LTC1258 Series Micropower Low Dropout References U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 200mV Max Dropout at 10mA Output Current 4µA Typical Quiescent Current 0.15% Max Initial Accuracy (S8) No Output Capacitor Required Output Sources 10mA, Sinks 2mA 40ppm/°C Max Drift (S8) Available in Small MSOP Package Voltage Options: 2.5V, 3V, 4.1V, 5V and Adjustable 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 10mA and sink up to 2mA, making them ideal for precision regulator applications. They are stable without an output bypass capacitor, but are also stable with capacitance up to 1µF. This feature is important in critical applications where PC board space is a premium and fast settling is demanded. U APPLICATIO S ■ ■ ■ ■ The LTC®1258/LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5 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 200mV max. makes them ideal for battery-powered equipment. The output voltage is set by an external resistor divider for the adjustable LTC1258. Battery-Powered Systems Handheld Instruments Precision Power Supplies A/D and D/A Converters The LTC1258 series references provide power dissipation advantages over shunt references. In addition to supply current, shunt references must also idle the entire load current to operate. , LTC and LT are registered trademarks of Linear Technology Corporation. The LTC1258 series is available in the 8-pin MSOP and SO packages. U TYPICAL APPLICATION LTC1258-2.5 Temperature Drift 2.5V Battery-Powered Reference 2.7V TO 12.6V 2 IN OUT 1 2.5V 0.1µF GND 1258 TA01 4 REFERENCE VOLTAGE CHANGE (mV) LTC1258-2.5 4 3 2 1 0 –1 –2 –3 –4 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1258 TA02 1 LTC1258 Series W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage ........................................................ 13V Input Voltages ........................................... –0.3V to 13V Output Voltages ......................................... –0.3V to 13V Output Short Circuit Duration .......................... Indefinite Operating Temperature Range (Note 2) – 40°C to 100°C Specified Temperature Range ...................... 0°C to 70°C Storage Temperature Range (Note 3) ....–65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C W U U PACKAGE/ORDER INFORMATION ORDER PART NUMBER TOP VIEW OUT IN **DNC/FB GND 8 7 6 5 1 2 3 4 LTC1258CMS8 LTC1258CMS8-2.5 LTC1258CMS8-3 LTC1258CMS8-4.1 LTC1258CMS8-5 DNC* DNC* DNC* DNC* MS8 PACKAGE 8-LEAD PLASTIC MSOP ORDER PART NUMBER TOP VIEW OUT 1 8 DNC* IN 2 7 DNC* **DNC/FB 3 6 DNC* GND 4 5 DNC* S8 PACKAGE 8-LEAD PLASTIC SO S8 PART MARKING MS8 PART MARKING * CONNECTED INTERNALLY. DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS ** DNC FOR LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5, FB FOR LTC1258 TJMAX = 125°C, θJA = 250°C/W LTEL LTCF LTEU LTEN LTEM LTC1258CS8 LTC1258CS8-2.5 LTC1258CS8-3 LTC1258CS8-4.1 LTC1258CS8-5 * CONNECTED INTERNALLY. DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS ** DNC FOR LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5, FB FOR LTC1258 TJMAX = 125°C, θJA = 190°C/W 1258 12582 12583 125841 12585 Consult factory for Industrial and Military grade parts. U AVAILABLE OPTIO S OUTPUT VOLTAGE (V) TEMPERATURE RANGE (°C) ACCURACY (%) TEMPERATURE COEFFICIENT (ppm/°C) 2.5 2.5 0 to 70 0 to 70 0.15 0.21 3 3 0 to 70 0 to 70 4.096 4.096 PACKAGE TYPE S8 ORDER NUMBER PART MARKING 40 60 LTC1258CS8-2.5 12582 0.15 0.20 40 60 LTC1258CS8-3 0 to 70 0 to 70 0.15 0.18 40 60 LTC1258CS8-4.1 5 5 0 to 70 0 to 70 0.15 0.18 40 60 LTC1258CS8-5 Adjustable Adjustable 0 to 70 0 to 70 0.4 0.46 40 60 LTC1258CS8 2 MS8 ORDER NUMBER PART MARKING LTC1258CMS8-2.5 LTCF LTC1258CMS8-3 LTEU LTC1258CMS8-4.1 LTEN LTC1258CMS8-5 LTEM LTC1258CMS8 LTEL 12583 125841 12585 1258 LTC1258 Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the specified temperature range, otherwise specifications are TA = 25°C. VIN = VOUT(NOMINAL) + 0.2V, IOUT = 0mA, FB = OUT for the LTC1258 unless otherwise noted. SYMBOL VIN IIN PARAMETER Input Voltage Range Input Current CONDITIONS MIN TYP 2.3755 2.4963 2.9955 4.090 4.9925 2.374 2.4948 2.994 4.0885 4.991 2.385 2.5 3 4.096 5 2.385 2.5 3 4.096 5 8 15 ● FB = OUT for LTC1258 ● VOUT Output Voltage (Note 4) en TC Output Voltage Noise (Note 5) Output Voltage Temp Coefficient (Note 6) VOUT/VIN VOUT/IOUT Line Regulation Load Regulation (Note 7) ISC Short-Circuit Output Current ∆VDO Dropout Voltage (Note 8) VHYST Output Hysteresis (Note 9) IFB FB Pin Input Current LTC1258 (S8), FB = OUT LTC1258-2.5 (S8) LTC1258-3 (S8) LTC1258-4.1 (S8) LTC1258-5 (S8) LTC1258 (MS8), FB = OUT LTC1258-2.5 (MS8) LTC1258-3 (MS8) LTC1258-4.1 (MS8) LTC1258-5 (MS8) 0.1Hz ≤ f ≤ 10Hz TMIN ≤ TJ ≤ TMAX (S8) TMIN ≤ TJ ≤ TMAX (MS8) VIN = (VOUT(NOMINAL) + 0.2V) to 12.6V Sourcing 0mA to 10mA Sinking 0mA to 2mA ● ● 30 0.1 1.75 ● ● ● VOUT Shorted to GND VOUT Shorted to VIN IOUT = 0, ∆VOUT ≤ 0.1% IOUT = 10mA, ∆VOUT ≤ 0.1% ∆T = –40°C to 85°C ∆T = 0°C to 70°C LTC1258, OUT = FB Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LTC1258 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 (Electrostatic Discharge) sensitive device. Extensive use of ESD protection devices are used internal to the LTC1258, 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. 20 2 MAX 12.6 6.5 8.5 2.3945 2.5037 3.0045 4.102 5.0075 2.396 2.5052 3.006 4.1035 5.009 40 60 90 0.3 4.0 6.5 40 4 100 200 ● ● 200 50 10 UNITS V µA µA V V V V V V V V V V ppmP-P ppm/°C ppm/°C ppm/V mV/mA mV/mA mV/mA mA mA mV mV ppm ppm nA Note 6: 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 (VIN – VOUT) when VOUT falls to 0.1% below its nominal value at VIN = VOUT + 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. 3 LTC1258 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LTC1258-2.5* Dropout Voltage vs Output Source Current 100 8 70 OUTPUT SHORT-CIRCUIT CURRENT (mA) VIN = 2.7V TA = 25°C 90 7 80 6 INPUT CURRENT (µA) DROPOUT VOLTAGE (mV) LTC1258 Series Output Short-Circuit Current vs Temperature LTC1258-2.5* Input Current vs Temperature 70 60 50 40 30 5 4 3 2 20 1 10 0 0 1 10 0.1 OUTPUT SOURCE CURRENT (mA) 0 –50 –25 100 0 0 4 6 8 10 INPUT VOLTAGE (V) 12 TA = 25°C OUTPUT SHORTED TO GND 14 2 4 6 8 10 INPUT VOLTAGE (V) 12 TA = 25°C VIN = VOUT(NOM) + 0.2V SINKING 2 1 SOURCING 0 –1 –2 –3 0 1 10 0.1 OUTPUT CURRENT (mA) LTC1258-2.5 Input Current vs Input Voltage 7 TA = 25°C INPUT CURRENT (µA) TA = 25°C 2.5005 2.5000 2 4 6 8 10 INPUT VOLTAGE (V) 12 14 1258 G07 *Similar performance characteristics can be expected for all voltage options. 6 5 4 2 100 1258 G06 1258-G05 2.5010 OUTPUT VOLTAGE (V) 25 50 75 100 125 150 TEMPERATURE (°C) 3 –5 14 LTC1258-2.5 Output Voltage vs Input Voltage 4 0 –4 1258-G04 2.4995 5 4 41 2 OUTPUT SHORTED TO VIN LTC1258 Series Load Regulation ∆VOUT FROM NO LOAD (mV) 5 10 5 OUTPUT SHORT-CIRCUIT CURRENT (mA) OUTPUT SHORT-CIRCUIT CURRENT (mA) 10 20 1258 G03 42 15 30 LTC1258-2.5* Output Short-Circuit Current vs Input Voltage 25 20 40 1258 G02 LTC1258-2.5* Output Short-Circuit Current vs Input Voltage TA = 25°C OUTPUT SHORTED TO VIN OUTPUT SHORTED TO GND 50 0 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 1258 G01 TA = 25°C VIN = VOUT(NOM) + 0.2V 60 4 6 8 10 INPUT VOLTAGE (V) 12 14 1258 G08 LTC1258 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LTC1258-2.5 PSRR vs Frequency LTC1258-2.5 0.1Hz to 10Hz Noise POWER SUPPLY REJECTION RATIO (dB) 60 VIN = 2.7V VIN = 2.7V 50 40 30 5µV/DIV 20 10 0 10 1k 100 FREQUENCY (Hz) 1SEC/DIV 10k 1258 G10 1258 G09 U U U PIN FUNCTIONS OUT (Pin 1): Reference Output. The output can source up to 10mA and sink up to 2mA. It is stable with output bypass capacitor ranging from 0µF to 1µF. IN (Pin 2): Positive Supply. Bypassing with a 0.1µF capacitor is recommended if the output loading changes. (VOUT + 0.2V) ≤ VIN ≤ 12.6V. DNC (Pin 3): (LTC1258-2.5/LTC1258-3/LTC1258-4.1/ LTC1258-5) Do Not Connect. Connected internally for post package trim. This pin must be left unconnected. R1 + R2 VOUT = 2.385V ; R1 is connected from OUT R2 to FB and R2 from FB to GND. GND (Pin 4): Negative Supply or Ground Connection. DNC (Pins 5, 6, 7, 8): Do Not Connect. Connected internally for post package trim. These pins must be left unconnected. FB (Pin 3): (LT1258) Resistor Divider Feedback Pin. Connect a resistor divider from OUT to GND and the center tap to FB. This pin sets the output potential. W BLOCK DIAGRAM 2 IN + OUT 1 – 2.385V R1 FB 3 (LTC1258) R2 GND 4 1258 BD NOTE: R1 AND R2 ARE NOT CONNECTED FOR LTC1258 5 LTC1258 Series U W U U APPLICATIONS INFORMATION 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 LTC1258 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 circuitry being regulated does not demand current, the LTC1258 series reduces its dissipation and battery life is extended. If the reference is not delivering load current it dissipates only 10.8µW when operating on a 2.7V supply for LTC1258-2.5, yet the same connection can deliver 10mA of load current when demanded. Output Bypass Capacitor The LTC1258 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 1µF can be used to improve the output transient response. Figure 1 shows the response of the reference to a 1mA to 0µA load step with a 1µF output capacitor. If more than 1µF of output capaci- tance 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 1µF. Figure 3 shows the resistor and capacitor values required to achieve critical damping. LTC1258-5 5.2V TO 12.6V OUT GND 4 5V COUT >1µF DAMPING RESISTOR <1k 10k 1k 100 10 1 10 100 OUTPUT CAPACITOR VALUE (µF) 1000 1258 F03 Figure 3. Damping Resistance vs Output Capacitor Value VOUT 100mV/DIV VOUT 100mV/DIV 0.5ms/DIV 1258 F01a Figure 1. Reference Output Load Transient Response, 1µF Output Capacitor 6 1 Figure 2. Adding a Damping Resistor with Output Capacitors Greater Than 1µF 0mA 10ms/DIV IN 1258 F02 1mA IOUT 0mA 1mA IOUT 2 0.1µF RESISTOR VALUE (Ω) Longer Battery Life 1258 F01b LTC1258 Series U U W U APPLICATIONS INFORMATION Internal P-Channel Pass Transistor The LTC1258 series features an internal P-channel MOSFET pass transistor. This provides several advantages over similar designs using a PNP bipolar pass transistor. U PACKAGE DESCRIPTION These references consume only 4µA 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 LTC1258 series provides a lower dropout voltage (200mV max) than PNP-based references. Dimenshions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.040 ± 0.006 (1.02 ± 0.15) 0.007 (0.18) 0.118 ± 0.004* (3.00 ± 0.102) 0.034 ± 0.004 (0.86 ± 0.102) 8 7 6 5 0° – 6° TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC 0.021 ± 0.006 (0.53 ± 0.015) 0.118 ± 0.004** (3.00 ± 0.102) 0.193 ± 0.006 (4.90 ± 0.15) 0.006 ± 0.004 (0.15 ± 0.102) 1 * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 4 2 3 MSOP (MS8) 1098 S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.014 – 0.019 (0.355 – 0.483) 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 8 7 6 5 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) BSC 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 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. 2 3 4 SO8 1298 7 LTC1258 Series U TYPICAL APPLICATIONS Micropower Low Dropout Negative Reference Supply Splitter 0.2V ≤ VCC ≤ 8.5V 2 IN 1 OUT LTC1258-2.5 2 VCC = 5V LTC1258-3 IN OUT 1 0.1µF 2 – 1/2 LTC1542 3 + 0.1µF 8 GND GND 4 4 1 1258 TA04 VOUT = – 3V 4 2.5V VIRTUAL 0.1µF GROUND 1258 TA03 VSS = – 4V Low Power, Low Voltage Supply Reference for LTC1096L ANALOG INPUT 0V TO 3V RANGE 1 CS/ VCC 2 SHDN +IN CLK LTC1096L 3 –IN DOUT 4 GND VREF 1µF 8 MPU 7 6 5 SERIAL DATA LINK SERIAL DATA LINK (MICROWIRETM AND SPI COMPATIBLE) 1 OUT 4 GND IN 2 LTC1258-3 VIN 3.2V TO 0.1µF 12.6V 1258 TA05 MICROWIRE is a trademark of National Semiconductor Corp. RELATED PARTS 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 Reference 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 LTC1440 Micropower Comparator with Reference 3.7µA Max ICC, 1% 1.182V Reference, Adjustable Hysteresis LTC1540 Nanopower Comparator with Reference 600nA Max ICC, 2% 1.182V Reference, Adjustable Hysteresis ® 8 Linear Technology Corporation 1258f LT/TP 0999 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1998