User guide

DS1875
PON Triplexer and SFP Controller
90 ______________________________________________________________________________________
Table 07h Register Descriptions
Table 07h, Register 80h to A3h: PWM REFERENCE LUT
FACTORY DEFAULT 00h
READ ACCESS PW2
WRITE ACCESS PW2
MEMORY TYPE Nonvolatile (EE)
80h to A3h 2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
BIT 7 BIT 0
The PWM REFERENCE LUT is a set of registers assigned to hold the temperature profile for the PWM feedback.
The values in this table determine the set point for the PWM loop. The temperature measurement is used to
index the LUT (TINDEX, Table 02h, Register 81h) in 4°C increments from -40°C to +100°C, starting at Register
80h in Table 07h. Register 80h defines the -40°C to -36°C PWM reference value, Register 81h defines the -36°C
to -32°C PWM reference value, and so on. Values recalled from this EEPROM memory table are written into the
PWM DAC (Table 02h, Register FEh) location that holds the value until the next temperature conversion. The
DS1875 can be placed into a manual mode (PWM EN bit, Table 02h, Register 80h), where PWM DAC can be
directly controlled for calibration. If temperature compensation is not required by the application, program the
entire LUT to the desired PWM set point.
Table 07h, Register A4h to A7h: RESERVED
FACTORY DEFAULT 00h
READ ACCESS PW2
WRITE ACCESS PW2
MEMORY TYPE Nonvolatile (SEE)
These registers are reserved.