SMB119 datasheet(2/34 Pages) SUMMIT

2 / 34 page

SMB119

Summit Microelectronics, Inc

3.0 10/8/2008

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 I

2C 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 I

2C 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 I

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 I

2C 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 I

2C serial bus. For

fastest possible production times Summit offers an

evaluation card and a Graphical User Interface (GUI).

GENERAL DESCRIPTION

SMB119 датащи(PDF) 2 Page - Summit Microelectronics, Inc.

SMB119 датащи(HTML) 2 Page - Summit Microelectronics, Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

датащи скачать

ссылки URL