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MIC37139
Micrel
MIC37139
1.5A, Low-Voltage Cap LDO Regulator
General Description
The Micrel MIC37139 is a 1.5A low-dropout linear voltage regulator that provides a low-voltage, high-current output with a minimum of external components. It offers high precision, ultra-low dropout (500mV overtemperature), and low ground current. The MIC37139 operates from an input of 2.25V to 6.0V. It is designed to drive digital circuits requiring low-voltage at high currents (i.e., PLDs, DSPs, microcontrollers, etc.). It is available in fixed output voltages, including 1.5V, 1.65V, 1.8V, 2.5V and 3.3V. Features of the MIC37139 LDO include thermal and currentlimit protection, and reverse-current and reverse-battery protection. Junction temperature range of the MIC37139 is from -40C to +125C. All support documentation can be found on Micrel's web site at www.micrel.com.
Features
* 1.5A minimum guaranteed output current * 500mV maximum dropout voltage overtemperature Ideal for 3.0V to 2.5V conversion Ideal for 2.5V to 1.8V, 1.65V, or 1.5V conversion * Stable with ceramic or tantalum capacitor * Wide input voltage range: VIN: 2.25V to 6.0V * +1.0% initial output tolerance * Fixed 1.8V output voltage * Excellent line and load regulation specifications * Thermal shutdown and current-limit protection * Reverse-leakage protection * Low profile SOT-223 package
Applications
* * * * * * * * * LDO linear regulator for low-voltage digital IC PC add-in cards High-efficiency linear power supplies SMPS post regulator Battery charger Set-top boxes Digital video recorders PowerPC(R) power supplies Multimedia and PC processor supplies
Typical Application
VIN 3.3V
MIC37139 IN OUT GND
1.8V 10F ceramic
1.8V/1.5A Regulator
Super eta PNP is a registered trademark of Micrel, Inc. PowerPC is a registered trademark of IBM Corporation. Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
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Ordering Information
Part Number MIC37139-1.8BS Output Current 1.5A Voltage 1.8V Junction Temp. Range -40C to +125C Package SOT-223
Pin Configuration
OUT
TAB
1
2
3
GND OUT
IN
SOT-223 (S)
Pin Description
Pin Number 1 2 3 Pin Name GND OUT IN Pin Function Ground. Regulator Output. Supply (Input).
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Absolute Maximum Rating(1)
Supply Voltage (VIN) .................................................... 6.5V Enable Input Voltage (VEN) .......................................... 6.5V Power Dissipation .................................... Internally Limited Junction Temperature (TJ) ................. -40C TJ +125C Storage Temperature (TS) ................. -65C TJ +150C Lead Temperature (soldering, 5 sec.) ....................... 260C ESD(4)
Operating Maximum Rating(2)
Supply Voltage (VIN) ..................................... 2.25V to 6.0V Enable Input Voltage (VEN) ................................ 0V to 6.0V Junction Temperature (TJ) ................. -40C TJ +125C Maximum Power Dissipation(3) Package Thermal Resistance SOT-223(JC) .................................................. 15C/W
Electrical Characteristics(5)
TA = 25C with VIN = VOUT + 1V; VEN = VIN; bold values indicate -40C < TJ < +125C; unless otherwise noted. Parameter Output Voltage Accuracy Condition IL = 10mA 10mA < IOUT < IL(max), VOUT + 1 VIN 6V Output Voltage Line Regulation Output Voltage Load Regulation VIN - VOUT; Dropout Ground Pin Voltage(6) VIN = VOUT +1.0V to 6.0V IL = 10mA to 1.5A IL = 750mA IL = 1.5A Current(7) IL = 1.5A VIL 0.5V, VIN = VOUT + 1V VOUT = 0 17 1.0 2.25 4.0 Ground Pin Current in Shutdown Current Limit
Notes: 1. Exceeding the absolute maximum ratings may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. PD(max) = (TJ(max) - TA) / JA, where JA, depends upon the printed circuit layout. See "Applications Information." 4. Device is ESD sensitive. Handling precautions recommended. 5. Specification for packaged product only. 6. VDO = VIN - VOUT when VOUT decreased to 98% of its nominal output voltage with VIN = VOUT +1V. For output voltages below 1.75V, dropout voltage specification does not apply due to a minimum input operating voltage of 2.25V. 7. IGND is the quiescent current. IIN = IGND + IOUT.
Min -1 -2
Typ
Max +1 +2
Units % % % % mV mV mA A A
0.06 0.2
0.5 1 350 500 30
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Typical Characteristics
Power Supply Rejection Ratio
80 VIN = 3.3V VOUT = 2.5V
PSRR (dB)
Power Supply Rejection Ratio
80
DROPOUT VOLTAGE (mV)
Dropout Voltage vs. Output Current
350 300 250 200 150 100 50 0 0 400 800 1200 1600 OUTPUT CURRENT (mA) 2.5VOUT
VIN = 3.3V VOUT = 2.5V
60 PSRR (dB)
60
40 IOUT = 1.5A COUT = 10F CIN = 0
40 IOUT = 1.5A COUT = 47F CIN = 0
20
20
0 1E-2 1E-1 1E+0 1E+1 1E+2 1E+3 1 10 1k 0.01 0.1 100 FREQUENCY (Hz)
0 1E-2 1E-1 1E+0 1E+1 1E+2 1E+3 1 10 1k 0.01 0.1 100 FREQUENCY (Hz)
500 DROPOUT VOLTAGE (mV) 450 400 350 300 250 200 150 100 50
Dropout Voltage vs. Temperature
3.0
OUTPUT VOLTAGE (V)
Dropout Characteristics
18
GROUND CURRENT (mA)
Ground Current vs. Output Current
16 14 12 10 8 6 4 2 0
0 1000 1200 1400 1600 200 400 600 800
2.5VOUT
2.5 2.0 1.5 1.0 0.5 0 1 1.5 2 2.5 3 INPUT VOLTAGE (V) 3.5 750mA 100mA 1.5A
2.5VOUT
1.5VOUT
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
OUTPUT CURRENT (mA)
Ground Current vs. Supply Voltage
1.4 45 GROUND CURRENT (mA)
Ground Current vs. Supply Voltage
GROUND CURRENT (mA) 40 35 30 25 20 15 10 5 0 0 750mA 1 2 3 4 5 6 SUPPLY VOLTAGE (V) 1500mA 1000mA VOUT = 2.5V 0.5 0.445 0.44 0.435 0.43 0.4 0.42 0.415 0.41
Ground Current vs. Temperature
VOUT = 2.5V ILOAD = 10mA
GROUND CURRENT (mA)
1.2 1 0.8 0.6 0.4 0.2 0 0
VOUT = 2.5V
100mA
10mA
1 2 3 4 5 SUPPLY VOLTAGE (V)
6
0.405 0.4 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
Ground Current vs. Temperature
7
Ground Current vs. Temperature
GROUND CURRENT (mA)
VOUT =2.5V ILOAD = 1.5A
GROUND CURRENT (mA)
6 5.0 4 3 2 1
VOUT = 2.5V I = 750mA
LOAD
SHORT CIRCUIT CURRENT (mA)
20 18 16 14 12 10 8 6
3.0 2.5 2.0 1.5 1.0 0.5
Short Circuit Current vs. Temperature
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
4 2 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
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Output Voltage vs. Temperature
2.60
OUTPUT VOLTAGE (V)
2.58 2.56 2.54 2.52 2.50 2.48 2.46 2.44 2.42 2.40 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
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Functional Characteristics
Load Transient Response
OUTPUT VOLTAGE (50mV/div.) OUTPUT VOLTAGE (50mV/div.)
Load Transient Response
VIN = 3.3V VOUT = 2.5 COUT = 10 F
VIN = 3.3V VOUT = 2.5V COUT = 47 F
5V 1.5A 10mA
LOAD CURRENT (1A/div.)
3.3V 1.5A
OUTPUT CURRENT (1A/div.)
100mA
TIME (400 s/div.)
TIME (400 s/div.)
Line Transient Response
OUTPUT VOLTAGE (20mV/div.) VOUT = 2.5V COUT = 10 F
INPUT VOLTAGE (2V/div.)
5V 3.3V
TIME (250 s/div.)
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Functional Diagram
IN
OUT
Ref.
1.240V
Thermal Shutdown
MIC37139 Fixed Regulator Block Diagram
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Refer to "Application Note 9" for further details and examples on thermal design and heat sink applications. Output Capacitor The MIC37139 requires an output capacitor for stable operation. As a Cap LDO, the MIC37139 can operate with ceramic output capacitors as long as the amount of capacitance is 47F or greater. For values of output capacitance lower than 47F, the recommended ESR range is 200m to 2. The minimum value of output capacitance recommended for the MIC37139 is 10F. For 47F or greater, the ESR range recommended is less than 1. Ultra-low ESR ceramic capacitors are recommended for output capacitance of 47F or greater to help improve transient response and noise reduction at high frequency. X7R/X5R dielectric-type ceramic capacitors are recommended because of their temperature performance. X7Rtype 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.
VIN MIC37139 IN CIN OUT GND COUT VOUT
Applications Information
The MIC37139 is a high-performance low-dropout voltage regulator suitable for moderate to high-current regulator applications. Its 500mV dropout voltage at full load and overtemperature makes it especially valuable in batterypowered systems and as high-efficiency noise filters in postregulator applications. Unlike older NPN-pass transistor designs, there the minimum dropout voltage is limited by the based-to-emitter voltage drop and collector-to-emitter saturation voltage, dropout performance of the PNP output of these devices is limited only by the low VCE saturation voltage. A trade-off for the low-dropout voltage is a varying base drive requirement. Micrel's Super eta PNP(R) process reduces this drive requirement to only 2% to 5% of the load current. The MIC37139 regulator is fully protected from damage due to fault conditions. Current limiting is provided. This limiting is linear; output current during overload conditions is constant. Thermal shutdown disables the device when the die temperature exceeds the maximum safe operating temperature. Transient protection allows device (and load) survival even when the input voltage spikes above and below nominal. The output structure of these regulators allows voltages in excess of the desired output voltage to be applied without reverse current flow. Thermal Design Linear regulators are simple to use. The most complicated design parameters to consider are thermal characteristics. Thermal design requires the following application-specific parameters: * Maximum ambient temperature (TA) * Output current (IOUT) * Output voltage (VOUT) * Input voltage (VIN) * Ground current (IGND) First, calculate the power dissipation of the regulator from these numbers and the device parameters from this datasheet. PD = (VIN - VOUT) IOUT + VIN IGND where the ground current is approximated by using numbers from the "Electrical Characteristics" or "Typical Characteristics." Then, the heat sink thermal resistance is determined with this formula: SA = ((TJ(max) - TA)/ PD) - (JC + CS) Where TJ(max) 125C and CS is between 0C and 2C/W. The heat sink may be significantly reduced in applications where the minimum input voltage is known and is large compared with the dropout voltage. Use a series input resistor to drop excessive voltage and distribute the heat between this resistor and the regulator. The low dropout properties of Micrel Super eta PNP(R) regulators allow significant reductions in regulator power dissipation and the associated heat sink without compromising performance. When this technique is employed, a capacitor of at least 1.0F is needed directly between the input and regulator ground.
Figure 1. Capacitor Requirements Input Capacitor An input capacitor of 1.0F or greater is recommended when the device is more than 4 inches away from the bulk and supply capacitance, or when the supply is a battery. Small, surface-mount chip capacitors can be used for the bypassing. The capacitor should be place within 1" of the device for optimal performance. Larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity of the output voltage. Transient Response and 3.3V to 2.5V, 2.5V to 1.8V or 1.65V, or 2.5V to 1.5V Conversions The MIC37139 has excellent transient response to variations in input voltage and load current. The device has been designed to respond quickly to load current variations and input voltage variations. Large output capacitors are not required to obtain this performance. A standard 10F output capacitor, preferably tantalum, is all that is required. Larger values help to improve performance even further.
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By virtue of its low-dropout voltage, this device does not saturate into dropout as readily as similar NPN-based designs. When converting from 3.3V to 2.5V, 2.5V to 1.8V or 1.65V, or 2.5V to 1.5V, the NPN-based regulators are already operating in dropout, with typical dropout requirements of 1.2V or greater. To convert down to 2.5V without operating in dropout, NPN-based regulators require an input voltage of 3.7V at the very least. The MIC37139 regulator will provide excellent performance with an input as low as 3.0V or 2.25V, respectively. This gives the PNP-based regulators a distinct advantage over older, NPN-based linear regulators.
Micrel
Minimum Load Current The MIC37139 regulator is specified between finite loads. If the output current is too small, leakage currents dominate and the output voltage rises. A 10mA minimum load current is necessary for proper operation.
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Package Information
3.15 (0.124) 2.90 (0.114)
C L
C L
3.71 (0.146) 7.49 (0.295) 3.30 (0.130) 6.71 (0.264)
2.41 (0.095) 2.21 (0.087) 4.7 (0.185) 4.5 (0.177) 6.70 (0.264) 6.30 (0.248)
1.04 (0.041) 0.85 (0.033) DIMENSIONS: MM (INCH) 1.70 (0.067) 16 1.52 (0.060) 10 10 MAX
0.10 (0.004) 0.02 (0.0008)
0.38 (0.015) 0.25 (0.010)
0.84 (0.033) 0.64 (0.025) 0.91 (0.036) MIN
SOT-223 (S)
MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
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. (c) 2003 Micrel, Incorporated.
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