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MIC5256
150mA Cap LDO with Error Flag
General Description
The MIC5256 is an efficient, precise CMOS voltage regulator. It offers better than 1% initial accuracy, extremely low-dropout voltage (typically 135mV at 150mA) and low ground current (typically 90A) over load. The MIC5256 features an error flag that indicates an output fault condition such as overcurrent, thermal shutdown and dropout. Designed specifically for handheld and battery-powered devices, the MIC5256 provides a TTL-logic-compatible enable pin. When disabled, power consumption drops nearly to zero. The MIC5256 also works with low-ESR ceramic capacitors, reducing the amount of board space necessary for power applications, critical in hand-held wireless devices. Key features include current limit, thermal shutdown, faster transient response, and an active clamp to speed up (R) device turnoff. Available in the IttyBitty SOT-23-5 package and the new Thin SOT-23-5, which offers the same footprint as the standard IttyBitty(R) SOT-23-5, but only 1mm tall. The MIC5256 offers a range of output voltages. Data sheets and support documentation can be found on Micrel's web site at www.micrel.com.
Features
* * * * * * Input voltage range: 2.7V to 6.0V Thin SOT package: 1mm height Error flag indicates fault condition Stable with ceramic output capacitor Ultralow dropout: 135mV @ 150mA High output accuracy: - 1.0% initial accuracy - 2.0% over temperature Low quiescent current:90A Tight load and line regulation Thermal-shutdown and current-limit protection "Zero" off-mode current TTL logic-controlled enable input
* * * * *
Applications
* * * * * Cellular phones and pagers Cellular accessories Battery-powered equipment Laptop, notebook, and palmtop computers Consumer/personal electronics
___________________________________________________________________________________________________________
Typical Application
Low-Noise Regulator Application
IttyBitty is a registered trademark of Micrel, Inc. Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com
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Ordering Information
Part Number Standard MIC5256-1.5BM5 MIC5256-1.8BM5 MIC5256-2.5BM5 MIC5256-2.6BM5 MIC5256-2.7BM5 MIC5256-2.8BM5 MIC5256-2.85BM5 MIC5256-2.9BM5 MIC5256-3.0BM5 MIC5256-3.1BM5 MIC5256-3.3BM5 MIC5256-2.85BD5
Notes: * Under bar symbol ( _ ) may not be to scale. ** Other Voltage available. Contact Micrel for details.
Marking Pb-Free Standard LX15 LX18 LX25 LX26 LX27 LX28 LX2J LX29 LX30 LX31 LX33 NX2J Pb-Free* LX15 LX18 LX25 LX26 LX27 LX28 LX2J LX29 LX30 LX31 LX33 NX2J
Voltage** 1.5V 1.8V 2.5V 2.6V 2.7V 2.8V 2.85V 2.9V 3.0V 3.1V 3.3V 2.85V
Junction Temperature Range -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C -40 to +125C
Package 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 5-Pin TSOT23
MIC5256-1.5YM5 MIC5256-1.8YM5 MIC5256-2.5YM5 MIC5256-2.6YM5 MIC5256-2.7YM5 MIC5256-2.8YM5 MIC5256-2.85YM5 MIC5256-2.9YM5 MIC5256-3.0YM5 MIC5256-3.1YM5 MIC5256-3.3YM5 MIC5256-2.85YD5
Pin Configuration
MIC5256-x.xBM5 5-Pin SOT23
MIC5256-x.xBD5 5-Pin Thin SOT23
MIC5256-x.xYM5 5-Pin SOT23
MIC5256-x.xYD5 5-Pin Thin SOT23
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Pin Description
Pin Number 1 2 3 4 5 Pin Name IN GND EN FLG OUT Pin Name Supply Input. Ground. Enable/Shutdown (Input): CMOS compatible input. Logic high = enable; logic low = shutdown. Do not leave open. Error Flag (Output): Open-drain output. Active low indicates an output undervoltage condition. Regulator Output.
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Absolute Maximum Ratings(1)
Supply Voltage (VIN) ............................................. 0V to +7V Enable Voltage (VEN)............................................ 0V to +7V Power Dissipation (PD) ........................... Internally Limited(3) Junction Temperature (TJ) ........................-40C to +125C Storage Temperature (Ts) .........................-60C to +150C Lead Temperature (soldering, 5 sec.)........................ 260C EDS Rating(4) .................................................................. 2kV
Operating Ratings(2)
Supply Voltage (VIN)........................................ +2.7V to +6V Enable Voltage (VEN).............................................. 0V to VIN Junction Temperature (TJ) ........................ -40C to +125C Thermal Resistance SOT23-5 (JA) ..................................................235C/W
Electrical Characteristics(5)
VIN = VOUT + 1V, VEN = VIN; IOUT = 100A; TJ = 25C, bold values indicate -40C TJ +125C; unless noted. Symbol VO VLNR VLDR VIN - VOUT IQ IGND Parameter Output Voltage Accuracy Line Regulation Load Regulation Condition IOUT = 100A VIN = VOUT + 1V to 6V IOUT = 0.1mA to 150mA IOUT = 100A Dropout Voltage(7) IOUT = 100mA IOUT = 150mA VEN 0.4V (shutdown) IOUT = 0mA IOUT = 150mA f = 10Hz, VIN = VOUT + 1V; COUT = 1.0F PSRR Ripple Rejection f = 100Hz, VIN = VOUT + 0.5V; COUT = 1.0F f = 10kHz, VIN = VOUT + 0.5V ILIM en VIL VIH IEN Current Limit Output Voltage Noise Enable Input Logic-Low Voltage Enable Input Logic-High Voltage Enable Input Current Shutdown Resistance Discharge VIN = 2.7V to 5.5V, regulator shutdown VIN = 2.7V to 5.5V, regulator enabled VIL 0.4V, regulator shutdown VIH 1.6V, regulator enabled 1.6 0.01 0.01 500 VOUT = 0V 160
(6)
Min. -1 -2
Typ.
Max. 1 2
Units % % %/V % mV mV mV mV A A A dB dB dB mV V(rms)
0.02 1.5 0.1 90 135 0.2 90 117 60 60 45 425 TBD
0.05 2.5 5 150 200 250 1 150
Quiescent Current Ground Pin Current(8)
Enable Input 0.4 V V A A
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Electrical Characteristics(5) (Continued)
VIN = VOUT + 1V, VEN = VIN; IOUT = 100A; TJ = 25C, bold values indicate -40C TJ +125C; unless noted. Symbol Error Flag VFLG VOL IFL Low Threshold High Threshold Output Logic-Low Voltage Flag Leakage Current Thermal-Shutdown Temperature Thermal-Shutdown Hysteresis
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 of any TA (ambient temperature) is PD(max) = TJ(max)-TA / JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The JA of the MIC5255-x.xBM5 (all versions) is 235C/W on a PC board (see "Thermal Considerations" section for further details). 4. Devices are ESD sensitive. Handling precautions recommended. 5. Specification for packaged product only. 6. 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 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 7. Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1Vdifferential. For outputs below 2.7V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.7V. Minimum input operating voltage is 2.7V. 8. Ground pin current is the regulator quiescent current. The total current drawn from the supply is the sum of the load current plus the ground pin current.
Parameter
Condition % of VOUT (Flag ON) % of VOUT (Flag OFF) IL = 100A, fault condition flag off, VFLG = 6V
Min. 90
Typ.
Max.
Units % % V A
96 0.02 0.01 0.1
Thermal Protection 150 10 C C
Test Circuit
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Typical Characteristics
130 GROUND CURRENT (A) 125 120 115 110 105 100 0.1
Ground Pin Current
VIN = VOUT + 1V 1 10 100 1000 OUTPUT CURRENT (mA)
140 GROUND CURRENT (A) 120 100 80 60 40 20
Ground Pin Current
OUTPUT VOLTAGE (V)
3.5
Dropout Characteristics
3 ILOAD = 100A 2.5 2 1.5 1 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 INPUT VOLTAGE (V) ILOAD = 150mA
ILOAD = 150mA 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 INPUT VOLTAGE (V)
180 DROPOUT VOLTAGE (mV) 160 140 120 100 80 60 40 20
Dropout Voltage
DROPOUT VOLTAGE (mV)
180 160 140 120 100 80 60 40 20
Dropout Voltage
T = -40C
T = 25C
T = 125C
I = 150mA LOAD 0 -40 -20 0 20 40 60 80 100120140 TEMPERATURE ( C)
0 0 20 40 60 80 100 120 140 160 OUTPUT CURRENT (mA)
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Typical Characteristics (Continued)
Short Circuit Current
SHORT CIRCUIT CURRENT (mA)
600 500 400 300 200 100 0 3
3.5 4 4.5 5 5.5 INPUT VOLTAGE (V)
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Functional Characteristics
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Functional Diagram
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MIC5256 drain transistor to indicate a fault. This prevents chattering or inadvertent triggering of the error flag. The error flag must be pulled-up using a resistor from the flag pin to either the input or the output. The error flag circuit was designed essentially to work with a capacitor to ground to act as a power-on reset generator, signaling a power-good situation once the regulated voltage was up and/or out of a fault condition. This capacitor delays the error signal from pulling high, allowing the down stream circuits time to stabilize. When the error flag is pulled-up to the input without using a pull-down capacitor, then there can be a glitch on the error flag upon start up of the device. This is due to the response time of the error flag circuit as the device starts up. When the device comes out of the "zero" off mode current state, all the various nodes of the circuit power up before the device begins supplying full current to the output capacitor. The error flag drives low immediately and then releases after a few microseconds. The intelligent circuit that triggers an error detects the output going into current limit AND the output being low while charging the output capacitor. The error output then pulls low for the duration of the turn-on time. A capacitor from the error flag to ground will filter out this glitch. The glitch does not occur if the error flag pulled up to the output. Active Shutdown The MIC5256 also features an active shutdown clamp, which is an N-channel MOSFET that turns on when the device is disabled. This allows the output capacitor and load to discharge, de-energizing the load. No Load Stability The MIC5256 will remain stable and in regulation with no load unlike many other voltage regulators. This is especially important in CMOS RAM keep-alive applications. Thermal Considerations The MIC5256 is designed to provide 150mA of continuous current in a very small package. Maximum power dissipation can be calculated based on the output current and the voltage drop across the part. To determine the maximum power dissipation of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation:
TJ(max) - TA PD(max) = JA
Application Information
Enable/Shutdown The MIC5256 comes with an active-high enable pin that allows the regulator to be disabled. Forcing the enable pin low 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. Forcing the enable pin high enables the output voltage. This part is CMOS and the enable pin cannot be left floating; a floating enable pin may cause an indeterminate state on the output. Input Capacitor The MIC5256 is a high-performance, high-bandwidth device. Therefore, it requires a well-bypassed input supply for optimal performance. A 1F capacitor is required from the input to ground to provide stability. Low-ESR ceramic capacitors provide optimal performance at a minimum of space. Additional highfrequency capacitors, such as small valued NPO dielectric type capacitors, help filter out high frequency noise and are good practice in any RF based circuit. Output capacitor The MIC5256 requires an output capacitor for stability. The design requires 1F or greater on the output to maintain stability. The design is optimized for use with low-ESR ceramic-chip capacitors. High-ESR capacitors may cause high-frequency oscillation. The maximum recommended ESR is 300m. The output capacitor can be increased, but performance has been optimized for a 1F ceramic output capacitor and does not improve significantly with larger capacitance. X7R/X5R dielectric-type ceramic capacitors are recommended because of their temperature performance. X7R-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. Z5U and Y5V dielectric capacitors change value by as much as 50% and 60% respectively over their operating temperature ranges. To use a ceramic chip capacitor with Y5V dielectric, the value must be much higher than an X7R ceramic capacitor to ensure the same minimum capacitance over the equivalent operating temperature range. Error Flag The error flag output is an active-low, open-drain output that drives low when a fault condition AND an undervoltage detection occurs. Internal circuitry intelligently monitors overcurrent, overtemperature and dropout conditions and ORs these outputs together to indicate some fault condition. The output of that OR gate is ANDed with an output voltage monitor that detects an undervoltage condition. That output drives the openAugust 2010 10
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JA Recommended Minimum Footprint 235C/W JA 1" Square Copper Clad 185C/W JC 145C/W
MIC5256 can be determined. Because this device is CMOS and the ground current is typically 100A over the load range, the power dissipation contributed by the ground current is < 1% and can be ignored for this calculation. 315mW = (VIN - 3.0V) 150mA 315mW = VIN**150mA - 450mW 810mW = VIN**150mA VIN(max) = 5.4V Therefore, a 3.0V application at 150mA of output current can accept a maximum input voltage of 5.4V in a SOT23-5 package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to the "Regulator Thermals" section of Micrel's Designing with Low-Dropout Voltage Regulators handbook. Fixed Regulator Applications
Package SOT23-5 (M5 or D5)
Table 1. SOT-23-5 Thermal Resistance
The actual power dissipation of the regulator circuit can be determined using the equation: PD = (VIN - VOUT) IOUT + VIN IGND Substituting PD(max) for PD and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. For example, when operating the MIC5256-3.0BM5 at 50C with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows:
125C - 50C PD(max) = 235C/W
Figure 1. Low-Noise Fixed Voltage Application
PD(max) = 315mW The junction-to-ambient thermal resistance for the minimum footprint is 235C/W, from Table 1. The maximum power dissipation must not be exceeded for proper operation. Using the output voltage of 3.0V and an output current of 150mA, the maximum input voltage
Figure 1 shows a standard low-noise configuration with a 47k pull-up resistor from the error flag to the input voltage and a pull-down capacitor to ground for the purpose of fault indication. EN (Pin 3) is connected to IN (Pin 1) for an application where enable/shutdown is not required. COUT = 1.0F minimum.
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Package Information
5-Pin SOT (M5)
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Package Information (Continued)
5-Pin Thin SOT (D5)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The 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. (c) 2003 Micrel, Incorporated.
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