Circuit Note CN-0276 Devices Connected/Referenced Variable Resolution, 10-Bit to 16-Bit R/D AD2S1210 Converter with Reference Oscillator AD8397 Rail-to-Rail, High Output Current Amplifier Circuits from the Lab reference circuits are engineered and ADG1611/ 1 On Resistance, 5 V, +12 V, +5 V, and tested for quick and easy system integration to help solve todays ADG1612 +3.3 V Quad SPST Switches analog, mixed-signal, and RF design challenges. For more Ultralow Power, 3-Lead, SOT-23 information and/or support, visit www.analog.com/CN0276. ADM6328 Microprocessor Reset Circuits ADP7104 20 V, 500 mA, Low Noise, CMOS LDO AD8692/ Low Cost, Low Noise, Dual/Quad CMOS, AD8694 RRO Op Amps High Performance, 10-Bit to 16-Bit Resolver-to-Digital Converter EVALUATION AND DESIGN SUPPORT CIRCUIT FUNCTION AND BENEFITS Circuit Evaluation Boards The circuit shown in Figure 1 is a complete high performance CN-0276 Circuit Evaluation Board (EVAL-CN0276-SDPZ) resolver-to-digital (RDC) circuit that accurately measures System Demonstration Platform (EVAL-SDP-CB1Z) angular position and velocity in automotive, avionics, and Design and Integration Files critical industrial applications where high reliability is required Schematics, Layout Files, Bill of Materials over a wide temperature range. THIRD ORDER BUTTERWORTH LOW PASS FILTER 3.3V 5V 5V 5V V v(t) = A sint CC 1 1 V DV AV DRIVE DD DD AD8692 AD8397 RESOLVER 2 2 R1 S2 EXC v(t) 1 1 AD8692 AD8397 2 2 EXC S4 R2 AD2S1210 S1 S3 VREF VREFOUT 2.5V 5V 5V 1 1 AD8694 AD8694 4 4 SIN SIN 1 1 AD8694 AD8694 4 4 SINLO 1 1 AD8694 AD8694 4 4 COS COS 1 1 AD8694 AD8694 4 4 COSLO DGND AGND THIRD ORDER BUTTERWORTH LOW PASS FILTER Figure 1. High Performance Resolver-to-Digital (RDC) Circuit. Simplified Schematic: All Components, Connections, and Decoupling Not Shown Rev. 0 Circuits from the Lab circuits from Analog Devices have been designed and built by Analog Devices engineers. Standard engineering practices have been employed in the design and construction of each circuit, and their function and performance have been tested and verified in a lab environment at room temperature. However, you are solely responsible for testing the circuit and determining its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. suitability and applicability for your use and application. Accordingly, in no event shall Analog Devices Tel: 781.329.4700 www.analog.com be liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause whatsoever connected to the use of any Circuits from the Lab circuits. (Continued on last page) Fax: 781.461.3113 2013 Analog Devices, Inc. All rights reserved. 10793-001CN-0276 Circuit Note quantization noise and distortion. For this reason, the dual The circuit has an innovative resolver rotor driver circuit that AD8692 op amp is configured as a third-order active Butterworth has two modes of operation: high performance and low power. filter in order to reduce the noise of the drive signals. Similarly, In the high performance state, the system operates on a single the SIN and COS receiver circuits use two quad AD8694 op 12 V supply and can supply 6.4 V rms (18 V p-p) to the resolver. amps as an active noise filter. In the low power state, the system operates on a single 6 V supply and can supply 3.2 V rms (9.2 V p-p) to the resolver, with less Signal Chain Design than 100 mA of current consumption. Active filtering is provided These factors must be considered in the design of the signal chain: in both the driver and receiver to minimize the effects of AD2S1210 excitation signal output range : 3.2 V min, quantization noise. 3.6 V typical, 4.0 V max The maximum tracking rate of the RDC is 3125 rps in the 10- AD8692 output voltage range: 0.29 V to 4.6 V with bit mode (resolution = 21 arc min) and 156.25 rps in the 16-bit +5 V supply mode (resolution = 19.8 arc sec). AD8397 output voltage range: 0.18 V to 5.87 V with CIRCUIT DESCRIPTION +6 V supply. AD8397 output voltage range: 0.35 V to 11.7 V with The signal chain must be designed with care to consider not +12 V supply only amplitude and frequency, but also phase shift and stability. Resolver(TS2620N21E11) transformation ratio: 0.5 In addition, the resolver rotor winding impedance has both a resistive and an inductive component. Resolver(TS2620N21E11) phase shift: 0 The AD2S1210 RDC excitation signal range is 2 kHz to 20 kHz AD8694 output voltage range: 0.37 V to 4.6 V with +5 V and can be set in increments of 250 Hz. Most resolvers are supply specified at a fixed excitation fequency, typically around 10 kHz. AD2S1210 input differential p-p signal range (SIN, Different resolvers have difference phase shifts that must also be COS) is 2.3 V min, 3.15 V typ, 4.0 V max considered in the signal chain design. Resolver output SIN, COS loads should be equal. Resolver output loads should be at least 20 times the The excitation signal is applied to the resolver rotor winding resolver output impedance which is a non-ideal inductor and has a typical resistive component Total signal chain phase shift range: n 180 44 of 50 to 200 and a reactive component of 0 to 200 . For example, the impedance of the Tamagawa TS2620N21E11 resolver n 180 + 44, n is an integer. used in the circuit of Figure 1 is 70 + j100 at 10 kHz. Resolver Excitation Filter and Driver Circuits Typical excitation voltages can be as high as 20 V p-p (7.1 V rms), The AD2S1210 excitation signal filter and power amplifier circuit so both maximum current and maximum power consumption are shown in Figure 2. Careful attention must be paid to the gain of the resolver driver must be considered. The AD8397 was and signal levels at each point in the chain so that the AD8397 chosen for the circuit because of its wide supply range (24 V), output driver does not saturate for the maximum excitation (EXE) high output current (310 mA peak into 32 on 12 V supplies), of 4.0 V p-p from the AD2S1210. Note that because the resolver rail-to-rail output voltage, and low thermal resistance package is driven differentially there are two identical channels as shown (JA = 47.2C/W for the 8-pin SOIC EP package). in Figure 2 corresponding to the true and complementary EXE The excitation output signals from the AD2S1210 are generated outputs, respectively. from an internal DAC that produces a certain amount of Rev. 0 Page 2 of 10