SMM153
Preliminary Information
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 senses converter input current using a
sense resistor connected 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 R
S
(see Figure 1).
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.
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 I
2
C 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 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.
Summit Microelectronics, Inc
2.0 8/12/2008
2
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
