AS ma Low Drop Out Voltage Regulator

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ma Low Drop Out oltage Regulator FEATURES Output Accuracy, 3.

1 ma Low Drop Out oltage Regulator FEATURES Output Accuracy, ma Output ery Low Quiescent Current Low Dropout oltage Extremely Tight Load And Line Regulation ery Low Temperature Coefficient Current & Thermal Limiting Improved Replacement With Hight I OUT For LP94 Sockets ersion Over LP94 Error Flag Warns Of Output Dropout Logic-Controlled Electronic Shutdown Output Programmable From.4 to 9 Input Can Withstand -0 Reverse Battery & Positive Transient APPLICATIONS Battery Powered Systems Cordless Telephones Radio Control Systems Portable/Palm Top/Notebook Computers Portable Consumer Equipment Portable Instrumentation Automotive Electronics SMPS Post-Regulator oltage Reference Avionics PRODUCT DESCRIPTION The is a low power voltage regulator. This device is an excellent choice for use in battery-powered applications such as cordless telephones, radio control systems, and portable computers. The features very low quiescent current (7µA Typ.) and very low dropout voltage. This includes a tight initial tolerance of ± 0.% max and ± % max., and very low output temperature coefficient, making the useful as a low-power voltage reference. The key features include protection against reversed battery, fold-back current limiting, and automotive load dump protection ( positive transient). The error flag output feature is used as power-on reset for warning of a low output voltage, due to falling voltage input of batteries. Another feature is the logic compatible shutdown input which enables the regulator to be switched on and off. The is offered in a 3-pin TO-9and TO-3 package compatible with other volt regulators, in -Pin plastic, SO-, (same pin out as AS9), TO- 0 and TO-3. The regulator output voltage (of the -pin) may be pin-strapped for a and 3.3 or programmed from.4 to 9 with an external pair of resistors. Look for AS9 for ma and LP9 for ma applications. PIN CONNECTIONS TO-3-3 Package TO-3- Package -Pin Surface Mount (S) SOT-3 Package TO-0-3 Package TO-0- Package ADJ IN ) ) 3) 4) ) SENSE Top iew TO-9 (N) FEEDBACK, 3.3 TAP 3 IN OUT Front iew ) ) 3) 4) ) Top iew Top iew 3 3 IN 3 4 Front iew Front iew Bottom iew

2 ORDERING INFORMATION TO-3 TO-3 TO-9 TO-0 TO-0 PLASTIC SOIC SOT-3 OPER.TEMP. 3-PIN -PIN 3 PIN 3 PIN PIN PIN 3 PIN RANGE YT3-X YT-X YN-X YU3-X YU-X YS-X YM3-X -40 C to C X= : (3.3 for 3.3,.0 for.0) Y= Output Tolerance (A = 0.%, Blank = %; B = %) ABSOLUTE MAXIMUM RATINGS Power Dissipation...Internally Limited Input Supply oltage...-0 to Lead Temp. (Soldering, Seconds)... C Feedback Input oltage...-. to 30 Storage Temperature Range... - to C Shutdown Input oltage to 30 Operating Junction Temperature Range (Note 9) Error Comparator Output to C to C ESD Rating...K Min ELECTRICAL CHARACTERISTICS at S =±, T A = C, unless otherwise noted. Boldface applies over the full operating temperature range. 3.3 ersion ersion All oltage Options Parameter Conditions Typical A T J = C - C T J C -40 C T J C ma I L ma T J T JMAX T J = C - C T J C -40 C T J C ma I L ma T J T JMAX B ppm/ C Temperature Coefficient (Note ) Line Regulation (Note 3) IN 30 (Note 4) %max Load Regulation (Note 3) I L = to ma %max I L = 0. to ma Dropout oltage (Note ) I L = ma m I L = 0mA I L = ma I L = ma Ground Current I L = ma I L = 0mA I L = ma I L = ma Current Limit = 0 0 Thermal Regulation %/w Output Noise, 0Hz to khz I L = ma C L =.µf C L = 33 µf µ rms -Pin ersions only Typical A B Reference oltage Reference oltage Over Temperature (Note ) Feedback Pin Bias Current 0 40 Reference oltage Temperature Coefficient (Note 7) 0 Feedback Pin Bias Current Temperature Coefficient Units µa ma ma na ppm/ C na/ C

3 (Continued) Parameter Conditions (Note ) Typical A B Units Applies for YT-X, YU-X and YS-X Error Comparator Output Leakage Current OH = Output Low oltage IN = 4. I OL = µa Upper Threshold oltage (Note ) m Lower Threshold oltage (Note ) m Hysteresis (Note ) m µa m Shutdown Input SD Output Turn-On Threshold oltage Hysteresis(HYST) m Input Bias Current(I B ) IN(SD) = 0 to 0 Note : Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range. Note : Unless otherwise specified all limits are guaranteed for T J = C, IN =, I L = µa and C L = µf. Additional conditions for the -pin versions are feedback tied to tap and output tied to output sense ( = ) and 0.. Note 3: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are covered under the specification for thermal regulation. Note 4: Line regulation for the is tested at C for I L = ma. For I L = µa and T J = C, line regulation is guaranteed by design to 0.%. See typical performance characteristics for line regulation versus temperature and load current. Note : Dropout voltage is defined as the input to output differential at which the output voltage drops m below its nominal value measured at differential at very low values of programmed output voltage, the minimum input supply voltage of (.3 over temperature) must be taken into account. Note : REF ( IN - ),.3 IN 30, µa I L ma, T J T JMAX. Note 7: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = / REF = (R R )/R. For example, at a programmed output voltage of, the output is guaranteed to go low when the output drops by 9 m x /.3 = 34 m. Thresholds remain constant as a percent of as is varied, with the dropout warning occurring at typically % below nominal, 7.% guaranteed. Note :, IN 30, =0, feedback pin tied to Tap. Note 9: The junction -to-ambient thermal resistance of the TO-9 package is 0 C/ W with 0.4 leads and C/ W with 0. leads to a PC board. The thermal resistance of the -Pin DIP package is 0 C/W junction-to-ambient when soldered directly to a PC board. Junction-to-ambient thermal resistance for the SOIC (S) package is C/W. na UNREGULATED DC O 7 ma MAX SENSE FROM CMOS OR TTL 3 m.3 REFERENCE AMPLIFIER COMPARATOR 0kΩ.. k Ω.. TAP 4 GROUND µ F.. 330kΩ.. TO CMOS OR TTL Block Diagram

4 APPLICATION HINTS EXTERNAL CAPACITORS For the stability of the requires a.µf or greater capacitor between output and ground. Oscillation could occur without this capacitor. Most types of tantalum or aluminum electrolytic works fine here. For operations of below - C solid tantalum is recommended since the many aluminum types have electrolytes the freeze at about C. The ESR of about Ω or less and resonant frequency above 00kHz are the most important parameters in the value of the capacitor. The capacitor value can be increased without limit. At lower values of output current, less output capacitance is required for stability. For the currents below 0mA the value of the capacitor can be reduced to 0.µF and 0.µF for ma. More output capacitance needed for the -pin version at voltages below since it runs the error amplifier at lower gain. At worst case µf or greater must be used for the condition of ma load at.3 output. The, unlike other low dropout regulators will remain stable and in regulation with no load in addition to the internal voltage divider. This feature is especially important in application like CMOS RAM keep-alive. When setting the output voltage of the, a minimum load of µa is recommended If there is more than 0 inches of wire between the input and the AC filter capacitor or if a battery is used as the input then a µa tantalum or aluminum electrolytic capacitor should be placed from the input to the ground. Instability can occur if there is stray capacitance to the feedback terminal (pin 7). This could cause more problems when using a higher value of external resistors to set the output voltage. This problem can be fixed by adding a pf capacitor between output and feedback and increasing the output capacitor to at least 3.3µF. DETECTION COMPARATOR The Comparator produces a logic low output whenever the output falls out of regulation by more than around %. This is around m offset divided by the.3 reference voltage. This trip level remains % below normal regardless of the programmed output voltage of the regulator. Figure shows the timing diagram depicting the signal and the regulator output voltage as the input is ramped up and down. The signal becomes low at around.3 input, and goes high around input (input voltage at which = 4.7. Since the s dropout voltage is load dependent, the input voltage trip point (around ) will vary with the load current. The output voltage trip point (approx. 4.7) does not vary with load. The error comparator has an open-collector output, which requires an external pull-up resistor. Depending on the system requirements the resistor may be returned to output or other supply voltage. In determining the value of this resistor, note that the output is rated to sink µa, this value adds to battery drain in a low battery condition. Suggested values range from K to MΩ. If the output is unused this resistor is not required. PROGRAMMING THE OLTAGE OF The may be pin-strapped for using its internal voltage divider by tying Pin (output) to Pin (sense) and Pin 7 (feedback) to Pin ( Tap). IN OLTAGE * 4.7 OLTAGE.3.0 K 3 SD IN 4 7 FB.3 REF. to 30 R 3.3uF.0uF R * See Application Info. Figure. Output Timing Figure. Adjustable Regulator

5 Also, it may be programmed for any output voltage between its.3 reference and its 30 maximum rating. As seen in Figure, an external pair of resistors is required. Refer to the below equation for the programming of the output voltage: = REF ( R \ R ) I FB R The REF is.3 and I FB is the feedback bias current, nominally -0nA. The minimum recommended load current of µa forces an upper limit of. MΩ on value of R. If no load is presented the I FB produces an error of typically % in, which may be eliminated at room temperature by trimming R. To improve the accuracy choose the value of R = k this reduces the error by 0.7% and increases the resistor program current by µa. Since the LP9 typically draws µa at no load with Pin opencircuited this is a small price to pay REDUCING NOISE It may be an advantage to reduce the AC noise present at the output. One way is to reduce the regulator bandwidth by increasing the size of the output capacitor. This is the only way that noise can be reduced on the 3 lead but is relatively inefficient, as increasing the capacitor from µf to 0µF only decreases the noise from 430µ to µ rms for a khz bandwidth at output. Noise could also be reduced fourfold by a bypass capacitor across R, since it reduces the high frequency gain from 4 to unity. Pick C BYPASS / πr 00 Hz or choose 0.0µF. When doing this, the output capacitor must be increased to 3.3µF to maintain stability. These changes reduce the output noise from 430µ to µ RMS for a khz bandwidth at output. With the bypass capacitor added, noise no longer scales with output voltage so that improvements are more dramatic at higher output voltages. HEATSINK REQUIREMENTS Depending on the maximum ambient temperature and maximum power dissipation a heatsink may be required with the. The junction temperature range has to be within the range specified under Absolute Maximum Ratings under all possible operating conditions. To find out if a heatsink is required, the maximum power dissipation of the device needs to be calculated. This is the maximum specific AC voltage that must be taken into consideration at input. Figure 3 shows the condition and power dissipation which should be calculated with the following formula: IN I IN IN OUT I L P TOTAL = ( IN - ) I L ( IN )I G Next step is to calculate the temperature rise T R ( MAX ). T J ( MAX ) maximum allowable junction temperature, T A ( MAX ) maximum ambient temperature :. uf LOAD T R ( MAX ) = T J ( MAX ) - T A ( MAX ) Junction to ambient thermal resistance θ (j-a) can be calculated after determining of P TOTAL & T R ( MAX ): I IN = I L I G I G Figure 3. Regulator Circuit θ (J-A) = T R (max)/p (MAX) If the θ (J-A) is C/W or higher, the device could be operated without a heatsink. If the value is below C/W then the heatsink is required and the thermal resistance of the heatsink can be calculated by the following formula, θ (J-C) junction to case, case to heatsink, θ (H-A) heatsink to ambient: θ (C-H) θ (J-A) = θ (J-C) θ (C-H) θ (H-A)

6 TYPICAL APPLICATIONS IN IN * = IN 3 SD FB 4 7 *MINIMUM - OLTAGE RANGES FROM 4m TO m. DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY ma Wide Input oltage Range Current Limited IN IN * = 4 0uF FIXED REGULATOR

Advanced Monolithic Systems

Advanced Monolithic Systems FEATURES.,.,. and. ersions High Accuracy Output oltage Extremely Low Quiescent Current Low Dropout oltage Extremely Tight Load and Line Regulation ery Low Temperature Coefficient