LTC1798CS8#PBF

LTC1798 Series Micropower Low Dropout References FEATURES n n n n n n n DESCRIPTION 200mV Max Dropout at 10mA Output Current 4µA Typical Quiescent Current 0.15% Max Initial Accuracy No Output Capacitor Required Output Sources 10mA, Sinks 2mA 40ppm/°C Max Drift Voltage Options: 2.5V, 3V, 4.1V, 5V and Adjustable APPLICATIONS n n n n n Battery-Powered Systems Handheld Instruments Precision Power Supplies A/D and D/A Converters 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. The LTC®1798/LTC1798-2.5/LTC1798-3/LTC1798-4.1/ LTC1798-5 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 LTC1798. 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. The LTC1798 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 LTC1798 series is available in the SO-8 package. TYPICAL APPLICATION LTC1798-2.5 Temperature Drift 2.5V Battery-Powered Reference LTC1798-2.5 2.7V TO 12.6V 2 IN OUT 6 0.1µF GND 4 1798 TA01 2.5V REFERENCE VOLTAGE CHANGE (mV) 4 3 2 1 0 –1 –2 –3 –4 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 1798 TA02 1798fc 1 LTC1798 Series ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Operating Temperature Range...................... 0°C to 70°C Extended Commercial Operating Temperature Range................................... –40°C to 85°C Junction Temperature............................................ 110°C Storage Temperature Range.................... –65°C to 150°C Lead Temperature (Soldering, 10 sec)................... 300°C *DNC 1 8 DNC* IN 2 7 DNC* **DNC/FB 3 6 OUT GND 4 5 DNC* S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125°C, qJA = 190°C/W * CONNECTED INTERNALLY. DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS ** DNC FOR LTC1798-2.5/LTC1798-3/LTC1798-4.1/LTC1798-5, FB FOR LTC1798 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LTC1798CS8#PBF (OBSOLETE) LTC1798CS8#TRPBF 1798 8-Lead Plastic SO 0°C to 70°C LTC1798CS8-2.5#PBF LTC1798CS8-2.5#TRPBF 179825 8-Lead Plastic SO 0°C to 70°C LTC1798CS8-3#PBF LTC1798CS8-3#TRPBF 17983 8-Lead Plastic SO 0°C to 70°C LTC1798CS8-4.1#PBF LTC1798CS8-4.1#TRPBF 179841 8-Lead Plastic SO 0°C to 70°C LTC1798CS8-5#PBF LTC1798CS8-5#TRPBF 17985 8-Lead Plastic SO 0°C to 70°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: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ AVAILABLE OPTIONS OUTPUT VOLTAGE (V) TEMPERATURE RANGE (ºC) ACCURACY (%) TEMPERATURE COEFFICIENT (PPM/ºC) 2.5 0 to 70 0.15 3 0 to 70 4.096 5 Adjustable PACKAGE STYLE SO-8 (S8) ORDER NUMBER PART MARKING 40 LTC1798CS8-2.5 179825 0.15 40 LTC1798CS8-3 17983 0 to 70 0.15 40 LTC1798CS8-4.1 179841 0 to 70 0.15 40 LTC1798CS8-5 17985 0 to 70 0.4 40 LTC1798CS8 1798 1798fc 2 LTC1798 Series ELECTRICAL CHARACTERISTICS l denotes specifications which apply over the full specified temperature The range, otherwise specifications are at TA = 25°C. VIN = VOUT(NOMINAL) + 0.2V, IOUT = 0mA unless otherwise noted. FB = OUT for the LTC1798. SYMBOL PARAMETER VIN Input Voltage Range IIN Input Current CONDITIONS MIN TYP MAX UNITS 12.6 V 4 6.5 8.5 µA µA 2.385 2.3945 0.4 2.5037 3.0045 4.102 5.0075 0.15 V % V V V V % l FB = OUT for LTC1798 l VOUT Output Voltage (Note 4) 2.3755 –0.4 2.4963 2.9955 4.090 4.9925 –0.15 LTC1798, FB = OUT LTC1798 ADJ LTC1798-2.5 LTC1798-3 LTC1798-4.1 LTC1798-5 LTC1798 All Fixed Options 2.5 3 4.096 5 en Output Voltage Noise (Note 5) 0.1Hz ≤ f ≤ 10Hz TC Output Voltage Temp Coefficient (Note 6) TMIN ≤ TJ ≤ TMAX l 15 40 VOUT/VIN Line Regulation VIN = (VOUT(NOMINAL) + 0.2V) to 12.6V l 30 120 ppm/V VOUT/IOUT Load Regulation (Note 7) Sourcing 0mA to 10mA l 0.1 0.3 mV/mA 1.75 4 6.5 mV/mA mV/mA 8 Sinking 0mA to 2mA l 40 4 ppm/°C ISC Short-Circuit Output Current VOUT Shorted to GND VOUT Shorted to VIN ∆VDO Dropout Voltage (Note 8) IOUT = 0, ∆VOUT ≤ 0.1% IOUT = 10mA, ∆VOUT ≤ 0.1% VHYST Output Hysteresis (Note 9) ∆T = –40°C to 85°C ∆T = 0°C to 70°C 200 50 ppm ppm IFB FB Pin Input Current LTC1798, OUT = FB 10 nA Note 1: 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 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. 20 2 ppmP-P mA mA 100 200 l l mV mV 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. 1798fc 3 LTC1798 Series TYPICAL PERFORMANCE CHARACTERISTICS LTC1798-2.5* Input Current vs Temperature 8 100 TA = 25°C 80 70 60 50 40 30 20 0 0.1 1 10 OUTPUT SOURCE CURRENT (mA) 4 3 2 0 1798 G02 LTC1798-2.5* Output Short-Circuit Current vs Input Voltage LTC1798-2.5* Output Short-Circuit Current vs Input Voltage 15 10 5 2 4 6 8 10 INPUT VOLTAGE (V) 12 TA = 25°C OUTPUT SHORTED TO GND 2 4 6 8 10 INPUT VOLTAGE (V) 12 14 1798 G07 0 25 50 75 100 125 150 TEMPERATURE (°C) TA = 25°C VIN = VOUT(NOM) + 0.2V 3 SINKING 2 1 SOURCING 0 –1 –2 –3 0 0.1 1 10 OUTPUT CURRENT (mA) LTC1798-2.5 PSRR vs Frequency 60 6 5 4 100 1798 G06 POWER SUPPLY REJECTION RATIO (dB) INPUT CURRENT (µA) OUTPUT VOLTAGE (V) 2.5000 12 5 –5 14 TA = 25°C 2.5005 OUTPUT SHORTED TO VIN –4 7 TA = 25°C 6 8 10 INPUT VOLTAGE (V) 10 LTC1798-2.5* Input Current vs Input Voltage 2.5010 4 20 1798 G05 LTC1798-2.5* Output Voltage vs Input Voltage 2 30 5 1798 G04 2.4995 40 4 41 14 50 LTC1798 Series Load Regulation ∆VOUT FROM NO LOAD (mV) 20 OUTPUT SHORTED TO GND 1798 G03 42 TA = 25°C OUTPUT SHORTED TO VIN TA = 25°C VIN = VOUT(NOM) + 0.2V 60 0 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 1798 G01 OUTPUT SHORT-CIRCUIT CURRENT (mA) OUTPUT SHORT-CIRCUIT CURRENT (mA) 5 0 –50 –25 100 25 0 6 1 10 0 70 VIN = 2.7V 7 INPUT CURRENT (µA) DROPOUT VOLTAGE (mV) 90 LTC1798 Series Output Short-Circuit Current vs Temperature OUTPUT SHORT-CIRCUIT CURRENT (mA) LTC1798-2.5* Dropout Voltage vs Output Source Current 2 4 6 8 10 INPUT VOLTAGE (V) 12 14 1798 G08 VIN = 2.7V 50 40 30 20 10 0 10 100 1k FREQUENCY (Hz) 10k 1798 G09 1798fc 4 LTC1798 Series TYPICAL PERFORMANCE CHARACTERISTICS LTC1798-2.5 0.1Hz to 10Hz Noise LTC1798-5 Input Current vs Input Voltage in Dropout LTC1798-2.5 Input Current vs Input Voltage in Dropout 1400 250 TA = –55°C INPUT CURRENT (µA) 1200 5µV/DIV 200 TA = 25°C 1000 INPUT CURRENT (µA) VIN = 2.7V TA = 125°C 800 600 400 0 1798 G10 150 TA = 25°C 100 TA = –55°C 50 200 1SEC/DIV TA = 125°C 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1798 G11 0 0 0.5 1 1.5 2 2.5 3 3.5 INPUT VOLTAGE (V) 4 4.5 5 1798 G12 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 0.1µF capacitor is recommended if the output loading changes. (VOUT + 0.2V) ≤ VIN ≤ 12.6V. DNC (Pin 3): (LTC1798-2.5/LTC1798-3/LTC1798-4.1/ LTC1798-5) 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. Selecting R2 ≥ 10k will make IOUT < 250µA. 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. It is stable with output bypass capacitor ranging from 0µF to 1µF. FB (Pin 3): (LTC1798) Resistor Divider Feedback Pin. Connect a resistor divider from OUT to GND and the center tap to FB. This pin sets the output potential. 1798fc 5 LTC1798 Series BLOCK DIAGRAM 2 IN + – 2.385V OUT 6 R1 FB 3 (LTC1798) R2 GND 4 1798 BD NOTE: R1 AND R2 ARE NOT CONNECTED FOR LTC1798 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 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 circuitry 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 IOUT 1mA dissipates only 10.8µW 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 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 capacitance is required, a resistor in series with the capacitor is recommended IOUT 0mA VOUT 100mV/DIV 1mA 0mA VOUT 100mV/DIV 1798 F01a 10ms/DIV 1798 F01b 0.5ms/DIV Figure 1. Reference Output Load Transient Response, 1µF Output Capacitor 1798fc 6 LTC1798 Series APPLICATIONS INFORMATION 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. Internal P-Channel Pass Transistor 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 LTC1798 series provides a lower dropout voltage (200mV max) than PNP-based references. The LTC1798 series features an internal P-channel MOSFET pass transistor. This provides several advantages over similar designs using a PNP bipolar pass transistor. 5.2V TO 12.6V 2 0.1µF IN OUT GND 4 6 5V COUT >1µF DAMPING RESISTOR