
DS1884
SFP and PON ONU Controller
with Digital LDD Interface
34
Maxim Integrated
Power Leveling
The DS1884 supports power leveling as described in
G.984.2. The POW_LEV[1:0] bits in UPDATE
A2h Lowertings: 0dB, -3dB, and -6dB. Depending on the operation
mode, a combination of SET_IMOD and the KRMD bits
(MAX3710 TXCTRL3 register) are adjusted to meet these
power-level settings. The KRMD bits adjust the gain of
the APC loop and extinction ratio loop.
Manual MAX3710 Operations
The master interface is controllable using four registers
in the DS1884: 3WCTRL, ADDRESS, WRITE, READ.
Commands can be manually issued while the DS1884 is
in normal operation mode. It is also possible to suspend
normal 3-wire commands so that only manual operation
I2C Communication
I2C Definition
The following terminology is commonly used to describe
I2C data transfers.
Master Device: The master device controls the slave
devices on the bus. The master device generates SCL
clock pulses and START and STOP conditions.
Slave Devices: Slave devices send and receive data
at the master’s request.
Bus Idle or Not Busy: Time between STOP and
START conditions when both SDA and SCL are inac-
tive and in their logic-high states.
START Condition: A START condition is generated by
the master to initiate a new data transfer with a slave.
Transitioning SDA from high to low while SCL remains
high generates a START condition. See
Figure 18 for
applicable timing.
STOP Condition: A STOP condition is generated
by the master to end a data transfer with a slave.
Transitioning SDA from low to high while SCL remains
high generates a STOP condition. See
Figure 18 for
applicable timing.
Repeated START Condition: The master can use a
repeated START condition at the end of one data transfer
to indicate that it will immediately initiate a new data trans-
fer following the current one. Repeated STARTs are com-
monly used during read operations to identify a specific
memory address to begin a data transfer. A repeated
START condition is issued identically to a normal START
condition. See
Figure 18 for applicable timing.
Bit Write: Transitions of SDA must occur during the
low state of SCL. The data on SDA must remain valid
and unchanged during the entire high pulse of SCL
plus the setup and hold time requirements (
Figure 18).
Data is shifted into the device during the rising edge
of the SCL.
Bit Read: At the end a write operation, the master
must release the SDA bus line for the proper amount
of setup time before the next rising edge of SCL during
data on SDA at the falling edge of the previous SCL
pulse and the data bit is valid at the rising edge of the
current SCL pulse. Remember that the master gener-
ates all SCL clock pulses, including when it is reading
bits from the slave.
Table 13. Power Leveling Details
LOOP OPERATING
MODE
POWER LEVEL
(dB)
POW_LEV[1:0]
MODULATION CHANGE
KRMD[2:1]
(MAX3710)
Open Loop
0
00
None
1X
-3
01
Right-shift value written to SET_IMOD once
01
-6
11
Right-shift value written to SET_IMOD twice
00
APC Loop
0
00
None
1X
-3
01
Right-shift value written to SET_IMOD once
01
-6
11
Right-shift value written to SET_IMOD twice
00
Dual Closed Loop
0
00
None
1X
-3
01
None
01
-6
11
None
00