MSP430F6438, MSP430F6436, MSP430F6435, MSP430F6433
SLAS720D – AUGUST 2010 – REVISED DECEMBER 2015
5.43 REF, External Reference
over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)
(1)
PARAMETER
TEST CONDITIONS
V
CC
MIN
TYP
MAX
UNIT
Positive external
V
eREF+
V
eREF+
> V
REF-
/V
eREF-
(2)
1.4
AV
CC
V
reference voltage input
Negative external
V
REF-
/V
eREF-
V
eREF+
> V
REF-
/V
eREF-
(3)
0
1.2
V
reference voltage input
V
eREF+
–
Differential external
V
eREF+
> V
REF-
/V
eREF-
(4)
1.4
AV
CC
V
V
REF-
/V
eREF-
reference voltage input
1.4 V
≤
V
eREF+
≤
V
AVCC
, V
eREF-
= 0 V,
f
ADC12CLK
= 5 MHz, ADC12SHTx = 1h,
2.2 V, 3 V
–26
26
Conversion rate 200 ksps
I
VeREF+
, I
VREF-
Static input current
µA
/VeREF-
1.4 V
≤
V
eREF+
≤
V
AVCC
, V
eREF-
= 0 V,
f
ADC12CLK
= 5 MHZ, ADC12SHTx = 8h,
2.2 V, 3 V
–1.2
+1.2
Conversion rate 20 ksps
Capacitance at VREF+
C
VREF+/-
10
µF
or VREF- terminal
(5)
(1)
The external reference is used during ADC conversion to charge and discharge the capacitance array. The input capacitance, C
i
, is also
the dynamic load for an external reference during conversion. The dynamic impedance of the reference supply should follow the
recommendations on analog-source impedance to let the charge settle for 12-bit accuracy.
(2)
The accuracy limits the minimum positive external reference voltage. Lower reference voltage levels may be applied with reduced
accuracy requirements.
(3)
The accuracy limits the maximum negative external reference voltage. Higher reference voltage levels may be applied with reduced
accuracy requirements.
(4)
The accuracy limits minimum external differential reference voltage. Lower differential reference voltage levels may be applied with
reduced accuracy requirements.
(5)
Two decoupling capacitors, 10 µF and 100 nF, should be connected to VREF to decouple the dynamic current required for an external
reference source if it is used for the ADC12_A. See also the
MSP430x5xx and MSP430x6xx Family User's Guide
(
).
44
Specifications
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