LTC1967 Precision Extended Bandwidth, RMS-to-DC Converter FEATURES DESCRIPTIO n High Linearity: The LTC 1967 is a true RMS-to-DC converter that uses an 0.02% Linearity Allows Simple System Calibration innovative delta-sigma computational technique. The ben- n Wide Input Bandwidth: efits of the LTC1967 proprietary architecture when com- Bandwidth to 0.1% Additional Gain Error: 40kHz pared to conventional log-antilog RMS-to-DC converters Bandwidth Independent of Input Voltage Amplitude are higher linearity and accuracy, bandwidth independent n No-Hassle Simplicity: of amplitude and improved temperature behavior. True RMS-DC Conversion with Only One External The LTC1967 operates with single-ended or differential in- Capacitor put signals (for EMI/RFI rejection) and supports crest fac- Delta Sigma Conversion Technology tors up to 4. Common mode input range is rail-to-rail. Dif- n Low Supply Current: ferential input range is 1V , and offers unprecedented PEAK 330m A Typ linearity. The LTC1967 allows hassle-free system calibra- n Ultralow Shutdown Current: tion at any input voltage. 0.1m A n The LTC1967 has a rail-to-rail output with a separate out- Flexible Inputs: put reference pin providing flexible level shifting it oper- Differential or Single Ended ates on a single power supply from 4.5V to 5.5V. A low power Rail-to-Rail Common Mode Voltage Range shutdown mode reduces supply current to 0.1m A. Up to 1V Differential Voltage PEAK n Flexible Output: The LTC1967 is packaged in the space-saving MSOP pack- Rail-to-Rail Output age, which is ideal for portable applications. Separate Output Reference Pin Allows Level Shifting , LTC and LT are registered trademarks of Linear Technology Corporation. n Protected under U.S. Patent Numbers 6,359,576, 6,362,677 and 6,516,291 Small Size: Space Saving 8-Pin MSOP Package U APPLICATIO S n True RMS Digital Multimeters and Panel Meters n True RMS AC + DC Measurements TYPICAL APPLICATIO Linearity Performance 0.2 LTC1967, S Single Supply RMS-to-DC Converter 0 4.5V TO 5.5V 0.2 + V 0.4 IN1 OUTPUT DIFFERENTIAL C + AVE LTC1967 V OUT INPUT 1F 0.6 CONVENTIONAL IN2 OUT RTN LOG/ANTILOG EN GND 0.1F 0.8 OPT. AC COUPLING 60Hz SINEWAVE 1967 TA01 1.0 0 100 200 300 400 500 V (mV AC ) 1967 TA01b IN RMS 1967f 1 LINEARITY ERROR (V mV DC V mV AC ) OUT IN RMS U ULTC1967 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage ORDER PART + NUMBER V to GND ............................................................. 6V TOP VIEW Input Currents (Note 2) ..................................... 10mA LTC1967CMS8 GND 1 8 ENABLE + Output Current (Note 3) ..................................... 10mA IN1 2 7 V LTC1967IMS8 IN2 3 6 OUT RTN ENABLE Voltage ......................................... 0.3V to 6V NC 4 5 V OUT + OUT RTN Voltage........................................ 0.3V to V MS8 PACKAGE MS8 PART MARKING 8-LEAD PLASTIC MSOP Operating Temperature Range (Note 4) T = 150 C, q = 220 C/ W JMAX JA LTC1967C/LTC1967I ......................... 40 C to 85 C LTTJ Specified Temperature Range (Note 5) LTC1967C/LTC1967I ......................... 40 C to 85 C Maximum Junction Temperature ......................... 150 C Consult LTC Marketing for parts specified with wider operating temperature ranges. Storage Temperature Range ................ 65 C to 150 C Lead Temperature (Soldering, 10 sec)................. 300 C ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating + temperature range, otherwise specifications are T = 25 C. V = 5V, V = 2.5V, C = 10m F, V = 200mV , V = 0.5V A OUTRTN AVE IN RMS ENABLE unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Conversion Accuracy G Low Frequency Gain Error 50Hz to 5kHz Input (Notes 6, 7) 0.1 0.3 % ERR l 0.4 % V Output Offset Voltage (Notes 6, 7) 0.1 0.55 mV OOS D V /D T Output Offset Drift (Note 11) l 210 m V/ C OOS LIN Linearity Error 50mV to 350mV (Notes 7, 8) l 0.02 0.15 % ERR PSRRG Power Supply Rejection (Note 9) 0.02 0.15 %/V l 0.20 %/V V Input Offset Voltage (Notes 6, 7, 10) 0.2 1.5 mV IOS D V /D T Input Offset Drift (Note 11) l 110 m V/ C IOS Additional Error vs Crest Factor (CF) CF = 3 60Hz Fundamental, 200mV l 0.2 mV RMS CF = 5 60Hz Fundamental, 200mV l 5mV RMS Input Characteristics V Maximum Peak Input Swing Accuracy = 1% (Note 14) l 1 1.05 V IMAX + I Input Voltage Range l0V V VR Z Input Impedance Average, Differential (Note 12) 5 MW IN Average, Common Mode (Note 12) 100 MW CMRRI Input Common Mode Rejection (Note 13) l 50 400 m V/V V Minimum RMS Input l 5mV IMIN PSRRI Power Supply Rejection (Note 9) l 250 600 m V/V 1967f 2 U WWW