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MIC5231
Micrel
MIC5231
Micropower Cap LDO Regulator Preliminary Information
General Description
The MIC5231 Cap low-dropout voltage regulator is intended for low-output-current biasing applications. It features extremely low ground current, not greater than 4A 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 IttyBittyTM package. Contact Micrel for other voltage options.
Features
* * * * * * * * * * * * * * * * Extremely low quiescent current--only 0.65A No output capacitor requirement Stable with ceramic or tantalum capacitors IttyBittyTM 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 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
Applications
Ordering Information
Part Number MIC5231-2.75BM5 MIC5231-3.0BM5 MIC5231-3.3BM5 MIC5231-5.0BM5 Marking LM2H LM30 LM33 LM50 Voltage 2.75V 3.0V 3.3V 5.0V Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5
Typical Application
MIC5231-5.0BM5 VIN 6V IN EN GND OUT VOUT 5V
5V Linear Regulator Application
IttyBitty is a trademark of Micrel, Inc. MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970
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MIC5231
MIC5231
Micrel
Pin Configuration
IN GND EN
3 2 1
LM50
4 5
Part Identification
OUT
NC
MIC5231-5.0BM5
Pin Description
Pin Number 1 2 3 4 5 Pin Name EN GND IN OUT 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)
Supply Voltage (VIN) .................................... -0.6V to +14V Lead Temperature (soldering, 5 sec.) ....................... 260C Storage Temperature (TA) ....................... -60C to +150C ESD, Note 3 .................................................................. 2kV
Operating Ratings (Note 2)
Input Voltage (VIN) ........................................... 3.5V to 12V Ambient Temperature (TA) ......................... -40C to +85C Junction Temperature (TJ) ....................... -40C to +125C Thermal Resistance, Note 4
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Electrical Characteristics
VIN = VOUT + 1V; IL = 100A; CL = 0.47F; TJ = 25C, bold values indicate -40C TJ +125C; unless noted. Symbol VOUT VOUT/T VOUT/VOUT VOUT/VOUT VDO IQ PSRR Enable Input VENL IENL IENH
Note 1. Note 2. Note 3. Note 4: Note 5: Note 6: Note 7:
Parameter Output Voltage Accuracy Output Voltage Temperature Coefficient Line Regulation Load Regulation Dropout Voltage, Note 7
Conditions variation from nominal VOUT Note 5 VIN = 6V to 12V IL = 10A to 10mA, Note 6 IL = 1mA IL = 10mA VIN = 6V, IL = 10mA VIN = 12V, IL = 10mA f = 100Hz, IL = 100A VEN = logic low (regulator off) VEN = logic high ((regulator on)
Min -2 -3
Typ
Max +2 +3
Units % % ppm/C
250 0.2 0.2 15 150 0.65 1.1 50 300 3 4 0.25 1
% % mV mV A A dB
Ground Pin Current
Ripple Rejection
Enable Input Voltage
0.4 1.4 1 1
0.18
V V nA nA
Enable Input Current Enable Input Current
VENL 0.18V (regulator off) VENH 1.4V (regulator on)
Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. The maximum allowable power dissipation at any TA (ambient temperature) is PD(max) = (TJ(max) - TA) / JA. The JC of the MIC5231 is 130C/W. Mounted to a standard PC board, the JA is approximately 235C/W. 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. 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.
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Micrel
Ground Current vs. Output Current
1 GROUND CURRENT (A) Ground Current (A) 0.8 0.7 0.6 0.5 0.4 0.3 0 0 1 10 OUTPUT CURRENT (mA) 0.2 2
Ground Current vs. Supply Voltage
1 GROUND CURRENT (A) 0.8 0.6 0.4 0.2 0 -40
Ground Current vs. Temperature
0.5
4
6 8 10 Supply Voltage (V)
12
0 40 80 TEMPERATURE (C)
120
Ground Current vs. Temperature
SHORT CIRCUIT CURRENT (mA) 3.10 OUTPUT VOLTAGE (V) 150
Short Circuit Current vs. Temperature
3.05
100
3.00
50
2.95
2.90 -50
-20 10 40 70 100 130 TEMPERATURE (C)
0 -50
-20 10 40 70 100 130 TEMPERATURE (C)
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Block Diagram
IN OUT
EN
Bandgap Reference
MIC5231 GND
Applications Information
Input Capacitor A 0.1F (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 1F or larger capacitor is recommended between OUT (output) and GND to improve the regulator's transient response. A 0.1F 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 10F tend to increase the settling time after a step change in input voltage or output current. 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 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.
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 125C, and it is important that this is not exceeded for any length of time. Thermal Considerations 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 125C. 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. PD = (VIN - VOUT )*IOUT The MIC5231, in the IttyBitty SOT23-5 package, has a thermal resistance, junction-to-ambient, of 235C/W. Using this number, the power dissipation capability of that package, without exceeding a 125C junction temperature rating, can easily be calculated. PD(max) = (Tj(max) - Ta)/JA PD(max) = (125C - Ta)/235C/W If the device is being operated at 85C, the maximum power
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dissipation allowed can easily be determined. PD(max) = (125C - 85C)/235C/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 85C before the die temperature exceeds 125C.
Micrel
MIC5231
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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) 1.30 (0.051) 0.90 (0.035) 10 0 0.15 (0.006) 0.00 (0.000) 0.20 (0.008) 0.09 (0.004)
0.50 (0.020) 0.35 (0.014)
0.60 (0.024) 0.10 (0.004)
SOT-23-5 (M5)
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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. (c) 2000 Micrel Incorporated
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