STEVAL-CCA057V2

AN4574 Application note STEVAL-CCA057V2 evaluation board user guidelines for dual operational amplifiers in an MSO8 package Introduction The STEVAL-CCA057V2 evaluation board from STMicroelectronics is designed to help customers quickly prototype new dual op amp circuits in an MSO8 package and reduce design time. The evaluation board can be used with almost any STMicroelectronics dual op amp in various configurations and applications. The evaluation board is a bare board (that is, there are no components or amplifier soldered to the board; these must be ordered separately). This document provides: • A description of the evaluation board • A layout of the top and bottom layers Some examples of classic configurations that can be tested with the board. Figure 1. MSO8 pinout Figure 2. STEVAL-CCA057V2 evaluation board September 2014 DocID026855 Rev 1 1/16 www.st.com Contents AN4574 Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Different possible configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Low-pass Sallen-key configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 High-pass Sallen-key configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Instrumentation amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.4 Transimpedance configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.5 AC coupled circuit configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 4 Associated products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2/16 DocID026855 Rev 1 AN4574 1 Description Description This board is designed with versatility in mind, and allows many circuits to be constructed easily and quickly. A few possible circuits are as follows: • Voltage follower • Non-inverting amplifier • Inverting amplifier • Sallen-key filter • Instrument amplifier • AC-coupled circuit • Out-of-loop compensation circuit Circuit The circuit schematic in Figure 3 shows the connections for all possible components. Each configuration uses only some of the components. The board is designed for surface-mounted components and can be used to perform onboard characterization prior to the integration of STMicroelectronics products in your designs. Resistor and capacitor footprints are implemented for the 1206 series. DocID026855 Rev 1 3/16 16 Description AN4574 Figure 3. Evaluation board schematics 5)%$ &)%$ 5$ *1' &$39&&1 *1' 37B9287B$ 9&&1 95()$ 9,1$ PP 9,1$21 5$ 9,1$2)) 9,1$B'& 9$  9$  5$  &,1$ 5B$ ,&$ $233,16 9 9  9RXW$ &287B$ 9287$60% 5/B$ 9&&3 95()$ *1' 9,1$ *1' &$39&&3 9,1$21 PP &,1$ &/B$ 5B$ *1' 9287B$ PP 5B$  *1' *1' *1' 9,1$2)) *1' 9,1$B'& 5)LOWHU$ 9&&3B60% *1' 9&&3 PP &,1B9&&3B21 *1' *1' 5)%% & *1' PP 9&&1B60% 9&&1 9&&3 & 9&&3B5()B60% *1' 9&&1B5()B60% 9&&1 PP &,1B9&&1B21 & &)%% *1' & *1' 5% *1' 37B9287B% 95()% &,1% 9,1% PP *1' 9,1%21 PP &,1% 5% 9,1%2)) 9,1%B'& 95()% *1' 9,1% 5B% 9%  9% 5% *1'  PP ,&%  9RXW% 5B% $233,16 9287B% &287B% 9287%60% 5/B% 5B% 5 &/B% *1' 9,1%21 *1' 9,1%2)) *1' 5)LOWHU% 9,1%B'& *63*6* *1' Power requirements A 0 Ω resistance must be connecting on CIN_VCCN_ON and CIN_VCCP_ON in order to supply power to the dual amplifier. A set of two decoupling capacitors (C1, C2 and C3, C4) have been implemented on both power supply pins, so as to benefit from the maximum performance of ST products. In order to reject low frequencies, 1 µF and 10 µF are good values for these. Others decoupling capacitors (CAPVCCN, CAPVCCP) as close as possible to the SO8 package, might also be used to obtain excellent power supply decoupling. 100 pF values can be used in order to reject high frequencies. When using single-supply circuits, the negative supply is shorted to ground by bridging C3 or C4 capacitances. Power is therefore between VCCP and GND. 4/16 DocID026855 Rev 1 AN4574 Description Output options The outputs have additional resistor (RL_A, RL_B) and capacitor (CL_A, CL_B) placements for loading. Or it might be used as an anti-alias filter, or to limit amplifier output noise by reducing its output bandwidth. Note: Operational amplifiers are sensitive to output capacitance and may oscillate. In the event of oscillation, reduce output capacitance by using shorter cables, or add a resistor in series on COUT_A, COUT_B placement with a suitable value in order to improve amplifier phase margin. Measurement tips In the datasheet, some measurements, such as settling time and peaking, have been performed with 50 Ω output equipment. In order to keep the integrity of the square input signal, the input tracks from VINA+, VINB+, VINA-, VINB+, have an impedance of 50 Ω. And in order to adapt input impedance, 50 Ω resistances can be added on the R50_1A, R50_2A and R50_1B, R50_2B. DocID026855 Rev 1 5/16 16 Layout 2 AN4574 Layout The board has the following physical characteristics: – Board dimensions: 3526 x 3300 mils (89.6 x 83.8 mm) – 2-layer PCB – Both sides have a ground plane. For Vout_A, Vout_B, VinA+, VinA-, VinB+ and VinB- female SMB or female 2 mm connectors can be implanted. You can also implant test points on these voltages. They will facilitate the visualization of your signals. Top and bottom layers are shown on Figure 4 and Figure 5: Figure 4. Top layer Figure 5. Bottom layer 6/16 DocID026855 Rev 1 AN4574 3 Different possible configurations Different possible configurations The following provides some instructions on how to set up the board in order to perform several classical configurations. • Figure 6: Low-pass Sallen-key filter order 4 • Figure 7: High-pass Sallen-key filter order 4 • Figure 8: Instrumentation amplifier • Figure 9: Transimpedance configuration • Figure 10: AC coupled configuration You can also put several boards in cascade which allows you to obtain a more complex configurations. 3.1 Low-pass Sallen-key configuration The following low-pass Sallen-key configuration is a fourth order filter configuration. This circuit has 80 dB roll-off per decade. The transfer function is: Equation 1 The low frequency gain is: Equation 2 DocID026855 Rev 1 7/16 16 Different possible configurations AN4574 Figure 6. Low-Pass Sallen-key 4th order configuration GND RFA CAPVCCN GND PT_VOUT_A VCCN VREFARGA VA+ VV+ 3 VINA-_DC 2mm 0 ohms VOUT_A VOUTASMB 0 ohm VCCP R2 GND VREFA+ GND 1 VoutA 8 VINA- 2mm VA- 2 IC1A AOP-8PINS 4 GND GND C1 CAPVCCP VINA+ 2mm GND 0 ohm R1 GND GND VINA+_DC GND C2 RFB GND PT_VOUT_B VREFB- GND RGB 2mm IC1B VOUT_B VINB- 2mm VB- 6 VB+ 7 VoutB 5 VINB-_DC 0 ohm VOUTBSMB 0 ohm AOP-8PINS R4 GND VREFB+ GND GND VINB+ 2mm C3 0 ohm R3 GND GND VINB+_DC C4 GSPG0809141050SG GND 3.2 High-pass Sallen-key configuration Like the low-pass Sallen-key configuration above, this one is also a fourth order. It has a slope of +80 dB per decade. The transfer function is: Equation 3 The high frequency gain is: Equation 4 8/16 DocID026855 Rev 1 AN4574 Different possible configurations Figure 7. High-Pass Sallen-key configuration GND RFA CAPVCCN GND PT_VOUT_A VCCN VREFA- GND 4 RGA IC1A AOP-8PINS VA- 2 VA+ 3 1 VoutA V+ VINA-_DC 2mm VOUT_A 0 ohms 8 VINA- 2mm V- VOUTASMB 0 ohm VCCP C2 GND VREFA+ GND R1 GND CAPVCCP VINA+ 2mm GND 0 ohm C1 GND GND VINA+_DC GND R2 RFB GND PT_VOUT_B VREFB- GND RGB 2mm IC1B VOUT_B VINB- 2mm VB- 6 VB+ 7 VoutB 5 VINB-_DC 0 ohm VOUTBSMB 0 ohm AOP-8PINS C4 GND VREFB+ GND GND R3 VINB+ 2mm GND 0 ohm C3 GND VINB+_DC R4 GSPG0809141145SG GND The upper limit of the frequency range is determined by the GBP of the op amp 3.3 Instrumentation amplifier The instrumentation amplifiers are generally used for precise measurement in a differential way. The architecture of the instrumentation amplifier with dual op amps is the simplest one. The input impedance is high as the non-inverting of the both op amps are used as input. By considering R1.R2 = RFA.RFB And Vout = Vreference for Vdiff = 0 V The gain can be expressed as follows: Equation 5 DocID026855 Rev 1 9/16 16 Different possible configurations AN4574 Figure 8. Instrumentation amplifier Rg GND RFA CAPVCCN GND PT_VOUT_A VCCN VREFAVA- 2 Reference IC1A AOP-8PINS 4 GND VINA- 0 ohms 0 ohms R1 VA+ 3 VINA-_DC R2 VOUTASMB 0 ohm VCCP 0 ohm GND VREFA+ GND 1 VoutA V+ 2mm VOUT_A 8 2mm V- GND CAPVCCP GND 2mm Inverting Input VINA+ 0 ohm 0 ohm GND GND VINA+_DC GND RFB GND PT_VOUT_B VREFB- GND 2mm IC1B VOUT_B 2mm VB- 6 VINB- 0 ohms 0 ohms 0 ohms VB+ 5 7 VoutB VINB-_DC Output 0 ohm VOUTBSMB 0 ohm AOP-8PINS 0 ohm GND VREFB+ GND Non Inverting Input GND VINB+ 2mm GND 0 ohm 0 ohm GND VINB+_DC GSPG00809141200SG GND 3.4 Transimpedance configuration The Figure 9 shows how to configure op amp IC1A as a transimpedance amplifier (TIA). The output voltage of the TIA is the input current multiplied by the feedback resistor RFA: Equation 6 where Iin is defined as the input current source applied at the VINA- pad, IBIAS is the input bias current, and VOS is the input offset voltage of the op amp. For the type of usage, the feedback resistor RFA is generally high and the impedance seen on the VA- node is pretty capacitive (ex: photodiode). In order to stabilize the op amp it is recommended to connect a feedback capacitance CF. 10/16 DocID026855 Rev 1 AN4574 Different possible configurations Figure 9. Transimpedance configuration Cf GND RFA CAPVCCN GND PT_VOUT_A VCCN VREFAVA- 2 IC1A AOP-8PINS 4 GND 0 ohms 0 ohms 0 ohms VA+ 3 VINA-_DC 1 VoutA V+ 0 ohm 8 2mm V- VINA- 2mm VOUT_A VOUTASMB 0 ohm VCCP VREFA+ GND GND GND 0 ohm CAPVCCP GND GND 2mm VINA+ GND VINA+_DC GND 0 ohm GND PT_VOUT_B VREFB- GND 2mm VOUT_B IC1B VINB- 2mm VB- 6 VB+ 5 7 VoutB VINB-_DC 0 ohm VOUTBSMB 0 ohm AOP-8PINS VREFB+ GND GND GND 0 ohm GND GND 2mm VINB+ VINB+_DC GSPG0809141430SG GND Note: If only IC1A op amp is used as transimpedance amplifier, the second one, IC1B, should be configured in follower mode in order to avoid any undesired oscillation on its output. 3.5 AC coupled circuit configuration This typical configuration allows you to amplify the AC part of the input signal only; for example, a typical stereo audio amplifier. DocID026855 Rev 1 11/16 16 Different possible configurations AN4574 Figure 10. AC coupled circuit configuration GND RFA CAPVCCN GND PT_VOUT_A VCCN VREFAVA- 2 IC1A AOP-8PINS 4 GND 0 ohms RGA- CinA- VA+ 3 VINA-_DC V+ 2mm 0 ohm VOUT_A VOUTASMB Rout VCCP RGA+ CoutA GND VREFA+ GND 1 VoutA 8 VINA- 2mm V- R2 GND CAPVCCP 2mm GND VINA+ 0 ohms CinA+ GND GND VINA+_DC GND RFB GND PT_VOUT_B VREFB- GND 2mm VOUT_B IC1B VINB- 2mm VB- 6 0 ohms RGB- CinB- VB+ 5 7 VoutB VINB-_DC 0 ohm VOUTBSMB RoutB AOP-8PINS CoutB RGB+ GND VREFB+ GND GND R3 2mm GND VINB+ 0 ohms CinB+ GND VINB+_DC GSPG0809141440SG GND 12/16 DocID026855 Rev 1 AN4574 4 Associated products Associated products Table 1. Associated products Part number LM258ST General description Low-power dual op amps with low input bias current LM258WST Low power dual operational amplifiers LM2904ST Low power, bipolar op amp LM358ST Low-power dual op amps with low input bias current LM358W Low power dual operational amplifiers LMV358LIST Low-power, general-purpose operational amplifier op amp LMV822IST Low power, high accuracy, general purpose operational amplifier LMV822AIST Low power, high accuracy, general purpose operational amplifier LMX358IST Low-power, general-purpose operational amplifier TS1852IST 1.8 V min. voltage supply, micropower TS1852AIST 1.8 V min. voltage supply, micropower TS1872AIST 1.8 V min. voltage supply, micropower TS462IST Output rail-to-rail op amps TS972IST Output rail-to-rail very low-noise op amps TSU102IST Nanopower 5 V CMOS op amp TSV358IST General purpose low voltage rail to rail input/output op amp TSV522IST High merit factor (1.15 MHz for 45 µA) CMOS op amps TSV522AIST High merit factor (1.15 MHz for 45 µA) CMOS op amps TSV612IST Rail to rail input/output CMOS op amp TSV612AIST Rail to rail input/output CMOS op amp TSV6192IST Rail to rail input/output CMOS op amp TSV6192AIST Rail to rail input/output CMOS op amp TSV622IST Micro-power CMOS op amp TSV622AIST Micro-power CMOS op amp TSV6292IST Micro-power CMOS op amp TSV6292AIST Micro-power CMOS op amp TSV632IST Micro-power CMOS op amp TSV632AIST Micro-power CMOS op amp TSV6392IST Micro-power CMOS op amp TSV6392AIST Micro-power CMOS op amp TSV712IST High accuracy TSV732IST High accuracy DocID026855 Rev 1 13/16 16 Associated products AN4574 Table 1. Associated products (continued) Part number TSV852IST Low-power, high accuracy, general-purpose operational amplifier TSV852AIST Low-power, high accuracy, general-purpose operational amplifier TSV912IST Rail to rail input/output widebandwidth op amps TSV912AIST Rail to rail input/output widebandwidth op amps TSV992IST Rail to rail input/output high merit factor op amps TSV992AIST Rail to rail input/output high merit factor op amps TSX562IST Micropower, wide bandwidth 16 V CMOS op amps TSX562AIST Micropower, wide bandwidth 16 V CMOS op amps TSX632IST Micropower, rail-to-rail 16 V CMOS op amps TSX632AIST Micropower, rail-to-rail 16 V CMOS op amps TSX922IST 10 MHz, rail-to-rail 16 V CMOS op amps TSX9292IST 16 MHz, rail-to-rail 16 V CMOS op amps TSZ122IST 14/16 General description Very high accuracy (5 µV) zero drift micropower 5 V DocID026855 Rev 1 AN4574 5 Revision history Revision history Table 2. Document revision history Date Revision 10-Sep-2014 1 Changes Initial release. DocID026855 Rev 1 15/16 16 AN4574 IMPORTANT NOTICE – PLEASE READ CAREFULLY STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgement. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of Purchasers’ products. No license, express or implied, to any intellectual property right is granted by ST herein. Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product. ST and the ST logo are trademarks of ST. All other product or service names are the property of their respective owners. Information in this document supersedes and replaces information previously supplied in any prior versions of this document. © 2014 STMicroelectronics – All rights reserved 16/16 DocID026855 Rev 1