SLAU144K December 2004 – August 2022 MSP430AFE221 , MSP430AFE222 , MSP430AFE223 , MSP430AFE231 , MSP430AFE232 , MSP430AFE233 , MSP430AFE251 , MSP430AFE252 , MSP430AFE253 , MSP430F2001 , MSP430F2002 , MSP430F2003 , MSP430F2011 , MSP430F2012 , MSP430F2013 , MSP430F2101 , MSP430F2111 , MSP430F2112 , MSP430F2121 , MSP430F2122 , MSP430F2131 , MSP430F2132 , MSP430F2132-EP , MSP430F2232 , MSP430F2234 , MSP430F2252 , MSP430F2252-Q1 , MSP430F2254 , MSP430F2272 , MSP430F2272-Q1 , MSP430F2274 , MSP430F2274-EP , MSP430F233 , MSP430F2330 , MSP430F235 , MSP430F2350 , MSP430F2370 , MSP430F2410 , MSP430F2416 , MSP430F2417 , MSP430F2418 , MSP430F2419 , MSP430F247 , MSP430F2471 , MSP430F248 , MSP430F2481 , MSP430F249 , MSP430F2491 , MSP430F2616 , MSP430F2617 , MSP430F2618 , MSP430F2619 , MSP430G2001 , MSP430G2101 , MSP430G2102 , MSP430G2111 , MSP430G2112 , MSP430G2121 , MSP430G2131 , MSP430G2132 , MSP430G2152 , MSP430G2153 , MSP430G2201 , MSP430G2201-Q1 , MSP430G2202 , MSP430G2203 , MSP430G2210 , MSP430G2211 , MSP430G2212 , MSP430G2213 , MSP430G2221 , MSP430G2230 , MSP430G2231 , MSP430G2231-Q1 , MSP430G2232 , MSP430G2233 , MSP430G2252 , MSP430G2253 , MSP430G2302 , MSP430G2303 , MSP430G2312 , MSP430G2313 , MSP430G2332 , MSP430G2333 , MSP430G2352 , MSP430G2353 , MSP430G2402 , MSP430G2403 , MSP430G2412 , MSP430G2413 , MSP430G2432 , MSP430G2433 , MSP430G2444 , MSP430G2452 , MSP430G2453 , MSP430G2513 , MSP430G2533 , MSP430G2544 , MSP430G2553 , MSP430G2744 , MSP430G2755 , MSP430G2855 , MSP430G2955 , MSP430TCH5E
This mode allows internal routing of the OA signals for a two-opamp or three-opamp instrumentation amplifier. Figure 20-2 shows a two-opamp configuration with OA0 and OA1. In this mode the output of the OAx is connected to RTOP by routing through another OAx in the Inverting PGA mode. RBOTTOM is unconnected providing a unity gain buffer. This buffer is combined with one or two remaining OAx to form the differential amplifier. The OAx output is connected to the ADC input channel as selected by the OAxCTL0 bits.
Figure 20-2 shows an example of a two-opamp differential amplifier using OA0 and OA1. The control register settings and are shown in Table 20-3. The gain for the amplifier is selected by the OAFBRx bits for OA1 and is shown in Table 20-4. The OAx interconnections are shown in Figure 20-3.
Register | Settings (binary) |
---|---|
OA0CTL0 | xx xx xx 0 0 |
OA0CTL1 | 000 111 0 x |
OA1CTL0 | 11 xx xx x x |
OA1CTL1 | xxx 110 0 x |
OA1 OAFBRx | Gain |
---|---|
000 | 0 |
001 | 1/3 |
010 | 1 |
011 | 1 2/3 |
100 | 3 |
101 | 4 1/3 |
110 | 7 |
111 | 15 |
Figure 20-4 shows an example of a three-opamp differential amplifier using OA0, OA1 and OA2 (Three opamps are not available on all devices. See device-specific data sheet for implementation.). The control register settings are shown in Table 20-5. The gain for the amplifier is selected by the OAFBRx bits of OA0 and OA2. The OAFBRx settings for both OA0 and OA2 must be equal. The gain settings are shown in Table 20-6. The OAx interconnections are shown in Figure 20-5.
Register | Settings (binary) |
---|---|
OA0CTL0 | xx xx xx 0 0 |
OA0CTL1 | xxx 001 0 x |
OA1CTL0 | xx xx xx 0 0 |
OA1CTL1 | 000 111 0 x |
OA2CTL0 | 11 11 xx x x |
OA2CTL1 | xxx 110 0 x |
OA0/OA2 OAFBRx | Gain |
---|---|
000 | 0 |
001 | 1/3 |
010 | 1 |
011 | 1 2/3 |
100 | 3 |
101 | 4 1/3 |
110 | 7 |
111 | 15 |