ADM1066 Analog Devices, ADM1066 Datasheet - Page 25

• Manufacturer Part Number: ADM1066
• Manufacturer: Analog Devices

Specifications of ADM1066

• # Supplies Monitored: 12
• Volt Monitoring Accuracy: 1%
• # Output Drivers: 10
• Fet Drive/enable Output: Both
• Voltage Readback: 12-bit ADC
• Supply Adj/margining: 12-bit ADC+6 DACs
• Package: 40 ld LFCSP ,48 ld TQFP

COMMUNICATING WITH THE ADM1066
CONFIGURATION DOWNLOAD AT POWER-UP
The configuration of the ADM1066 (undervoltage/overvoltage
thresholds, glitch filter timeouts, PDO configurations, and so on)
is dictated by the contents of the RAM. The RAM comprises
digital latches that are local to each function on the device. The
latches are double-buffered and have two identical latches, Latch A
and Latch B. Therefore, when an update to a function occurs,
the contents of Latch A are updated first, and then the contents
of Latch B are updated with identical data. The advantages of
this architecture are explained in detail in the Updating the
Configuration section.
The two latches are volatile memory and lose their contents at
power-down. Therefore, the configuration in the RAM must be
restored at power-up by downloading the contents of the
EEPROM (nonvolatile memory) to the local latches. This
download occurs in steps, as follows:
1.
2.
3.
4.
5.
6.
Note that any attempt to communicate with the device prior to
the completion of the download causes the ADM1066 to issue
a no acknowledge (NACK).
UPDATING THE CONFIGURATION
After power-up, with all the configuration settings loaded from
the EEPROM into the RAM registers, the user may need to alter
the configuration of functions on the ADM1066, such as changing
the undervoltage or overvoltage limit of an SFD, changing the
fault output of an SFD, or adjusting the rise time delay of one of
the PDOs.
With no power applied to the device, the PDOs are all high
impedance.
When 1.2 V appears on any of the inputs connected to the
VDD arbitrator (VH or VPx), the PDOs are all weakly
pulled to GND with a 20 kΩ resistor.
When the supply rises above the undervoltage lockout of
the device (UVLO is 2.5 V), the EEPROM starts to
download to the RAM.
The EEPROM downloads its contents to all Latch As.
When the contents of the EEPROM are completely
downloaded to the Latch As, the device controller signals
all Latch As to download to all Latch Bs simultaneously,
completing the configuration download.
At 0.5 ms after the configuration download completes, the
first state definition is downloaded from the EEPROM into
the SE.
Rev. E | Page 25 of 32
The ADM1066 provides several options that allow the user to
update the configuration over the SMBus interface. The following
three options are controlled in the UPDCFG register.
Option 1
Update the configuration in real time. The user writes to the
RAM across the SMBus, and the configuration is updated
immediately.
Option 2
Update the Latch As without updating the Latch Bs. With this
method, the configuration of the ADM1066 remains unchanged
and continues to operate in the original setup until the instruction
is given to update the Latch Bs.
Option 3
Change the EEPROM register contents without changing the RAM
contents, and then download the revised EEPROM contents to
the RAM registers. With this method, the configuration of the
ADM1066 remains unchanged and continues to operate in the
original setup until the instruction is given to update the RAM.
The instruction to download from the EEPROM in Option 3
is also a useful way to restore the original EEPROM contents
if revisions to the configuration are unsatisfactory. For example,
if the user needs to alter an overvoltage threshold, the RAM
register can be updated as described in Option 1. However,
if the user is not satisfied with the change and wants to revert to
the original programmed value, the device controller can issue
a command to download the EEPROM contents to the RAM
again, as described in Option 3, restoring the ADM1066 to its
original configuration.
The topology of the ADM1066 makes this type of operation
possible. The local, volatile registers (RAM) are all double-
buffered latches. Setting Bit 0 of the UPDCFG register to 1 leaves
the double-buffered latches open at all times. If Bit 0 is set to 0
when a RAM write occurs across the SMBus, only the first side
of the double-buffered latch is written to. The user must then
write a 1 to Bit 1 of the UPDCFG register. This generates a pulse
to update all the second latches at once. EEPROM writes occur
in a similar way.
The final bit in this register can enable or disable EEPROM page
erasure. If this bit is set high, the contents of an EEPROM page can
all be set to 1. If this bit is set low, the contents of a page cannot be
erased, even if the command code for page erasure is programmed
across the SMBus. The bit map for the UPDCFG register is shown
in the AN-698 Application Note at www.analog.com. A flow
diagram for download at power-up and subsequent configuration
updates is shown in Figure 35.
ADM1066