FEATURES DESCRIPTIO APPLICATIO S. LT1120 Micropower Regulator with Comparator and Shutdown TYPICAL APPLICATIO

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1 LT Micropower Regulator with Comparator and Shutdown FEATRES μa Supply Current ma Output Current.V Reference Voltage Reference Output Sources ma and Sinks ma Open Collector Comparator Sinks ma Logic Shutdown.V Dropout Voltage Thermal Limiting Available in 8-Lead DIP and SO Packages APPLICATIO S Battery Systems Battery-Backup System Portable Terminals Portable Instruments Memory Keep-Alive DESCRIPTIO The LT is a combination micropower positive regulator and free collector comparator on a single monolithic chip. With only μa supply current, the LT can supply over ma of output current. Input voltage range is from.v to 3V and dropout voltage is.v at ma. Dropout voltage decreases with lower load currents. Also included on the chip is a class B output.v reference that can either source or sink current. A shutdown pin allows logic shutdown of the output. The comparator can be used for system or battery monitoring. For example, the comparator can be used to warn of low system voltage. Frequency compensation of the comparator for amplifier applications can be obtained by adding external output capacitance. The.V reference will source or sink current. This allows it to be used as a supply splitter or auxiliary output., LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATIO. Dropout Voltage and Supply Current V Regulator >.V I Q = μa μf SHDN 3 LT.μF M M V μf DROPOT VOLTAGE (V). SPPLY CRRENT (ma) SHTDOWN TA... OTPT CRRENT (ma) TA fd

2 LT ABSOLTE AXI RATI GS W W W Input Voltage... 3V NPN Collector Voltage... 3V Output Short-Circuit Duration... Indefinite Power Dissipation... Internally Limited (Note ) Operating Temperature Range LTC... C to C LTI... to C Storage Temperature Range... C to C W PACKAGE/ORDER I FOR ATIO SHDN 3 TOP VIEW 8 INPT COMPOT N8 PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC SO T JMAX = C, θ JA = 3 C/W (N) T JMAX = C, θ JA = C/W (S) J8 PACKAGE 8-LEAD CERDIP T JMAX = C, θ JA = C/W (J) ORDER PART NMBER LTCN8 LTCS8 LTIN8 LTIS8 S8 PART MARKING I ORDER PART NMBER Consult LTC Marketing for parts specified with wider operating temperature ranges. LTCJ8 OBSOLETE PACKAGES Consider the N8 and S8 Packages for Alternate Source TOP VIEW INPT 8 COMPOT SHDN 3 H PACKAGE 8-LEAD TO- METAL CAN T JMAX = C, θ JA = C/W, θ JC = C/W ORDER PART NMBER LTCH ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. T j = C. PARAMETER CONDITIONS MIN TYP MAX NITS Reference Reference Voltage.V 3V... V Line Regulation.V 3V.. %/V Load Regulation ma I ma, = V.3. % Output Source Current = V ma Output Sink Current = V ma Temperature Stability % Regulator Supply Current = V, I OT μa 8 μa = 3V, I OT μa μa = V, I OT = ma ma Output Current ( ) V, V ma Load Regulation ( ) V, V.. % Line Regulation V 3V.. %/V Dropout Voltage I OT = μa.. V I OT = ma.. V fd

3 LT ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. T j = C. PARAMETER CONDITIONS MIN TYP MAX NITS Feedback Sense Voltage = V... V Shutdown Pin Voltage Normal. V.V Shutdown.. V Shutdown Pin Current =.V μa Feedback Bias Current na Minimum Load Current = 3V μa Short-Circuit Current = 3V 3 ma Comparator Offset Voltage = 3V 3 mv Bias Current = 3V (Note ) na Gain Δ = 9V, R L = k V/V Power Supply Rejection.V V S 3V 8 9 db Output Sink Current =.V 8 ma Saturation Voltage I OT = ma.. V Input Voltage Range V Response Time μs Leakage Current μa The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. PARAMETER CONDITIONS MIN TYP MAX NITS Reference Reference Voltage.V 3V... V Line Regulation.V 3V.. %/V Load Regulation ma I ma, = V..8 % Output Source Current = V ma Output Sink Current = V ma Regulator Supply Current = V, I OT μa 9 μa = 3V, I OT μa 8 μa = V, I OT = ma ma Output Current ( ) V, V ma Load Regulation ( ) V, V % Line Regulation V 3V. %/V Dropout Voltage I OT = μa. V I OT = ma.8 V Feedback Sense Voltage = V.38.. V Feedback Bias Current na Minimum Load Current = 3V μa Short-Circuit Current = 3V 3 ma fd 3

4 LT ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. PARAMETER CONDITIONS MIN TYP MAX NITS Comparator Offset Voltage mv Bias Current = 3V (Note ) na Gain Δ = 9V, R L = k V/V Output Sink Current =.V (Note 3) ma Leakage Current = 3V 8 μa Note : Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note : T A > 8 C, I bias maximum is na. Note 3: For T A C output current sink drops to.ma. TYPICAL PERFOR A CE CHARACTERISTICS OTPT VOLTAGE CHANGE (%).3... W Regulator Load Regulation Supply Current Regulator Short-Circuit Current T J = C T J = C T J = C. PRELOAD = μa.3. OTPT CRRENT (ma) G SPPLY CRRENT (ma). T J = C TO C.. REGLATOR OTPT CRRENT (ma) G SHORT-CIRCIT CRRENT (ma) 3 3 CRRENT LIMIT TIED TO GROND 3 TEMPERATRE ( C) G3 REGLATOR INPT-OTPT DIFFERENTIAL (V). Dropout Voltage Δ = mv.. REGLATOR OTPT CRRENT (ma) MINIMM LOAD CRRENT (μa) Regulator Minimum Load Current TEMPERATRE ( C) RIPPLE REJECTION (db) 3 Regulator Ripple Rejection I OT = ma I OT = ma = VDC, V P P = V C OT = μf I OT = ma 3 k k k RIPPLE FREQENCY (Hz) G G G fd

5 LT TYPICAL PERFOR A CE CHARACTERISTICS W Supply Current I OT = ma Supply Current at Dropout T J = C TO C I OT = ma SPPLY CRRENT (ma). I OT = ma I OT = ma = V T J = C TO C. REGLATOR INPT-OTPT DIFFERENTIAL (V) G SPPLY CRRENT (ma) I OT = ma. I OT = ma REGLATOR INPT-OTPT DIFFERENTIAL (V) G8 Reference Regulation Feedback Pin Current ERENCE VOLTAGE CHANGE (mv) 3 3 FEEDBACK CRRENT (na) 3 3 T J = C T J = C T J = C ERENCE OTPT CRRENT (ma) G9. REGLATOR OTPT CRRENT (ma) G OTPT VOLTAGE CHANGE (%) OTPT CRRENT (ma).. Regulator Thermal Regulation = V = V 8 8 TIME (ms) G OTPT VOLTAGE (V) LT Turn-On Characteristic = V NO LOAD R L = Ω R L = Ω 3 8 INPT VOLTAGE (V) G3 fd

6 LT PI F CTIO S (Pin ): Ground. (Pin ): Feedback. This is the feedback point of the regulator. When operating, it is nominally at.v. Optimum source resistance is k to k. The feedback pin should not be driven below ground or more positive than V. SHDN (Pin 3): Shutdown. A logic shuts off the main regulator. Caution: noise or leakage into the shutdown pin can affect output voltage. (Pin ): Regulator Output. Main output, requires a μf output capacitor. Can be shorted to or ground without damaging the device. (Pin ): Input Supply. Bypass with a μf capacitor. Must always be more positive than ground. (Pin ): Reference..V can source or sink current. May be shorted to ground or up to V. Voltages in excess of V can damage the device. COMPOT (Pin ): Comparator Output. Open Collector NPN Output. May be connected to any voltage from ground to 3V more positive than ground (operates above ). Short-circuit protected. INPT (Pin 8): Comparator Input. Inverting comparator input. BLOCK DIAGRA W COMPOT k.v k 3 SHDN 8 INPT BD APPLICATIO S I FOR ATIO W The LT is especially suited for micropower system applications. For example, the comparator section of the LT may be used as a battery checker to provide an indication of low battery. Another type of system application for the LT would be to generate the equivalent of split supplies off of a single power input. The regulator section provides regulated output voltage and the reference, which can both source and sink current, is then an artificial system ground providing a split supply for the system. For many applications the comparator can be frequency compensated to operate as an amplifier. Compensation values for various gains are given in the data sheet. The comparator gain is purposely low to make it easier to frequency compensate as an amplifier. The NPN output is capable of sinking ma and can drive loads connected to voltages in excess of the positive power supply. This is useful for driving switches or linear regulators off of a higher input voltage. fd

7 LT APPLICATIO S I FOR Reference ATIO W Internal to the LT is a.v trimmed class B output reference. The reference was designed to be able to source or sink current so it could be used in supply splitting applications as well as a general purpose reference for external circuitry. The design of the reference allows it to source typically ma or ma and sink ma. The available source and sink current decreases as temperature increases. It is sometimes desirable to decrease the AC output impedance by placing an output capacitor on them. The reference in the LT becomes unstable with large capacitive loads placed directly on it. When using an output capacitor, about Ω should be used to isolate the capacitor from the reference pin. This Ω resistor can be placed directly in series with the capacitor or alternatively the reference line can have Ω placed in series with it and then a capacitor to ground. This is shown in Figure. Other than placing large capacitive loads on the reference, no other precautions are necessary and the reference is stable with nominal stray capacitances. Ω μf OTPT OR Ω μf OTPT F Figure. Bypassing Reference Overload Protection The main regulator in the LT is current limited at approximately ma. The current limit is stable with both input voltage and temperature. Like most other IC regulators, a minimum load is required on the output of the LT to maintain regulation. For most standard regulators this is normally specified at ma. Of course, for a micropower regulator this would be a tremendously large current. The output must be large enough to absorb all the leakage current of the pass transistor at the maximum operating temperature. It also effects the transient response; low output currents have long recovery times from load transients. At high operating temperatures the minimum load current increases and having too low of a load current may cause the output to go unregulated. Devices are tested for minimum load current at high temperature. The output voltage setting resistors to the feedback terminal can usually be used to provide the minimum load current. Frequency Compensation The LT is frequency compensated by a dominant pole on the output. An output capacitor of μf is usually large enough to provide good stability. Increasing the output capacitor above μf further improves stability. In order to ensure stability, a feedback capacitor is needed between the output pin and the feedback pin. This is because stray capacitance can form another pole with the large value of feedback resistors used with the LT. Also, a feedback capacitor minimizes noise pickup and improves ripple rejection. With the large dynamic operating range of the output current, :, frequency response changes widely. Low AC impedance capacitors are needed to insure stability. While solid tantalum are best, aluminum electrolytics can be used but larger capacitor values may be needed. fd

8 LT TYPICAL APPLICATIO S Regulator with Output Voltage Monitor V LT VOT V LOGIC OTPT LOGIC k INPT 8.μF 98k k k μf PIN LOGIC OTPT LOGIC OTPT GOES LOW WHEN DROPS BY mv TA3 Compensating the Comparator as an Op Amp A Low Dropout Regulator μa.k 8 M AT Av =, SLEW RATE =.V/μs V/μs * MJE9 V R C R C LT Ω* k* k k.μf μf TA Av R C C R 33Ω.μF.μF Ω.μF k k.μf k * FOR CRRENT LIMIT.A MST HAVE LOW ESR. SEVERAL μf CAPACITORS CAN BE PARALLELED. TA 8 fd

9 LT TYPICAL APPLICATIO S V Regulator Regulator with Improved Transient Response >.V I Q = μa V >.V V μf LT.μF M M μf LT.μF.μF k M M μf TA TA Battery-Backup Regulator V BATTERY INPT LT.μF M k μf LT MAIN POWER INPT M INTERNAL PARASITIC DIODES OF LT TA8 V Regulator with Feedback Shutdown >.V I Q = μa LT.μF M M V OT μf N39* LOGIC INPT * TRANSISTOR SED BECASE OF LOW LEAKAGE CHARACTERISTICS. TO TRN OFF THE OTPT OF THE LT FORCE (PIN ) >.V. NC TA9 fd 9

10 LT fd SCHE ATIC DIAGRA W W Q3 8 Q Q Q3 Q3 Q3 Q Q3 Q Q9 Q9 Q Q Q8 Q9 INPT 3 SHDN Schem VOT COMPOT R Ω R k R3 k R38 k R k R 8k R9 k R8 k 8k k R k R k R9 Ω R3 k R8 k Q3 Q Q Q3 R k Q3 Q Q Q R3 k R k Q Q38 Q39 Q C pf Q8 R8 k Q Q Q33 R k C3 pf C pf R.8k C pf Q9 Q3 Q Q Q8 Q R 3k R3 k R3.8k R k R3 k Q R Ω Q Q Q Q Q3 Q Q8 Q Q R8 k R3 k Q Q Q R 3k Q Q8 Q Q3 Q R 39k R3 3k k k pf R3 Ω pf C pf Q9 Q R33 k 38.3k

11 LT PACKAGE DESCRIPTIO H Package 8-Lead TO- Metal Can (.3 Inch PCD) (Reference LTC DWG # -8-3) SEATING PLANE..* (..3).33.3 ( ) DIA.3.33 (. 8.9). (.) MAX. (.) MAX..8 (.9.99)..** (..33) GAGE PLANE ERENCE PLANE.. (. 9.) * LEAD DIAMETER IS NCONTROLLED BETWEEN THE ERENCE PLANE AND THE SEATING PLANE.. ** FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS (..) TYP.8.3 (..8).. (.9.) INSLATING STANDOFF.. (.8.3) PIN.3 (.8) TYP H8 (TO-).3 PCD 8.3 BSC (. BSC) CORNER LEADS OPTION ( PLCS) J8 Package 8-Lead CERDIP (Narrow.3 Inch, Hermetic) (Reference LTC DWG # -8-). (.8) MAX. (.) MIN. (.8) MAX (.3.)..8 (.3.) FLL LEAD OPTION NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS.3. (.8.3) HALF LEAD OPTION.. (.3.).. (.3.).. (.38.). (.) BSC. 3. MIN. (.3) RAD TYP 3..3 (.88.8) J8 8 OBSOLETE PACKAGES.3.3 (. 8.) N8 Package 8-Lead PDIP (Narrow.3 Inch) (Reference LTC DWG # -8-).. (.3.).3 ±. (3.3 ±.).* (.) MAX 8.8. (.3.38) ( ) NOTE: INCHES. DIMENSIONS ARE MILLIMETERS. (.) TYP. (.) BSC. ±.* (. ±.38) *THESE DIMENSIONS DO NOT INCLDE MOLD FLASH OR PROTRSIONS. MOLD FLASH OR PROTRSIONS SHALL NOT EXCEED. INCH (.mm). (3.8) MIN. (.8) 3.8 ±.3 (. ±.) MIN Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. N8 fd

12 LT TYPICAL APPLICATIO Current Limited A Regulator.k.Ω* MJE9 N39* LT Ω.μF k k V AT A μf * SETS CRRENT LIMIT BT INCREASES DROPOT VOLTAGE BY.V MST HAVE LOW ESR. SEVERAL μf CAPACITORS CAN BE PARALLELED TA PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow. Inch) (Reference LTC DWG # -8-).8. (.3.).. (..8) 8 TYP.3.9 (.3.)....9 (..) (.3.83) NOTE: INCHES TYP. DIMENSIONS IN (MILLIMETERS). DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLDE MOLD FLASH OR PROTRSIONS. MOLD FLASH OR PROTRSIONS SHALL NOT EXCEED." (.mm).. (..). (.) BSC.8. (.9.9).89.9 (.8.) NOTE ( ) NOTE 3 SO8 33. MIN.3 ±. TYP. BSC RECOMMENDED SOLDER PAD LAYOT. ±.. ±. RELATED PARTS PART NMBER DESCRIPTION COMMENTS LT ma Micropower Low Dropout Regulator.V Dropout Voltage, Includes Shutdown, SOT-3, S8 Packages LT 3mA Mircopower Low Dropout Regulator Lowest I Q Low Dropout Regulator, SOT-3, S8, MS8 Packages LT ma Micropower Low Noise, Low Dropout Regulator SOT-3, μv RMS Noise, μa I Q, ThinSOT Package LT 9 REV D PRINTED IN SA Linear Technology Corporation 3 McCarthy Blvd., Milpitas, CA 93- (8) 3-9 FAX: (8) 3- LINEAR TECHNOLOGY CORPORATION 989 fd

FEATURES DESCRIPTIO TYPICAL APPLICATIO. LT1020 Micropower Regulator and Comparator APPLICATIO S

FEATURES DESCRIPTIO TYPICAL APPLICATIO. LT1020 Micropower Regulator and Comparator APPLICATIO S Micropower Regulator and Comparator FEATRES Input Voltage Range:. to V µa Supply Current ma Output Current. Reference Voltage Reference Output Sources ma and Sinks.mA Dual Output Comparator Comparator