SWR200 SWR200 ® P r oSWR200 d uu cc tt IInnnnoovvaatti ioonn FFr roomm Precision Sine Wave Reference FEATURES DESCRIPTION SWR200 is a Precision Sine Wave Reference providing an ultra stable sine wave output of +7.071 V at ±0.5% initial accuracy and temperature coefficient as low as 20 ppm/°C over the full military temperature range. The extreme accuracy is made possible by a chopper-based AGC circuit. The temperature characteristic of the chopper circuit compensates the typical nonlinearity of the internal DC zener reference, resulting in a nearly linear amplitude-temperature characteristic. Frequency of the SWR200 is programmable with two external capacitors. ♦ Very High Accuracy: +7.071 Vrms ±0.5% ♦ Extremely Low Drift: 20 ppm/°C (-55°C to +125°C) ♦ Excellent Stability: 10 ppm/1000 Hrs. Typical ♦ Low Distortion: 0.1% Thd @ f = 3300 Hz ♦ Hermetic 14-pin Ceramic DIP ♦ Military Processing Option APPLICATIONS ♦ Transducer Excitation ♦ High Resolution Servo Systems ♦ High Precision Test and Measurement Instruments ♦ AC Voltage Standard ♦ LVDT Or RVDT Reference ♦ Multiplying D/A Reference The SWR200 is available in a 14-pin bottom braze package. They are hermetically sealed and “M” versions are screened for high reliability and quality. SWR200 is well suited for any application requiring a stable sine wave source. The SWR200 can be used as a reference source in precision sensing systems based on LVDT or RVDT position sensors. A programmable AC reference can be constructed using the SWR200 as a reference for a high accuracy multiplying Digital to Analog Converter. Figure 1. BLOCK DIAGRAM +15V +15V +15V -15V -15V +15V -15V 3 SWR200DS www.cirrus.com 12 Copyright © Cirrus Logic, Inc. 2010 (All Rights Reserved) MAY 20101 APEX − SWR200DSREVH SWR200 Product Innovation From SELECTION GUIDE Temperature Operating Range Package +7.071V -25°C to +85°C DIP +7.071V -55°C to +125°C DIP Type Output (Typ.) SWR200C SWR200M 1. CHARACTERISTICS AND SPECIFICATIONS Hermetic 14-pin Ceramic DIP Package Style HC ELECTRICAL SPECIFICATIONS VPS =±15V, T = +25°C, RL = 10KΩ UNLESS OTHERWISE NOTED. Model Parameter SWR200C SWR200M Min Typ Max Min Typ Max Units ±13.5 ±15 ±22 * * * V ABSOLUTE MAXIMUM RATINGS Power Supply Operating Temperature -25 +85 -55 +125 ºC Storage Temperature -65 +85 * * ºC Short Circuit Protection OUTPUT VOLTAGE Continuous * Vrms 7.071 * V OUTPUT VOLTAGE ERRORS Initial Error ±0.5 Warmup Drift * 100 DC Offset * 3 DC Offset Over Temp. 3 TMIN - TMAX * 18 * 20.0 Long-Term Stability 10 % µV mV * µV/ ºC 30.0 ppm/ ºC * ppm/ ºC OUTPUT CURRENT Range ±10 * mA REGULATION Line 10 * ppm/V Load 3 * ppm/mA POWER SUPPLY CURRENTS +PS 10.5 13 * * mA -PS 9.5 13 * * mA * % * Hz * Hz * ppm/ºC DISTORTION 0.5 FREQUENCY 10-5 Range (f) f = C C 1 2 ∆f vs. temperature f 2 .98 400 1 1.02 * 10K * 15 * SWR200DS SWR200 Product Innovation From NOTES: * Same as C Models. 1. Using the box method, the specified value is the maximum deviation from the output voltage at +25°C over the specified operating temperature range. 2. The specified values are unloaded. 3. Pin 8 is internally connected to Pin 7 and can be used as Ref. GND. 4. The frequency range can be extended to any desired lower value by using 2 external AGC capacitors (see AN-3). 5. The increase in distrotion at lower frequencies can be eliminated by using external AGC capacitors (see AN-3). 2. TYPICAL PERFORMANCE GRAPHS VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE 20 % ∆ FREQ. vs. TEMP. % ∆ FREQ. vs. TEMP. 50 35 15.6 0 0 -15.6 -35 -50 -20 Temperature oC SWR200C Temperature oC SWR200M DISTORTION VS. TEMP Temperature oC POWER SUPPLY CURRENT vs. TEMP. Temperature oC SWR200DS Temperature oC SWR200C DISTORTION vs. FREQUENCY Frequency (Hz) CASE TEMP. RISE ABOVE AMBIENT vs. OUTPUT CURRENT Output Current (mA) Temperature oC SWR200M NORMALIZED DISTORTION vs. C2/C1 C2/C1 JUNCTION TEMP. RISE ABOVE CASE TEMP. vs OUTPUT CURRENT Output Current (mA) 3 SWR200 Product Innovation From 3. THEORY OF OPERATION The following refers to the schematic in Figure 1. A1 and A2 are connected as a phase-shift oscillator circuit with the frequency set by the external capacitors C1 and C2. Q4 is included in the feedback loop of A1 as a gain control element. The oscillator output is fed to the chopper amplifier which develops an absolute value representation of the oscillator output. The chopper output is compared to a precision DC reference in integrator amplifier A3. This DC error signal is used ot control the gain setting FET Q4. As in all precision zener based DC references, the drift of the zener becomes nonlinear at temperature extremes. The chopper amplifier drift characteristic is complementary to this nonlinearity and compensates for the reference drift. 4. APPLICATION INFORMATION Figure 1 shows the connections for the SWR200 including the two frequency setting capacitors. The frequency is: f= 10-5 C1 C2 The frequency stability is directly related to the stability of the capacitors, therefore stable capacitors like NPO ceramic, or polycarbonate or polystyrene film should be used. Two separate ground pins are provided for accurate ground sensing. This minimizes errors due to drops in the ground pin which can become a significant source of error in sockets. The offset of the SWR200 is fully specified for initial offset and drift and is low enough that it can normally be neglected. In applications which are especially sensitive to offset the output can be AC coupled. Proper capacitor sizing and high impedance sensing will minimize errors due to capacitive coupling. EXTERNAL CONNECTIONS PIN CONFIGURATION TOP VIEW C1 C2 C1 C2 +PS -PS NC NC NC NC NC OUTPUT GND 4 SWR200 GND SENSE SWR200DS Product Innovation From SWR200 CONTACTING CIRRUS LOGIC SUPPORT For all Apex Precision Power product questions and inquiries, call toll free 800-546-2739 in North America. For inquiries via email, please contact [email protected]. International customers can also request support by contacting their local Cirrus Logic Sales Representative. To find the one nearest to you, go to www.cirrus.com IMPORTANT NOTICE Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. 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