MSP430I2041: SD24, SD24_A and SD24_B External reference input loading characteristics

Part Number: MSP430F6769
I would like to know the input loading characteristics of the external voltage reference on the following 24-bit Sigma-delta ADC modules on MSP430:
SD24 on MSP430I20xx,
SD24_A on MSP430AFE2xx,
SD24_B on MSP430F67xx(A),
Specifically:
Are the external voltage reference pins buffered or unbuffered?
If unbuffered, what are the input R and C values of the external voltage references? I need this info for SPICE modeling. (Sigma-delta ADC's reference input is a switching capacitor). The respective datasheets only list an external reference input current of 50nA for all of SD24, SD24_A and SD24_B.

I have additional questions about the analog input characteristics of SD24, SD24_A and SD24_B:
The User Guide for MSP430F67xx(A) (SLAU208Q), Section 29.2.6.3 Analog Input Characteristics, indicates that some devices with SD24_B have buffered input, while some don't.
On the following datasheets:
SLAS731D, Table 5-36
SLASE46A, Table 5-36
SLAS768E, Section 5.49
SLAS983A, Table 5-40
They all indicate 5pF input capacitance and 200kOhm input impedance for the SD24_B analog inputs. Does it mean all these MSP430F67xx(A) devices have UNbuffered inputs on their SD24_B?
And the same question for MSP430AFE2xx (user guide is SLAU144J, Section 27.2.6), Do MSP430AFE2xx have buffered or unbuffered inputs on their SD24_A? I can't find the relevant information on their datasheet (SLAS701B).
While the User Guide for MSP430I20xx (SLAU335) doesn't indicate the same information of switching capacitor inputs. Does this mean the SD24 module on all MSP430I20xx devices have buffered inputs? The datasheet (SLAS887B) Section 5.7.7, Table 5-21 only lists 200kOhm input impedance, but gives no further information.