VSC055
Enhanced I2C Backplane
Controller
Product Brief
Overview
The VSC055 Enhanced I2C Backplane Controller is
an integrated CMOS circuit that significantly
reduces system cost by integrating all of the digital
logic typically required to monitor a storage
enclosure. The VSC055 may be used in any
embedded control application including parallel
SCSI, Fibre Channel or any other application where
the monitoring and control of a large number of
digital I/O signals is required. Programming the
VSC055 is easy through a convenient programming
model, which reduces the overall duration of the
design-in cycle. Data is read and written to the
device over an addressable (3-bit) I2C serial
interface, allowing multiple VSC055 devices on a
single two-wire bus.
Device Features
• Up to 64 bits of user-definable, bi-directional
general purpose I/O (5 volt tolerant)
• Slave mode I2C serial interface
• Integrated Port Bypass, Clock Recovery and
Signal Detect support for up to 16 drives
• Eight programmable fan speed monitoring
inputs
• Eight programmable pulse width modulated fan
control outputs
• Pairing of GPI/O pins for direct input/output
signal routing/buffering
• Two clock input ranges: 8 to 10MHz (crystal) or
8.0 to 53.125MHz (oscillator)
• Automatic synchronization control between
multiple devices
• Selectable direct LED drive flashing capability
• Pin-programmable addressing for up to 16
devices on a single serial bus
• 100 PQFP Package
I2C Serial Interface
The VSC055 uses an I2C serial interface to
communicate with embedded controllers such as
Vitesse’s SSC100/200 and VSC205/210. The slave
interface on the VSC055 uses a three-bit (A2:0)
addressing scheme for identification on the serial
interface. The ASEL pin determines the four-bit
device type identifier. Up to sixteen, VSC055 or
SSC050 devices may reside on a single I2C
interface.
I/O Pins
The VSC055 has 64 bi-directional I/O pins. The
functionality of these pins is configurable via
programming of the VSC055. All I/O pins have a
12mA drive strength, support 3.3V TTL, and are 5V
tolerant. To enable the designer to configure and
program the VSC055, the 64 I/Os are arranged in
registers of eight pins. Certain groups of pins have
additional functionality beyond simple input or
output to support the integrated fan speed sensors,
PWM control, and FC-AL port bypass control.
X24C16
EEPROM
Local I/O (x8)
VITESSE
Embedded
Controller
(SSC100)
Cu or
Optics
PBC_EN VSC7120
PBC_EN
I2C Serial
Interface
Flash
(64K x 8)
PBC_EN1
PBC_EN2
PBC_EN3
PBC_EN4
VSC7122
Drive Bay 1
Drive Bay 2
Drive Bay 3
Drive Bay 4
Temperature
Sensor (LM75)
VITESSE
Enhanced Backplane
Controller
(VSC055)
LEDs (x8)
Power Supplies
Fans (x4)
.
Application for a Single Loop, Single Controller with Four Drives