SMS64
Preliminary
3.3V
2.7V
2.5V
2.0V
1.8V
1.5V
RST_A#
RST_B#
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t2
Figure 1 – Example Power Supply Sequencing and System Start-up Initialization using the SMS64 as
shown in the Simplified Applications Drawing on page 1. Any order of supply sequencing can be applied
using the SMS64
GENERAL DESCRIPTION
The SMS64 has four major functional blocks; the
supply managers and the sequencing outputs; the
programmable reset and interrupt circuitry; the timing
and control block; and the nonvolatile memory array.
The managers are comprised of a voltage monitor
with a programmable threshold input. The monitored
voltage threshold can be programmed anywhere
between 0.9V and 6.0V in 20mV increments. Each
monitor provides an under-voltage/over-voltage
(UV/OV) signal to the internal bus.
The other major block is a programmable reset and
interrupt block. The SMS64 provides a great deal of
flexibility in choosing the trigger source for the resets
and interrupt.
The sources include multiple
combinations of UV/OV conditions, and programmable
Watchdog and Longdog timers.
Programming of the SMS64 is performed over the
industry standard I2C, 2-wire serial data interface. It
allows configuration of the device, real-time control of
the power-on/power-off processes and instant-access
to the power supply status of the application circuit.
The bus interfaces the host to 4k bits of nonvolatile
memory and the programmable configuration
registers.
Associated with each monitor is an output circuit
(PUP circuit) that can be used to enable or switch an
external power supply to the application’s circuits. The
point in time and position in a sequence when the
output is asserted is programmable and is controlled
by the sequence position assignments and the PUP
delays in the timing and control block.
Summit Microelectronics, Inc
2060 2.22 10/09/03
2
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
