SMT4504
Preliminary Information
3 .3 V
2 .5 V
1 .8 V
1 .5 V
Figure 2A – Example Power Supply Sequencing and Tracking using the SMT4504. Any order of supply
sequencing/tracking can be applied using the SMT4504.
GENERAL DESCRIPTION
The SMT4504 consists of several major functional
blocks: the power supply monitors, the sequencing and
tracking outputs; the programmable output circuitry; the
timing and control block; the I
2
C interface and the
nonvolatile memory array.
The analog acquisition system monitors all channels via
the OV/UV sensors. The UV/OV sensors are the four
power supply voltage channels and the VDD and
VCTRL_SUP supplies. The setting of the OV/UV trip
points is made via the I
2
C serial data port.
Once PWR_ON is asserted a programmable delay timer
must first expire after which the PUP (Point of Use
Power) output(s) so required are enabled. The PUPs are
generally connected to the Enable pin of the converter
controlled by the SMT4504 Any channel not requiring
closed-loop tracking of the voltage is programmed to
assert its output (PUP) once the previous sequence
timer has expired. Otherwise all PUPs are asserted
upon the completion of the PWR_ON delay timer.
The power supply manager block is also used to assign
a given power supply a sequence position; sequence
timeout period and track-up/down slew rate setting.
These settings determine the time and the rate at which
each supply is turned on. When more than one supply is
assigned to a sequence position their voltages will be
tracked during the period of time when they are turned
on via the VCTRL
X
pins and monitored via the VM
X
pins.
These events are controlled by the sequence and
tracking block.
An additional feature of the SMT4504 allows the
supplies that are assigned the same sequence position
to be tracked at the same or different slew rates for
applications requiring supplies to be started at the same
time but to ramp up at different rates. (Figure 2A)
The next major block is a programmable output block.
The SMT4504 provides a great deal of flexibility in
choosing the fault trigger source for the fault outputs.
The sources include multiple combinations of UV/OV
conditions. The fault outputs’ assertion polarities are
also programmable.
Programming of the SMT4504 is performed over the
industry standard I
2
C, 2-wire serial data interface. It
allows configuration of the device, real-time control of
the power-on/power-off processes and reading of the
status registers. The bus interfaces the host to 4k bits of
nonvolatile memory and the programmable configuration
registers.
The 4k bits of user configurable nonvolatile memory
uses industry standard non-volatile memory technology.
Summit Microelectronics, Inc
2071 1.1 01/07/05
2
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
