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MIC5246
Micrel
MIC5246
150mA Cap CMOS LDO Regulator Preliminary Information
General Description
The MIC5246 is an efficient, precise CMOS voltage regulator optimized for low-noise applications. The MIC5246 offers better than 1% initial accuracy, extremely-low-dropout voltage (typically 150mV at 150mA) and constant ground current (typically 85A)over load . The MIC5246 features an error flag that indicates an output fault condition such as overcurrent, thermal shutdown and dropout. The MIC5246 provides a very low noise output, ideal for RF applications where quiet voltage sources are required. Designed specifically for hand-held and battery-powered devices, the MIC5246 provides a TTL-logic-compatible enable pin. When disabled, power consumption drops nearly to zero. The MIC5246 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, a pushpull output for faster transient response, and an active clamp to speed up device turnoff. Available in the IttyBittyTM SOT-23-5 package, the MIC5246 also offers a range of fixed output voltages.
Features
* * * * * * * * * * * * * * * * * * * Error flag indicates fault condition Ultralow dropout--100mV @ 100mA Load independent, ultralow ground current: 85A 150mA output current Current limiting Thermal Shutdown Tight load and line regulation "Zero" off-mode current Stability with low-ESR capacitors Fast transient response TTL-Logic-controlled enable input Cellular phones and pagers Cellular accessories Battery-powered equipment Laptop, notebook, and palmtop computers PCMCIA VCC and VPP regulation/switching Consumer/personal electronics SMPS post-regulator/dc-to-dc modules High-efficiency linear power supplies
Applications
Ordering Information
Part Number MIC5246-2.6BM5 MIC5246-2.7BM5 MIC5246-2.8BM5 MIC5246-2.85BM5 MIC5246-3.0BM5 MIC5246-3.3BM5 Marking LT26 LT27 LT28 LT2J LT30 LT33 Voltage 2.6V 2.7V 2.8V 2.85V 3.0V 3.3V Junction Temp. Range -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
Other voltages available. Contact Micrel for details.
Typical Application
47k VIN MIC5246-x.xBM5
1 2 Enable Shutdown 3 4 5
VOUT COUT FLG CFLG
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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MIC5246
MIC5246
Micrel
Pin Configuration
EN GND IN
3 2 1
LTxx
4 5
FLG
OUT
MIC5246-x.xBM5
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
Absolute Maximum Ratings (Note 1)
Supply Input Voltage (VIN) .................................. 0V to +7V Enable Input Voltage (VEN) .................................. 0V to VIN Flag Output Voltage (VFLG) .................................. 0V to VIN Junction Temperature (TJ) ...................................... +150C Storage Temperature ............................... -65C to +150C Lead Temperature (soldering, 5 sec.) ....................... 260C ESD, Note 3
Operating Ratings (Note 2)
Input Voltage (VIN) ......................................... +2.7V to +6V Enable Input Voltage (VEN) .................................. 0V to VIN Flag Output Voltage (VFLG) .................................. 0V to VIN Junction Temperature (TJ) ....................... -40C to +125C Thermal Resistance (JA)...................................... 235C/W
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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 5 Conditions IOUT = 0mA VIN = VOUT + 0.1V to 6V IOUT = 0.1mA to 150mA, Note 4 IOUT = 100A IOUT = 50mA IOUT = 100mA IOUT = 150mA IQ IGND PSRR ILIM 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 VIH 1.6V Shutdown Resistance Discharge Thermal Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis Error Flag VFLG VOL IFL
Note 1. Note 2. Note 3. Note 4. Note 5.
Min -1 -2 -0.3
Typical
Max 1 2
Units % % %/V % mV mV mV mV mV A A A dB mA
0 2 1.5 50 100 150 0.2 85 85 50
0.3 3 5 85 150 200 250 1 150 150
Quiescent Current Ground Pin Current, Note 6
VEN 0.4V (shutdown) IOUT = 0mA IOUT = 150mA f = 120Hz, COUT = 10F VOUT = 0V 160
Power Supply Rejection Current Limit
300
0.8 1.6 1 0.01 0.01 500
0.4
V V A A C C
150 10
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 0.4
% % V A
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. 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. The error flag is a function of the output voltage being 5% low and the detection of one of the following: overcurrent, overtemperature or dropout. See "Applications Information" section for additional information.
Note 6. Note 7.
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Typical Characteristics
Power Supply Rejection Ratio
60 50
PSRR (dB) PSRR (dB)
Power Supply Rejection Ratio
60 50
PSRR (dB)
Power Supply Rejection Ratio
60 50 40 30 20 10
40 30 20 10
1
40 30 20 10
1x102
1x103
1x104
1x105
1x106
1
1x102
1x103
1x104
1x105
1x106
1
1x102
1x103
1x104
1x105 = 150mA
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
Power Supply Rejection Ratio
60 50
PSRR (dB) GROUND CURRENT (A) 90
Ground Current vs. Output Current
GROUND CURRENT (A)
Ground Pin Current
100 80 60 40 20 Iload = 100A 0 -40 -10 20 50 80 110 140 TEMPERATURE (C)
88 86 84 82 80 0
40 30 20 10
1
1x102
1x103
1x104
1x105
1x106
0
ILOAD = 150mA
1x10
1 10 100 1000 OUTPUT CURRENT (mA)
FREQUENCY (Hz)
Ground Pin Current
100 GROUND CURRENT (A) GROUND CURRENT (A) 80 60 40 20 0 -40 ILOAD = 150mA -10 20 50 80 110 140 TEMPERATURE (C) 100 80 60 40 20
Ground Pin Current
100 GROUND CURRENT (A) 80 60 40 20
Ground Pin Current
ILOAD = 100A 0 0 1 2 3 4 VOLTAGE IN (V) 5
I 0 0 1
LOAD
2 3 4 VOLTAGE IN (V)
Dropout Characteristics
4 DROPOUT VOLTAGE (V) 100A 150mA 200
Dropout Voltage
250 DROPOUT VOLTAGE (V) 200 150 100 50 0 -40
Dropout Voltage
VOLTAGE OUT (V)
3
150
2
100
1
50 ILOAD = 100A -10 20 50 80 110 140 TEMPERATURE (C)
0 0
1
2 3 4 VOLTAGE IN (V)
5
0 -40
ILOAD = 150mA -10 20 50 80 110 140 TEMPERATURE (C)
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1x106 5
0
ILOAD = 100A
1x10
0
ILOAD= 50mA
1x10
0
ILOAD = 100mA
1x10
MIC5246
Micrel
Typical Characteristics
Short Circuit Current vs. Temperature
SHORT CIRCUIT CURRENT (mA) 400 OUTPUT VOLTAGE (V) 3.40 3.36 3.32 3.28 3.24 3.20 -40
Output Voltage vs. Temperature
300
200
100 VOUT = 0V -10 20 50 80 110 140 TEMPERATURE (C)
0 -40
-10 20 50 80 110 140 TEMPERATURE (C)
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Block Diagrams
IN EN Reference Voltage Startup/ Shutdown Control Quickstart
PULL UP
Thermal Sensor
FAULT
Error Amplifier
Current Amplifier
PULL DOWN
OUT
Undervoltage Lockout
ACTIVE SHUTDOWN
Out of Regulation Detection FLG Overcurrent Dropout Detection GND
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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. This glitch is filtered by putting a capacitor from the error flag to ground. The glitch does not occur if the error flag pulled up to the output. Transient Response The MIC5246 implements a unique output stage to dramatically improve transient response recovery time. The output is a totem-pole configuration with a P-channel MOSFET pass device and an N-channel MOSFET clamp. The N-channel clamp is a significantly smaller device that prevents the output voltage from overshooting when a heavy load is removed. This feature helps to speed up the transient response by significantly decreasing transient response recovery time during the transition from heavy load (100mA) to light load (85A). Active Shutdown The MIC5246 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. Thermal Considerations The MIC5246 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 MIC5246.
Package SOT-23-5 (M5) JA Recommended Minimum Footprint 235C/W JA 1" Square Copper Clad 185C/W JC 145C/W
Applications Information
Enable/Shutdown The MIC5246 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 An input capacitor is not required for stability. A 1F input capacitor is recommended when the bulk ac supply capacitance is more than 10 inches away from the device, or when the supply is a battery. Output Capacitor The MIC5246 requires an output capacitor for stability. The design requires 1F or greater on the output to maintain stability. The capacitor can be a low-ESR ceramic chip capacitor. The MIC5246 has been designed to work specifically with the low-cost, small chip capacitors. Tantalum capacitors can also be used for improved capacitance over temperature. The value of the capacitor can be increased without bound. X7R dielectric 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 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 or a tantalum capacitor to ensure the same minimum capacitance value over the operating temperature range. Tantalum capacitors have a very stable dielectric (10% over their operating temperature range) and can also be used with this device. 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. Error Flag Circuit 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 downstream circuits time to stabilize. When the error flag is pulled up to the June 2000 7
Table 1. SOT-23-5 Thermal Resistance
MIC5246
MIC5246
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 MIC5246-3.0BM5 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 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 MIC5246-x.xBM5
1 2 3 4 5
Micrel
VOUT 1F
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. Dual-Supply Operation When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground.
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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 (M)
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MIC5246
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Micrel
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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
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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