W83791G Datasheet, PDF (7/99 Pages) Winbond – Winbond H/W Monitoring IC

W83791D/G
1. GENERAL DESCRIPTION
W83791D/G is an evolving version of the W83782D/G --- Winbond's most popular hardware status
monitoring IC. Besides the conventional functions of W83782D/G, W83791D/G uniquely provides
several innovative features such as speech function, ASF sensor compliant, SMBus 2.0 ARP
command compatible, VID table selection trapping, and 5VID output control. Conventionally,
W83791D/G can be used to monitor several critical hardware parameters of the system, including
power supply voltages, fan speeds, and temperatures, which are very important for a high-end
computer system to work stably and efficiently. As for data access, W83791D/G provides slave
SMBus 2.0 interface which can reply PEC (Packet Error Code) when as ASF sensor.
An 8-bit analog-to-digital converter (ADC) was built inside W83791D/G. W83791D/G can
simultaneously monitor 10 analog voltage inputs (including power VDD/5VSB monitoring), 5 fan
tachometer inputs, 3 remote temperatures, and one case open detection signal. The sense of remote
temperature can be performed by thermistors, 2N3904 NPN-type transistors, or directly from Intel^TM
CPU with thermal diode output. W83791D/G provides 3 PWM (pulse width modulation) outputs for two
modes of smart fan control-S Thermal Cruise^TM T mode and SSpeed CruiseS mode. Under S Thermal
Cruise^TM T mode, temperatures of CPU and the system can be maintained within specific
programmable ranges under the hardware control. SSpeed CruiseS, namely, is to keep the fan operate
in the specific programmable r.p.m. As for warning mechanism, W83791D/G provides speech voice
warning, beep tone warning, and SMI#, OVT#, IRQ signals for system protection events.
Additionally, 5 VID inputs are provided to read the VID of CPU (i.e. Pentium^TM II/III) if applicable.
These VID inputs provide the information of Vcore voltage that CPU expects. Furthermore,
W83791D/G provides programmable VID output control to alter the voltage CPU consumes.
W83791D/G also uniquely provides an optional feature: early stage (before BIOS was loaded) beep /
speech warning to detect if the fatal elements present --- Vcore or +3.3V voltage fail and thus the
system can not be boomed up. If the VSB power on setting refers to Intel VRM 9.x, the VID table
within W83791D/G will be according to the new one. W83791D/G also has 2 specific pins to provide
selectable address setting for application of multiple devices (up to 4 devices) wired through I²C^TM
interface.
W83791D/G speech function is enabled by building in a programmable speech synthesizer with a 9-bit
current DAC output as well as a connectable external flash memory for storing voice data.
W83791D/G supports 1 CPU present or absent event trap, 5 external event traps, 17 hardware
monitor event traps (10 analog voltage, 3 fan tachometer, 3 remote temperature, 1 case open) and
128 internal programmable event traps, amounting to 151 different speech outputs. If more than two
events happen simultaneously, the priority set is: SLOTOCC# > EVNTRP1 > EVNTRP2 > EVNTRP3
> EVNTRP4 > EVNTRP5 > 128 Programmable events (Bank0 index 09h) > 17 Hardware status
events. Voice data stored in the external flash memory interface with Winbond W55FXX is flexible to
change by Winbond application software and on-line programming flash data is provided also.
Besides, an external resistor is added to provide ring oscillator.
When you do not use the speech function, W83791D/G provides a set of flexible I/O control functions
to the system designer through a set of General Purpose I/O ports. These GPIO ports may serve as
simple I/O or may be individually configured to provide a pre-defined alternate function. If pin 9
(SPEECH_SEL) is trapped to high at VSB power on, this function will be active.
Publication Release Date: April 14, 2006
-1-
Revision 1.1