MIC5271 Micrel MIC5271 µCap Negative Low-Dropout Regulator General Description Features The MIC5271 is a µCap 100mA negative regulator in a SOT-23-5 package. With better than 2% initial accuracy, this regulator provides a very accurate supply voltage for applications that require a negative rail. The MIC5271 sinks 100mA of output current at very low dropout voltage (600mV maximum at 100mA of output current). The µCap regulator design is optimized to work with lowvalue, low-cost ceramic capacitors. The output typically requires only a 1µF capacitance for stability. Designed for applications where small packaging and efficiency are critical, the MIC5271 combines LDO design expertise with IttyBitty packaging to improve performance and reduce power dissipation. Ground current is optimized to help improve battery life in portable applications. The MIC5271 also includes a TTL-compatible enable pin, allowing the user to put the part into a zero-current off-mode. The MIC5271 is available in the SOT-23-5 package for space saving applications and it is available with an adjustable output. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • • • • • • • • • • Stable with ceramic or tantalum capacitor Positive and negative enable thresholds Low dropout voltage: 500mV @ 100mA Low ground current: 35µA @ load = 100µA Tight initial accuracy: ±2% Tight load and line regulation Thermal shutdown Current limiting IttyBitty SOT-23-5 packaging Zero-current off-mode Applications • • • • • GaAsFET bias Portable cameras and video recorders PDAs Battery-powered equipment Post-regulation of DC-DC converters Ordering Information Part Number Marking Voltage* Junction Temp. Range Package MIC5271BM5 L9AA MIC5271-3.0BM5 L930 Adj. –40°C to +125°C SOT-23-5 –3.0V –40°C to +125°C SOT-23-5 MIC5271-5.0BM5 L950 –5.0V –40°C to +125°C SOT-23-5 * For other voltage options, please contact Micrel Marketing. Typical Application Enable Input MIC5271BM5 2 1 VIN –6.0V 5 GND ADJ 1µF R1 3 R2 EN –IN ENABLE VOLTAGE (V) 5 4 –OUT 4 VOUT –5.0V 10µF 3 2 1 0 Regulator On Regulator Off -1 -2 -3 -4 -5 -3 Regulator On -5 -7 -9 -11 -13 -15 SUPPLY VOLTAGE (V) Regulator With Adjustable Output IttyBitty is a registered trademark of Micrel, Inc. Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com October 2003 1 MIC5271 MIC5271 Micrel Pin Configuration ADJ GND EN 3 2 1 L9AA 4 5 –OUT –IN MIC5271BM5 Adjustable Output Voltage Pin Description Pin Number (Adj.) Pin Name 1 EN 2 GND Ground. 3 ADJ Adjustable (Input): Adjustable feedback output connects to resistor voltage divider. 4 –OUT 5 –IN MIC5271 Pin Function Enable Input. TTL logic compatible enable input. Logic High = ON, Logic Low or open = OFF. Negative Regulator Output. Negative Supply Input. 2 October 2003 MIC5271 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Input Voltage (V–IN) ...................................... –20V to +0.3V Enable Voltage (VEN) .................................... –20V to +20V Power Dissipation (PD) ............................ Internally Limited Junction Temperature (TJ) ....................... –40°C to +125°C Lead Temperature (soldering, 5 sec.) ....................... 260°C Storage Temperature (TS) ....................... –65°C to +150°C ESD Rating, Note 3 Input Voltage (VIN) ....................................... –16V to –3.3V Enable Voltage (VEN) .................................... –16V to +16V Junction Temperature (TJ) ....................... –40°C to +125°C Thermal Resistance (θJA) Note 4 ......................... 235°C/W Electrical Characteristics (Note 5) VIN = VOUT – 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted. Symbol Parameter Condition VOUT Output Voltage Accuracy Variation from nominal VOUT ∆VOUT/∆T Output Voltage Temperature Coefficient Note 6 100 ∆VOUT/VOUT Line Regulation VIN = VOUT – 1V to –16V 0.04 0.15 0.2 %/V ∆VOUT/VOUT Load Regulation IOUT = 100µA to 100mA, Note 7 0.4 1.8 2.0 % % VIN – VOUT Dropout Voltage, Note 8 IOUT = 100µA 55 IOUT = 50mA 360 500 mV IOUT = 100mA 500 700 900 mV IOUT = 100µA 25 100 µA IOUT = 50mA 0.9 IOUT = 100mA 2.0 3.0 mA 0.1 +1.0 µA IGND Ground Current, Note 9 Min Typ –2 –3 IGND_SD Ground current in shutdown VEN = ±0.6V –1.0 PSRR Ripple Rejection f = 120Hz 50 ILIMIT Current Limit VOUT = 0V 235 TON Turn-on Time Time to VOUT = 90% nom. 60 VEN Input Low voltage Regulator OFF Input High Voltage Regulator ON Enable Input Current VEN = ± 0.6V and –2.0V VEN = +2.0V Max Units 2 3 % % ppm/°C mV mA dB 350 mA Enable Input IEN µs V ±0.6 V ±2.0 5.6 0.1 10.0 µA 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. Devices are ESD sensitive. Handling precautions recommended. Note 4. 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, where θJA is 235°C/W. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. See the “Thermal Considerations” section for details. Note 5. Specification for packaged product only. Note 6. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 7. 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 100mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. Note 8. 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. Note 9. 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. October 2003 3 MIC5271 MIC5271 Micrel Typical Characteristics Dropout Characteristics -3.305 -1.5 -1 -100mA Load -1 -2 -3 -4 SUPPLY VOLTAGE (V) -3.275 -3.27 -3.265 -5 -3.26 0 -90 GROUND CURRENT (µA) GROUND CURRENT (mA) -3.28 Ground Current vs. Output Current -2.5 -2 -1.5 -1 -0.5 5VIN 0 0 -30 GROUND CURRENT (µA) -3.29 -3.285 Ground Current vs. Temperature -1mA Load 0A Load -15 -10 -5 Negative Enable Threshold vs. Supply Voltage DROPOUT VOLTAGE (mV) ENABLE THRESHOLD (V) -1.2 -1 Enable Off -0.8 -0.6 -0.4 -0.2 0 -4 -7 -10 -13 SUPPLY VOLTAGE (V) -30 -20 -16 0µA Load -10 -1 -2 -3 -4 SUPPLY VOLTAGE (V) -3.22 -3.2 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) -2.5 -100mA Load -1.5 -1 -50A Load -50mA Load -1 -400 -300 -200 -100 -20 -40 -60 -80 -100 OUTPUT CURRENT (mA) 4 -10mA Load -0.5 0 0 1.6 -1 -2 -3 -4 SUPPLY VOLTAGE (V) -5 Positive Enable Threshold vs. Supply Voltage 1.4 Enable On 1.2 1 Enable Off 0.8 0.6 0.4 0.2 0 -4 Dropout vs. Output Current -500 0 0 -1.5 Ground Current vs. Temperature -2 Ground Current Characteristics -2 -100mA Load -5 -3 -600 -1.6 Enable On -3.26 -3.24 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) -1.4 -1mA Load -50 -100µA Load -40 -0.5 -3.3 -3.28 -2.5 -60 -3.5 -3.34 -3.32 Ground Current Characteristics -70 0 0 -20 -40 -60 -80 -100 OUTPUT CURRENT (mA) -25 -20 -80 -20 -40 -60 -80 -100 OUTPUT CURRENT (mA) -3.38 -3.36 GROUND CURRENT (mA) 0 0 -3.295 -400 DROPOUT VOLTAGE (mV) -0.5 OUTPUT VOLTAGE (V) -2 Output Voltage vs. Temperature -3.4 ENABLE THRESHOLD (V) OUTPUT VOLTAGE (V) 0 Load -2.5 MIC5271 Output Voltage vs. Output Current -3.3 -3 GROUND CURRENT (µA) OUTPUT VOLTAGE (V) -3.5 -350 -7 -10 -13 SUPPLY VOLTAGE (V) -16 Dropout vs. Temperature -10mA Load -300 -250 -200 -150 0A Load -100 -50 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) October 2003 MIC5271 Micrel Typical Characteristics (continued) DROPOUT VOLTAGE (mV) -700 -600 Dropout vs. Temperature -100mA Load -500 -400 -300 -50mA Load -200 -100 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) October 2003 5 MIC5271 MIC5271 Micrel Functional Characteristics Load Transient VOUT (10mV/div.) -10mA -100mA COUT = 1µF Ceramic VIN = 5V VOUT = 3V Output Current (50mA/div.) Output Current (50mA/div.) VOUT (10mV/div.) Load Transient TIME (2ms/div.) -10mA -100mA TIME (2ms/div.) 0V VOUT (1V/div.) 0V Enable (1V/div.) Enable (1V/div.) VOUT (1V/div.) 0V TIME (20ms/div.) MIC5271 COUT = 1µF Ceramic VIN = 5V VOUT = 3V 0V TIME (20ms/div.) 6 October 2003 MIC5271 Micrel Functional Diagram GND ADJ VEN VIN VOUT MIC5271-x.x October 2003 7 MIC5271 MIC5271 Micrel Applications Information Thermal Considerations The MIC5271 is a general-purpose negative regulator that can be used in any system that requires a clean negative voltage from a negative output. This includes post regulating of DC-DC converters (transformer based or charge pump based voltage converters). These negative voltages typically require a negative low dropout voltage regulator to provide a clean output from typically noisy lines. Input Capacitor A 1µF input capacitor should be placed from IN to GND if there is more than 2 inches of wire or trace between the input and the AC filter capacitor, or if a battery is used as the input. Output Capacitor The MIC5271 requires an output capacitor for stable operation. A minimum of 1µF of output capacitance is required. The output capacitor can be increased without limitation to improve transient response. The output does not require ESR to maintain stability, therefore a ceramic capacitor can be used. High-ESR capacitors may cause instability. Capacitors with an ESR of 3Ω or greater at 100kHz may cause a high frequency oscillation. Low-ESR tantalums are recommended due to the tight capacitance tolerance over temperature. Ceramic chip capacitors have a much greater dependence on temperature, depending upon the dielectric. The X7R is recommended for ceramic capacitors because the dielectric will change capacitance value by approximately 15% over temperature. The Z5U dielectric can change capacitance value by as much 50% over temperature, and the Y5V dielectric can change capacitance value by as much as 60% over temperature. To use a ceramic chip capacitor with the Y5V dielectric, the value must be much higher than a tantalum to ensure the same minimum capacitor value over temperature. No-Load Stability The MIC5271 does not require a load for stability. Enable Input The MIC5271 comes with an enable pin that allows the regulator to be disabled. Forcing the enable pin higher than the negative threshold and lower than the positive threshold disables the regulator and sends it into a “zero” off-mode current state. In this state, current consumed by the regulator goes nearly to zero. The MIC5271 will be in the on mode when the voltage applied to the enable pin is either greater than the positive threshold or less than the negative threshold. Absolute values will be used for thermal calculations to clarify the meaning of power dissipation and voltage drops across the part. Proper thermal design for the MIC5271-5.0BM5 can be accomplished with some basic design criteria and some simple equations. The following information must be known to implement your regulator design: VIN = input voltage VOUT = output voltage IOUT = output current TA = ambient operating temperature IGND = ground current Maximum power dissipation can be determined by knowing the ambient temperature, TA, the maximum junction temperature, 125°C, and the thermal resistance, junction to ambient. The thermal resistance for this part, assuming a minimum footprint board layout, is 235°C/W. The maximum power dissipation at an ambient temperature of 25°C can be determined with the following equation: PD(max) = PD(max) = PD = (VIN – VOUT)IOUT + VIN × IGND Substituting PD(max), determined above, for PD and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. The maximum power dissipation number cannot be exceeded for proper operation of the device. The maximum input voltage can be determined using the output voltage of 5.0V and an output current of 100mA. Ground current, of 1mA for 100mA of output current, can be taken from the “Electrical Characteristics ” section of the data sheet. ( ) 425mW = (100mA × VIN + 1mA × VIN ) − 500mW 425mW = VIN − 5.0V 100mA + VIN × 1mA 925mW = 101mA × VIN ENABLE VOLTAGE (V) -5 -3 MIC5271 VIN = 9.16Vmax Therefore, a –5.0V application at 100mA of output current can accept a maximum input voltage of –9.16V in a SOT-23-5 package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to Regulator Thermals section of Micrel’s “Designing with Low Dropout Voltage Regulators” handbook. Regulator On Regulator Off -1 -2 -3 -4 125°C − 25°C 235°C/W The actual power dissipation of the regulator circuit can be determined using one simple equation. 5 4 1 0 θ JA PD(max) = 425mW Enable Input 3 2 TJ(max) − TA Regulator On -5 -7 -9 -11 -13 -15 SUPPLY VOLTAGE (V) 8 October 2003 MIC5271 Micrel Adjustable Regulator Application MIC5271BM5 –VIN 5 –IN –OUT 4 R2 –VOUT –EN 2 GND ADJ 3 R1 Figure 1. Adjustable Voltage Application The MIC5271BM5 can be adjusted from 1.20V to 14V by using two external resistors (Figure 1). The resistors set the output voltage based on the following equation: R2 ) R1 Where VREF = 1.20V VOUT = VREF (1 + October 2003 9 MIC5271 MIC5271 Micrel 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) 1.30 (0.051) 0.90 (0.035) 3.02 (0.119) 2.80 (0.110) 0.20 (0.008) 0.09 (0.004) 10° 0° 0.15 (0.006) 0.00 (0.000) 0.50 (0.020) 0.35 (0.014) 0.60 (0.024) 0.10 (0.004) SOT-23-5 (M5) MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA 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. MIC5271 10 October 2003