C8051F000/1/2/5/6/7
C8051F010/1/2/5/6/7
Figure 9.2. REF0CN: Reference Control Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
Bit7
-
Bit6
-
Bit5
-
Bit4
-
Bit3
TEMPE
Bit2
BIASE
Bit1
REFBE
Bit0
00000000
SFR Address:
0xD1
Bits7-3: UNUSED. Read = 00000b; Write = don’t care
Bit2:
TEMPE: Temperature Sensor Enable Bit
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
Bit1:
BIASE: Bias Enable Bit for ADC and DAC’s
0: Internal Bias Off.
1: Internal Bias On (required for use of ADC or DAC’s).
Bit0:
REFBE: Internal Voltage Reference Buffer Enable Bit
0: Internal Reference Buffer Off. System reference can be driven from external source on
VREF pin.
1: Internal Reference Buffer On. System reference provided by internal voltage reference.
Table 9.1. Reference Electrical Characteristics
VDD = 3.0V, AV+ = 3.0V, -40°C to +85°C unless otherwise specified.
PARAMETER
CONDITIONS
INTERNAL REFERENCE (REFBE = 1)
Output Voltage
25°C ambient
VREF Short Circuit Current
VREF Power Supply
Current (supplied by AV+)
VREF Temperature
Coefficient
Load Regulation
Load = (0-to-200µA) to AGND (Note 1)
VREF Turn-on Time1
4.7µF tantalum, 0.1µF ceramic bypass
VREF Turn-on Time2
0.1µF ceramic bypass
VREF Turn-on Time3
no bypass cap
EXTERNAL REFERENCE (REFBE = 0)
Input Voltage Range
Input Current
MIN
2.34
TYP
2.43
50
15
0.5
2
20
10
1.00
0
(AV+)
– 0.3V
1
MAX
2.50
30
UNITS
V
mA
µA
ppm/°C
ppm/µA
ms
µs
µs
V
µA
Note 1: The reference can only source current. When driving an external load, it is recommended to add a load
resistor to AGND.
61
Rev. 1.7