LTC6943

LTC6943 Micropower, Dual Precision Instrumentation Switched Capacitor Building Block DESCRIPTIO The LTC®6943 is a monolithic, charge-balanced, dual switched capacitor instrumentation building block. A pair of switches alternately connects an external capacitor to an input voltage and then connects the charged capacitor across an output port. The internal switches have a break-before-make action. An internal clock is provided and its frequency can be adjusted with an external capacitor. The LTC6943 can also be driven with an external CMOS clock. The LTC6943, when used with low clock frequencies, provides ultra precision DC functions without requiring precise external components. Such functions are differential voltage to single-ended conversion, voltage inversion, voltage multiplication and division by 2, 3, 4, 5, etc. The LTC6943 is manufactured using Linear Technology’s enhanced LTCMOSTM silicon gate process, and it is functionally compatible with the LTC1043. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ Low Power, IS = 60µA(Max) Robust, Latch Up Proof Instrumentation Front End with 120dB CMRR Precise, Charge-Balanced Switching Operates from 5V to 18V Internal or External Clock Operates up to 5MHz Clock Rate Two Independent Sections with One Clock Tiny SSOP-16 Package APPLICATIO S ■ ■ ■ ■ ■ Ultra Precision Voltage Inverters, Multipliers and Dividers V–F and F–V Converters Sample-and-Hold Current Sources Precision Instrumentation Amplifiers , LTC and LT are registered trademarks of Linear Technology Corporation. LTCMOS is a trademark of Linear Technology Corporation. TYPICAL APPLICATIO 5V INPUT 0V TO 3.7V 3 Precision Voltage Controlled Current Source with Ground Referred Input and Output Precision Current Sensing in Supply Rails 1 + – 5 LTC2050 4 2 0.68µF 5V 1k 7 3 1/2 LTC6943 POSITIVE OR NEGATIVE RAIL I E RSHUNT 1/2 LTC6943 11 12 6 9 1µF 10 1µF 1k 12 15 0.001µF 11 14 IOUT = VIN 1000Ω OPERATES FROM A SINGLE 5V SUPPLY 6943 • TA01a U U U 10 1µF 9 1µF E I= E RSHUNT 6 7 14 0.01µF 15 6943 • TA01b 6943f 1 LTC6943 ABSOLUTE (Note 1) AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW CB+ 1 CB– 2 V+ 3 S2B 4 S1B 5 S1A 6 S2A 7 SHA 8 16 S3B 15 V– 14 COSC 13 S4B 12 S4A 11 S3A 10 CA– 9 CA+ Supply Voltage ........................................................ 18V Input Voltage at Any Pin .......... –0.3V ≤ VIN ≤ V+ + 0.3V Operating Temperature Range (Note 2) ............................................ –40°C to 125°C Specified Temperature Range (Note 2) .............................................–40°C to 125°C Storage Temperature Range ................. –65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C ORDER PART NUMBER LTC6943CGN LTC6943IGN LTC6943HGN GN PART MARKING 6943C 6943I 6943H GN PACKAGE 16-LEAD NARROW PLASTIC SSOP TJMAX = 125°C, θJA = 110°C/W Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS + SYMBOL PARAMETER IS Power Supply Current CONDITIONS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V = 10V, V– = 0V LTC6943C LTC6943I MIN TYP MAX 40 ● MIN LTC6943H TYP MAX 40 80 6 240 400 185 30 40 25 75 5 120 60 90 150 170 100 200 400 700 700 1 50 75 70 100 UNITS µA µA µA µA pA nA Ω Ω Ω kΩ kHz kHz kHz µA µA ns ns MHz dB Pin 14 Connected High or Low COSC (Pin 14 to V –) = 100pF 60 90 150 170 100 40 400 700 700 1 50 75 70 100 20 10 80 ● II RON RON fOSC OFF Leakage Current ON Resistance ON Resistance Internal Oscillator Frequency Any Switch, Test Circuit 1 (Note 3) ● 6 240 ● Test Circuit 2, VIN = 7V, 1 = ± 0.5mA V+ = 10V, V – = 0V Test Circuit 2, VIN = 3.1V, 1 = ±0.5mA V + = 5V, V – = 0V COSC (Pin 14 to V –) = 0pF COSC (Pin 14 to V –) = 100pF Test Circuit 3 Pin 14 at V+ or V – 400 ● ● ● 20 12 185 30 40 25 IOSC Pin Source or Sink Current Break-Before-Make Time Clock to Switching Delay COSC Pin Externally Driven V+ = 5V, V – = – 5V, –5V < VCM < 5V DC to 400Hz 75 5 120 fM CMRR Maximum External CLK Frequency COSC Pin Externally Driven with CMOS Levels Common Mode Rejection Ratio Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: All versions of the LTC6943 are guaranteed functional over the operating temperature range of –40°C to 125°C. The LTC6943CGN is guaranteed to meet 0°C to 70°C specifications and is designed, characterized and expected to meet the specified performance from –40°C to 85°C but it is not tested or QA sampled at these temperatures. The LTC6943IGN is guaranteed to meet specified performance from –40°C to 85°C. The LTC6943HGN is guaranteed to meet specified performance from –40°C to 125°C. Note 3: OFF leakage current at 25°C is guaranteed by design and it is not 100% tested in production. 6943f 2 U W U U WW W LTC6943 TYPICAL PERFOR A CE CHARACTERISTICS Power Supply Current vs Power Supply Voltage 0.50 0.45 0.40 SUPPLY CURRENT (mA) 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 0 COSC = 0pF, TA = –55°C COSC = 0pF, TA = 25°C COSC = 0pF, TA = 125°C COSC = 4700pF, TA = –55°C COSC = 4700pF, TA = 25°C COSC = 4700pF, TA = 125°C RON (Ω) RON (Ω) 2 4 6 8 10 12 VSUPPLY (V) 14 RON vs VIN 260 240 220 V IN 200 RON (Ω) 180 160 140 120 100 80 0 2 4 6 8 10 12 14 16 18 20 VIN (V) LTC1043 • TPC04 RON (PEAK) I = 100µA V+ = 15V V – = 0V TA = 25°C RON (Ω) I = 100µA I = mA 500 400 300 200 100 0 0 RON (Ω) Oscillator Frequency, fOSC vs COSC 1000 TA = 25°C 250 225 200 OSCILLATOR FREQUENCY NORMALIZED TO fOSC AT 5V SUPPLY 100 fOSC (kHz) IOSC (kHz) 10 VS = 5V VS = 10V 1 VS = 15V 0.1 0 1000 2000 3000 COSC (pF) 4000 5000 6943 TPC07 UW 16 18 6943 TPC01 (Test Circuits 2 through 4) RON vs VIN 550 500 450 V IN 400 350 300 250 200 150 100 0 1 2 VIN (V) LTC1043 • TPC02 RON vs VIN V+ = 5V V – = 0V TA = 25°C 280 260 240 VIN 220 200 180 160 140 120 100 3 4 5 0 1 2 3 4 56 VIN (V) 7 8 9 10 I = 100µA I = mA RON (PEAK) I = 100µA V+ = 10V V – = 0V TA = 25°C RON (PEAK) I = 100µA I = 100µA I = mA LTC1043 • TPC03 RON (Peak) vs Power Supply Voltage 1000 900 800 700 600 VIN ≈ 3.2V VIN ≈ 7V 3V ≤ V+ + ≤18V V – = 0V TA = 25°C 2 4 6 VIN = 1.6V VIN RON (PEAK) I = 100µA 1100 1000 900 800 700 600 500 400 300 200 100 RON (Peak) vs Power Supply Voltage and Temperature RON (PEAK) VIN I = 100µA TA = 125°C VIN ≈ 11V TA = 70°C TA = –55°C 0 2 4 6 8 10 12 14 16 18 20 VSUPPLY (V) LTC1043 • TPC06 VIN ≈ 15.1V 8 10 12 14 16 18 20 VSUPPLY (V) LTC1043 • TPC05 Oscillator Frequency, fOSC vs Supply Voltage TA = 25°C Normalized Oscillator Frequency, fOSC vs Supply Voltage 1.5 TA = 25°C 1.3 COSC = 0pF 1.0 COSC = 100pF 0.5 COSC = 10,000pF 0.3 COSC = 1,000pF 175 150 125 100 75 50 25 0 0 2 4 6 8 COSC = 0pF COSC = 100pF 10 12 VSUPPLY (V) 14 16 18 0 0 2 4 6 8 10 12 VSUPPLY (V) 14 16 18 6943 TPC08 6943 TPC09 6943f 3 LTC6943 TYPICAL PERFOR A CE CHARACTERISTICS Oscillator Frequency, fOSC vs Ambient Temperature 350 300 VS = 5V 250 fOSC (kHz) PIN 14 SOURCE OR SINK CURRENT (µA) COSC = 0pF 50 ISOURCE, TA = –55°C ISOURCE, TA = 25°C tNOV (ns) 200 150 100 50 VS = 10V VS = 15V 0 –50 –25 50 25 75 0 TEMPERATURE (°C) BLOCK DIAGRA 4 UW 100 6943 TPC10 (Test Circuits 2 through 4) Break-Before-Make Time, tNOV, vs Supply Voltage 80 TA = 25°C 70 60 50 40 30 COSC Pin ISINK, ISOURCE vs Supply Voltage 100 ISINK, TA = –55°C 75 ISINK, TA = 25°C 25 ISINK, TA = 125°C ISOURCE, TA = 125°C 0 0 2 4 6 8 10 12 14 16 18 20 10 0 2 4 6 8 10 12 14 16 18 20 VSUPPLY (V) LTC1043 • TPC12 125 LTC1043 • TPC11 W S1A 6 7 S2A SHA 8 9 CA+ 10 CA– S3A 11 CHARGE BALANCING CIRCUITRY S1B 5 4 S2B 12 S4A 1 CB+ 2 CB– S3B 16 CHARGE BALANCING CIRCUITRY 13 S4B NON-OVERLAPPING CLOCK V+ V– COSC 14 OSCILLATOR 15 V– 3 V+ THE CHARGE BALANCING CIRCUITRY SAMPLES THE VOLTAGE AT S3 WITH RESPECT TO S4 (PIN 14 HIGH) AND INJECTS A SMALL CHARGE AT THE C+ PIN (PIN 14 LOW). THIS BOOSTS THE CMRR WHEN THE LTC6943 IS USED AS AN INSTRUMENTATION AMPLIFIER FRONT END. FOR MINIMUM CHARGE INJECTION IN OTHER TYPES OF APPLICATIONS, S3A AND S3B SHOULD BE GROUNDED THE SWITCHES ARE TIMED AS SHOWN WITH PIN 14 HIGH 6943 • BD01 6943f LTC6943 TEST CIRCUITS Test Circuit 1. Leakage Current Test (6, 11, 5, 16) (7, 12, 4, 13) NOTE: TO OPEN SWITCHES, S1 AND S3 PIN 14, SHOULD BE CONNECTED TO V –. TO OPEN S2, S4, THE COSC PIN 14 SHOULD BE CONNECTED TO V+ COSC 6943 • TC01 Test Circuit 2. RON Test (6, 11, 5, 16) (7, 12, 4, 13) A + 0V TO 10V + (9, 10, 1, 2) VIN (9, 10, 1, 2) 100µA to 1mA CURRENT SOURCE A 6943 • TC02 Test Circuit 3. Oscillator Frequency, fOSC 6 (TEST PIN) 1 V+ V– COSC Test Circuit 4. CMRR Test 7 VOUT 15 8 14 9 1µF 1µF CAPACITORS ARE NOT ELECTROLYTIC + 3 LTC6943 4 10 + 5 IV 6943 • TC03 11 12 + V– ≤ VCM ≤ V+ CMRR = 20 LOG () VCM VOUT 6943 • TC04 NOTE: FOR OPTIMUM CMRR, THE COSC SHOULD BE LARGER THAN 0.0047µF, AND THE SAMPLING CAPACITOR ACROSS PINS 9 AND 10 SHOULD BE PLACED OVER A SHIELD TIED TO PIN 8 APPLICATIO S I FOR ATIO Common Mode Rejection Ratio (CMRR) The LTC6943, when used as a differential to single-ended converter rejects common mode signals and preserves differential voltages (Figure 1). Unlike other techniques, the LTC6943’s CMRR does not degrade with increasing common mode voltage frequency. During the sampling mode, the impedance of Pins 1, 2 (and 9, 10) should be balanced, otherwise, common mode signals will appear differentially. The value of the CMRR depends on the value of the sampling and holding capacitors (CS, CH) and on the sampling frequency. Since the common mode voltages are not sampled, the common mode signal frequency can well exceed the sampling frequency without experiencing aliasing phenomena. The CMRR of Figure 1 is measured by shorting Pins 6 and 11 and by observing, with a U 1/2 LTC6943 6 7 C+ VD 9 W UU + + CS C– 10 VD CH 11 VCM 12 + CS, CH ARE MYLAR OR POLYPROPYLENE 6943 • AI01 Figure 1. Differential to Single-Ended Converter 6943f 5 LTC6943 APPLICATIO S I FOR ATIO precision DVM, the change of the voltage across CH with respect to an input CM voltage variation. During the sampling and holding mode, charges are being transferred and minute voltage transients will appear across the holding capacitor. Although the RON on the switches is low enough to allow fast settling, as the sampling frequency increases, the rate of charge transfer increases and the average voltage measured with a DVM across it will increase proportionally; this causes the CMRR of the sampled data system, as seen by a “continuous” instrument (DVM), to decrease (Figure 2). Switch Charge Injection Figure 3 shows one out of the eight switches of the LTC6943, configured as a basic sample-and-hold circuit. When the switch opens, a ‘‘hold step’’ is observed and its magnitude depends on the value of the input voltage. Figure 4 shows charge injected into the hold capacitor. For instance, a 2pCb of charge injected into a 0.01µF capacitor causes a 200µV hold step. As shown in Figure 4, there is a predictable and repeatable charge injection cancellation when the input voltage is close to half the supply voltage of the LTC6943. This is a unique feature of this product, containing charge-balanced switches fabricated with a self-aligning gate CMOS process. Any switch of the LTC6943, when powered with symmetrical dual supplies, will sample-and-hold small signals around ground without any significant error. 140 120 100 CMRR (dB) CS = CH = 1µF CS = 1µF, CH = 0.1µF 80 60 40 20 100 1k fOSC (Hz) 10k 100k 6943 • AI02 Figure 2. CMRR vs Sampling Frequency 6 U Shielding the Sampling Capacitor for Very High CMRR Internal or external parasitic capacitors from the C + pin(s) to ground affect the CMRR of the LTC6943 (Figure 1). The common mode error due to the internal junction capacitances of the C + Pin(s) 1 and 9 is cancelled through internal circuitry. The C + pin, therefore, should be used as the top plate of the sampling capacitor. A shield placed underneath the sampling capacitor and connected to C – helps to boost the CMRR to 120dB (Figure 5). Excessive external parasitic capacitance between the C – pins and ground indirectly degrades CMRR; this becomes visible especially when the LTC6943 is used with clock frequencies above 2kHz. Because of this, if a shield is used, the parasitic capacitance between the shield and circuit ground should be minimized. It is recommended that the outer plate of the sampling capacitor be connected to the C – pin(s). COSC Pin (14) The COSC pin can be used with an external capacitor, COSC, connected from Pin 14 to Pin 15, to modify the internal oscillator frequency. If Pin 16 is floating, the internal 24pF capacitor, plus any external interpin capacitance, set the oscillator frequency around 190kHz with ± 5V supply. The typical performance characteristics curves provide the necessary information to set the oscillator frequency for various power supply ranges. Pin 14 can also be driven with an external CMOS level clock to override the internal oscillator. 5V 1 1/8 LTC6943 VIN 1000pF 5 W UU + 1/2 LTC1013 VOUT – –5V V+ 0V SAMPLE HOLD TO PIN 14 6943 • AI03 Figure 3 6943f LTC6943 APPLICATIO S I FOR ATIO 12 10 V+ = 15V V– = 0V CHARGE INJECTION (pCb) 8 6 4 2 0 0 2 4 6 V+ = 10V V– = 0V V+ = 5V V– = 0V 10 8 VIN (V) 12 14 16 6943 • AI04 Figure 4. Individual Switch Charge Injection vs Input Voltage TYPICAL APPLICATIO S Divide by 2 Multiply by 2 Ultra Precision Voltage Inverter 1/2 LTC6943 1/2 LTC6943 VIN 6 7 VOUT = VIN /2 VOUT 1µF 9 1µF 10 1µ F 6 11 12 14 0.01µF 15 VOUT = VIN /2 ± 1ppm 0 ≤ VIN ≤ V+ 3 ≤ V+ ≤ 18V 6943 • TA03 U OUTSIDE FOIL CS 1 2 PRINTED CIRCUIT BOARD AREA LTC6943 6943 • AI05 W U UU Figure 5. Printed Circuit Board Layout Showing Shielding the Sampling Capacitor 1/2 LTC6943 7 VIN 6 7 VOUT = –VIN 9 9 1µF 1µF 10 1µF 10 VIN 11 12 11 12 14 15 0.01µF 14 0.01µF 15 VOUT = 2VIN ± 5ppm 0 ≤ VIN ≤ V+ / 2 3 ≤ V+ ≤ 18V VOUT = –VIN ±2ppm V – < VIN < V + V + = +5V, V – = –5V 6943 • TA02 6943 • TA03 6943f 7 LTC6943 TYPICAL APPLICATIO S Precision Multiply by 3 VIN LTC6943 6 7 9 1µF 10 11 VOUT 5 2 1µF 3 1µF 1µF 16 14 0.01µF VOUT = 3VIN ±10ppm 0 < VIN < V+/3 3V < V+ < 18V VIN 0V TO 3V 8 U Divide by 3 LTC6943 VIN 6 7 9 1µF 10 11 12 12 VOUT 1µF 4 5 4 2 1µF 3 VOUT 13 16 13 1µF 14 15 0.01µF 15 VOUT = VIN /3 ±3ppm 0 ≤ VIN ≤ V+ 6943 • TA07 6943 • TA06 0.01% V/F Converter –5V 1k LT1009 2.5V 15 5V 7 1/2 LTC6943 6 1µF 9 12 11 fOUT: 0kHz TO 30kHz 3 GAIN 2.5k 6.19k** 1µF 3 5V 2 10 0.01µF* 6 14 – + 7 LT1056 4 –5V *POLYPROPYLENE **1% FILM RESISTOR 22k Q1 2N2907A –5V 30pF 330k 1µF 6943 • TA08 6943f LTC6943 TYPICAL APPLICATIO S 0.01% Analog Multiplier 1/4 LTC6943 12 11 LT1004-1.2V 10 5V YINPUT 7.5k* 2 1µF 0.001µF † – + 7 LT1056 6 14 1/4 LTC6943 XINPUT 30pF 5 4 2 5V 7 LT1056 330k OPERATE LTC6943 FROM ± 5V † POLYPROPYLENE, MOUNT CLOSE *1% FILM RESISTOR ADJUST OUTPUT TRIM SO X • Y = OUTPUT ± 0.01% 3 1 0.001µF † 3 4 –5V 22k 2N2907A (FOR START-UP) –5V + INPUT 10 – 43k V+ = 5V 1N914 2 U 1k –5V 1µF 20k OUTPUT TRIM 0.01µF 80.6k* – + 6 OUTPUT XY ±0.01% 4 –5V 1µF 6943 • TA09 Single 5V Supply, Ultra Precision Low Power with True Rail-to-Rail In/Out Instrumentation Amplifier 5V LTC6943 6 7 3 5 1 OUTPUT AV = 1000 + – LTC2054CS 4 9 1µF 1µF 2 100Ω 11 12 99.9k 5 4 0.22µF 10k 1 1µF 1µF NONPOLARIZED 16 13 ≈ – 0.5V 14 15 3 5V INPUT AND OUTPUT VOLTAGE RANGE INCLUDES GROUND. INPUT REFERRED OFFSET ERRORS ARE TYPICALLY 3µV WITH 2µV OF PEAK-TO-PEAK DC TO 10Hz NOISE CMRR ~ 120dB 6943 • TA10 0.0047 6943f 9 LTC6943 TYPICAL APPLICATIO S Voltage Controlled Current Source with Ground Referred Input and Output 5V INPUT 0V TO 2V 3 8 1 THERMISTOR BRIDGE IS THE SIGNAL SOURCE 10k* T1 500Hz SINE DRIVE 4 1 6.19k 6.19k 3 3 6.19k 2 5V RT PHASE TRIM 0.002 2 5V 5V 8 LT1011 3 7 4 1 –5V ZERO CROSSING DETECTOR 1k 50k 10k 10 U + – 1/2 LT1013 2 4 0.68µF 5V 1k 3 7 6 9 1µF 10 1µF 100Ω 12 1/2 LTC6943 15 11 IOUT = 14 VIN 100Ω 0.001µF OPERATES FROM A SINGLE 5V SUPPLY 6943 • TA11 Lock-In Amplifier (= Extremely Narrow-Band Amplifier) SYNCHRONOUS DEMODULATOR 10k* 5V 2 + LT1007 6 11 – LT1056 1/4 LTC6943 10 100k 3 5V 2 1M – –5V + –5V – LT1012 6 VOUT = 1000 • DC BRIDGE SIGNAL 12 100Ω 14 1µF 3 + 4 –5V + 0.01µF 47µF T1 = TF5SX17ZZ, TOROTEL RT = YSI THERMISTOR 44006 ≈ 6.19k AT 37.5°C *MATCH 0.05% 6.19k = VISHAY S-102 OPERATE LTC6943 WITH ± 5V SUPPLIES LOCK-IN AMPLIFIER TECHNIQUE USED TO EXTRACT VERY SMALL SIGNALS BURIED INTO NOISE 6943 • TA13 + – 6943f LTC6943 TYPICAL APPLICATIO S 50MHz Thermal RMS/DC Converter 5V 5V 3 30k** 30k** 5 10k 1 1µF 2 0.01µF 10k 16 300mV– 10VRMS INPUT BRN T1 GRN RED RED T2 GRN 2% ACCURACY DC-50MHZ 100:1 CREST FACTOR CAPABILITY T1 – T2 = YELLOW SPRINGS INST. CO. THERMISTOR COMPOSITE ENCLOSE T1 AND T2 IN STYROFOAM *1% RESISTOR **0.1% RESISTOR 1µF 15 BRN 13 0.01µF 1µF 14 301Ω* 10k 10k 1µF 2 1/2 LTC6943 4 3 5V Single Supply Precision Linearized Platinum RTD Signal Conditioner 250k* 5V 3 10k* (LINEARITY CORRECTION LOOP) + – 8 1 2.74k* 50k ZERO ADJUST 8.25k* 1/2 LT1013 2 4 0.1µF 2k 6 1/2 LTC6943 7 9 1µF 10 1µF 887Ω* 11 12 1mA Rp 100Ω AT 0°C U + – 8 LT1013 4 1 CALIBRATION ADJUST 20k 5 100k* 5V + LT1013 7 DC OUTPUT 0V TO 3.5V 10k 6 – 6943 • TA13 2.4k LT1009 2.5V 5V 3 1/2 LTC6943 4 5 5 + 1/2 LT1013 0V TO 4V = 0°C TO 400°C ± 0.05°C 7 5k LINEARITY ADJUST 6 1 1µF 2 1µF – 1k GAIN ADJUST 8.06k* 13 16 1k* Rp = ROSEMOUNT 118MFRTD * 1% FILM RESISTOR TRIM SEQUENCE: SET SENSOR TO 0°C VALUE. ADJUST ZERO FOR 0V OUT SET SENSOR TO 100°C VALUE. ADJUST GAIN FOR 1000V OUT SET SENSOR TO 400°C VALUE. ADJUST LINEARITY FOR 4000V OUT 6943 • TA14 REPEAT AS REQUIRED 14 0.01µF 15 6943f 11 LTC6943 TYPICAL APPLICATIO S 0.01% F/V Converter 10k GAIN TRIM 1µF 75k* 1k –5V LT1004-1.2C 1µF 11 FREQUENCY IN 0kHz TO 30kHz GAIN CONTROL 0kHz TO 10kHz = GAIN 0 TO 1000 VIN FOR DIFFERENTIAL INPUT, GROUND PIN 7A AND USE PINS 11A AND 6A FOR INPUTS fIN • 0.01µF GAIN = ; GAIN IS NEGATIVE AS SHOWN 1kHz • 100pF FOR SINGLE-ENDED INPUT AND POSITIVE GAIN, GROUND PIN 8A AND USE PIN 7A FOR INPUT OPERATES THE LTC6943'S WITH ±5V SUPPLIES 5V 2 0.01µF 6 7 LT1056 3 VOUT 12 U 1/4 LTC6943 12 2 5V – + 7 LT1056 6 0V TO 3V OUTPUT 3 10 1000pF** 14 4 –5V 3 15 5V –5V * 1% FILM RESISTOR ** POLYPROPYLENE 6943 • TA15 Frequency-Controlled Gain Amplifier 11A 1/2 LTC6943A 12A 11B 1/2 LTC6943B 12B 14A 10A 0.01µF 9A 1kHz 14B 10B 100pF 9B 6A 7A 6B 7B 3 5V 15 –5V – + 4 –5V 6943 • TA16 6943f LTC6943 TYPICAL APPLICATIO S Battery Powered Relative Humidity Sensor Signal Conditioner 0.1 100pF +9 4.7k 2.32k* 10k 0.1 1.8k* LT1004 1.2V 90% TRIM 500Ω 11 10 0.1µF SENSOR RESPONSE RH% 5 25 50 75 90 CAPACITANCE 379.3pF 413.3pF 455.8pF 498.3pF 523.8pF 6 0.1 SENSOR 22M – A1 LT1006 + OUTPUT 0-1.00V = 0-100% RH LTC6943 12 +9 1 10pF≤ 5% TRIM 16 2 13 ≤ 5V Powered, Frequency Output, Relative Humidity Sensor Signal Conditioner 80.6k* OUT 1N4148 125kHz 4V LTC6943 14 13.3k* 4V 0.1µF 6 9 SENSOR 10 CHARGE PUMP 5V 200Ω TO ALL 4V POINTS 1k* 11 1µ F 12 562k* 100k RH = 25% TRIM (204.5pF) 4V 1N5712 110k* * = 1% METAL FILM RESISTOR † = WIMA, TYPE MKP-2 SENSOR = PANAMETRICS MC-2 0% RH = 196.7pF 100% RH = 227.8pF 0.31pF/RH 20k RH = 100% TRIM (227.8pF) 6943 TA20 1µ F LT1634 4V U +9 3 15 4 5 9 7 * = 1% FILM RESISTOR ≤ = POLYPROPYLENE SENSOR = PANAMETRICS TYPE RHS 500pF AT RH = 76% 1.7pF/RH 6943 TA17 RSET LTC1799 O1 VIN CLOCK 5V GND 10k BAT85 Q1 VN2222L 4V 5V 15 10k 7 4V 3 1000pF † 5V S D RESET COMPARATOR – A1 LTC1050 L + 300k* 4V 5V Q + INTEGRATOR C1 +V LT1671 – Q OUT 0% TO 100% RH = 0Hz TO 1kHz 300pF 6943f 13 LTC6943 TYPICAL APPLICATIO S Linear Variable Differential Transformer (LVDT), Signal Conditioner 1/4 LTC6943 6 5V 30k 3 5V 1 1.5kHz YEL-BLK 4 – 5V BLUE GRN 10k 4.7k 1N914 LT1004 1.2V YEL-RED BLK LVDT 10 10µF 7.5k 11 1/4 LTC6943 LVDT = SCHAEVITZ E-100 5V 100k 0.01µF 3 100k PHASE TRIM 5V 1k 7 1 4 –5V 6943 • TA18 0.005µF 30k 0.005µF + – 8 LT1013 2 AMPLITUDE STABLE SINE WAVE SOURCE Q1 2N4338 1.2k +15V 1 5 500k 549k* 49.9k* Q1 2N3906 1M 10k Q2 TEMPERATURE SENSOR TRANSISTOR *0.1% FILM RESISTOR SENSOR TRANSISTOR MAY BE ANY SMALL SIGNAL NPN-2N2222, 3904, ETC. DO NOT USE GOLD DOPED TRANSISTORS. 14 U 7 3 9 RD-BLUE 100k 1µ F 5 + 1/2 LT1013 7 6 – OUTPUT 0V ±2.5V 0mm ±2.50mm 200k 15 12 –5V 10k GAIN TRIM + – 8 LT1011 TO PIN 14, LTC6943 2 ∆VBE Based Thermometer Requires No Calibration C1 1µ F 2 14 LTC6943 16 C2 1µF +15 + A1 LTC1150 13 0.01 +15 10k – 0-10VOUT = 0-100°C, 1°C ACCURACY C3 0.1 86k* 1M* 2.019k* LT1009 2.5V 6943 TA21 6943f LTC6943 PACKAGE DESCRIPTIO .254 MIN .0165 ± .0015 RECOMMENDED SOLDER PAD LAYOUT .007 – .0098 (0.178 – 0.249) .016 – .050 (0.406 – 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE *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 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. U GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .045 ± .005 .189 – .196* (4.801 – 4.978) 16 15 14 13 12 11 10 9 .009 (0.229) REF .150 – .165 .229 – .244 (5.817 – 6.198) .150 – .157** (3.810 – 3.988) .0250 TYP 1 23 4 56 7 8 .004 – .0098 (0.102 – 0.249) .015 ± .004 × 45° (0.38 ± 0.10) 0° – 8° TYP .053 – .068 (1.351 – 1.727) .008 – .012 (0.203 – 0.305) .0250 (0.635) BSC GN16 (SSOP) 0502 6943f 15 LTC6943 TYPICAL APPLICATIO S 5V Powered Voltage-to-Frequency Converter 5VIN 16 3 22k 5 4 LTC6943 fOUT 0kHz TO 13 3kHz 2 15 INPUT 0V TO 2V RELATED PARTS PART NUMBER LTC1043 LTC1152 LTC2050 LTC2051 LTC2052 LTC2053 LTC2054 LTC6800 LTC6915 DESCRIPTION Dual Precision Instrumentation Switched Cap, Building Block Rail-to-Rail In/Out, Zero Drift Op Amp Zero Drift Op Amp Zero Drift Dual Op Amp Zero Drift Quad Op Amp Precision, Rail-to-Rail Zero Drift I.A. Low Power, Zero Drift Op Amp Low Cost, Rail-to-Rail I.A. Precision Instrumentation Amplifier with Digitally Programmable Gain COMMENTS 120dB CMRR, 3V to 18V Operation Operates Up to 14V Supply Voltage Single Supply Operation on 2.7V to 11V, SOT-23 Package Dual LTC2050, 8-Lead DFN, MS8 Packages Dual LTC2050, GN16 Package 120dB CMRR at Low Gains 150µA Supply Current, SOT-23 Package VOS(MAX) = 100µV, DFN 8 Package 14 Levels of Programmable Gain, 125dB CMRR 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● U + 22µF 1 LT1034 1.2V 2 16 C1** 0.01 µF 13 14 10k FULL SCALE TRIM 5VIN 75k* 1µF – A1 1/2 LT1017 D1 1N4148 C2 560pF + 1N5712 50k 120pF 1.6M (10Hz TRIM) 6943 TA19 10k * = 1% FILM RESISTOR, TYPE TRW-MTR+120ppm/°C ** = POLYPROPYLENE 6943f LT/TP 0804 1K • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 2004