Rainbow Electronics LM93 - Manual

LM93
Hardware Monitor with Integrated Fan Control for Server
Management
1.0 General Description
The LM93, hardware monitor, has a two wire digital interface
compatible with SMBus 2.0. Using an 8-bit
Σ∆ ADC, the
LM93 measures the temperature of two remote diode con-
nected transistors as well as its own die and 16 power supply
voltages.
To set fan speed, the LM93 has two PWM outputs that are
each controlled by up to four temperature zones. The fan-
control algorithm is lookup table based. The LM93 includes a
digital filter that can be invoked to smooth temperature read-
ings for better control of fan speed. The LM93 has four
tachometer inputs to measure fan speed. Limit and status
registers for all measured values are included.
The LM93 builds upon the functionality of previous mother-
board management ASICs and uses some of the LM85’s
features (i.e. smart tachometer mode). It also adds measure-
ment and control support for dynamic Vccp monitoring and
PROCHOT. It is designed to monitor a dual processor Xeon
class motherboard with a minimum of external components.
2.0 Features
n 8-bit Σ∆ ADC
n Monitors 16 power supplies
n Monitors 2 remote thermal diodes
n Internal ambient temperature sensing
n Programmable autonomous fan control based on
temperature readings with fan boost support
n Fan control based on 13-step lookup table
n Temperature reading digital filter
n 1.0˚C digital temperature sensor resolution
n 0.5˚C temperature resolution for fan control
n 2 PWM fan speed control outputs
n 4 fan tachometer inputs
n Dual processor thermal throttling (PROCHOT)
monitoring
n Dual dynamic VID monitoring (6 VIDs per processor)
n 8 general purpose I/Os:
— 4 can be configured as fan tachometer inputs
— 2 can be configured to connect to THERMTRIP from
a processor
— 2 are standard GPIOs that could be used to monitor
IERR signal
n 2 general purpose inputs that can be used to monitor
SCSI termination signals
n Limit register comparisons of all monitored values
n 2-wire, SMBus 2.0 compliant, serial digital interface
— Supports byte/block read and write
— Configurable slave address (tri-level pin selects 1 of
3 possible addresses)
n 2.5V reference voltage output
n 56-pin TSSOP package
n XOR-tree test mode
3.0 Key Specifications
n Voltage Measurement Accuracy ± 2% FS (max)
n Resolution 8-bits, 1˚C
n Temperature Sensor Accuracy ± 3˚C (max)
n Temperature Range:
— LM93 Operational 0˚C to +85˚C
— Remote Temp Accuracy 0˚C to +125˚C
n Power Supply Voltage +3.0V to +3.6V
n Power Supply Current 0.9 mA
4.0 Applications
n Servers
n Workstations
n Multi-Microprocessor based equipment
5.0 Ordering Information
Order Number NS Package Number Transport media
LM93CIMT MTD56 34 units in rail
LM93CIMTX MTD56 1000 units in tape-and-reel
I2C is a registered trademark of the Philips Corporation.
April 2004
LM93
Hardware
Monitor
with
Integrated
Fan
Control
for
Server
Management
© 2004 National Semiconductor Corporation DS200682 www.national.com