ASC7621 Datasheet, PDF (1/50 Pages) List of Unclassifed Manufacturers – HARDWARE MONITOR WITH INTEGRATED FAN CONTROL

Preliminary Specification
aSC7621
HARDWARE MONITOR
WITH INTEGRATED FAN CONTROL
PRODUCT SPECIFICATION
Product Description
The aSC7621 has a two wire digital interface compatible
with SMBus 2.0. Using a 10-bit ΣΔ- ADC, the aSC7621
measures the temperature of two remote diode connected
transistors as well as its own die. Support for Platform
Environmental Control Interface (PECI) is included.
Using temperature information from these four zones, an
automatic fan speed control algorithm is employed to
minimize acoustic impact while achieving recommended
CPU temperature under varying operational loads.
To set fan speed, the aSC7621 has three independent
pulse width modulation (PWM) outputs that are controlled
by one, or a combination of three, temperature zones.
Both high- and low-frequency PWM ranges are supported.
The aSC7621 also includes a digital filter that can be
invoked to smooth temperature readings for better control
of fan speed and minimum acoustic impact. The aSC7621
has tachometer inputs to measure fan speed on up to four
fans. Limit and status registers for all measured values are
included to alert the system host that any measurements
are outside of programmed limits via status registers.
System voltages of VCCP, 2.5V, 3.3V, 5.0V, and 12V
motherboard power are monitored efficiently with internal
scaling resistors.
Features
• Supports PECI interface and monitors internal and
remote thermal diodes
• 2-wire, SMBus 2.0 compliant, serial interface
• 10-bit ΣΔ-ADC
• Monitors VCCP, 2.5V, 3.3V, 5.0V, and 12V
motherboard/processor supplies
• Programmable autonomous fan control based on
temperature readings
• Noise filtering of temperature reading for fan
speed control
• 0.25°C digital temperature sensor resolution
• 3 PWM fan speed control outputs for 2-, 3- or 4-
wire fans and up to 4 fan tachometer inputs
• Enhanced measured temperature to Temperature
Zone assignment.
• Provides high and low PWM frequency ranges
• 3 GPIO pins for custom use
• 24-Lead QSOP package
Measurement System
Temperature:
• 0.25°C resolution, ±2°C accuracy on remote diode
• 0.25°C resolution, ±3°C accuracy on local sensor
• Temperature measurement range on remote
sensor –55°C to +125°C using 2’s complement
coding.
Voltage:
• 10-bit Resolution, ±2% (TUE)
Fan Tachometer:
• 16-bit count of 90kHz clock periods
Limit alarms for all measured values
Applications
• Desktop Computers – Motherboards and Graphics
Cards
• Microprocessor based equipment (e.g. Base-
stations, Routers, ATMs, Point of Sales)
Connection Diagram
SMBDAT
1
SMBCLK
2
24
PWM1/
XTESTOUT
23
VCCP
GND
3
22
2.5V
3.3V
4
21
12V
GPIO2
GPIO1
5
20
5V
6
aSC7621 ¹⁹
GPIO3
PECI
7
18
REMOTE 1+
Vtt
8
17
REMOTE 1-
TACH3
9
16
REMOTE 2+
PWM2
10
15
REMOTE 2-
TACH1
11
TACH2
12
14
TACH4/
AddressSelect
13
PWM3/
AddressEnable
Ordering Information
Part Number
Package
aSC7621QS24
24-lead QSOP
Ayww – Assembly site, year, workweek
© Andigilog, Inc. 2006
Temperature Range
and Operating Voltage
0°C to +120°C, 3.3V
-1-
www.andigilog.com
Marking
aSC7621
Ayww
How Supplied
2500 units Tape & Reel
October 2006 - 70A06010