MPC92433 Data Sheet
1428MHZ DUAL OUTPUT LVPECL CLOCK SYNTHESIZER
MPC92433 REVISION 3 FEBRUARY 6, 2013
10
2013 Integrated Device Technology, Inc.
Figure 3. I2C Mode Register Set
Figure 3 illustrates the synthesizer register set. PLL_L and
PLL_H store a PLL configuration and are fully accessible (Read/
Write) by the I2C bus. CMD (Write only) accepts commands
(LOAD, GET, INC, DEC) to update registers and for direct PLL
frequency changes.
Set the synthesizer frequency:
1) Write the PLL_L and PLL_H registers with a new config-
2) Write the LOAD command to update the PLL dividers by
the current PLL_L, PLL_H content.
Read the synthesizer frequency:
1) Write the GET commands to update the PLL_L, PLL_H
registers by the PLL divider setting
2) Read the PLL_L, PLL_H registers through I2C
Change the synthesizer frequency in small steps:
1) Write the INC or DEC command to change the PLL fre-
quency immediately. Repeat at any time if desired.
LOAD and GET are inverse command to each other. LOAD
updates the PLL dividers and GET updates the configuration
registers. A fast and convenient way to change the PLL frequency
is to use the INC (increment M) and DEC (decrement M)
commands of the synthesizer. INC (DEC) directly increments
(decrements) the PLL-feedback divider M and immediately
changes the PLL frequency by the smallest step G (see
Table 7for the frequency granularity G). The INC and DEC commands are
designed for multiple and rapid PLL frequency changes as
required in frequency margining applications. INC and DEC do not
require the user to update the PLL dividers by the LOAD
command, INC and DEC do not update the PLL_L and PLL_H
registers either (use LOAD for an initial PLL divider setting and, if
desired, use GET to read the PLL configuration). Note that the
synthesizer does not check any boundary conditions such as the
VCO frequency range. Applying the INC and DEC commands
could result in invalid VCO frequencies (VCO frequency beyond
lock range).
Register Maps
Register 0x00 (PLL_L) contains the least significant bits of the
PLL feedback divider M.
Register content:
M[7:0]
PLL feedback-divider M, bits 7–0
Register 0x01 (PLL_H) contains the two most significant bits of
the PLL feedback divider M, four bits to control the PLL post-
dividers N and the PLL pre-divider P. The bit 0 in PLL_H register
indicates the lock condition of the PLL and is set by the
synthesizer automatically. The LOCK state is a copy of the PLL
lock signal output (LOCK). A write-access to LOCK has no effect.
Register content:
M[9:8]
PLL feedback-divider M, bits 9–8
NA[2:0]
NB
P
LOCK
Copy of LOCK output signal (read-only)
Note that the LOAD command is required to update the PLL
dividers by the content of both PLL_L and PLL_H registers.
Register 0xF0 (CMD) is a write-only command register.
The purpose of CMD is to provide a fast way to increase or
decrease the PLL frequency and to update the registers. The
register accepts four commands, INC (increment M), DEC
(decrement M), LOAD and GET (update registers). It is
recommended to write the INC, DEC commands only after a valid
PLL configuration is achieved. INC and DEC only affect the M-
divider of the PLL (PLL feedback). Applying INC and DEC
commands can result in a PLL configuration beyond the specified
lock range and the PLL may lose lock. The MPC92433 does not
verify the validity of any commands such as LOAD, INC, and
DEC. The INC and DEC commands change the PLL feedback
divider without updating PLL_L and PLL_H.
Configuration Latches
I2C Registers
I2C Access
Synthesizer – PLL
PN
M
LOAD/GET
PLL_L (R/W)
0x00
PLL_H (R/W)
0x01
CMD (W)
0xF0
Table 12. Configuration Registers
Address
Name
Content
Access
0x00
PLL_L
Least significant 8 bits of M
R/W
0x01
PLL_H Most significant 2 bits of M, P, NA,
NB, and lock state
R/W
0xF0
CMD
Command register (write only)
W only
Table 13. PLL_L (0x00, R/W) Register
Bit
7654321
0
Name
M7
M6
M5
M4
M3
M2
M1
M0
Table 14. PLL_H (0x01, R/W) Register
Bit
76
5
432
1
0
Name
M9
M8
NA2
NA1
NA0
NB
P
LOCK