.1mA to 500mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 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. 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. Note 4. Note 5. Note 6. Note 7. April 2003 3 MIC5212 MIC5212 Micrel Typical Characteristics MIC5212 PSRR 500mA Load 90 80 80 70 70 70 60 60 60 1M 0 10 1M 60 50 40 30 COUT = 10µF Tantulum VIN = 4.3V VOUT = 3.3V VIN = VOUT + 1V 0 10 100 1k 10k 100k FREQUENCY (Hz) 10k 100k 100 1k FREQUENCY (Hz) 1M S/C Current vs. Temperature 10 8 6 300mA 4 2 150mA 100µA 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 3.305 3.300 3.295 3.290 3.285 3.280 DROPOUT VOLTAGE (mV) 3.310 600 500 400 300 200 100 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) Dropout Voltage vs. Temperature 3.320 3.315 700 500mA 12 Output Voltage vs. Temperature Dropout Voltage vs. Load Current 350 500 450 400 350 500mA 300 250 300mA 200 150 150mA 100 50 3.275 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 1M 800 LOAD CURRENT (mA) GROUND CURRENT (mA) 70 PSRR (dB) 100 1k 10k 100k FREQUENCY (Hz) 14 80 10 10 COUT = 10µF Tantulum VIN = 4.3V VOUT = 3.3V VIN = VOUT + 1V Ground Current vs. Temperature MIC5212-2.5 PSRR 500mA Load 90 20 20 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 300 250 200 150 100 50 0 500 0 10 30 400 450 1k 100 10k 100k FREQUENCY (Hz) 10 40 0 50 0 10 20 500mA COUT = 10µF Tantulum VIN = 4.3V VOUT = 3.3V VIN = VOUT + 1V DROPOUT VOLTAGE (mV) 10 COUT = 10µF Tantulum VIN = 4.3V VOUT = 3.3V VIN = VOUT + 1V 30 50 300 350 30 40 200 250 40 50 100 150 50 PSRR (dB) 90 80 20 OUTPUT VOLTAGE (V) MIC5212-2.5 PSRR 150mA Load 90 PSRR (dB) PSRR (dB) MIC5212-3.3 PSRR 150mA Load OUTPUT CURRENT (mA) Ground Current vs. Load GROUND CURRENT (mA) 14 12 10 8 6 4 2 0 0 MIC5212 100 200 300 400 500 OUTPUT CURRENT (mA) 4 April 2003 MIC5212 Micrel OUTPUT 2 OUTPUT 1 (20mV/div) (20mV/div) OUTPUT 2 CURRENT (200mA/div) 1000mA 500mA 10mA 10mA VIN = 3.3V VOUT = 2.5V COUT = 10 F Ceramic 1000mA 500mA 10mA 10mA TIME (1ms/div.) TIME (1ms/div.) Output 1 Line Transient Response Line Transient Response VIN = 3.3V VOUT = 2.5V COUT = 10 F Ceramic 7V 6V VIN (2V/div) 4.3V 3.5V VOUT 2 (10mV/div) VOUT 1 VOUT 2 (10mV/div) (10mV/div) 1000mA VOUT 1 (10mV/div) VIN (2V/div) Output 2 Load Transient Response VIN = 3.3V VOUT = 2.5V COUT = 10 F Ceramic OUTPUT CURRENT (500mA/div) OUTPUT 1 OUTPUT 2 (20mV/div) (20mV/div) Output 1 Load Transient Response 10mA TIME (1ms/div.) TIME (1ms/div.) VSUPPLY (2V/div) 2.5V, 200mA OUTPUT 2 (1V/div) 3.3V, 500mA OUTPUT 1 (1V/div) Turn-On Response TIME (40µs/div.) April 2003 5 MIC5212 MIC5212 Micrel Functional Diagram INA OUTA Bandgap Ref. V REF Current Limit Thermal Shutdown INB OUTB Bandgap Ref. V REF Current Limit Thermal Shutdown GND MIC5212 6 April 2003 MIC5212 Micrel Lower thermal resistance is achieved by joining the four ground leads with the die attach paddle to create a singlepiece electrical and thermal conductor. This concept has been used by MOSFET manufacturers for years, proving very reliable and cost effective for the user. Applications Information 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. Thermal resistance consists of two main elements, θJC (junction-to-case thermal resistance) and θCA (case-to-ambient thermal resistance). See Figure 1. θJC is the resistance from the die to the leads of the package. θCA is the resistance from the leads to the ambient air and it includes θCS (case-tosink thermal resistance) and θSA (sink-to-ambient thermal resistance). Output Capacitor An output capacitor is required between OUT and GND to prevent oscillation. 1.0µF minimum is recommended. Larger values improve the regulator’s transient response. The output capacitor value may be increased without limit. The output capacitor should have an ESR (Effective Series Resistance) of about 5Ω or less and a resonant frequency above 1MHz. Ultra-low-ESR capacitors may cause a lowamplitude oscillation and/or underdamped transient response. Most tantalum or aluminum electrolytic capacitors are adequate; film types will work, but are more expensive. Since many aluminum electrolytic capacitors have electrolytes that freeze at about –30°C, solid tantalum capacitors are recommended for operation below –25°C. At lower values of output current, less output capacitance is required for output stability. The capacitor can be reduced to 0.47µF for current below 10mA or 0.33µF for currents below 1mA. SO-8 θJA θJC ground plane heat sink area AMBIENT printed circuit board No-Load Stability The MIC5212 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. Figure 1. Thermal Resistance Using the power SO-8 reduces the θJC dramatically and allows the user to reduce θCA. The total thermal resistance, θJA (junction-to-ambient thermal resistance) is the limiting factor in calculating the maximum power dissipation capability of the device. Typically, the power SO-8 has a θJC of 20°C/W, this is significantly lower than the standard SO-8 which is typically 75°C/W. θCA is reduced because pins 5 through 8 can now be soldered directly to a ground plane which significantly reduces the case-to-sink thermal resistance and sink to ambient thermal resistance. Dual-Supply Operation When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground. Power SO-8 Thermal Characteristics One of the secrets of the MIC5212’s performance is its power SO-8 package featuring half the thermal resistance of a standard SO-8 package. Lower thermal resistance means more output current or higher input voltage for a given package size. April 2003 θCA 7 MIC5212 MIC5212 Micrel Quick Method Low dropout linear regulators from Micrel are rated to a maximum junction temperature of 125°C. It is important not to exceed this maximum junction temperature during operation of the device. To prevent this maximum junction temperature from being exceeded, the appropriate ground plane heat sink must be used. Determine the power dissipation requirements for the design along with the maximum ambient temperature at which the device will be operated. Refer to Figure 3, which shows safe operating curves for three different ambient temperatures: 25°C, 50°C and 85°C. From these curves, the minimum amount of copper can be determined by knowing the maximum power dissipation required. If the maximum ambient temperature is 50°C and the power dissipation is as above, 920mW, the curve in Figure 3 shows that the required area of copper is 500mm2. 40°C 50°C 55°C 65°C 75°C 85°C COPPER AREA (mm2) 800 700 100°C 900 600 500 400 The θJA of this package is ideally 63°C/W, but it will vary depending upon the availability of copper ground plane to which it is attached. 300 200 100 900 0.25 0.50 0.75 1.00 1.25 1.50 POWER DISSIPATION (W) COPPER AREA (mm2) 0 0 Figure 2. Copper Area vs. Power-SO Power Dissipation (∆ (∆TJA) Figure 2 shows copper area versus power dissipation with each trace corresponding to a different temperature rise above ambient. From these curves, the minimum area of copper necessary for the part to operate safely can be determined. The maximum allowable temperature rise must be calculated to determine operation along which curve. 800 T = 125°C J 700 85°C 50°C 25°C 600 500 400 300 200 100 0 0 0.25 0.50 0.75 1.00 1.25 1.50 POWER DISSIPATION (W) Figure 3. Copper Area vs. Power-SO Power Dissipation (TA) ∆T = TJ(max) – TA(max) TJ(max) = 125°C TA(max) = maximum ambient operating temperature For example, the maximum ambient temperature is 50°C, the ∆T is determined as follows: ∆T = 125°C – 50°C ∆T = 75°C Using Figure 2, the minimum amount of required copper can be determined based on the required power dissipation. Power dissipation in a linear regulator is calculated as follows: PD = (VIN1 – VOUT1) × IOUT1 + VIN1 × IGND1 + (VIN2 – VOUT2) × IOUT2 + VIN2 × IGND2 With a common 5V input, a 3.3V, 300mA output on LDO 1 and a 2.5V, 150mA output on LDO 2, power dissipation is as follows: PD = (5V – 3.3V) × 300mA + 5V × 5mA + (5V – 2.5V) × 150mA + 5V × 1.8mA PD = 0.919W From Figure 2, the minimum amount of copper required to operate this application at a ∆T of 75°C is 500mm2. MIC5212 8 April 2003 MIC5212 Micrel Package Information 0.026 (0.65) MAX) PIN 1 0.157 (3.99) 0.150 (3.81) DIMENSIONS: INCHES (MM) 0.020 (0.51) 0.013 (0.33) 0.050 (1.27) TYP 0.064 (1.63) 0.045 (1.14) 45° 0.0098 (0.249) 0.0040 (0.102) 0.197 (5.0) 0.189 (4.8) 0°–8° SEATING PLANE 0.010 (0.25) 0.007 (0.18) 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79) 8-Pin SOIC (M) MICREL, INC. TEL 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com The information furnished by Micrel in this datasheet 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2003 Micrel, Incorporated. April 2003 9 MIC5212