HI-8436
REGISTER DESCRIPTIONS (cont.)
SUPPLY/OPEN THRESHOLD CENTER VALUE AND HYSTERESIS REGISTER: SOCENHYS
Read: SPI Op-code 0xBC
Write: SPI Op-code 0x3C
Reset Value 00
[Opcode, DB1, DB0]
Bit
Name R/W Default Description
XX
SOHYSSO5HYSSO4HYSSO3HYSSO2 HYS1
76543210
MSB
LSB
XX
SOCVSAOLC5VSAOL4CVSAOL3CVSAOL2CVAL1
76543210
MSB
LSB
DATA BYTE 1
DATA BYTE 0
DATA WORD 1
7-6
-
R/W 0
Not Used.
5-0 SOHYS5-0 R/W 0
Supply/Open Hysteresis. For all inputs programmed to be Supply/Open sensors the hysteresis
is set by these 6 bits. Hysteresis = 0.2V x SOHYS.
DATA WORD 0
7-6
-
R/W 0
Not Used.
5- 0 SOCVAL5-0 R/W 0
Supply/Open Threshold Center Value. For all inputs programmed to be Supply/Open sensors
the center threshold is set by these 6 bits. Center Threshold = 0.1V x SOCVAL.
VTHI = Threshold center value + ½ Hysteresis, Max limit = 5.2V, Min limit = 0.6V
VTLO = Threshold center value - ½ Hysteresis, Max limit = 5.0V, Min limit = 0.4V
Example: Supply/Open sensor with VTHI = 5V and VTLO = 2V:
a) Program SOHYS
Hysteresis = VTHI - VTLO = 0.2V x SOHYS
SOHYS = (5V - 2V)/(0.2V) = 15 LSB
b) Program SOCVAL
Center Value = (VTHI + VTLO) / 2 = 0.1V x SOCVAL
SOCVAL = (5V + 2V) / (2 x 0.1) = 35 LSB
c) write 0x3C 0x0F 0x23 to SPI
0x3C writes to the Supply/Open Threshold and Hysteresis Registers.
0x0F = 15 LSB x 0.2V/LSB = 3V Hysteresis
0x23 = 35 LSB x 0.1V/LSB = 3.5V Center Value
VTHI = 3.5 + ½ (3) = 5V
VTLO = 3.5 - ½ (3) = 2V
Note: The maximum value for VTHI = 5.2V and the minimum value for VTLO = 0.4V. Also VTHI - VTLO >= 0.2V.
TABLE 7.
HOLT INTEGRATED CIRCUITS
8