SMB113A/B/SMB117/A
Preliminary Information
GENERAL DESCRIPTION
The SMB113A/B and SMB117/A are fully programmable
DC-DC controllers that incorporate power delivery and
advanced power monitoring and control functionality.
The devices integrate four synchronous “buck” step-
down controllers in a space saving package.
individually through an I2C command or by assertion of
the enable pin.
Each output voltage is monitored for under-voltage and
over-voltage (UV/OV) conditions, using a comparator-
based circuit where the output voltage is compared
The SMB113A uses a fixed 800kHz whereas the
SMB113B uses a fixed 1MHz, the SMB117 a fixed
400kHz and the SMB117A a fixed 250kHz Pulse Width
Modulation (PWM) control circuit. A type-three voltage
mode compensation network is used offering a cost
effective solution without compromising transient
response performance. By utilizing external N- and P–
type MOSFET transistors the efficiency and load current
level can be customized to fit a wide array of system
requirements.
against an internal programmable reference.
An
additional feature of the output voltage monitoring is a
programmable glitch filter capable of digitally filtering a
transient OV/UV fault condition from a true system error.
When a fault is detected for a period in excess of the
glitch filter, all supplies may be sequenced down or
immediately disabled and an output status pin can be
asserted.
The current system status is always
accessible via internal registers containing the status of
all four channels.
The SMB113A/B and SMB117/A contain four buck
outputs capable of producing an output voltage less than
the input voltage. Each buck output voltage is set by an
internal resistor divider and a programmable voltage
reference. The integrated resistor divider eliminates the
cost and space necessary for external components and
The SMB113A/B and SMB117/A also possess an
Under-voltage Lockout (UVLO) circuit to ensure the
devices will not power up until the input voltage has
reached a safe operating voltage. The UVLO function
exhibits hysteresis, ensuring that noise or a brown out
voltage on the supply rail does not inadvertently lead to
a system failure.
The SMB113A/B and SMB117/A provide dynamic
voltage management over all of their output voltages.
Through an I2C command, all output voltage levels can
be increased or decreased to a pre-programmed level.
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 SMB113A/B and the
SMB117/A are stored in non-volatile registers and are
easily accessed and modified over an industry standard
I2C serial bus. For fastest prototype development times
Summit offers an evaluation card and a Graphical User
Interface (GUI).
has several programmable values.
Through the
programmability of the reference and the resistor divider,
practically any output voltage smaller than the battery
can be produced without the need to change external
components.
The SMB113A/B and SMB117/A are capable of power-
on/off cascade sequencing where each channel can be
assigned one of four unique sequence positions. During
sequencing each channel in a given sequencing position
is guaranteed to reach its programmed output voltage
before the channel(s) occupying the next sequence
position initiate their respective soft-start sequence. A
unique programmable delay exists between each power
on/off sequence position. In addition to power on/off
sequencing all supplies can be powered on/off
Summit Microelectronics, Inc.
2111 2.4 6/24/2008
2
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
