ADM1168 Analog Devices, ADM1168 Datasheet - Page 14

• Manufacturer Part Number: ADM1168
• Description: Super Sequencer and Monitor with Nonvolatile Fault Recording
• Manufacturer: Analog Devices

Specifications of ADM1168

• # Supplies Monitored: 8
• Volt Monitoring Accuracy: 1%
• # Output Drivers: 8
• Fet Drive/enable Output: Both
• Package: 32 ld LQFP

ADM1168
OUTPUTS
SUPPLY SEQUENCING THROUGH
CONFIGURABLE OUTPUT DRIVERS
Supply sequencing is achieved with the ADM1168 using the
programmable driver outputs (PDOs) on the device as control
signals for supplies. The output drivers can be used as logic
enables or as FET drivers.
The sequence in which the PDOs are asserted (and, therefore,
the supplies are turned on) is controlled by the sequencing
engine (SE). The SE determines what action is taken with the
PDOs, based on the condition of the ADM1168 inputs. Therefore,
the PDOs can be set up to assert when the SFDs are in tolerance,
the correct input signals are received on the VXx digital pins,
and no warnings are received from any of the inputs of the device.
The PDOs can be used for a variety of functions. The primary
function is to provide enable signals for LDOs or dc-to-dc
converters that generate supplies locally on a board. The PDOs
can also be used to provide a PWRGD signal when all the SFDs
are in tolerance or a RESET output if one of the SFDs goes out
of specification (this can be used as a status signal for a DSP, FPGA,
or other microcontroller).
The PDOs can be programmed to pull up to a number of different
options. The outputs can be programmed as follows:
•
•
•
•
•
•
•
The last option (available only on PDO1 to PDO6) allows the
user to directly drive a voltage high enough to fully enhance an
external NFET, which is used to isolate, for example, a card-side
voltage from a backplane supply (a PDO can sustain greater
than 10.5 V into a 1 μA load). The pull-down switches can also
be used to drive status LEDs directly.
Open drain (allowing the user to connect an external pull-up
resistor)
Open drain with weak pull-up to V
Open drain with strong pull-up to V
Open drain with weak pull-up to VPx
Open drain with strong pull-up to VPx
Strong pull-down to GND
Internally charge-pumped high drive (12 V, PDO1 to
PDO6 only)
SMBus DATA
CLK DATA
SE DATA
CFG4 CFG5 CFG6
DD
DD
Figure 18. Programmable Driver Output
SEL
Rev. 0 | Page 14 of 28
VP1
The data driving each of the PDOs can come from one of three
sources. The source can be enabled in the PDOxCFG configuration
register (see the
The data sources are as follows:
•
•
•
DEFAULT OUTPUT CONFIGURATION
All of the internal registers in an unprogrammed ADM1168
device from the factory are set to 0. Because of this, the PDOx pins
are pulled to GND by a weak (20 kΩ), on-chip, pull-down resistor.
As the input supply to the ADM1168 ramps up on VPx or VH,
all PDOx pins behave as follows:
•
•
•
The internal pull-down can be overdriven with an external pull-up
of suitable value tied from the PDOx pin to the required pull-up
voltage. The 20 kΩ resistor must be accounted for in calculating
a suitable value. For example, if PDOx must be pulled up to 3.3 V,
and 5 V is available as an external supply, the pull-up resistor
value is given by
Therefore,
Output from the SE.
Directly from the SMBus. A PDO can be configured so the
SMBus has direct control over it. This enables software
control of the PDOs. Therefore, a microcontroller can be
used to initiate a software power-up/power-down sequence.
On-chip clock. A 100 kHz clock is generated on the device.
This clock can be made available on any of the PDOs. It
can be used, for example, to clock an external device such
as an LED.
Input supply = 0 V to 1.2 V. PDOs high impedance.
Input supply = 1.2 V to 2.7 V. PDOs pulled to GND by a
weak (20 kΩ), on-chip, pull-down resistor.
Supply > 2.7 V. Factory programmed devices continue to pull
all PDOs to GND by a weak (20 kΩ), on-chip, pull-down
resistor. Programmed devices download current EEPROM
configuration data, and the programmed setup is latched. The
PDO then goes to the state demanded by the configuration,
providing a known condition for the PDOs during power-up.
3.3 V = 5 V × 20 kΩ/(R
R
VP4
UP
= (100 kΩ − 66 kΩ)/3.3 V = 10 kΩ
V
DD
VFET (PDO1 TO PDO6 ONLY)
AN-721 Application Note
UP
+ 20 kΩ)
PDO
for details).