Si1000/1/2/3/4/5
6. Programmable Current Reference (IREF0)
Si1000/1/2/3/4/5 devices include an on-chip programmable current reference (source or sink) with two out-
put current settings: Low Power Mode and High Current Mode. The maximum current output in Low Power
Mode is 63 µA (1 µA steps) and the maximum current output in High Current Mode is 504 µA (8 µA steps).
The current source/sink is controlled though the IREF0CN special function register. It is enabled by setting
the desired output current to a non-zero value. It is disabled by writing 0x00 to IREF0CN. The port I/O pin
associated with ISRC0 should be configured as an analog input and skipped in the Crossbar. See Section
“21. Port Input/Output” on page 207 for more details.
SFR Definition 6.1. IREF0CN: Current Reference Control
Bit
7
6
5
4
3
2
1
0
SINK
MODE
IREF0DAT
R/W
Name
Type
Reset
R/W
0
R/W
0
0
0
0
0
0
0
SFR Page = 0x0; SFR Address = 0xB9
Bit
Name
Function
7
SINK
IREF0 Current Sink Enable.
Selects if IREF0 is a current source or a current sink.
0: IREF0 is a current source.
1: IREF0 is a current sink.
6
MDSEL
IREF0 Output Mode Select.
Selects Low Power or High Current Mode.
0: Low Power Mode is selected (step size = 1 µA).
1: High Current Mode is selected (step size = 8 µA).
5:0 IREF0DAT[5:0] IREF0 Data Word.
Specifies the number of steps required to achieve the desired output current.
Output current = direction x step size x IREF0DAT.
IREF0 is in a low power state when IREF0DAT is set to 0x00.
6.1. IREF0 Specifications
See Table 4.12 on page 62 for a detailed listing of IREF0 specifications.
98
Rev. 1.0
SILICON [ SILICON ]
