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MIC5256
Micrel
MIC5256
150mA Cap LDO with Error Flag Final Information
General Description
The MIC5256 is an efficient, precise CMOS voltage regulator. It offers better than 1% initial accuracy, extremely lowdropout 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 device turnoff. Available in the IttyBittyTM SOT-23-5 package and the new Thin SOT-23-5, which offers the same footprint as the standard IttyBittyTM SOT-23-5, but only 1mm tall. The MIC5256 offers a range of output voltages.
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 Cellular phones and pagers Cellular accesories Battery-powered equipment Laptop, notebook, and palmtop computers Consumer/personal electronics
* * * * * * * * * *
Applications
Ordering Information
Part Number MIC5256-2.6BM5 MIC5256-2.7BM5 MIC5256-2.8BM5 MIC5256-2.85BM5 MIC5256-3.0BM5 MIC5256-3.3BM5 MIC5256-2.85BD5 Marking LX26 LX27 LX28 LX2J LX30 LX33 NX2J Voltage 2.6V 2.7V 2.8V 2.85V 3.0V 3.3V 2.85V Junction Temp. Range -40C to +125C -40C to +125C -40C to +125C -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 SOT-23-5 SOT-23-5 TSOT-23-5
Other voltages available. Contact Micrel for details.
Typical Application
CIN = 1.0F Ceramic
Enable Shutdown
VIN
MIC5256-x.xBM5
1 2 3 4 5
VOUT COUT = 1.0F Ceramic
FLG
EN
EN (pin 3) may be connected directly to IN (pin 1).
Low-Noise 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 * http://www.micrel.com
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Pin Configuration
EN GND IN
3 2 1
EN GND IN
3 2 1
LXxx
4 5
4
NWxx
5
FLG
OUT
BYP
OUT
MIC5256-x.xBM5 (SOT-23-5)
MIC5256-x.xBD5 (TSOT-23-5)
Pin Description
Pin Number 1 2 3 4 5 Pin Name IN GND EN FLG OUT Pin Function 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 (Note 1)
Supply Input Voltage (VIN) .................................. 0V to +7V Enable Input Voltage (VEN) ................................. 0V to +7V Power Dissipation (PD) ............... Internally Limited, Note 3 Junction Temperature (TJ) ....................... -40C to +125C Storage Temperature ............................... -65C to +150C Lead Temperature (soldering, 5 sec.) ....................... 260C ESD, Note 4 .................................................................. 2kV
Operating Ratings (Note 2)
Input Voltage (VIN) ......................................... +2.7V to +6V Enable Input Voltage (VEN) .................................. 0V to VIN Junction Temperature (TJ) ....................... -40C to +125C Thermal Resistance SOT-23 (JA) .....................................................235C/W
Electrical Characteristics
VIN = VOUT + 1V, VEN = VIN; IOUT = 100A; TJ = 25C, bold values indicate -40C TJ +125C; unless noted. Symbol VO VLNR VLDR VIN - VOUT Parameter Output Voltage Accuracy Line Regulation Load Regulation Dropout Voltage, Note 6 Conditions IOUT = 100A VIN = VOUT + 1V to 6V IOUT = 0.1mA to 150mA, Note 5 IOUT = 100A IOUT = 100mA IOUT = 150mA IQ IGND PSRR Quiescent Current Ground Pin Current, Note 7 VEN 0.4V (shutdown) IOUT = 0mA IOUT = 150mA Power Supply Rejection f = 10Hz, VIN = VOUT + 1V; COUT = 1F f = 100Hz, VIN = VOUT + 0.5V; COUT = 1F f = 10kHz, VIN = VOUT + 0.5V ILIM en Enable Input VIL VIH IEN Enable Input Logic-Low Voltage Enable Input Logic-High Voltage Enable Input Current 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 Shutdown Resistance Discharge Error Flag VFLG VOL IFL Low Threshold High Threshold Output Logic-Low Voltage Flag Leakage Current % of VOUT (Flag ON) % of VOUT (Flag OFF) IL = 100A, fault condition flag off, VFLG = 6V 90 96 0.02 0.01 0.1 % % V A C C 1.6 0.01 0.01 500 0.4 V V A A Current Limit Output Voltage Noise VOUT = 0V 160 Min -1 -2 0.02 1.5 0.1 90 135 0.2 90 117 60 60 45 425 tbd Typical Max +1 +2 0.05 2.5 5.0 150 200 250 1 150 Units % % %/V % mV mV mV mV A A A dB dB dB mA V(rms)
Thermal Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis
Note 1. Note 2. Note 3. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = TJ(max)-TA/JA. Exceeding the maximum allowable
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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). Note 4. Note 5. Note 6. Devices are ESD sensitive. Handling precautions recommended. 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. 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 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. 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.
Note 7.
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Typical Characteristics
Power Supply Rejection Ratio
70 60 50
Power Supply Rejection Ratio
70 60 50
PSRR vs. Voltage Drop
70 60 50 PSRR (dB) ILOAD = 100A
PSRR (dB)
40 30 20
100A* 50mA* 100mA* 150mA*
PSRR (dB)
40 30 20 10
100A* 50mA* 100mA* 150mA* *ILOAD COUT = 4.7F Ceramic
40 30 20 10
ILOAD = 150mA
*ILOAD 10 C OUT = 1.0F Ceramic
COUT = 1F 200 400 600 800 1000 VOLTAGE DROP (mV)
10
10000
1000000
10000
1000
10
FREQUENCY (Hz)
FREQUENCY (Hz)
Ground Pin Current
130 GROUND CURRENT (A) GROUND CURRENT (A) 125 120 115 110 105 100 0.1 VIN = VOUT + 1V 1 10 100 1000 OUTPUT CURRENT (mA) 115 113 111 109 107 105 103 101 99 97
Ground Pin Current
125 GROUND CURRENT (A) 120 115 110 105 100
1000000
100000
1000
100
100
100000
0
0
0 0
Ground Pin Current
95 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
ILOAD = 100A
I = 150mA LOAD 95 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
Ground Pin Current
140 GROUND CURRENT (A) 120 100 80 60 40 20 I = 100A GROUND CURRENT (A) 140 120 100 80 60 40 20
Ground Pin Current
3.5 OUTPUT VOLTAGE (V)
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) I
LOAD
= 150mA
0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 INPUT VOLTAGE (V)
LOAD
I
0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 INPUT VOLTAGE (V)
LOAD
= 150mA
Dropout Voltage
0.14 DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) 0.12 0.1 0.08 0.06 0.04 0.02 ILOAD = 100A 180 140 120 100 80 60 40 20 160
Dropout Voltage
180 DROPOUT VOLTAGE (mV) 160 140 120 100 80 60 40 20 0 0
Dropout Voltage
T = -40C
T = 25C
T = 125C
0 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
ILOAD = 150mA
20 40 60 80 100 120 140 160 OUTPUT CURRENT (mA)
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Short Circuit Current
SHORT CIRCUIT CURRENT (mA) SHORT CIRCUIT CURRENT (mA) 600 500 400 300 200 100 0 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) 6 500 490 480 470 460 450 440 430 420 410
Short Circuit Current
VIN = VOUT + 1V OUTPUT VOLTAGE (V) 3.05 3.04 3.03 3.02 3.01 3.00 2.99 2.98 2.97 2.96
Output Voltage vs. Temperature
400 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
ILOAD = 100A 2.95 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
ENABLE THRESHOLD VOLTAGE (V)
Enable Threshold vs. Temperature
1.3 1.25 FLAG VOLTAGE (V) 1.2 1.15 1.1 1.05 1 0.95 0.9 0.85 ILOAD = 100A 4.5 4 3.5 3 2.5 2 1.5 1 0.5
Error Flag Pull-Up Resistor
Power Good
VIN = 4V
0.8 -40 -20 0 20 40 60 80 100120140 TEMPERATURE (C)
0 0.1
1
Power Fail 10 100 1000 10000 RESISTANCE (k)
Test Circuits
MIC5256
1.0F* Ceramic
0V ON OFF
47k
0.01F
1.0F* Ceramic
Error Flag Output
* CIN = COUT = 1F
Figure 1. Test Circuit
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Functional Characteristics
Load Transient Response
Output Voltage (50mV/div)
Line Transient Response
CIN = 1F Ceramic COUT = 1F Ceramic IOUT = 100A
CIN = 1F Ceramic COUT = 1F Ceramic VIN = 4V
Output Voltage (50mV/div)
Output Current (100mA/div)
150mA 100A
TIME (4s/div)
Input Voltage (1V/div)
TIME (400s/div)
Enable Pin Delay
Enable Voltage (1V/div)
Shutdown Delay
Enable Voltage (1V/div)
CIN = 1F Ceramic COUT = 1F Ceramic IL = 100A
CIN = 1F Ceramic COUT = 1F Ceramic IOUT = 100A
Output Voltage (1V/div)
TIME (10s/div)
Output Voltage (1V/div)
TIME (400s/div)
Error Flag Start-up*
Enable Voltage (2V/div)
Error Flag Shutdown*
Enable Voltage (2V/div)
Output Voltage (2V/div)
Error Flag (2V/div)
TIME (400s/div)
Error Flag (2V/div)
Output Voltage (2V/div)
TIME (400s/div)
* See Test Circuit Figure 1
* See Test Circuit Figure 1
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Block Diagram
IN EN Reference Voltage Startup/ Shutdown Control Quickstart
Thermal Sensor
FAULT
Error Amplifier
Current Amplifier
OUT
Undervoltage Lockout
ACTIVE SHUTDOWN
Out of Regulation Detection FLG Overcurrent Dropout Detection GND
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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 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 examples of junction-toambient thermal resistance for the MIC5256.
Package SOT-23-5 (M5 or D5) JA Recommended Minimum Footprint 235C/W JA 1" Square Copper Clad 185C/W JC 145C/W
Applications 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-modecurrent 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 high-frequency 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. 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. 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 open-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 stablilize. When the error flag is pulled-up to June 2003 9
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 PD(max) = 315mW MIC5256
MIC5256
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 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 SOT-23-5 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
47k VIN CIN= 1.0F Ceramic MIC5256-x.xBM5
1 2 3 4 5
Micrel
VOUT COUT = 1.0F Ceramic
Figure 1. Low-Noise Fixed Voltage Application 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
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
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
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) 2003 Micrel, Incorporated
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MIC5256

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