SMM153
GENERAL DESCRIPTION
The SMM153 is a highly accurate power supply
voltage/current supervisor and monitor that allows real-
time power measurement for power-critical designs. This
advance functionality allows the development of “Green”
systems and introduces higher levels of system
reliability.
The SMM153 also provides real-time, differential voltage
measurement of the converter output voltage. The
differential sensing of the VM+ and VM- inputs
eliminates the ground or low-side error sometimes
encountered with a single-ended sensing schemes.
Programming of the SMM153 is performed over the
industry standard I2C 2-wire serial data interface. A
status register is available to read the state of the part
and a Write Protect (WP) pin is available to prevent
writing to the configuration registers and EE memory.
The SMM153 senses converter input current using a
Kelvin-connected sense resistor in series with the
converter supply whose terminals are connected to the
CS+ and CS- pins. The internal ADC, also used for
measuring the converter’s output voltage, is used to
measure the converter’s input current using the voltage
dropped across the current sense resistor RS (see
Figure 1).
The SMM153 also provides four programmable general-
purpose inputs/outputs. The power-on state of these
I/Os is determined via NV memory. Volatile
programming allows the user to select the logic level
(HIGH or LOW) of each I/O, which can also be read via
a status register.
The SMM153 has two additional input pins and one
additional output pin. The input pins, COMP1 and
COMP2, are high impedance inputs, each connected to
a comparator and compared against the internal
reference. Each comparator can be independently
programmed to monitor for under- or over-voltage
conditions. When either of the COMP1 or COMP2
inputs are in fault the open-drain FAULT# output will be
pulled low.
Summit Microelectronics, Inc
2134 3.0 1/20/2010
2
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
