MIC5231 Micrel MIC5231 Micropower µCap LDO Regulator Preliminary Information General Description Features The MIC5231 µCap low-dropout voltage regulator is intended for low-output-current biasing applications. It features extremely low ground current, not greater than 4µA under all load and temperature conditions, making it efficient and ideal for keep-alive applications in devices such as notebook computers. • • • • • • • • • The MIC5231 offers better than 2% initial accuracy and low dropout (typically 150mV at 10mA output current). An output capacitor is not required for stable operation, decreasing cost and board space. Tiny ceramic chip capacitors may be used to improve transient response. The MIC5231 also features a control pin which allows the regulator to be shut down when not required. Its shutdownstate draws zero current, benefitting battery-powered applications. The MIC5231 is available in fixed output voltages of 2.75V, 3.0V, 3.3V and 5V in the small SOT-23-5 IttyBitty™ package. Contact Micrel for other voltage options. Extremely low quiescent current—only 0.65µA No output capacitor requirement Stable with ceramic or tantalum capacitors IttyBitty™ SOT-23-5 surface-mount package 10mA output drive Low 150mV at 10mA dropout voltage Tight load and line regulation Low temperature coefficient Logic-level enable input Applications • • • • • • • Real time clocks SRAM backup Cellular telephones Laptop, notebook and palmtop computers Battery-powered equipment Bar code scanners SMPS post-regulator and dc-to-dc modules Ordering Information Part Number Marking Voltage Temperature Range Package MIC5231-2.75BM5 LM2H 2.75V –40°C to +125°C SOT-23-5 MIC5231-3.0BM5 LM30 3.0V –40°C to +125°C SOT-23-5 MIC5231-3.3BM5 LM33 3.3V –40°C to +125°C SOT-23-5 MIC5231-5.0BM5 LM50 5.0V –40°C to +125°C SOT-23-5 Typical Application MIC5231-5.0BM5 VIN 6V IN OUT VOUT 5V EN GND 5V Linear Regulator Application IttyBitty is a trademark of Micrel, Inc. MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA June 2000 1 TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 MIC5231 MIC5231 Micrel Pin Configuration IN GND EN 3 2 1 Part Identification LM50 4 5 OUT NC MIC5231-5.0BM5 Pin Description Pin Number Pin Name 1 EN 2 GND 3 IN 4 OUT 5 NC Pin Function Enable (Input): Active high. Logic high = enable; logic low = shutdown. Do not float. Ground Supply Input Regulated Output not internally connected Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage (VIN) .................................... –0.6V to +14V Lead Temperature (soldering, 5 sec.) ....................... 260°C Storage Temperature (TA) ....................... –60°C to +150°C ESD, Note 3 .................................................................. 2kV Input Voltage (VIN) ........................................... 3.5V to 12V Ambient Temperature (TA) ......................... –40°C to +85°C Junction Temperature (TJ) ....................... –40°C to +125°C Thermal Resistance, Note 4 MIC5231 2 June 2000 MIC5231 Micrel Electrical Characteristics VIN = VOUT + 1V; IL = 100µA; CL = 0.47µF; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted. Symbol Parameter Conditions VOUT Output Voltage Accuracy variation from nominal VOUT ∆VOUT/∆T Output Voltage Temperature Coefficient Note 5 250 ∆VOUT/VOUT Line Regulation VIN = 6V to 12V 0.2 0.25 % ∆VOUT/VOUT Load Regulation IL = 10µA to 10mA, Note 6 0.2 1 % VDO Dropout Voltage, Note 7 IL = 1mA 15 IL = 10mA 150 300 mV VIN = 6V, IL = 10mA 0.65 3 µA VIN = 12V, IL = 10mA 1.1 4 µA Ripple Rejection f = 100Hz, IL = 100µA 50 Enable Input Voltage VEN = logic low (regulator off) 0.4 IQ Ground Pin Current PSRR Min Typ –2 –3 Max Units +2 +3 % % ppm/°C mV dB Enable Input VENL VEN = logic high ((regulator on) 0.18 V 1.4 V IENL Enable Input Current VENL ≤ 0.18V (regulator off) 1 nA IENH Enable Input Current VENH ≥ 1.4V (regulator on) 1 nA 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 at any TA (ambient temperature) is PD(max) = (TJ(max) – TA) ÷ θJA. The θJC of the MIC5231 is 130°C/W. Mounted to a standard PC board, the θJA is approximately 235°C/W. Note 5: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 6: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Note 7: 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. For outputs below 3.5V, dropout voltage is the input-to-output differential with the minimum input voltage 3.5V. Minimum input operating voltage is 3.5V. June 2000 3 MIC5231 MIC5231 Micrel Ground Current vs. Output Current Ground Current vs. Supply Voltage Ground Current vs. Temperature 0.5 1 GROUND CURRENT (µA) 0.8 Ground Current (µA) GROUND CURRENT (µA) 1 0.7 0.6 0.5 0.4 0.3 0 0 0.2 2 1 10 OUTPUT CURRENT (mA) 4 6 8 10 Supply Voltage (V) 12 Ground Current vs. Temperature SHORT CIRCUIT CURRENT (mA) OUTPUT VOLTAGE (V) MIC5231 0.6 0.4 0.2 0 -40 0 40 80 TEMPERATURE (°C) 120 Short Circuit Current vs. Temperature 3.10 3.05 3.00 2.95 2.90 -50 0.8 -20 10 40 70 100 130 TEMPERATURE (°C) 4 150 100 50 0 -50 -20 10 40 70 100 130 TEMPERATURE (°C) June 2000 MIC5231 Micrel Block Diagram IN OUT EN Bandgap Reference MIC5231 GND Safe Operating Conditions The MIC5231 does not incorporate current limit or thermal shutdown in the design. The output pass element is approximately 15 ohms, therefore, when a short occurs from the output to ground, the current is self-limited. The pass element has a positive temperature coefficient, such that when the device gets hot, the output impedance goes up, limiting the current even further. The maximum junction temperature for the device is 125°C, and it is important that this is not exceeded for any length of time. Thermal Considerations Applications Information Input Capacitor A 0.1µF (or larger) capacitor should be placed from the IN (supply input) to GND (ground) if there is more than 20 cm of wire between IN and the ac filter capacitor or if supplied from a battery. Output Capacitors The MIC5231 does not require an output capacitor for stability. A 1µF or larger capacitor is recommended between OUT (output) and GND to improve the regulator’s transient response. A 0.1µF capacitor can be used to reduce overshoot recovery time at the expense of overshoot amplitude. The ESR (effective series resistance) of this capacitor has no effect on regulator stability, but low-ESR capacitors improve high frequency transient response. The value of this capacitor may be increased without limit, but values larger than 10µF tend to increase the settling time after a step change in input voltage or output current. The MIC5231 is not intended for sourcing currents that would cause a large power loss in the device, but since it is not current limited, it is possible to source more than the rated 10mA. At this point, it is important to ensure that the die temperature does not exceed 125°C. Power dissipation in the regulator is calculated as follows: PD = (VIN – VOUT)*IOUT+ VIN *IGND The MIC5231 consumes only 0.65uA over load and does not need to consider that contribution in the power dissipation equation, therefore the equation is simplified. The MIC5231 has no minimum load current; it will remain stable and in regulation with no load (other than the internal voltage divider). This is especially important in real-time clock and CMOS RAM keep-alive applications. Minimum Load Current PD = (VIN – VOUT )*IOUT The MIC5231, in the IttyBitty SOT23-5 package, has a thermal resistance, junction-to-ambient, of 235°C/W. Using this number, the power dissipation capability of that package, without exceeding a 125°C junction temperature rating, can easily be calculated. PD(max) = (Tj(max) – Ta)/θJA The MIC5231 does not require a minimum load for proper operation. This allows the device to operate in applications where very light output currents are required for keep-alive purposes. This is important for powering SRAM or Flash memory in low-power modes for handheld devices. PD(max) = (125°C – Ta)/235°C/W If the device is being operated at 85°C, the maximum power June 2000 5 MIC5231 MIC5231 Micrel dissipation allowed can easily be determined. PD(max) = (125°C – 85°C)/235°C/W PD(max) = 170mW Therefore, the device can only dissipate 170mW maximum. If the MIC5231 is powered off of a 12V source and the output voltage is 3.3V, the maximum output current can be calculated. PD = (Vin - Vout)·Iout 170mW = (12V - 3.3V)·Iout Iout = 170mW/8.7V Iout = 19.5mA Therefore, the device can source almost 20mA at an ambient of 85°C before the die temperature exceeds 125°C. MIC5231 6 June 2000 MIC5231 Micrel Package Information 1.90 (0.075) REF 0.95 (0.037) REF 1.75 (0.069) 3.00 (0.118) 1.50 (0.059) 2.60 (0.102) DIMENSIONS: MM (INCH) 3.02 (0.119) 2.80 (0.110) 0.50 (0.020) 0.35 (0.014) 1.30 (0.051) 0.90 (0.035) 0.20 (0.008) 0.09 (0.004) 10° 0° 0.15 (0.006) 0.00 (0.000) 0.60 (0.024) 0.10 (0.004) SOT-23-5 (M5) June 2000 7 MIC5231 MIC5231 Micrel MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated MIC5231 8 June 2000