291-02790-0-MIC29371

MIC2937A/29371/29372 Micrel 3-18 October 1999 1 2 3 Front View Features • High output voltage accuracy • Guaranteed 750mA output • Low quiescent current • Low dropout voltage • Extremely tight load and line regulation • Very low temperature coefficient • Current and thermal limiting • Input can withstand –20V reverse battery and +60V positive transients • Error flag warns of output dropout • Logic-controlled electronic shutdown • Output programmable from 1.24V to 26V(MIC29372) • Available in TO-220, TO-263, TO-220-5, and TO-263-5 packages. Applications • Battery Powered Equipment • Cellular Telephones • Laptop, Notebook, and Palmtop Computers • PCMCIA VCC and VPP Regulation/Switching • Bar Code Scanners • Automotive Electronics • SMPS Post-Regulator/ DC to DC Modules • High Efficiency Linear Power Supplies Pin Configuration GROUND OUTPUTINPUT TO-220-5 Package (MIC29371/29372BT) TO-220 Package (MIC2937A-xxBT) 1 2 3 4 5 General Description The MIC2937A family are “bulletproof” efficient voltage regulators with very low dropout voltage (typically 40mV at light loads and 300mV at 500mA), and very low quiescent current (160m A typical). The quiescent current of the MIC2937A increases only slightly in dropout, thus prolonging battery life. Key MIC2937A features include protection against reversed battery, fold-back current limiting, and automotive “load dump” protection (60V positive transient). The MIC2937 is available in several configurations. The MIC2937A-xx devices are three pin fixed voltage regulators with 3.3V, 5V, and 12V outputs available. The MIC29371 is a fixed regulator offering logic compatible ON/OFF switching input and an error flag output. This flag may also be used as a power-on reset signal. A logic-compatible shutdown input is provided on the adjustable MIC29372, which enables the regulator to be switched on and off. TO-263 Package (MIC2937A-xxBU) GROUND OUTPUTINPUT TO-263-5 Package (MIC29371/29372BU) 1 2 3 4 5 Five Lead Package Pin Functions: MIC29371 MIC29372 1) Error Adjust 2) Input Shutdown 3) Ground Ground 4) Output Input 5) Shutdown Output The TAB is Ground on the TO-220 and TO-263 packages. MIC2937A/29371/29372 750mA Low-Dropout Voltage Regulator MIC2937A/29371/29372 Micrel October 1999 19 MIC2937A/29371/29372 Ordering Information Part Number Voltage Temperature Range* Package MIC2937A-3.3BU 3.3 –40 ° C to +125° C TO-263-3 MIC2937A-3.3BT 3.3 –40 ° C to +125° C TO-220 MIC2937A-5.0BU 5.0 –40 ° C to +125° C TO-263-3 MIC2937A-5.0BT 5.0 –40 ° C to +125° C TO-220 MIC2937A-12BU 12 –40 ° C to +125° C TO-263-3 MIC2937A-12BT 12 –40 ° C to +125° C TO-220 MIC29371-3.3BT 3.3 –40 ° C to +125° C TO-220-5 MIC29371-3.3BU 3.3 –40 ° C to +125° C TO-263-5 MIC29371-5.0BT 5.0 –40 ° C to +125° C TO-220-5 MIC29371-5.0BU 5.0 –40 ° C to +125° C TO-263-5 MIC29371-12BT 12 –40 ° C to +125° C TO-220-5 MIC29371-12BU 12 –40 ° C to +125° C TO-263-5 MIC29372BT Adj –40 ° C to +125° C TO-220-5 MIC29372BU Adj –40 ° C to +125° C TO-263-5 Absolute Maximum Ratings If Military/Aerospace specified devices are required, contact your local Micrel representative/distributor for availability and specifications. Power Dissipation (Note 1) .............. Internally Limited Lead Temperature (Soldering, 5 seconds) ........ 260 ° C Storage Temperature Range ............ –65° C to +150 ° C Operating Junction Temperature Range ................................................. –40° C to +125 ° C TO-220 q JC ...................................................... 2.5 ° C/W TO-263 q JC ...................................................... 2.5 ° C/W Input Supply Voltage ............................... –20V to +60V Operating Input Supply Voltage ................... 2V† to 26V Adjust Input Voltage (Notes 9 and 10) ...................................................... –1.5V to +26V Shutdown Input Voltage ......................... –0.3V to +30V Error Comparator Output Voltage .......... –0.3V to +30V † Across the full operating temperature, the minimum input voltage range for full output current is 4.3V to 26V. Output will remain in-regulation at lower output voltages and low current loads down to an input of 2V at 25° C. * Junction temperatures MIC2937A/29371/29372 Micrel MIC2937A/29371/29372 20 October 1999 Electrical Characteristics Limits in standard typeface are for TJ = 25° C and limits in boldface apply over the full operating temperature range. Unless otherwise specified, VIN = VOUT + 1V, IL = 5mA, CL = 10 m F. The MIC29372 are programmed for a 5V output voltage, and VSHUTDOWN £ 0.6V (MIC29371-xx and MIC29372 only). Symbol Parameter Conditions Min Typical Max Units VO Output Voltage Variation from factory trimmed VOUT –1 1 % Accuracy –2 2 5mA £ IL £ 500mA –2.5 2.5 MIC2937A-12 and 29371-12 only: –1.5 1.5 –3 3 5mA £ IL £ 500mA –4 4 D VO Output Voltage (Note 2) 20 100 ppm/° C D T Temperature Coef. Output voltage > 10V 80 350 D VO Line Regulation VIN = VOUT + 1V to 26V 0.03 0.10 % VO 0.40 D VO Load Regulation IL = 5 to 500mA 0.04 0.16 % VO (Note 3) 0.30 VIN – VO Dropout Voltage IL = 5mA 80 150 mV (Note 4) 180 IL = 100mA 200 Output voltage > 10V 240 IL = 500mA 300 Output voltage > 10V 420 IL = 750mA 370 600 750 IGND Ground Pin Current IL = 5mA 160 250 m A (Note 5) 300 IL = 100mA 1 2.5 mA 3 IL = 500mA 8 13 16 IL = 750mA 15 25 IGNDDO Ground Pin VIN = 0.5V less than designed VOUT 200 500 m A Current at Dropout (VOUT ‡ 3.3V) (Note 5) IO = 5mA ILIMIT Current Limit VOUT = 0V 1.1 1.5 A (Note 6) 2 D VO Thermal Regulation (Note 7) 0.05 0.2 %/W D PD e n Output Noise CL = 10m F 400 m V RMS Voltage (10Hz to 100kHz) CL = 100m F 260 IL = 100mA MIC2937A/29371/29372 Micrel October 1999 21 MIC2937A/29371/29372 Electrical Characteristics (Continued) Parameter Conditions Min Typical Max Units Reference Voltage 1.223 1.235 1.247 V 1.210 1.260 V max Reference Voltage (Note 8) 1.204 1.266 V Adjust Pin 20 40 nA Bias Current 60 Reference Voltage (Note 7) 20 ppm/ ° C Temperature Coefficient Adjust Pin Bias 0.1 nA/° C Current Temperature Coefficient Error Comparator Output Leakage VOH = 26V 0.01 1.00 m A Current 2.00 Output Low VIN = 4.5V 150 250 mV Voltage IOL = 250 m A 400 Upper Threshold (Note 9) 40 60 mV Voltage 25 Lower Threshold (Note 9) 75 95 mV Voltage 140 Hysteresis (Note 9) 15 mV Shutdown Input Input Logic Voltage 1.3 V Low (ON) 0.7 High (OFF) 2.0 Shutdown Pin VSHUTDOWN = 2.4V 30 50 m A Input Current 100 VSHUTDOWN = 26V 450 600 m A 750 Regulator Output (Note 10) 3 10 m A Current in Shutdown 20 MIC29371 MIC29371/MIC29372 MIC29372 MIC2937A/29371/29372 Micrel MIC2937A/29371/29372 22 October 1999 Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its rated operating conditions. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ (MAX), the junction-to-ambient thermal resistance, q JA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P(MAX) = (TJ(MAX) – TA) / q JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. Note 2: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 3: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage due to heating effects are covered by the thermal regulation specification. Note 4: Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential. At low values of programmed output voltage, the minimum input supply voltage of 4.3V over temperature must be taken into account. The MIC2937A operates down to 2V of input at reduced output current at 25° C. Note 5: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current. Note 6: The MIC2937A family features fold-back current limiting. The short circuit (VOUT = 0V) current limit is less than the maximum current with normal output voltage. Note 7: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a 200mA load pulse at VIN = 20V (a 4W pulse) for T = 10ms. Note 8: VREF £ VOUT £ (VIN – 1 V), 4.3V £ VIN £ 26V, 5mA < IL £ 750 mA, TJ £ TJ MAX. Note 9: Comparator thresholds are expressed in terms of a voltage differential at the Adjust terminal below the nominal reference voltage measured at 6V input (for a 5V regulator). To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT /VREF = (R1 + R2)/R2. For example, at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output drops by 95 mV x 5V/1.235 V = 384 mV. Thresholds remain constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.7% guaranteed. Note 10: Circuit of Figure 3 with R1 ‡ 150kW . VSHUTDOWN ‡ 2V and VIN £ 26V,VOUT = 0. Note 11: 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. Note 12: Maximum positive supply voltage of 60V must be of limited duration (< 100ms) and duty cycle ( £ 1%). The maximum continuous supply voltage is 26V. FEEDBACK SENSE Q15A OUT Q24 Q26 R27 V TAP R28 R18 20kW Q25 Q23 Q22 R15 100 kW R16 30 kW Q29 Q28 R17 10 W R21 8 W R17 12 kW Q31Q30 R23 60 kW SHDN R24 50 kW R22 150 kW Q21 Q19 C2 40 pF R14 350 kW Q14 R13 100 kW Q18 R12 110 kW Q20 Q9 Q15B Q8 Q7 R11 20.6 kW Q5 R8 31.4 kW R10 150 kW R9 27.8 kW Q11 Q12Q13 R6 140 kW R5 180 kW R4 13 kW R3 50 kW Q2 C1 20 pF Q4Q3 R11 18 kW Q6 Q1 10 R1 20 kW R2 50 kW Q41 R30 30 kW Q40 Q34 GND Q36Q37 R25 2.8 kW Q38 ERROR R26 60 kW Q39 Q42 Q16 Q17 50 kW 10 kW IN DENOTES CONNECTION ON MIC2937A-xx AND MIC29371-xx VERSIONS ONLY Schematic Diagram MIC2937A/29371/29372 Micrel October 1999 23 MIC2937A/29371/29372 Typical Characteristics 0 100 200 300 400 500 0 200 400 600 800 D R O PO UT V O LT AG E (m V) OUTPUT CURRENT (mA) Dropout Voltage vs. Output Current 0 100 200 300 400 500 600 700 -60 -30 0 30 60 90 120 150 D R O PO UT V O LT AG E (m V) TEMPERATURE (° C) Dropout Voltage vs. Temperature ILOAD = 750mA 0 1 2 3 4 5 6 0 1 2 3 4 5 6 O UT PU T VO LT AG E (V ) INPUT VOLTAGE (V) Dropout Characteristics ILOAD = 5mA ILOAD = 750mA 0.1 1 10 30 1 10 100 1000 G RO UN D CU RR EN T (m A) OUTPUT CURRENT (mA) Ground Current vs. Output Current 0 50 100 150 200 0 1 2 3 4 5 6 7 8 G RO UN D CU RR EN T (mA ) SUPPLY VOLTAGE (V) Ground Current vs. Supply Voltage FIXED 5V VERSION ILOAD = 5mA 0 5 10 15 20 25 30 0 2 4 6 8 10 G RO UN D CU RR EN T (m A) INPUT VOLTAGE (V) Ground Current vs. Supply Voltage FIXED 5V ILOAD = 750mA 0.00 0.05 0.10 0.15 0.20 0.25 -60 -30 0 30 60 90 120 150 G RO UN D CU RR EN T (m A) TEMPERATURE ( ° C) Ground Current vs. Temperature ILOAD = 5mA 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 -60 -30 0 30 60 90 120 150 G RO UN D CU RR EN T (m A) TEMPERATURE ( ° C) Ground Current vs. Temperature ILOAD = 100mA 0 5 10 15 20 25 30 -60 -30 0 30 60 90 120 150 G RO UN D CU RR EN T (m A) TEMPERATURE (° C) Ground Current vs. Temperature ILOAD = 750mA 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 -60 -30 0 30 60 90 120 150 CU RR EN T (A ) TEMPERATURE (° C) Short Circuit and Maximum Current vs. Temperature VOUT = VNOMINAL – 0.5V VOUT = 0V FIXED 5V VERSION -100 0 100 200 300 400 500 -30 -20 -10 0 10 20 30 G RO UN D CU RR EN T (mA ) INPUT VOLTAGE (V) Ground Current vs. Input Voltage RLOAD = 100W 3.20 3.22 3.24 3.26 3.28 3.30 3.32 3.34 3.36 3.38 3.40 -60 -30 0 30 60 90 120 150 O UT PU T VO LT AG E (V ) TEMPERATURE (° C) Fixed 3.3V Output Voltage vs. Temperature MIC2937A/29371/29372 Micrel MIC2937A/29371/29372 24 October 1999 0 25 50 75 100 125 -60 -30 0 30 60 90 120 150 EN AB LE C UR RE NT (m A) TEMPERATURE (° C) MIC29371/2 Shutdown Current vs. Temperaure VEN = 5V VEN = 2V -300 -150 0 150 300 D O UT PU T (m V) -250 0 250 500 750 1000 -5 0 5 10 O UT PU T (m A) TIME (ms) Load Transient COUT = 10 m F 5mA -200 -100 0 100 200 D O UT PU T (m V) -250 0 250 500 750 1000 -5 0 5 10 O UT PU T (m A) TIME (ms) Load Transeint COUT = 100 m F 5mA 0 10 20 30 40 50 -60 -30 0 30 60 90 120 150 AD JU ST P IN C UR RE NT (n A) TEMPERATURE (° C) MIC29372/3 Adjust Pin Current vs. Temperature ILOAD = 1mA -40 -20 0 20 40 D O UT PU T (m V) 4 6 8 10 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 IN PU T (V ) TIME (ms) Line Transient COUT = 10 m F IL = 5mA -10 0 10 20 D O UT PU T (m V) 4 6 8 10 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 IN PU T (V ) TIME (ms) Line Transient COUT = 100 m F IL = 5mA 0.01 0.1 1 10 1x 10 0 10 x1 00 10 0x 10 0 1x 10 3 10 x1 03 10 0x 10 3 1x 10 6 O UT PU T IM PE DA NC E (W ) FREQUENCY (Hz) Output Impedance vs. Frequency ILOAD = 10mA MIC2937A/29371/29372 Micrel October 1999 25 MIC2937A/29371/29372 Applications Information External Capacitors A 10 m F (or greater) capacitor is required between the MIC2937A output and ground to prevent oscillations due to instability. Most types of tantalum or aluminum electrolytics will be adequate; film types will work, but are costly and therefore not recommended. Many aluminum electrolytics have electrolytes that freeze at about –30° C, so solid tantalums are recommended for operation below –25° C. The important parameters of the capacitor are an effective series resistance of about 5W or less and a resonant frequency above 500kHz. The value of this capacitor may be increased without limit. At lower values of output current, less output capacitance is required for output stability. The capacitor can be reduced to 0.5 m F for current below 10mA or 0.15m F for currents below 1 mA. Adjusting the MIC29372 to voltages below 5V runs the error amplifier at lower gains so that more output capacitance is needed. For the worst-case situation of a 750mA load at 1.23V output (Output shorted to Adjust) a 22 m F (or greater) capacitor should be used. The MIC2937A/29371 will remain in regulation with a minimum load of 5mA. When setting the output voltage of the MIC29372 version with external resistors, the current through these resistors may be included as a portion of the minimum load. A 0.1 m F capacitor should be placed from the input to ground if there is more than 10 inches of wire between the input and the AC filter capacitor or if a battery is used as the input. Error Detection Comparator Output (MIC29371) A logic low output will be produced by the comparator whenever the MIC29371 output falls out of regulation by more than approximately 5%. This figure is the comparator’s built-in offset of about 75mV divided by the 1.235V reference voltage. (Refer to the block diagram on Page 1). This trip level remains “5% below normal” regardless of the programmed output voltage of the MIC29371. For example, the error flag trip level is typically 4.75V for a 5V output or 11.4V for a 12V output. The out of regulation condition may be due either to low input voltage,extremely high input voltage, current limiting, or thermal limiting. Figure 1 is a timing diagram depicting the ERROR signal and the regulated output voltage as the MIC29371 input is ramped up and down. The ERROR signal becomes valid (low) at about 1.3V input. It goes high at about 5V input (the input voltage at which VOUT = 4.75). Since the MIC29371’s dropout voltage is load-dependent (see curve in Typical Performance Characteristics), the input voltage trip point (about 5V) will vary with the load current. The output voltage trip point (approximately 4.75V) does not vary with load. * SEE APPLICATIONS INFORMATION ** OUTPUT VOLTAGE INPUT VOLTAGE ERROR NOT VALID NOT VALID 5V 1.3V 4.75V Figure 1. ERROR Output Timing The error comparator has an NPN open-collector output which requires an external pull-up resistor. Depending on system requirements, this resistor may be returned to the 5V output or some other supply voltage. In determining a value for this resistor, note that while the output is rated to sink 250m A, this sink current adds to battery drain in a low battery condition. Suggested values range from 100k to 1MW . The resistor is not required if this output is unused. Programming the Output Voltage (MIC29372) The MIC29372 may programmed for any output voltage between its 1.235V reference and its 26V maximum rating. An external pair of resistors is required, as shown in Figure 3. The complete equation for the output voltage is VOUT = VREF x { 1 + R1/R2 } – |IFB| R1 where VREF is the nominal 1.235 reference voltage and IFB is the Adjust pin bias current, nominally 20nA. The minimum recommended load current of 1m A forces an upper limit of 1.2MW on the value of R2, if the regulator must work with no load (a condition often found in CMOS in standby), IFB will produce a –2% typical error in VOUT which may be eliminated at room temperature by trimming R1. For better accuracy, choosing R2 = 100k reduces this error to 0.17% while increasing the resistor program current to 12m A. Since the MIC29372 typically draws 100m A at no load with SHUTDOWN open- circuited, this is a negligible addition. Reducing Output Noise In reference applications it may be advantageous to reduce the AC noise present at the output. One method is to reduce the regulator bandwidth by increasing the size of the output capacitor. This is relatively inefficient, as increasing the capacitor from 1m F to 220 m F only decreases the noise from 430m V to 160 m VRMS for a 100kHz bandwidth at 5V output. Noise can be reduced by a factor of four with the adjustable MIC2937A/29371/29372 Micrel MIC2937A/29371/29372 26 October 1999 Automotive Applications The MIC2937A is ideally suited for automotive applications for a variety of reasons. It will operate over a wide range of input voltages with very low dropout voltages (40mV at light loads), and very low quiescent currents (100 m A typical). These features are necessary for use in battery powered systems, such as automobiles. It is a “bulletproof” device with the ability to survive both reverse battery (negative transients up to 20V below ground), and load dump (positive transients up to 60V) conditions. A wide operating temperature range with low temperature coefficients is yet another reason to use these versatile regulators in automotive designs. OUT GND +VIN *V » 5V OUTV V 10µF + IN VOUT = 5V Figure 2. MIC2937A-5.0 Fixed +5V Regulator Figure 3. MIC29372 Adjustable Regulator Typical Applications Figure 5. MIC29372 5.0V or 3.3V Selectable Regulator with Shutdown. Figure 4. MIC29372 Wide Input Voltage Range Current Limiter *MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV TO 400mV, DEPENDING ON LOAD CURRENT. SHUTDOWN PIN LOW= ENABLE OUTPUT. Q1 ON = 3.3V, Q1 OFF = 5.0V. SHUTDOWN V GND OUT +VIN ADJUST SHUTDOWN INPUT 100pF 2N2222 1% 300k W +5V to +7V 1% 180k W + 10µF 470 kW OFF ON 5V 3.3V 220k W 1% VCC OUT Input Output 0 3.3V 1 5.0V OUT GND ADJUST V VIN +VIN VOUT » VIN CBYPASS @ 1 2 R1 • 200 Hzp regulators with a bypass capacitor across R1, since it reduces the high frequency gain from 4 to unity. Pick or about 0.01 m F. When doing