10µA, Low-Dropout, Precision Voltage References MAX872/MAX874. General Description. Features. Applications. Ordering Information

Transcription

1 9-; Rev 2; 6/97, Low-Dropout, General Description The / precision 2. and 4.96 micropower voltage references consume a maximum of only and operate from supply voltages up to. The combination of ultra-low quiescent current and low dropout makes them ideal for battery-powered equipment. They source and sink up to with only input voltage headroom, which makes the 2. ideal for use with a 3 supply and the 4.96 ideal for use with a supply. Initial accuracy of.2% at +2 C (± for the, ±8 for the ) and low 4ppm/ C max drift make these references suitable for a wide range of precision applications. Hand-Held Instruments Battery-Operated Equipment Power Supplies 3. (). () Applications Typical Operating Circuit Features 2. ±.2% () 4.96 ±.2% () Wide Operating oltage Range 2.7 to () 4.3 to () Max Supply Current 4ppm/ C Max Drift Over Extended Temp. Range Over Temp. µ/ () 7µ/ () Load Regulation Over Temp..6/mA Max ()./ma Max () ± Sink/Source Current Ordering Information PART TEMP. RANGE PIN-PACKAGE CPA CSA C/D C to +7 C C to +7 C C to +7 C 8 Plastic DIP 8 SO Dice* EPA -4 C to +8 C 8 Plastic DIP ESA -4 C to +8 C 8 SO CPA C to +7 C 8 Plastic DIP CSA C to +7 C 8 SO C/D C to +7 C Dice* EPA -4 C to +8 C 8 Plastic DIP ESA -4 C to +8 C 8 SO * Dice are specified at +2 C only. / IN Pin Configuration TOP IEW I.C. 8 COMP IN TEMP I.C. 4 REFERENCE WITH MED OUTPUT DIP/SO Maxim Integrated Products For free samples & the latest literature: or phone For small orders, phone

2 / ABSOLUTE MAXIMUM RATINGS Supply oltage...24 Output Short-Circuit Duration...Continuous to Either Supply C COMP Input to Input to ( IN +.3) TEMP Output to ( IN +.3) Continuous Power Dissipation (T A = +7 C) Plastic DIP (derate 9.9mW/ C above +7 C)...727mW SO (derate.88mw/ C above +7 C)...47mW Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS ( IN = 2.7, I L = ma, T A = +2 C, unless otherwise noted.) Noise TEMP oltage Load Regulation (Note ) Change in Supply Current vs. IN Short-Circuit Output Current Adjustment Range e n / IN /I OUT / IN I SC TEMP ADJ.Hz to Hz IN = 4. to IN = 2.7 to. Sourcing ma to.ma Sinking ma to -.ma IN = 2.7 to short to short to IN +.2 Operating Temperature Ranges MAX87_C... C to +7 C MAX87_E...-4 C to +8 C Storage Temperature Range...-6 C to + C Junction Temperature Range (T j )...-6 C to +6 C Lead Temperature (soldering, sec)...+3 C /- +/ µp-p µ/ /ma / ma ELECTRICAL CHARACTERISTICS ( IN = 4.3, I L = ma, T A = +2 C, unless otherwise noted.) Noise e n.hz to Hz 9 µp-p / IN IN = 4.3 to 7 µ/ Load Regulation (Note ) /I OUT Sourcing ma to.ma Sinking ma to -.ma..9 6 /ma 6. Change in Supply Current vs. IN / IN IN = 4.3 to.3. / Short-Circuit Output Current I SC short to short to IN 6 2 ma TEMP oltage TEMP 69 Adjustment Range ADJ +.2 ± ± 2

3 ELECTRICAL CHARACTERISTICS C ( IN = 2.7, I L = ma, T A = C to +7 C, unless otherwise noted.) Temperature Load Regulation (Note ) Change in Supply Current vs. IN Adjustment Range TEMP Output Temperature TC / IN /I OUT / IN ADJ TC TEMP IN = 4. to IN = 2.7 to. Sourcing ma to.4ma Sinking ma to -.4mA IN = 2.7 to IN /- 2.3 ppm/ C µ/ /ma / / C / ELECTRICAL CHARACTERISTICS C ( IN = 4.3, I L = ma, T A = C to +7 C, unless otherwise noted.) Temperature TC 4 ppm/ C / IN IN = 4.3 to 7 µ/ Load Regulation (Note ) /I OUT Sourcing ma to.4ma Sinking ma to -.4mA. 2 /ma Change in Supply Current vs. IN / IN IN = 4.3 to / Adjustment Range ADJ IN +.2 ± TEMP Output Temperature TC TEMP 2.3 / C Note : If the load current exceeds 3, connect a minimum of pf from to. Note that if a capacitor larger than pf is used, a compensation capacitor of C OUT / must be connected from to COMP. 3

4 / ELECTRICAL CHARACTERISTICS E ( IN = 2.7, I L = ma, T A = -4 C to +8 C, unless otherwise noted.) Temperature Load Regulation Change in Supply Current vs. IN Adjustment Range TC / IN /I OUT / IN ADJ IN = 4. to IN = 2.7 to. Sourcing ma to.3ma Sinking ma to -.3mA IN = 2.7 to IN /- ppm/ C µ/ /ma / TEMP Output Temperature TC TEMP 2.3 / C ELECTRICAL CHARACTERISTICS E ( IN = 4.3, I L = ma, T A = -4 C to +8 C, unless otherwise noted.) Temperature TC 4 ppm/ C / IN IN = 4.3 to 7 µ/ Load Regulation /I OUT Sourcing ma to.3ma Sinking ma to -.3mA. 2 /ma Change in Supply Current vs. IN / IN IN = 4.3 to / Adjustment Range ADJ IN +.2 ± TEMP Output Temperature TC TEMP 2.3 / C 4

5 Typical Operating Characteristics ( IN = 3 (), IN = (), no load, T A = +2 C, unless otherwise noted.) DROPOUT OLTAGE () DROPOUT OLTAGE vs. SOURCE CURRENT T A = +8 C T A = +2 C T A = -4 C SOURCE CURRENT () /74- SUPPLY CURRENT () SUPPLY CURRENT vs. INPUT OLTAGE INPUT OLTAGE () /74-2 SUPPLY CURRENT () SUPPLY CURRENT vs. TEMPERATURE IN = IN = IN = NO LOAD IN = 3 /74-3 / SUPPLY CURRENT () 2 SUPPLY CURRENT vs. TEMPERATURE IN = IN = IN = /74-4 OUT () OUTPUT OLTAGE vs. INPUT OLTAGE /74- OUT () OUTPUT OLTAGE vs. INPUT OLTAGE / INPUT OLTAGE () INPUT OLTAGE () LOAD REGULATION (/ma) LOAD REGULATION vs. TEMPERATURE SINKING TO - SOURCING TO /74-7 LOAD REGULATION (/ma) LOAD REGULATION vs. TEMPERATURE SINKING TO - SOURCING TO /74-8 OUT () OUTPUT OLTAGE vs. SOURCE CURRENT / SOURCE CURRENT (ma)

6 / Typical Operating Characteristics (continued) ( IN = 3 (), IN = (), no load, T A = +2 C, unless otherwise noted.) OUT () OUTPUT OLTAGE vs. SOURCE CURRENT /74- OUT () OUTPUT OLTAGE vs. TEMPERATURE /74- OUT () OUTPUT OLTAGE vs. TEMPERATURE / SOURCE CURRENT (ma) PSRR (db) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY NO LOAD IN = +3 TO + () IN = + TO +7 () NO INPUT FILTER INPUT FILTER CIRCUIT IN FIGURE 2 k k FREQUENCY (Hz) /74-3 TEMP OUTPUT () TEMP OUTPUT vs. TEMPERATURE NO LOAD /74-4 NOISE (p-p) NOISE vs. FREQUENCY k k FREQUENCY (Hz) NOISE IS FROM.Hz TO FREQUENCY INDICATED /74- Hz TO Hz NOISE Hz TO Hz NOISE 6

7 PIN, NAME I.C. IN TEMP COMP Pin Description FUNCTION Internal Connection. Make no connection to this pin Input oltage Temperature-Proportional Output oltage. Generates an output voltage proportional to junction temperature. Ground Trim. Connect to the center of a voltage divider for output trimming. Otherwise make no connection. Reference Output Compensation Input. Connect C LOAD / capacitor from to COMP to provide capacitive load compensation. Applications Information Trimming the The / s output voltage is trimmed for.2% tolerance at +2 C. If additional OUT trimming is desired, connect a potentiometer to, as shown in Figures a and b. Adjusting OUT away from its factory-trimmed voltage typically changes the output voltage tempco by 7ppm/ C per. Reducing Input Ripple with an Input Filter The Power-Supply Rejection Ratio vs. Frequency graph in the Typical Operating Characteristics shows ripple rejection between Hz and 2kHz. As input RC filter with a pole less than Hz, as shown in Figure 2, further attenuates input ripple with this band. The voltage drop across the input resistor (due to supply and load current) slightly increases the dropout voltage. The increase is given by [(ILOAD + ISUPPLY) R]. Choosing the Output and Compensation Capacitors Connecting a capacitor between oid and reduces load transients. If the load exceeds 3, connect a minimum of pf from OUT to. The type of capacitor is not critical. If the total load capacitance from OUT to (CLOAD = output capacitor + other capacitive load) is larger than pf, connect a compensation capacitor with a value of CLOAD/ between COMP and OUT. 3 IN M.M RANGE: -3/+8 Figure a. Adjusting with the Input on the IN 2M M 4M RANGE: -/+3 Figure b. Adjusting with the Input on the / 7

8 / 3. (). () Ω µf IN COMP.47µF 4.7µF + IN TEMP 27k 4k 7k () 33k () + /2 MAX922 + /2 MAX922 REF OUT OER TEMP TEMP OUT OF RANGE UNDER TEMP /4 74HC86-4 C TO +8 C OPERATING RANGE Figure 2. Input Filter Reduces Input Ripple TEMP Output The TEMP output provides a voltage proportional to the / junction temperature. Since the power dissipation of the / is <µw typ, the junction temperature is within. C of the ambient temperature. Although it goes unused in most applications, the ambient temperature information given by the TEMP output may be used to control LCD contrast, or to provide ADC gain compensation or thermal out-of-range indication. TEMP must be buffered or connected to a high-impedance input. Operating Temperature Window Comparator In Figure 3, a window comparator monitors the TEMP output and indicates if the temperature is out of the nominal operating range. For the resistor values shown, the circuit will indicate an out-of-range condition if the ambient temperature should rise above +8 C or dip below -4 C. Start-Up When the input voltage is below the factory-selected output voltage, the / can draw excessive supply current (hundreds of microamps). If the source resistance is too high, the voltage drop across the source resistance can prevent the input voltage to the device from reaching the minimum dropout voltage. Therefore, when using the / in lowdropout applications, ensure that the power supply has a low source resistance. Figure 3. Operating Temperature Range Window Comparator Chip Topography IN TEMP / *N.C. COMP.72" (.829mm) *MAKE NO CONNECTIONS TO THESE PADS TRANSISTOR COUNT: 89 SUBSTRATE CONNECTED TO. *N.C. OUT." (2.794mm) Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 8 Maxim Integrated Products, San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.