MIC292A/292/2922/2924 MIC292A/292/2922/2924 4mA Low-Dropout Voltage Regulator General Description The MIC292A family are bulletproof efficient voltage regulators with very low drop out voltage (typically 4mV at light loads and 7mV at 25mA), and very low quiescent current (4µA typical). The quiescent current of the MIC292A increases only slightly in dropout, thus prolonging battery life. Key MIC292A features include protection against reversed battery, fold-back current limiting, and automotive load dump protection (6V positive transient). The MIC292 is available in several configurations. The MIC292A-xx devices are three pin fixed voltage regulators available in.v, 4.5V, 5V, and 2V outputs. The MIC292 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 MIC2922, which enables the regulator to be switched on and off. The eight-pin DIP and SOIC adjustable version, the MIC2924, includes both shutdown and error flag pins, and may be pin-strapped for 5V output, or programmed from.24 V to 26 V with the use of two external resistors. Pin Configuration Features High output voltage accuracy Guaranteed 4mA output Low quiescent current Low dropout voltage Extremely tight load and line regulation Very low temperature coefficient Current and thermal limiting Input can withstand 2V reverse battery and +6V positive transients Error flag warns of output dropout Logic-controlled electronic shutdown Output programmable from.24v to 26V (MIC2922/ MIC2924) Available in TO-22, TO-22-5, DIP, CerDIP, and Surface Mount TO-26-5, SOT-22, and SO- packages. Applications Battery Powered Equipment Cellular Telephones Laptop, Notebook, and Palmtop Computers PCMCIA V CC and V PP Regulation/Switching Bar Code Scanners Automotive Electronics SMPS Post-Regulator/ DC to DC Modules Voltage Reference High Efficiency Linear Power Supplies SENSE SHUTDOWN GROUND 2 4 7 6 5 SO/DIP Packages (MIC2924BJ/M/N) FEEDBACK 5V TAP 2 IN GND OUT MIC292A-xxBS Five Lead Package Pin Functions: MIC292 MIC2922 ) Error Adjust 2) Input Shutdown ) Ground Ground 4) Output Input 5) Shutdown Output 2 4 5 TO-26-5 Package (MIC292/2922BU) 2 GROUND Front View TO-22 Package (MIC292A-xxBT) 2 4 5 TO-22-5 Package (MIC292/2922BT) The TAB is Ground on the SOT-22, TO-22, and TO-26 packages. 997-9
MIC292A/292/2922/2924 Ordering Information Part Number Voltage Temperature Range* Package MIC292A-.BS. 4 C to +25 C SOT-22 MIC292A-.BT. 4 C to +25 C TO-22 MIC292A-4.BS 4.5 4 C to +25 C SOT-22 MIC292A-4.BT 4.5 4 C to +25 C TO-22 MIC292A-5.BS 5. 4 C to +25 C SOT-22 MIC292A-5.BT 5. 4 C to +25 C TO-22 MIC292A-2BS 2 4 C to +25 C SOT-22 MIC292A-2BT 2 4 C to +25 C TO-22 MIC292-.BT. 4 C to +25 C TO-22-5 MIC292-.BU. 4 C to +25 C TO-26-5 MIC292-4.BT 4.5 4 C to +25 C TO-22-5 MIC292-4.BU 4.5 4 C to +25 C TO-26-5 MIC292-5.BT 5. 4 C to +25 C TO-22-5 MIC292-5.BU 5. 4 C to +25 C TO-26-5 MIC292-2BT 2 4 C to +25 C TO-22-5 MIC292-2BU 2 4 C to +25 C TO-26-5 MIC2922BT Adj 4 C to +25 C TO-22-5 MIC2922BU Adj 4 C to +25 C TO-26-5 MIC2924BM 5 and Adj 4 C to +25 C SO- MIC2924BN 5 and Adj 4 C to +25 C -pin PDIP Absolute Maximum Ratings If Military/Aerospace specified devices are required, contact your local representative/distributor for availability and specifications. Power Dissipation (Note )... Internally Limited Lead Temperature (Soldering, 5 seconds)... 26 C Storage Temperature Range... 65 C to +5 C Operating Junction Temperature Range... 4 C to +25 C Thermal Characteristics: SOT 22 θ JC... 5 C/W TO-22 θ JC... C/W TO-26 θ JC... C/W -Pin CerDIP θ JA... C/W -Pin Plastic DIP θ JA... 5 C/W -Pin SOIC θ JA... See Note Input Supply Voltage... 2V to +6V Operating Input Supply Voltage... 2V to 26V Adjust Input Voltage (Notes 9 and )....5V to +26V Shutdown Input Voltage....V to +V Error Comparator Output Voltage....V to +V Across the full operating temperature, the minimum input voltage range for full output current is 4.V 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 - 997
MIC292A/292/2922/2924 Electrical Characteristics Limits in standard typeface are for T J = 25 C and limits in boldface apply over the full operating temperature range. Unless otherwise specified, V IN = V OUT + V, = ma, C L = µf. Adjustable version are set for an output of 5V. The MIC2922 V SHUTDOWN.7V. The eight pin MIC2924 is configured with the Adjust pin tied to the 5V Tap, the Output is tied to Output Sense (V OUT = 5V), and V SHUTDOWN.7V. Symbol Parameter Conditions Min Typical Max Units V O Output Voltage Variation from factory trimmed V OUT % Accuracy 2 2 ma 4mA, across temp. range 2.5 2.5 MIC292A-2 and 292-2 only.5.5 ma 4mA, across temp. range 4 4 V O Output Voltage (Note 2) 2 ppm/ C T Temperature Coef. V OUT > V only 5 V O Line Regulation V IN = V OUT + V to 26V.. % V O.4 V O Load Regulation = to 25mA (Note ).4.6 % V O. V IN V O Dropout Voltage = ma 5 mv (Note 4) = ma 25 V OUT > V only 5 = 25mA 7 V OUT > V only 5 = 4mA 45 6 75 I GND Ground Pin Current = ma 4 2 µa (Note 5) = ma. 2 ma 2.5 = 25mA 5 9 2 = 4mA 5 I GNDDO Ground Pin V IN =.5V less than designed V OUT 4 µa Current at Dropout (V OUT.V) (Note 5) I O = ma IMIT Current Limit V OUT = V 425 ma (Note 6) 2 V O Thermal Regulation (Note 7).5.2 %/W P D e n Output Noise C L = µf 4 µv RMS Voltage (Hz to khz) C L = µf 26 = ma 997 -
MIC292A/292/2922/2924 Electrical Characteristics (Continued) MIC2922, MIC2924 Parameter Conditions Min Typ Max Units Reference Voltage MIC2922.22.25.247 V.2.26 Reference Voltage MIC2922 (Note ).24.266 V Reference Voltage MIC2924.2.25.26 V.2.27 Reference Voltage MIC2924 (Note ).5.25 V Adjust Pin 2 4 na Bias Current 6 Reference Voltage (Note 7) 2 ppm/ C Temperature Coefficient Adjust Pin Bias. na/ C Current Temperature Coefficient Error Comparator MIC292, MIC2924 Output Leakage V OH = 26V.. µa Current 2. Output Low V IN = 4.5V 5 25 mv Voltage I OL = 25µA 4 Upper Threshold (Note 9) 4 6 mv Voltage 25 Lower Threshold (Note 9) 75 95 mv Voltage 4 Hysteresis (Note 9) 5 mv Shutdown Input MIC292, MIC2922, MIC2924 Input Logic Voltage. V Low (ON).7 High (OFF) 2. Shutdown Pin V SHUTDOWN = 2.4V 5 µa Input Current V SHUTDOWN = 26V 45 6 µa 75 Regulator Output (Note ) µa Current in Shutdown 2-2 997
MIC292A/292/2922/2924 General Note: Devices are ESD protected; however, handling precautions are recommended. Note : 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, T J (MAX), the junction-to-ambient thermal resistance, θ JA, and the ambient temperature, T A. The maximum allowable power dissipation at any ambient temperature is calculated using: P (MAX) = (T J(MAX) T A ) / θ Exceeding the maximum allowable JA. power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The junction to ambient thermal resistance of the MIC2924BM is 6 C/W mounted on a PC board. Note 2: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note : 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 mv below its nominal value measured at V differential. At low values of programmed output voltage, the minimum input supply voltage of 4.V over temperature must be taken into account. The MIC292A 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 supply is the sum of the load current plus the ground pin current. Note 6: The MIC292A features fold-back current limiting. The short circuit (V OUT = V) 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 2mA load pulse at V IN = 2V (a 4W pulse) for T = ms. Note : V REF V OUT (V IN V), 4.V V IN 26V, ma < 4 ma, T J T J 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. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = V OUT /V REF = (R + 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/.25 V = 4 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 : V SHUTDOWN 2V, V IN 26V,V OUT =, with Adjust pin tied to 5V Tap or to the R, R2 junction (see Figure ) with R 5. Note : 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 2: Maximum positive supply voltage of 6V must be of limited duration (< ms) and duty cycle ( %). The maximum continuous supply voltage is 26V. Schematic Diagram IN FEEDBACK Q5A Q9 Q5B Q25 R 2 Q26 Q24 OUT Q6 Q Q R C 2 pf Q4 Q5 R 2.6 Q2 Q7 Q Q6 Q7 Q4 R7 2 SENSE R27 V TAP R2 Q42 Q4 R R 2 R2 5 Q4 R 5 R5 Q R6 4 R4 Q2 R.4 R9 27. Q R 5 Q2 R2 R Q C2 4 pf R4 5 Q9 Q2 Q29 Q2 Q22 R5 R6 R7 Ω Q2 R2 Ω 5 Q7 Q6 R22 5 Q Q R24 5 R2 6 SHDN Q Q4 R26 6 R25 2. DENOTES CONNECTION ON MIC292A-xx AND MIC292-xx VERSIONS ONLY Q9 GND 997 -
MIC292A/292/2922/2924 Typical Characteristics 5 Dropout Voltage vs. Output Current 7 Dropout Voltage 6 Dropout Characteristics DROPOUT VOLTAGE (mv) 4 2 2 4 CURRENT (ma) DROPOUT VOLTAGE (mv) 6 5 4 OAD = 4mA 2-6 - 6 9 2 5 VOLTAGE (V) 5 4 OAD = ma 2 OAD = 4mA 2 4 5 6 VOLTAGE (V) 2 vs. Output Current 2 vs. Supply Voltage vs. Supply Voltage GROUND CURRENT (µa) 5 5 V OUT = 5V I OUT = ma 25 2 5 5 V OUT = 5V I OUT = 4mA. 4 CURRENT (ma) 2 4 5 6 7 SUPPLY VOLTAGE (V) 2 4 6 VOLTAGE (V).2 25.5..5 I OUT = ma 2 OAD = ma 2 5 5 OAD = 4mA. -6-6 9 2 5-6 - 6 9 2 5-6 - 6 9 2 5 VOLTAGE (V) Fixed.V Output Voltage.4..6.4.2..2.26.24.22.2-6 - 6 9 2 5 CURRENT (ma) 7 65 6 55 5 45 4 5 Short Circuit and Maximum Current V OUT = V NOMINAL.5V SAMPLES (HI/AVG/LO) V OUT =.V V OUT = V -6-6 9 2 5 GROUND CURRENT (µa) 9 7 6 5 4 2 - vs. Supply Voltage R LOAD = Ω - -2-2 VOLTAGE (V) -4 997
MIC292A/292/2922/2924 ENABLE CURRENT (µa) MIC292/2 Shutdown Current vs. Temperaure 25 V EN = 5V 75 5 V EN = 2V 25-6 - 6 9 2 5 (mv) (ma) Load Transient 2 C OUT = µf - -2 6 4 2 ma -2-5 5 5 2 25 TIME (ms) (mv) (ma) Load Transient C 5 OUT = µf -5-6 4 2 ma -2-5 5 5 2 25 TIME (ms) ADJUST PIN CURRENT (na) 5 4 2 MIC2922 Adjust Pin Current OAD = ma (mv) (V) 4 2-2 -4 6 Line Transient C OUT = µf = ma (mv) (V) 2 - -2 6 Line Transient C OUT = µf = ma -6-6 9 2 5 4 -.2..2.4.6...2.4 TIME (ms) 4 -.2..2.4.6...2.4 TIME (ms) IMPEDANCE (Ω). Output Impedance vs. Frequency OAD = ma. k k k M FREQUENCY (Hz) x x x x x x x 6 REJECTION (db) -2-4 -6 - Ripple Rejection C L = µf = ma ma - E+ E+2 E+ k E+4 k E+5 k E+6 M FREQUENCY (Hz) 997-5
MIC292A/292/2922/2924 Applications Information External Capacitors A µf (or greater) capacitor is required between the MIC292A 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 C, so solid tantalums are recommended for operation below 25 C. The important parameters of the capacitor are an effective series resistance of about 5Ω or less and a resonant frequency above 5kHz. 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 2.2µF for current below ma or µf for currents below ma. Adjusting the MIC2922/2924 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 5mA load at.2v output (Output shorted to Adjust) a 47µF (or greater) capacitor should be used. The MIC292A/292 will remain in regulation with a minimum load of ma. When setting the output voltage of the MIC2922/ 2924 versions with external resistors, the current through these resistors may be included as a portion of the minimum load. A.µF capacitor should be placed from the MIC292A input to ground if there is more than inches of wire between the input and the AC filter capacitor or if a battery is used as the input. Error Detection Comparator Output (MIC292/ MIC2924) A logic low output will be produced by the comparator whenever the MIC292/2924 output falls out of regulation by more than approximately 5%. This figure is the comparator s builtin offset of about 75mV divided by the.25v reference voltage. (Refer to the block diagram on Page ). This trip level remains 5% below normal regardless of the programmed output voltage of the MIC292/2924. For example, the error flag trip level is typically 4.75V for a 5V output or.4v for a 2V output. The out of regulation condition may be due either to low input voltage, extremely high input voltage, current limiting, or thermal limiting. Figure is a timing diagram depicting the signal and the regulated output voltage as the MIC292/2924 input is ramped up and down. The signal becomes valid (low) at about.v input. It goes high at about 5V input (the input voltage at which V OUT = 4.75). Since the MIC292/2924 s dropout voltage is load-dependent (see curve in Typical Performance Characteristics), the input voltage trip point VOLTAGE VOLTAGE VALID NOT 4.75V 5V.V NOT VALID (about 5V) will vary with the load current. The output voltage trip point (approximately 4.75V) does not vary with load. 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 25µA, this sink current adds to battery drain in a low battery condition. Suggested values range from k to MΩ. The resistor is not required if this output is unused. Programming the Output Voltage (MIC2922/2924) The MIC2922/2924 may be programmed for any output voltage between its.25v reference and its 26V maximum rating, using an external pair of resistors, as shown in Figure. The complete equation for the output voltage is V OUT = V REF x { + R /R 2 } I FB R where V REF is the nominal.25 reference voltage and I FB is the Adjust pin bias current, nominally 2nA. The minimum recommended load current of µa forces an upper limit of.2mω on the value of R 2, if the regulator must work with no load (a condition often found in CMOS in standby), I FB will produce a 2% typical error in V OUT which may be eliminated at room temperature by trimming R. For better accuracy, choosing R 2 = k reduces this error to.7% while increasing the resistor program current to 2 µa. Since the MIC2922/2924 typically draws µa at no load with SHUTDOWN open-circuited, this is a negligible addition. The MIC2924 may be pin-strapped for 5V using the internal voltage divider by tying Pin (output) to Pin 2 (sense) and Pin 7 (Adjust) to Pin 6 (V Tap). 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 * * * SEE APPLICATIONS INFORMATION Figure. Output Timing -6 997
MIC292A/292/2922/2924 capacitor. This is relatively inefficient, as increasing the capacitor from µf to 22 µf only decreases the noise from 4µV to 6µV RMS for a khz bandwidth at 5V output. Noise can be reduced fourfold by a bypass capacitor across R, since it reduces the high frequency gain from 4 to unity. Pick C BYPASS 2πR 2 Hz or about. µf. When doing this, the output capacitor must be increased to µf to maintain stability. These changes reduce the output noise from 4 µv to µv rms for a khz bandwidth at 5V output. With the bypass capacitor added, noise no longer scales with output voltage so that improvements are more dramatic at higher output voltages. Automotive Applications The MIC292A 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 (4mV at light loads), and very low quiescent currents (µa 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 2V below ground), and load dump (positive transients up to 6V) conditions. A wide operating temperature range with low temperature coefficients is yet another reason to use these versatile regulators in automotive designs. Typical Applications V IN +V IN *V OUT 5V V OUT V OUT = 5V +V IN VIN 5 V OUT VOUT.2 26V GND + µf SHUTDOWN SHUTDOWN OFF GND ADJUST ON 4 7.2V R pf µf 7 25 V OUT = V REF x ( + R ) R2 V REF R2 NOTE: PINS 2 AND 6 ARE LEFT OPEN Figure 2. MIC292A-5. Fixed +5V Regulator Figure. MIC2922/2924 Adjustable Regulator. Pinout is for MIC2924. 5.V +V IN 5 VOUT MIC295 SHUTDOWN SD OFF GND ADJUST FB ON 4 +V IN 7 *VOUT V IN SHUTDOWN LOW = ON HIGH = OFF HIGH = 5V OUT SHUT- DOWN +V IN VOUT GND ADJUST 4 7 47 pf 22 % % % + VCC OUT µf LOW =.V OUT 2N2222 *MINIMUM - VOLTAGE RANGES FROM 4mV TO 4mV, DEPENDING ON LOAD CURRENT. PIN LOW= ENABLE. Q ON =.V, Q OFF = 5.V. Figure 4. MIC2924 Wide Input Voltage Range Current Limiter Figure 5. MIC2922/2924 5.V or.v Selectable Regulator with Shutdown. Pinout is for MIC2924. 997-7