SMB119N View Datasheet(PDF) - Summit Microelectronics
Part Name
Description
MFG CO.
'SMB119N' PDF : 34 Pages View PDF
SMB119
GENERAL DESCRIPTION
The SMB119 is a fully-programmable power supply that
regulates, sequences, monitors, and margins, an entire
power subsystem. The device has 7 voltage outputs,
consisting of: three synchronous PWM “buck” step-down
converters, one configurable PWM “boost or buck”
converter, two “boost” step-up converters, and one Low
Dropout (LDO) linear regulator.
The SMB119 regulates each of the seven output
channels to an accuracy of +/-1.5% (typical). The output
is individually programmed and can be reprogrammed
via the I2C interface. In addition, several sophisticated
power management functions are built-in. The SMB119
is capable of power-on/off cascade sequencing where
each channel can be assigned one of eight sequence
positions. Supplies may also be individually powered
on/off through an I2C command or by assertion of two
general purpose enable pins. Cascade sequencing,
unlike time based sequencing, uses feedback to ensure
that each output is valid before the next channel is
enabled.
Each output voltage and the battery are monitored for
under-voltage and over-voltage conditions, using a
comparator based scheme. In the event of a fault, all
supplies may be sequenced down or immediately
disabled. Multiple output status pins are provided to
notify host processors or other supervisory circuits of
system faults.
The SMB119 features an Under-voltage Lockout (UVLO)
circuit to ensure the IC will not power up until the battery
voltage has reached a safe operating voltage. The
UVLO function exhibits hysteresis, ensuring that noise
on the supply rail does not inadvertently cause faults on
the internally regulated supply.
In the event of a system fault, all monitored supplies may
trigger fault actions such as power-off, or force-shutdown
operations. Each output on the SMB119 may also be
turned off individually at any point through an I2C
command or by a programmable enable pin.
When used in portable applications, the SMB119 is
powered from the main system battery. This input is
continuously monitored for under-voltage conditions.
The under-voltage setting for this supply is user-
programmable and has a corresponding status pin.
When the threshold level is reached, the POWER_FAIL
pin is asserted and latched. A second threshold level
also exists that asserts a status bit flag.
The SMB119 is equipped with three synchronous buck
outputs and one “buck-or-boost” output that use a
1000kHz oscillator frequency. The feedback circuitry on
each step-down channel is simplified by an internal
programmable resistor divider (buck-or-boost uses
external resistor divider).
The SMB119 is also equipped with two boost outputs.
Each boost output uses a 1000kHz oscillator, and an
asynchronous topology reducing the necessity for an
additional external MOSFET driver. All boost outputs use
an external p-channel sequencing MOSFET to isolate
load from the battery when not needed.
A Low Dropout (LDO) linear regulator with an adjustable
1.5V to 3.75V output provides a small dropout voltage
and ripple free supply that is optimal for “always on”
microcontrollers. The LDO has a separate input supply
pin.
The SMB119 provides margining control over all of its
output voltages. Through an I2C command, all outputs
can be margined by up to ±10% of the nominal output
voltage. The SMB119 also offers the ability to
dynamically change output voltage level (7 steps) for two
of its channels. In addition, each output is slew rate
limited by soft-start circuitry that is user programmable
and requires no external capacitors.
All programmable settings on the SMB119 are stored in
non-volatile registers and are easily accessed and
modified over an industry standard I2C serial bus. For
fastest possible production times Summit offers an
evaluation card and a Graphical User Interface (GUI).
Summit Microelectronics, Inc
3.0 10/8/2008
2
Share Link: 
