LTC1798 Series Micropower Low Dropout References FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION

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1 Micropower Low Dropout References FEATURES n mv Max Dropout at ma Output Current n µa Typical Quiescent Current n.% Max Initial Accuracy n No Output Capacitor Required n Output Sources ma, Sinks ma n ppm/ C Max Drift n Voltage Options:.V, V,.V, V and Adjustable APPLICATIONS n Battery-Powered Systems n Handheld Instruments n Precision Power Supplies n A/D and D/A Converters n Available in the SO-8 Package L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. DESCRIPTION The LTC 798/LTC798-./LTC798-/LTC798-./ LTC798- are micropower bandgap references that combine high accuracy and low drift with very low supply current and small package size. The combination of ultralow quiescent current and low dropout voltage of only mv (max) makes them ideal for battery-powered equipment. The output voltage is set by an external resistor divider for the adjustable LTC798. This series of references uses curvature compensation to obtain low temperature coefficient and trimmed thin-film resistors to achieve high output accuracy. These references can source up to ma and sink up to ma, making them ideal for precision regulator applications. They are stable without an output bypass capacitor, but are also stable with capacitance up to µf. This feature is important in critical applications where PC board space is a premium and fast settling is demanded. The LTC798 series references provided power dissipation advantages over shunt references. In addition to supply current, shunt references must also idle the entire load current to operate. The LTC798 series is available in the SO-8 package. TYPICAL APPLICATION.V Battery-Powered Reference LTC798-. Temperature Drift.7V TO.V.µF LTC798-. IN GND 798 TA.V REFERENCE VOLTAGE CHANGE (mv) 8 TEMPERATURE ( C) 798 TA

2 ABSOLUTE MAXIMUM RATINGS (Note ) Operating Temperature Range... C to 7 C Extended Commercial Operating Temperature Range... C to 8 C Junction Temperature... C Storage Temperature Range... C to C Lead Temperature (Soldering, sec)... C PIN CONFIGURATION *DNC IN **DNC/FB GND TOP VIEW 8 7 S8 PACKAGE 8-LEAD PLASTIC SO T JMAX = C, q JA = 9 C/W DNC* DNC* DNC* * CONNECTED INTERNALLY. DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS ** DNC FOR LTC798-./LTC798-/LTC798-./LTC798-, FB FOR LTC798 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LTC798CS8#PBF (OBSOLETE) LTC798CS8#TRPBF Lead Plastic SO C to 7 C LTC798CS8-.#PBF LTC798CS8-.#TRPBF Lead Plastic SO C to 7 C LTC798CS8-#PBF LTC798CS8-#TRPBF Lead Plastic SO C to 7 C LTC798CS8-.#PBF LTC798CS8-.#TRPBF Lead Plastic SO C to 7 C LTC798CS8-#PBF LTC798CS8-#TRPBF Lead Plastic SO C to 7 C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: For more information on tape and reel specifications, go to: AVAILABLE OPTIONS TEMPERATURE TEMPERATURE PACKAGE STYLE PUT VOLTAGE RANGE ACCURACY COEFFICIENT (V) SO-8 (S8) (ºC) (%) (PPM/ºC) ORDER NUMBER PART MARKING. to 7. LTC798CS to 7. LTC798CS to 7. LTC798CS to 7. LTC798CS8-798 Adjustable to 7. LTC798CS8 798

3 ELECTRICAL CHARACTERISTICS LTC798 Series The l denotes specifications which apply over the full specified temperature range, otherwise specifications are at T A = C. V IN = V (NOMINAL) +.V, I = ma unless otherwise noted. FB = for the LTC798. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V IN Input Voltage Range l. V I IN Input Current FB = for LTC798. µa l 8. µa V Output Voltage (Note ) LTC798, FB = LTC798 ADJ LTC798-. LTC798- LTC798-. LTC798- LTC798 All Fixed Options V % V V V V % e n Output Voltage Noise (Note ).Hz f Hz 8 ppmp-p TC Output Voltage Temp Coefficient (Note ) T MIN T J T MAX l ppm/ C V /V IN Line Regulation V IN = (V (NOMINAL) +.V) to.v l ppm/v V /I Load Regulation (Note 7) Sourcing ma to ma l.. mv/ma Sinking ma to ma l I SC Short-Circuit Output Current V Shorted to GND V Shorted to V IN V DO Dropout Voltage (Note 8) I =, V.% I = ma, V.% V HYST Output Hysteresis (Note 9) T = C to 8 C T = C to 7 C l l.7. mv/ma mv/ma ma ma mv mv ppm ppm I FB FB Pin Input Current LTC798, = FB na 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 : The LTC798 is guaranteed functional over the operating temperature range of C to C. Note : If the part is stored outside of the specified operating temperature range, the output may shift due to hysteresis. Note : ESD (Electostatic Discharge) sensitive device. Extensive use of ESD protection devices are used internal to the LTC798, however, high electrostatic discharge can damage or degrade the device. Use proper ESD handling precautions. Note : Peak-to-peak noise is measured with a single pole highpass filter at.hz and -pole lowpass filter at Hz. Note : Temperature coefficient is the change in output voltage divided by the nominal output voltage divided by the specified temperature range. Note 7: Load regulation is measured on a pulse basis from no load to the specified load current. Output changes due to die temperature change must be taken into account separately. Note 8: Dropout voltage is (V IN V ) when V falls to.% below its nominal value at V IN = V +.V. Note 9: Hysteresis in output voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower temperature. Output voltage is always measured at C, but the IC is cycled hot or cold before successive measurements. Hysteresis is not normally a problem for operational temperature excursions where the instrument might be stored at high or low temperature.

4 TYPICAL PERFORMANCE CHARACTERISTICS DROP VOLTAGE (mv) LTC798-.* Dropout Voltage vs Output Source Current T A = C INPUT CURRENT (µa) 8 7 LTC798-.* Input Current vs Temperature V IN =.7V PUT SHORT-CIRCUIT CURRENT (ma) 7 LTC798 Series Output Short-Circuit Current vs Temperature T A = C V IN = V (NOM) +.V PUT SHORTED TO GND PUT SHORTED TO V IN. PUT SOURCE CURRENT (ma) 7 TEMPERATURE ( C) 7 TEMPERATURE ( C) 798 G 798 G 798 G PUT SHORT-CIRCUIT CURRENT (ma) LTC798-.* Output Short-Circuit Current vs Input Voltage T A = C PUT SHORTED TO V IN 8 PUT SHORT-CIRCUIT CURRENT (ma) LTC798-.* Output Short-Circuit Current vs Input Voltage T A = C PUT SHORTED TO GND 8 V FROM NO LOAD (mv) LTC798 Series Load Regulation T A = C V IN = V (NOM) +.V SINKING SOURCING. PUT CURRENT (ma) 798 G 798 G 798 G PUT VOLTAGE (V)... LTC798-.* Output Voltage vs Input Voltage T A = C INPUT CURRENT (µa) 7 LTC798-.* Input Current vs Input Voltage T A = C POWER SUPPLY REJECTION RATIO (db) LTC798-. PSRR vs Frequency V IN =.7V k k FREQUENCY (Hz) 798 G7 798 G8 798 G9

5 TYPICAL PERFORMANCE CHARACTERISTICS LTC798 Series µv/div LTC798-..Hz to Hz Noise V IN =.7V INPUT CURRENT (µa) 8 LTC798- Input Current vs Input Voltage in Dropout T A = C T A = C T A = C INPUT CURRENT (µa) LTC798-. Input Current vs Input Voltage in Dropout T A = C T A = C T A = C SEC/DIV 798 G G 798 G PIN FUNCTIONS DNC (Pins,, 7, 8): Do Not Connect. Connected internally for post package trim. These pins must be left unconnected. IN (Pin ): Positive Supply. Bypassing with a.µf capacitor is recommended if the output loading changes. (V +.V) V IN.V. DNC (Pin ): (LTC798-./LTC798-/LTC798-./ LTC798-) Do Not Connect. Connected internally for post package trim. This pin must be left unconnected. FB (Pin ): (LTC798) Resistor Divider Feedback Pin. Connect a resistor divider from to GND and the center tap to FB. This pin sets the output potential. V V R + R =. 8 ; R is connected from R to FB and R from FB to GND. Selecting R k will make I < µa. GND (Pin ): Negative Supply or Ground Connection. (Pin ): Reference Output. The output can source up to ma and sink up to ma. It is stable with output bypass capacitor ranging from µf to µf.

6 BLOCK DIAGRAM IN +.8V R FB (LTC798) R GND 798 BD NOTE: R AND R ARE NOT CONNECTED FOR LTC798 APPLICATIONS INFORMATION Longer Battery Life Series references have an advantage over shunt style references. To operate, shunt references require a resistor between the power supply and the output. This resistor must be chosen to supply the maximum current that is demanded by the circuit being regulated. When the circuit being controlled is not operating at this maximum current, the shunt reference must always sink this current, resulting in high power dissipation and short battery life. The LTC798 series low dropout references do not require a current setting resistor and can operate with any supply voltage from (V (NOMINAL ) +.V) to.v. When the circuitry being regulated does not demand current, the LTC798 series reduces its dissipation and battery life is extended. If the reference is not delivering load current it dissipates only.8µw when operating on a.7v supply for LTC798-., yet the same connection can deliver ma of load current when demanded. Output Bypass Capacitor The LTC798 series is designed to be stable with or without capacitive loads. With no capacitive load, the reference is ideal for fast settling applications, or where PC board space is at a premium. In applications with significant output loading changes, an output bypass capacitor of up to µf can be used to improve the output transient response. Figure shows the response of the reference to a ma to µa load step with a µf output capacitor. If more than µf of output capacitance is required, a resistor in series with the capacitor is recommended ma ma I ma I ma V mv/div V mv/div 798 Fa 798 Fb ms/div.ms/div Figure. Reference Output Load Transient Response, µf Output Capacitor

7 APPLICATIONS INFORMATION to reduce the output ringing. Figure illustrates the use of a damping resistor for capacitive loads greater than µf. Figure shows the resistor and capacitor values required to achieve critical damping. Internal P-Channel Pass Transistor The LTC798 series features an internal P-channel MOSFET pass transistor. This provides several advantages over similar designs using a PNP bipolar pass transistor. LTC798 Series These references consume only µa of quiescent current under light and heavy loads as well as in dropout; whereas, PNP-based references waste considerable amounts of current when the pass transistor is saturated. In addition, the LTC798 series provides a lower dropout voltage (mv max) than PNP-based references. k.v TO.V.µF IN LTC798- GND V C >µf DAMPING RESISTOR <k RESISTOR VALUE (Ω) k 798 F Figure. Adding a Damping Resistor with Output Capacitors Greater Than µf PUT CAPACITOR VALUE (µf) 798 F Figure. Damping Resistance vs Output Capacitor Value 7

8 PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow. Inch) (Reference LTC DWG # -8-). BSC (.8.) NOTE 8 7. MIN...8. (.79.97)..7 (.8.988) NOTE.. TYP RECOMMENDED SOLDER PAD LAY.8. (..).. (..8) 8 TYP..9 (..7).. (..).. (..7) NOTE: INCHES. DIMENSIONS IN (MILLIMETERS)..9 (..8) TYP. DRAWING NOT TO SCALE. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED." (.mm). (.7) BSC SO8 8

9 REVISION HISTORY (Revision history begins at Rev C) REV DATE DESCRIPTION PAGE NUMBER C 9/ Added Maximum limit for V IN in Electrical Characteristics section 9

10 TYPICAL APPLICATION Micropower Low Dropout Negative Reference Supply Splitter + 8 / LTC.µF IN LTC798- GND 798 TA.V V CC 8.V V = V V CC = V.µF IN LTC798-. GND.µF 798 TA.V VIRTUAL GROUND V SS = V Low Power, Low Voltage Supply Reference for LTC9L ANALOG INPUT V TO V RANGE CS/ SHDN V CC +IN CLK LTC9L IN D GND V REF 8 7 µf SERIAL DATA LINK MPU SERIAL DATA LINK (MICROWIRE AND SPI COMPATIBLE) GND IN LTC798-.µF V IN.V TO.V 798 TA RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT 89 Nanopower Precision Shunt Voltage Reference 8nA Quiescent Current,.% Max, ppm/ C Max Drift.V and.v Versions, SO-8 Package LT Micropower Precision Shunt Voltage Reference.% Max, ppm/ C Max Drift,.V,.V,.9V and V Outputs LT Micropower Series Reference.7% Max, ppm/ C Max Drift,.V, V and V Outputs LT Micropower Precision Series Voltage Reference.% Max, ppm/ C Max Drift, µa Quiescent Current LT79 SOT-, LDO Precision Micropower Reference.% Max, ppm/ C Max,.V, µa Supply LT 9 REV C PRINTED IN USA Linear Technology Corporation McCarthy Blvd., Milpitas, CA 9-77 (8) -9 FAX: (8) -7 LINEAR TECHNOLOGY CORPORATION 8

Precision, Micropower, Low-Dropout, SC70 Series Voltage Reference

19-2428; Rev ; 4/2 Precision, Micropower, Low-Dropout, SC7 General Description The family of precision, low-dropout, micropower voltage references are available in the miniature 3-pin SC7 surface-mount