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LINEAR LTC1798 Series handbook

1. Q RESISTOR VALUE Q 1 10 100 1000 OUTPUT CAPACITOR VALUE uF 1798 F03 Figure 3 Damping Resistance vs Output Capacitor Value 1mA lour 24 Vour 100mv DIV SEM i00mv ch 2 00V 500ps Ch2 7 1 56V 0 5ms DIV 1798 FO1b Figure 1 Reference Output Load Transient Response 1 Output Capacitor neve LTC 1798 Series APPLICATIONS INFORMATION Internal P Channel Pass Transistor TheLTC1798 series features an internal P channel MOSFET pass transistor This provides several advantages over similar designs using a PNP bipolar pass transistor These references consume only 4uA 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 LTC1798 series provides a lower dropout voltage 200mV max than PNP based references PACKAGE DESCRIPTION Dimensions in inches millimeters unless otherwise noted 8 Package 8 Lead Plastic Small Outline Narrow 0 150 LTC DWG 05 08 1610 0 189 0 197 4 801 5 004 8 7 6 5 F 0 228 0 244 0 150 0 157 5 791 6 197 3 810 3 988
2. 4 0 0 0 0 0 1 1 10 100 50 25 0 25 50 75 100 125 150 50 25 0 25 50 75 100 125 150 OUTPUT SOURCE CURRENT mA TEMPERATURE C TEMPERATURE C 1798 601 Similar performance characteristics can be expected for all voltage options 1798 602 1798 G03 LTC 1798 Series TYPICAL PERFORMANCE CHARACTERISTICS LTC1798 2 5 Output Short Circuit Current vs Input Voltage 25 C OUTPUT SHORTED TO Vin OUTPUT SHORT CIRCUIT CURRENT mA 2 5010 rm e a 2 5000 OUTPUT VOLTAGE V 2 4995 5uV DIV 4 6 8 10 12 14 INPUT VOLTAGE V 1258 G04 LTC1798 2 5 Output Voltage vs Input Voltage Ta 25 2 4 6 8 1 0 12 144 V INPUT VOLTAGE 1798 G07 LTC1798 2 5 0 1Hz to 10Hz Noise cms L E 1SEC DIV 1798 G10 OUTPUT SHORT CIRCUIT CURRENT mA INPUT CURRENT pA INPUT CURRENT pA LTC1798 2 5 Output Short Circuit Current vs Input Voltage 42 fee lL TA 25 C OUTPUT SHORTED TO GND 2 4 6 8 10 12 14 INPUT VOLTAGE V 1798 G05 LTC1798 2 5 Input Current vs Input Voltage
3. 7 TA 25 C 6 5 4 2 4 6 8 10 12 14 INPUT VOLTAGE V 1798 G08 LTC1798 5 Input Current vs Input Voltage in Dropout 1400 1200 1000 800 600 400 200 0 9 10 INPUT VOLTAGE V 1798 G11 LTC1798 Series Load Regulation 5 4 L Tas 25 Vin Vour NoM 0 2V z 3 SINKING Z 0 lt S 1 M SOURCING g E 2 3 4 5 0 0 1 1 10 100 OUTPUT CURRENT mA 1798 G06 LTC1798 2 5 PSRR vs Frequency 60 FTT Vin 2 7V 50 amp 40 30 cc 21 amp 20 2 wn cc 10 0 10 100 1k 10k FREQUENCY Hz 1798 G09 LTC1798 2 5 Input Current vs Input Voltage in Dropout 250 200 3 TA 125 C 5 150 ce 2 2 100 z L TA 55 C Z 50 0 005 1 15 2 25 3 35 4 45 5 INPUT VOLTAGE V 1798 G12 LI LTC 1798 Series PIN FUNCTIONS DNC Pins 1 5 7 8 Do Not Connect Connected internally for post package trim These pins must be left unconnected IN Pin 2 Positive Supply Bypassing with a 0 1uF capacitor is recommended if the output loading changes Vout 0 2V lt Vin lt 12 6V DNC Pin 3 LTC1798 2 5 LTC1798 3 LTC1798 4 1 LTC1798 5 Do Not Connect Connected inter
4. Y 1 2 3 4 35 0509 I 0053 0069 1 346 1 752 0 008 0 010 0 004 0 010 0 203 0 254 i 0 254 TX m Eee 0 101 0 254 nou ooo p 0 355 0 483 1 270 TYP DIMENSION DOES NOT INCLUDE MOLD FLASH MOLD FLASH SHALL NOT EXCEED 0 006 0 152mm PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH INTERLEAD FLASH SHALL NOT EXCEED 0 010 0 254mm PER SIDE 508 1298 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 represen tation thatthe interconnection of its circuits as described herein will not infringe on existing patent rights LTC 1798 Series TYPICAL APPLICATIONS Micropower Low Dropout Negative Reference Supply Splitter 0 2V lt Vc lt 8 5V N LTC1798 2 5 2 5V OUT LTC1798 3 VIRTUAL o iyr GROUND GND Vout 3V L 1798 TA04 4 1798 TAOS Vss 4V Low Power Low Voltage Supply Reference for LTC1096L MPU ANALOG INPUT SERIAL DATA LINK MICROWIRE AND OV TO 3V RANGE D SPI COMPATIBLE MICROWIRE is a trademark of National Semiconductor Corporation PART NUMBER DESCRIPTION COMMENTS LT 1389 Nanopower Precision Shunt Voltage Reference 800nA Quiescent Current 0 05 Max 10ppm C Max Drift 1 25V and 2 5V Versions SO 8 Package LT1634 Micropower Precision Shunt Voltage R
5. operating temperature range AVAILABLE OPTIONS OUTPUT TEMPERATURE TEMPERATURE PACKAGE TYPE VOLTAGE RANGE ACCURACY COEFFICIENT S0 8 S8 V C ppm C ORDER NUMBER PART MARKING 25 0 to 70 0 15 40 LTC1798CS8 2 5 179825 3 0 to 70 0 15 40 LTC1798CS8 3 17983 4 096 0 to 70 0 15 40 LTC1798CS8 4 1 179841 5 0 to 70 0 15 40 LTC1798CS8 5 17985 Adjustable 0 to 70 04 40 LTC1798CS8 1798 ELECTRICAL CHARACTERISTICS The e denotes specifications which apply over the full specified temperature range otherwise specifications are at 25 C Vin Vout NominaL 9 2V lout OMA unless otherwise noted FB OUT for the LTC1798 SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Vin Input Voltage Range 12 6 V lin Input Current FB QUT for LTC1798 4 0 6 5 pA e 8 5 pA Vout Output Voltage Note 4 LTC1798 FB OUT 2 3755 2 385 2 3945 LTC1798 ADJ 04 0 4 LTC1798 2 5 2 4963 2 5 2 5037 V LTC1798 3 2 9955 3 3 0045 V LTC1798 4 1 4 000 4 096 4 102 V LTC1798 5 4 9925 5 5 0075 V LTC1798 AII Fixed Options 0 15 0 15 neve LTC 1798 Series ELECTRICAL CHARACTERISTICS The e denotes specifications which apply over the full specified temperature range otherwise specifications are at T4 25 C Vin Vout NominaL 9 2V lout OMA unless otherwise noted FB OUT for the LTC1798 SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS en Output Voltag
6. 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 Vout when falls to 0 1 below its nominal value at Viy Vour 0 5V 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 25 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 TYPICAL PERFORMANCE CHARACTERISTICS LTC1798 2 5 Dropout Voltage LTC1798 2 5 vs Output Source Current Input Current vs Temperature LTC1798 Series Output Short Circuit Current vs Temperature 100 T 8 T 70 T T g0 Ta 25 C Vin 2 7V 25 C OUTPUT 7 60 Vin Vour nom 0 2V SHORTED 80 E TO GND 5 50 7 g F 3 60 5 Ee 40 5 oe a 50 4 e 30 e e 2 40 5 3 20 a a e a 30 z T amp 2 10 OUTPUT 4 20 z SHORTED
7. Nt D LTC 1798 Series TECHNOLOGY Micropower Low Dropout References FEATURES DESCRIPTION 200mV Max Dropout at 10mA Output Current The LTC 1798 LTC1798 2 5 LTC1798 3 LTC1798 4 1 4uA Typical Quiescent Current LTC1798 5 are micropower bandgap references that com 0 15 Max Initial Accuracy bine high accuracy and low drift with very low supply No Output Capacitor Required currentand small package size The combination of ultralow Output Sources 10mA Sinks 2mA quiescent current and low dropout voltage of only 200mV m 40ppm C Max Drift max makes them ideal for battery powered equipment Voltage Options 2 5V 3V 4 1V 5V and Adjustable The output voltage is set by an external resistor divider for the adjustable LTC1798 APPLICATIONS This series of references uses curvature compensation to obtain low temperature coefficient and trimmed thin film Battery Powered Systems resistors to achieve high output accuracy These refer Handheld Instruments ences can source up to 10mA and sink up to 2mA making m Precision Power Supplies them ideal for precision regulator applications They are A D and D A Converters Stable without an output bypass capacitor but are also stable with capacitance up to 1uF This feature is important in critical applications where PC board space is apremium and fast settling is demanded The LTC1798 series references provided power dissipa tion advantages over shunt references In addition to supply c
8. cuitry being regulated does not demand current the LTC1798 series reduces its dissipation and battery life is extended If the reference is not delivering load current it dissipates only 10 8uW when operating on a 2 7V supply for LTC1798 2 5 yet the same connection can deliver 10mA of load current when demanded Output Bypass Capacitor The LTC1798 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 1uF can be used to improve the output transient response Figure 1 shows the response of the reference to a 1mA to OpA load step with a 1uF output capacitor If more than 1 of output 1mA lour i lt OMA gt Vout ee 100mV DIV i I omv ch 2 00V 10 0 Ch2 X 1 5 10ms DIV 1798 F01a capacitance is required a resistor in series with the capacitor is recommended to reduce the output ringing Figure 2 illustrates the use of a damping resistor for Capacitive loads greater than 1uF Figure 3 shows the resistor and capacitor values required to achieve critical damping LTC1798 5 5V luF DAMPING RESISTOR lk 1798 F02 Figure 2 Adding a Damping Resistor with Output Capacitors Greater Than 1uF 10k
9. e Noise Note 5 0 1Hz lt f lt 10Hz 8 ppmp p TC Output Voltage Temp Coefficient Note 6 Tmin lt Ty lt Tmax e 15 40 ppm C Vour ViN Line Regulation Vin VoUT NOMINAL 0 2V to 12 6V e 30 120 ppm V Vour lour Load Regulation Note 7 Sourcing to 10mA e 0 1 0 3 mV mA Sinking OmA to 2mA 1 75 4 0 mV mA e 6 5 mV mA lec Short Circuit Output Current Vout Shorted to GND 20 40 mA Vout Shorted to Vin 2 4 mA AVpo Dropout Voltage Note 8 lout 0 AVoyt lt 0 1 e 100 mV lout 10mA AVoyr lt 0 1 e 200 mV Vuyst Output Hysteresis Note 9 AT 40 C to 85 C 200 ppm AT 0 C to 70 C 50 ppm FB Pin Input Current LTC1798 OUT FB 10 nA Vote 1 Absolute Maximum Ratings are those values beyond which the life of the device may be impaired Note 2 The LTC1798 is guaranteed functional over the operating temperature range of 40 C to 100 C Note 3 If the part is stored outside of the specified operating temperature range the output may shift due to hysteresis Note 4 ESD Electostatic Discharge sensitive device Extensive use of ESD protection devices are used internal to the LTC1798 however high electrostatic discharge can damage or degrade the device Use proper ESD handling precautions Note 5 Peak to peak noise is measured with a single pole highpass filter at 0 1Hz and 2 pole lowpass filter at 10Hz Note 6 Temperature coefficient is the change in output voltage divided by the nominal output
10. eference 0 05 Max 25ppm C Max Drift 1 25V 2 5V 4 096V and 5V Outputs LT1460 Micropower Series Reference 0 075 Max 10ppm C Max Drift 2 5V 5V and 10V Outputs LT1461 Micropower Precision Series Voltage Reference 0 04 Max 3ppm C Max Drift 35uA Quiescent Current LT1790 SOT 23 LDO Precision Micropower Reference 0 05 Max 10ppm C Max 2 5V 60pA Supply Li near Technology Corporation 1798fa LT LCG 1100 2K REV A PRINTED IN USA 1630 McCarthy Blvd Milpitas CA 95035 7417 TECHNOLOGY 408 432 1900 FAX 408 434 0507 e www linear tech com 6 LINEAR TECHNOLOGY CORPORATION 1999
11. nally for post package trim This pin must be left unconnected FB Pin 3 LTC1798 Resistor Divider Feedback Pin Connecta resistor divider from OUT to GND andthe center tap to FB This pin sets the output potential R1 R2 Vout 2 385V i R1 is connected from OUT to FB and R2 from FB to GND Selecting R2 2 10k will make lout lt 250 GND Pin 4 Negative Supply or Ground Connection OUT Pin 6 Reference Output The output can source up to 10mA and sink up to 2mA Itis stable with output bypass capacitor ranging from OuF to 1pF BLOCK DIAGRAM 2 385V mem mm er FB 1 3 LTC1798 1798 BD NOTE R1 AND R2 ARE NOT CONNECTED FOR LTC1798 LTC 1798 Series 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 result ing in high power dissipation and short battery life The LTC1798 series low dropout references do not require a current setting resistor and can operate with any supply voltage from VoUT NOMINAL 0 2V to 12 6V When the cir
12. urrent shunt references must also idle the entire load current to operate The LTC1798 series is available in the SO 8 package 7 LTC and LT are registered trademarks of Linear Technology Corporation TYPICAL APPLICATION LTC1798 2 5 Temperature Drift 2 5V Battery Powered Reference LTC1798 2 5 REFERENCE VOLTAGE CHANGE mV 40 20 0 20 40 60 80 100 TEMPERATURE C 1798 TA02 AL Ure 1 LTC 1798 Series ABSOLUTE MAXIMUM RATINGS PACKAGE ORDER INFORMATION Note 1 S pply uec fie pao orm etre emat 13V SM Input Voltages 0 3v to 13V Output Voltages 0 3 to 13V DNC 1 8 DNC LTC1798CS8 Output Short Circuit Duration Indefinite IN 2 7 DNC LTC1798CS8 2 5 Operating Temperature Range DNC FB 3 6 OUT LTC1798CS8 3 Note 2 NL 40 C to 100 C 5 LTC1798C58 4 1 Specified Temperature Range 0 C to 70 C S8 PACKAGE LTC1798CS8 5 Storage Temperature Range Note 3 65 C to 150 C S8 PART MARKING Lead Temperature Soldering 10 sec 300 C 1798 CONNECT EXTERNAL CIRCUITRY TO 179825 THESE PINS 17983 LTCIT98 LULTCI799 8 FB FOR LIC1798 179841 17985 Consult factory for parts specified with wider

LINEAR LTC1798 Series handbook

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