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MIC37500/37501/37502
Micrel
MIC37500/37501/37502
5A, Low Voltage Cap LDO Regulator Advance Information
General Description
The Micrel MIC37500/01/02 is a 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), and low ground current. The MIC37500/01/02 operates from an input of 2.3V to 6.0V. It is designed to drive digital circuits requiring low voltage at high currents (i.e. PLDs, DSP, microcontroller, etc.). It is available in fixed and adjustable output voltages. Fixed voltages include 1.5V. The adjustable version is capable of 1.24V to 5.5V. Features of the MIC37500/01/02 LDO include thermal and current limit protection, and reverse current & reverse battery protection. Logic enable and error flag pins are available. Junction temperature range of the MIC37500/01/02 is from -40C to 125C. For applications requiring input voltage greater than 6.0V, see MIC3910x, MIC3915x, MIC3930x, and MIC3950x LDOs.
Features
* 5A minimum guaranteed output current * 500mV maximum dropout voltage 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: 2.3V to 6.0V * 1.0% initial output tolerance * Fixed and adjustable output voltages * Excellent line and load regulation specifications * Logic controlled shutdown * Thermal shutdown and current limit protection * Reverse-leakage protection * Low profile S-Pak package
Applications
* * * * * LDO linear regulator for low-voltage digital IC PC add-in cards High efficiency linear power supplies SMPS post regulator Battery charger
Typical Application
VIN = 3.0V CIN MIC37500 VIN VOUT VIN VEN GND VOUT FLG 100k VOUT = 2.5V COUT 100F, Ceramic
VIN CIN MIC37502 VIN VOUT VIN VEN GND VOUT ADJ R2 R1 COUT 100F, Ceramic 1.3V
Fixed 2.5V Regulator with Error Flag
Adjustable Regulator
SuperSwitcher 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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MIC37500/37501/37502
Micrel
Ordering Information
Part Number MIC37502BR MIC37501-1.5BR Output Current 5A 5A Voltage* ADJ. 1.5V Junction Temp. Range -40C to +125C -40C to +125C Package S-Pak-7 S-Pak-7
*For other voltages contact Micrel.
Pin Configuration
7 6 5 4 3 2 1 FLG/ADJ VOUT VOUT GND VIN VIN EN
TAB
S-PAK7
Pin Description
Pin Number 1 2, 3 4 5, 6 7 Pin Name EN VIN GND VOUT FLG. ADJ. Pin Function Enable (Input): CMOS compatible input. Logic high = enable, logic low = shutdown Input voltage which supplies current to the output power device. Connect pins 2 and 3 together externally. Ground (TAB is connected to ground on S-Pak) Regulator Output. Connect pins 5 and 6 together externally. Error Flag (Output): Open collector output. Active low indicates an output fault condition. Adjustable regulator feedback input. Connect to resistor voltage divider.
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Absolute Maximum Rating (Note 1)
Supply Voltage (VIN) .................................................... 6.5V Enable Input Voltage (VEN) .......................................... 6.5V Power Dissipation .................................... Internally Limited Junction Temperature ........................ -40C TJ +125C Storage Temperature ......................... -65C TJ +150C Lead Temperature (soldering, 5 sec.) ....................... 260C ESD, Note 3
Operating Maximum Rating (Note 2)
Supply Voltage (VIN) ....................................... 2.3V to 6.0V Enable Input Voltage (VEN) ................................ 0V to 6.0V Junction Temperature Range ............. -40C TJ +125C Maximum Power Dissipation ................. ............... Note 4 Package Thermal Resistance S-Pak(JC) ........................ ............. ............2C/W
Electrical Characteristics
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 Voltage ; Note 5 Ground Pin Current, Note 6 Ground Pin Current in Shutdown Current Limit Start-up Time Enable Input Enable Input Threshold Regulator enable Regulator shutdown Enable Pin Input Current VIL < 0.8V (Regulator shutdown) VIH > 2.25V (Regulator enabled) Flag Output IFLG(LEAK) VFLG(LO) VFLG VOH = 6V VIN = 2.25V, IOL = 250uA, Note 7 Low Threshold, % of Vout below nominal Hysteresis High Threshold, % of Vout below nominal MIC37502 Only Reference Voltage Adjust Pin Bias Current 1.228 1.215 1.240 40 1.252 1.265 80 120 V V nA nA 93 2 99.2 210 1 2 A A mV mV % % % 1 15 2.25 0.8 2 4 30 75 V V A A A A VIN = VOUT +1.0V to 6.0V IL = 10mA to 5A IL = 2.5A IL = 5A IL = 5A VIL < 0.5V, VIN = VOUT + 1V VOUT = 0 VEN = VIN, IOUT = 10mA, COUT = 22F 330 57 1.0 7.5 170 500 Min -1 -2 0.06 0.2 Typ Max +1 +2 0.5 1 350 500 Units % % % % mV mV mA A A s
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Note 1. Note 2. Note 3. Note 4. Note 5. Note 6. Note 7. Exceeding the absolute maximum ratings may damage the device. The device is not guaranteed to function outside its operating rating. Device is ESD sensitive. Handling precautions recommended. PD(MAX) = (TJ(MAX) - TA) / JA, where JA, depends upon the printed icurcuit layout. See "Applications Information."
Micrel
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 2.3V. IGND is the quiescent current. IIN = IGND + IOUT. For a 2.5V device, VIN = 2.3V (device is in dropout).
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Output Capacitor The MIC37500/01/02 requires an output capacitor for stable operation. As a Cap LDO, the MIC37500/01/02 can operate with ceramic output capacitors as long as the amount of capacitance is 100F or greater. For values of output capacitance lower than 100F, the recommended ESR range is 200m to 2. The minimum value of output capacitance recommended for the MIC37500/01/02 is 47F. For 100F or greater the ESR range recommended is less than 1 ultra-low ESR ceramic capacitors are recommended for output capacitance of 100F 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. The MIC37500/01/02 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 47F output capacitor, is all that is required. Larger values help to improve performance even further. Input Capacitor An input capacitor of 1.0F or greater is recommended when the device is more than 4 inches away from the bulk ad supply capacitance, or when the supply is a battery. Small, surfacemount 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 MIC37500/01/02 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 47F output capacitor, is all that is required. Larger values help to improve performance even further. 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 MIC37500/01/02 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. 5 MIC37500/37501/37502
Applications Information
The MIC37500/01/02 is a high-performance low-dropout voltage regulator suitable for moderate to high-current regulator applications. Its 500mV dropout voltage at full load makes it especially valuable in battery-powered systems and as high-efficiency noise filters in post-regulator applications. Unlike older NPN-pass transistor designs, there the minimum dropout voltage is limited by the based-to-emiiter 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 Beta PNPTM process reduces this drive requirement to only 2% to 5% of the load current. The MIC37500/01/02 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 votlage 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 Beta PNP 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. Refer to Application Note 9 for further details and examples on thermal design and heat sink applications. January 2002
MIC37500/37501/37502
Minimum Load Current The MIC37500/01/02 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. Error Flag The MIC37501 features an error flag circuit that monitors the output voltage and signals an error condition when the voltage 5% below the nominal output voltage. The error flag is an open-collector output that can sink 10mA during a fault condition. Low output voltage can be caused by a number of problems, including an overcurrent fault (device in current limit) or low input voltage. The flag is inoperative during overtemperature shutdown. Enable Input The MIC37501/37502 also feature an enable input for on/off control of the device. Its shutdown state draws "zero" current (only micoamperes of leakage). The enable input is TTL/ CMOS compatible for simple logic interface, but can be connected to up to VIN. When enabled, it draws approximately 15A. Adjustable Regulator Design
MIC37502 OUT R1
ENABLE SHUTDOWN
Micrel
VIN
IN
VOUT COUT
EN
ADJ GND
R2
R1 VOUT = 1.240V 1 + R2
Figure 2. Adjustable Regulator with Resistors The MIC37502 allows programming the output voltage anywhere between 1.24V and the 5.5V maximum operating rating of the family. Two resistors are used. Resistors can be quite large, up to 1M, because of the very high input impedance and low bias current of the sense comparator: The resistor values are calculated by:
V R1 = R2 OUT - 1 1.240
Where VOUT is the desired output voltage. Figure 2 shows component definition. Applications with widely varying load currents may scale the resistors to draw the minimum load current required for proper operation (see above).
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Package Information
0.375 (9.52) 0.365 (9.27) 0.360 (9.14) 0.350 (8.89) 0.050 (1.27) 0.030 (0.76) 0.256 BSC (6.50 BSC)
DIMENSIONS: INCH (MM)
0.080 (2.03) 0.070 (1.78) 0.010 BSC (0.25 BSC)
0.320 (8.13) 0.310 (7.87)
0.316 BSC (8.03 BSC) 0.420 (10.67) 0.410 (10.41)
0.045 (1.14) 0.035 (0.89)
0.050 BSC (1.27 BSC)
0.031 (0.79) 0.025 (0.63)
0.005 (0.13) 0.001 (0.03)
0.010 BSC (0.25 BSC)
6 0 SCALE 20:1
7-Lead S-PAK (R)
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MIC37500/37501/37502
MIC37500/37501/37502
Micrel
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) 2002 Micrel Incorporated
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