SWR200 Precision Sine Wave Reference THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000 FEATURES APPLICATIONS • VERY HIGH ACCURACY: 7.071 Vrms ±0.05% • TRANSDUCER EXCITATION • EXTREMELY LOW DRIFT: 3 ppm/°C (-55°C to +125°C) • HIGH RESOLUTION SERVO SYSTEMS • EXCELLENT STABILITY: 10 ppm/1000 Hrs. Typ. • LOW DISTORTION: 0.1% THD @ f = 3300 Hz • HERMETIC 14-PIN CERAMIC DIP • MILITARY PROCESSING OPTION • HIGH PRECISION TEST and MEASUREMENT INSTRUMENTS • AC VOLTAGE STANDARD • LVDT OR RVDT REFERENCE • MULTIPLYING D/A REFERENCE DESCRIPTION SWR200 is a Precision Sine Wave Reference providing an ultra stable sine wave output of 7.071V at ±0.05% initial accuracy and temperature coefficient as low as 3 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. 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. SELECTION GUIDE Type Output Temperature (Typ.) Operating Range Package SWR200C 7.071V -25°C to +85°C DIP SWR200M 7.071V -55°C to +125°C DIP 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. SWR200DS REV. D JUNE 1995 ELECTRICAL SPECIFICATIONS SWR200 Vps =±15V, T = 25°C, RL = 10KΩ unless otherwise noted. MODEL C PARAMETERS MIN M TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS ABSOLUTE MAXIMUM RATINGS Power Supply ±13.5 15 ±22 Operating Temperature -25 85 Storage Temperature -65 150 Short Circuit Protection Continuous OUTPUT VOLTAGE * -55 * * 125 * V °C °C * 7.071 * Vrms OUTPUT VOLTAGE ERRORS Initial Error Warmup Drift DC Offset DC Offset Over Temp. Tmin - Tmax Long-Term Stability 0.05 * 100 3 1 10 * 3 18 2.0 * 1 * * * 3.0 % µV mV µV/°C ppm/°C ppm/°C OUTPUT CURRENT Range ±10 * mA REGULATION Line Load 10 3 * * ppm/V ppm/mA POWER SUPPLY CURRENTS +PS -PS 10.5 9.5 DISTORTION 13 13 * * 0.5 * * mA mA * % * * * Hz Hz ppm/°C FREQUENCY Range (f) f= 10 -5 C1 C2 f vs. Temperature .98 400 1 ∇ f 1.02 10K 15 NOTES: * * *Same as C Models. 3.Pin 8 is internally connected to Pin 7 and can be used as Ref. GND. 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. 4. The frequency range can be extended to any desired lower value by using 2 external AGC capacitors (see AN-3). 2.The specified values are unloaded. 5.The increase in distrotion at lower frequencies can be eliminated by using external AGC capacitors (see AN-3). SWR200DS REV. D JUNE 1995 TYPICAL PERFORMANCE CURVES VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC SWR200C Temperature oC SWR200L DISTORTION VS. TEMP Temperature oC POWER SUPPLY CURRENT vs. TEMP. Temperature oC % ∆ FREQ. vs. TEMP. Temperature oC SWR200C DISTORTION vs. FREQUENCY Frequency (Hz) CASE TEMP. RISE ABOVE AMBIENT vs. OUTPUT CURRENT Output Current (mA) % ∆ FREQ. vs. TEMP. Temperature oC SWR200L NORMALIZED DISTORTION vs. C2/C1 C2/C1 JUNCTION TEMP. RISE ABOVE CASE TEMP. vs OUTPUT CURRENT Output Current (mA) SWR200DS REV. D JUNE 1995 DISCUSSION OF PERFORMANCE THEORY OF OPERATION APPLICATION INFORMATION 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. Figure 1 shows the connections for the SWR200 including the two frequency setting capacitors. The frequency is: 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. -5 f = 10 C1 C 2 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. SCHEMATIC FIGURE 1 SWR200DS REV. D JUNE 1995 EXTERNAL CONNECTIONS FIGURE 2 PIN CONFIGURATION TOP VIEW C1 C2 C1 C2 +PS -PS NC SWR200 NC NC NC NC OUTPUT GND GND SENSE MECHANICAL 14-PIN HYBRID PACKAGE INCHES DIM MIN MAX MILLIMETER MIN MAX INCHES DIM MIN MILLIMETER MAX MIN MAX E .480 .500 12.1 12.7 A .120 .155 3.0 4.0 L .195 .215 4.9 5.4 Q .015 .035 0.4 0.9 D .775 .805 19.7 20.4 Q1 N/A .030 N/A 0.7 B .016 .020 0.4 0.5 C .009 .012 0.2 0.3 B1 .038 .042 0.9 1.0 G1 .290 .310 7.3 7.8 B2 .095 .105 2.4 2.6 S .085 .105 2.1 2.6 P .004 .006 0.10 0.15 SWR200DS REV. D JUNE 1995