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MIC5238
Micrel
MIC5238
Ultra-Low Quiescent Current, 150mA Cap LDO Regulator
General Description
The MIC5238 is an ultra-low voltage output, 150mA LDO regulator. Designed to operate in a single supply or dual supply mode, the MIC5238 consumes only 23A of bias current, improving efficiency. When operating in the dual supply mode, the efficiency greatly improves as the higher voltage supply is only required to supply the 23A bias current while the output and base drive comes off of the much lower input supply voltage. As a Cap regulator, the MIC5238 operates with a 2.2F ceramic capacitor on the output, offering a smaller overall solution. It also incorporates a logic-level enable pin that allows the MIC5238 to be put into a zero off-current mode when disabled. The MIC5238 is fully protected with current limit and thermal shutdown. It is offered in the IttyBittyTM SOT-23-5 package with an operating junction temperature range of -40C to +125C.
Features
* * * * * * * * * * * * * * Ultra-low input voltage range: 1.5V to 6V Ultra-low output voltage: 1.1V minimum output voltage Low dropout voltage: 310mV at 150mA High output accuracy: 2.0% over temperature Cap: stable with ceramic or tantalum capacitors Excellent line and load regulation specifications Zero shutdown current Reverse leakage protection Thermal shutdown and current limit protection IttyBittyTM SOT-23-5 package PDAs and pocket PCs Cellular phones Battery powered systems Low power microprocessor power supplies
Applications
Ordering Information
Part Number MIC5238-1.1BM5 MIC5238-1.3BM5 MIC5238-1.1BD5 MIC5238-1.3BD5 Marking L411 L413 N411 N413 Voltage* 1.1V 1.3V 1.1V 1.3V Junction Temp. Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package* SOT-23-5 SOT-23-5 TSOT-23-5 TSOT-23-5
* For other voltages and package option contact the factory
Typical Application
MIC5238-1.0BM5
VIN=1.5V EN OFF
ON
1
5
CIN
2 3 4
1.0V COUT=2.2F ceramic
VBIAS=2.5V CBIAS
Ultra-Low Voltage 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 * http://www.micrel.com
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MIC5238
MIC5238
Micrel
Pin Configuration
EN GND IN
3 2 1
EN GND IN
3 2 1
L4xx
4 5 4
N4xx
5
BIAS
OUT
BIAS
OUT
SOT-23-5 (M5)
TSOT-23-5 (D5)
Pin Description
SOT-23-5 1 2 3 4 5 Pin Name IN GND EN BIAS OUT Pin Function Supply Input Ground Enable (Input): Logic low = shutdown; logic high = enable. Do no leave open. BiasSupply Input Regulator Output
MIC5238
2
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MIC5238
Micrel
Absolute Maximum Ratings (Note 1)
Input Supply Voltage ........................................ -0.3V to 7V BIAS Supply Voltage ........................................ -0.3V to 7V Enable Input Voltage ........................................ -0.3V to 7V Power Dissipation .................................... Internally Limited Junction Temperature .............................. -40C to +125C Storage Temperature ............................... -65C to +150C ESD Rating, >1.5A HBM, Note 3
Operating Ratings (Note 2)
Input Supply Voltage .......................................... 1.5V to 6V BIAS Supply Voltage .......................................... 2.3V to 6V Enable Input Voltage ............................................. 0V to 6V Junction Temperature (TJ) ....................... -40C to +125C Package Thermal Resistance SOT-23-5 (JA) .................................................. 235C/W
Electrical Characteristics (Note 4)
TA = 25C with VIN = VOUT + 1V; VBIAS = 3.3V; IOUT = 100A; VEN = 2V, Bold values indicate -40C < TJ < +125C; unless otherwise specified. Parameter Output Voltage Accuracy Line Regulation Input Line Regulation Load Regulation Dropout Voltage Condition Variation from nominal VOUT VBIAS = 2.3V to 6V, Note 5 VIN = (VOUT + 1V) to 6V Load = 100A to 150mA IOUT = 100A IOUT = 50mA IOUT = 100mA IOUT = 150mA BIAS Current, Note 6 Input Current, Pin 1 IOUT = 100A IOUT = 100A IOUT = 50mA, Note 7 IOUT = 100mA IOUT = 150mA VEN 0.2V; VIN = 6V; VBIAS = 6V VEN = 0V; VIN = 6V; VBIAS = 6V Short Circuit Current Reverse Leakage Enable Input Input Low Voltage Input High Voltage Enable Input Current
Note 1. Note 2. Note 3. Note 4. Note 5. Note 6. Note 7.
Min. -1.5 -2
Typ.
Max. +1.5 +2
Units % % % %
0.25 0.04 0.7 50 230 270 310 23 7 0.35 1 2 1.5 0.5 350 5
0.5
1 300 400
% mV mV mV mV mV mV mV A A mA mA mA A A
450 500
20
2.5 5
Ground Current in Shutdown
VOUT = 0V VIN = 0V; VEN = 0V; VOUT = nom VOUT Regulator OFF Regulator ON VEN = 0.2V; Regulator OFF VEN = 2.0V; Regulator ON 2.0 -1.0
500
mA A
0.2
V V A A
0.01 0.1
1.0 1.0
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. Human body model, 1.5k in series with 100pF. Specification for packaged product only. Line regulation measures a change in output voltage due to a change in the bias voltage. Current measured from bias input to ground. Current differential between output current and main input current at rated load current.
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MIC5238
MIC5238
Micrel
Typical Characteristics
80 70 60
PSRR (dB)
PSRR 150mA Load
OUTPUT VOLTAGE (V)
1.2 1.1 1 0.9 0.8 0.7 0.6 0.5
Output Voltage vs. VBIAS
100A 150mA
OUTPUT VOLTAGE (V)
1.15 1.1 1.05 1 0.95 0.9 0.85
Output Voltage vs. VIN
100A 150mA
50 40 30 COUT = 2.2F ceramic VIN = 2.1V 10 V = 1.1V OUT 20 0 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
0.4 1.2 1.7 2.2 2.7 3.2 3.7 4.2 4.7 5.2 INPUT BIAS (V)
0.8 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 INPUT VIN (V)
400
DROPOUT VOLTAGE (mV)
Dropout Voltage vs. Load
VIN = VOUT + 1
GROUND CURRENT (A) 1800 1600 1400 1200 1000 800 600 400 200 0 0
Ground Current (VIN) vs. Output Current
VIN GROUND CURRENT (mA) VIN = VOUT + 1
2.0
Ground Current (VIN) vs. VIN Supply
350 300 250 200 150 100 50 0 0
1.1V 1.8 150mA 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0
25 50 75 100 125 150 OUTPUT CURRENT (A)
25 50 75 100 125 150 OUTPUT CURRENT (mA)
0.5 1.0 1.5 VIN SUPPLY (V)
2.0
30 GROUND CURRENT (A) 25 20 15 10 5 0 0
Ground Current (VBIAS) vs. Output Current
VBIAS GROUND CURRENT (A) VIN = VOUT + 1
Ground Current (VBIAS) vs. Input Voltage
30 25 20 15 10 5 0
0 0.5 1 1.5 2 2.5 3
ILOAD = 150mA
GROUND CURRENT (A)
7 6 5 4 3 2 1 0
0
Shutdown Current of VIN
No Load
25 50 75 100 125 150 OUTPUT CURRENT (mA)
0.5
1
1.5
2
INPUT VOLTAGE (V)
ENABLE (V)
Shutdown Current of VBIAS
20
GROUND CURRENT (mA) GROUND CURRENT (mA)
Shutdown Current VBIAS + V Tied
IN
VIN GROUNF CURRENT (A)
30 No Load 25 20 15 10 5 0 0 0.5 1 1.5 ENABLE (V) 2
10 9 8 7 6 5 4 3 2 1
Ground Current (VIN) vs Temperature
1.1V 100A
18 No Load 16 14 12 10 8 6 4 2 0 0 0.5 1 1.5 ENABLE (V) 2
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
MIC5238
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MIC5238
Micrel
VIN GROUND CURRENT (mA)
VIN GROUND CURRENT (mA)
1.4 1.2 1 0.8 0.6 0.4 0.2 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
VIN GROUND CURRENT (A)
1.1V 1.8 75mA 1.6
2
VIN Ground Current vs. Temperature
2.4
VIN Ground Current vs. Temperature
40
V
BIAS
1.1V 2.2 150mA 2
Ground Current vs. Temperature
1.1V 35 100A 30 25 20 15 10 5 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
VBIAS Ground Current vs. Temperature
40
VIN GROUND CURRENT (A)
VBIAS Ground Current vs. Temperature
40
VIN GROUND CURRENT (A) OUTPUT VOLTAGE (V)
35 30 25 20 15 10 5
1.1V 75mA
35 30 25 20 15 10 5
1.1V 150mA
1.1025
Output Voltage vs. Temperature
1.1V 1.1020 100A 1.1015 1.1010 1.1005 1.1000 1.0995 1.0990 1.0985 1.0980 1.0975 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
500 450
LOAD CURRENT (mA)
Short Circuit Current vs. Temperature
DROPOUT VOLTAGE (mV)
500 450 400 350 300 250 200 150 100 50
Dropout Voltage vs. Temperature
Load = 150mA
400 350 300 250 200 150 100 50 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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MIC5238
MIC5238
Micrel
Line Transient Response
3.1V
INPUT VOLTAGE (1V/div.) OUTPUT VOLTAGE (200mV/div.)
Load Transient Response
1.1V output COUT = 4.7F ceramic
2.1V
1.1V Output COUT = 4.7 F ceramic
150mA
OUTPUT CURRENT (50mA/div.)
OUTPUT VOLTAGE (10mV/div.)
1mA
TIME (200 s/div.)
TIME (400 s/div.)
EN Turn-On Characteristic
Load Transient Response
OUTPUT CURRENT OUTPUT VOLTAGE (100mA/div.) (200mV/div.)
OUTPUT VOLTAGE (500mA/div.)
ENABLE (2V/div.)
150mA
0mA VIN = 4V VOUT = 3V COUT = 4.7F ceramic
TIME (40 s/div.)
TIME (400s/div.)
MIC5238
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MIC5238
Micrel
Functional Diagram
IN BIAS EN ENABLE OUT
VREF
GND
Block Diagram - Fixed Output Voltage
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MIC5238
MIC5238
Micrel
JA Recommended Minimum Footprint SOT-23-5 235C/W Table 1. SOT-23-5 Thermal Resistance Package The actual power dissipation of the regulator circuit can be determined using the equation: PD = (VIN - VOUT)IOUT + VINIGND 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 MIC5238-1.0BM5 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 PD(MAX) = 319mW The junction-to-ambient (JA) thermal resistance for the minimum footprint is 235C/W, from Table 1. It is important that the maximum power dissipation not be exceeded to ensure proper operation. With very high input-to-output voltage differentials, the output current is limited by the total power dissipation. Total power dissipation is calculated using the following equation: PD = (VIN - VOUT)IOUT + VIN x IGND + VBIAS x IBIAS Since the bias supply draws only 18A, that contribution can be ignored for this calculation. If we know the maximum load current, we can solve for the maximum input voltage using the maximum power dissipation calculated for a 50C ambient, 319mV. PDMAX = (VIN - VOUT)IOUT + VIN x IGND 319mW = (VIN - 1V)150mA + VIN x 2.8mA Ground pin current is estimated using the typical characteristics of the device. 469mW = VIN (152.8mA) VIN = 3.07V For higher current outputs only a lower input voltage will work for higher ambient temperatures. Assuming a lower output current of 20mA, the maximum input voltage can be recalculated: 319mW = (VIN - 1V)20mA + VIN x 0.2mA 339mW = VIN x 20.2mA VIN = 16.8V Maximum input voltage for a 20mA load current at 50C ambient temperature is 16.8V. Since the device has a 6V rating, it will operate over the whole input range. Dual Suppy Mode Efficiency By utilizing a bias supply the conversion efficiency can be greatly enhanced. This can be realized as the higher bias supply will only consume a few A's while the input supply will require a few mA's! This equates to higher efficiency saving valuable power in the system. As an example, consider an output voltage of 1V with an input supply of 2.5V at a load 8 August 2003
Applications Information
Enable/Shutdown The MIC5238 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-modecurrent state. In this state, current consumed by the regulator goes nearly to zero. Forcing the enable pin high enables the output voltage. Input Bias Capacitor The input capacitor must be rated to sustain voltages that may be used on the input. An input capacitor may be required when the device is not near the source power supply or when supplied by a battery. Small, surface mount, ceramic capacitors can be used for bypassing. Larger values may be required if the source supply has high ripple. Output Capacitor The MIC5238 requires an output capacitor for stability. The design requires 2.2F 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 3. The output capacitor can be increased without limit. Larger valued capacitors help to improve transient response. 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 a X7R ceramic capacitor to ensure the same minimum capacitance over the equivalent operating temperature range. No-Load Stability The MIC5238 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 MIC5238 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 TJ(MAX) is the maximum junction temperature of the die, 125C, and TA is the ambient operating temperature. JA is layout dependent; Table 1 shows the junction-to-ambient thermal resistance for the MIC5238.
MIC5238
MIC5238
current of 150mA. The input ground current under these conditions is 2mA, while the bias current is only 20A. If we calculate the conversion efficiency using the single supply approach, it is as follows: Input power = VIN x output current + VIN x (VBIAS ground current + VIN ground current) Input power = 2.5V x 150mA + 2.5 x (0.0002+0.002) = 380.5mW Output power = 1V x 0.15 = 150mW Efficiency = 150/380.5 x 100 = 39.4% Now, using a lower input supply of 1.5V, and powering the bias voltage only from the 2.5V input, the efficiency is as follows:
Micrel
Input power = VIN x output current + VIN x VIN ground current + VBIAS x VBIAS ground current Input power = 1.5 x 150mA + 1.5 x 0.002 + 2.5 x 0.0002 = 225mW Output power = 1V x 150mA = 150mW Efficiency = 150/225 x 100 = 66.6 % Therefore, by using the dual supply MIC5238 LDO the efficiency is nearly doubled over the single supply version. This is a valuable asset in portable power management applications equating to longer battery life and less heat being generated in the application. This in turn will allow a smaller footprint design and an extended operating life.
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MIC5238
MIC5238
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) 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)
1.90BSC
2.90BSC
0.30 0.45 1.90BSC
DIMENSIONS: Millimeter
0.90 0.80
2.9BSC
1.00 0.90
1.60BSC
1.60BSC
0.10 0.01 1.90BSC
0.20 0.12
0.30 0.50
TSOT-23-5 (D5)
MICREL, INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131
FAX
USA
+ 1 (408) 944-0800
+ 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.
MIC5238
10
August 2003

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