Rainbow Electronics MAX5945 - Manual (Page 34)

MAX5945
Use the program registers (Table 29) to set the nominal
value for t
FAULT
and t
START
for all ports according to
the following formula:
t FAULT nominal = 40.96ms + 2.72ms x N
t START nominal = 40.96ms + 2.72ms x N
where N is the decimal value of TF_PR[3:0] or
TS_PR[3:0], respectively.
A reset sets R28h = 77h, which sets t FAULT = t START =
60ms as shown in the Electrical Characteristics. Use
R28h in conjunction with the two TSTART and TFAULT
bits in register R16h to program the values of t
FAULT
and t START from about 20ms to almost 330ms with a
2.72ms resolution.
Example: Set TF_PR[3:0] = 1111b, TFAULT[1:0] = 11b
Then:
t FAULT = 4 x t FAULT nominal
= 4 x (40.96ms + 2.72ms x 15)
= 327ms
Note: The programmed value has the same percent-
age tolerance as the value specified in the Electrical
Characteristics.
Quad Network Power Controller
for Power-Over-LAN
34 ______________________________________________________________________________________
ADDRESS = 28h
SYMBOL BIT R/W
DESCRIPTION
7 R TF_PR[3]. t FAULT nominal programming bit 3.
6 R TF_PR[2]. t FAULT nominal programming bit 2.
5 R TF_PR[1]. t FAULT nominal programming bit 1.
TF_PR
4 R TF_PR[0]. t FAULT nominal programming bit 0.
3 R TS_PR[3]. t START nominal programming bit 3.
2 R TS_PR[2]. t START nominal programming bit 2.
1 R TS_PR[1]. t START nominal programming bit 1.
TS_PR
0 R TS_PR[0]. t
START
nominal programming bit 0.
Table 29. Program Register 3