Winbond Electronics W83783S Datasheet

W83783S
Winbond H/W
Monitoring IC

W83783S Data Sheet Revision History

Pages Dates Version Version

1

2

3

4

5

6

7

8

9

10

n.a. n.a. All the version before 0.50 are for internal use.

n.a. 98/7 0.5 n.a. First publication.

P.36 99/4 0.55 A1 Add the content of Diode Selection Register Index

P.38 99/4 0.55 A1 Add the content of 7.25 Fan Divisor Register and

Main Contents

on Web

59h( Bank0)

rename to VBAT Monitor Control Register Index
5Dh( Bank0)

Please note that all data and specifications are subject to change without notice. All
the trade marks of products and companies mentioned in this data sheet belong to
their respective owners.

LIFE SUPPORT APPLICATIONS

These products are not designed for use in life support appliances, devices, or
systems where malfunction of these products can reasonably be expected to result
in personal injury. Winbond customers using or selling these products for use in
such applications do so at their own risk and agree to fully indemnify Winbond for
any damages resulting from such improper use or sales.

W83783S

Preliminary

TABLE OF CONTENTS

1. GENERAL DESCRIPTION.......................................................................................................................1

2. FEATURES.....................................................................................................Error! Bookmark not defined.

2.1 Monitoring Items...................................................................................................................................2

2.2 Actions Enabling ...................................................................................................................................2

2.3 General..................................................................................................................................................2

2.4 Package ................................................................................................................................................. 2

3. KEY SPECIFICATIONS............................................................................................................................3

4. PIN CONFIGURATION .............................................................................................................................3

5. PIN DESCRIPTION....................................................................................................................................4

6. FUNCTIONAL DESCRIPTION.................................................................................................................6

6.1 General Description............................................................................................................................... 6

6.2 Access Interface.....................................................................................................................................6

6.2.1 The first serial bus access timing are shown as follow:.....................................................................6

6.2.2 The serial bus timing of the temperature 2 and 3 is shown as follow:................................................ 7

6.3 Analog Inputs......................................................................................................................................10

6.3.1 Monitor over 4.096V voltage:.........................................................................................................11

6.3.2 Monitor negative voltage:..............................................................................................................12

6.3.3 Monitor temperature from thermistor: ............................................................................................13

6.3.4 Monitor temperature from Pentium IITM thermal diode or bipolar transistor 2N3904 ..................... 13

6.4 FAN Speed Count and FAN Speed Control..........................................................................................14

6.4.1 Fan speed count.............................................................................................................................14

6.4.2 Fan speed control...........................................................................................................................15

6.5 Temperature Measurement Machine....................................................................................................16

6.5.1 The W83783S temperature sensor 2 SMI# interrupt has two modes:...............................................17

6.5.2 The W83783S temperature sensor 1 SMI# interrupt has three modes ..............................................18

6.5.3 The W83783S temperature sensor 1 Over-Temperature (OVT#) has three modes............................19

6.6 Voltage and Fan SMI# mode :..............................................................................................................20

6.6.1 Voltage SMI# mode :......................................................................................................................20

6.6.2 Fan SMI# mode :............................................................................................................................20

Publication Release Date: April 1999

- I - Version

0.55

W83783S

Preliminary

7. REGISTERS AND RAM .......................................................................................................................... 22

7.1 Configuration Register  Index 40h....................................................................................................22

7.2 Interrupt Status Register 1 Index 41h...............................................................................................23

7.3 Interrupt Status Register 2  Index 42h..............................................................................................23

7.4 SMI# Mask Register 1  Index 43h....................................................................................................24

7.5 SMI# Mask Register 2  Index 44h....................................................................................................25

7.6 Reserved Register  Index 45h-- 46h ..................................................................................................25

7.7 VID/Fan Divisor Register  Index 47h...............................................................................................26

7.8 Serial Bus Address Register  Index 48h ............................................................................................26

7.9 Value RAM  Index 20h- 3Fh or 60h - 7Fh........................................................................................27

7.10 Voltage ID (VID4) & Device ID - Index 49h......................................................................................29

7.11 Temperature 2 and Temperature 3 Serial Bus Address Register--Index 4Ah....................................... 29

7.12 Pin Control Register - Index 4Bh .......................................................................................................30

7.13 IRQ#/OVT# Property Select - Index 4Ch ........................................................................................... 31

7.14 FAN IN/OUT and BEEP/GPO# Control Register - Index 4Dh ........................................................... 32

7.15 Register 50h ~ 5Fh Bank Select - Index 4Eh......................................................................................33

7.16 Winbond Vendor ID - Index 4Fh........................................................................................................33

7.17 Winbond Test Register -- Index 50h - 55h (Bank 0)..........................................................................34

7.18 BEEP Control Register 1-- Index 56h (Bank 0)..................................................................................34

7.19 BEEP Control Register 2-- Index 57h (Bank 0)..................................................................................35

7.20 Chip ID -- Index 58h (Bank 0)...........................................................................................................36

7.21 Diode Selection Register -- Index 59h (Bank 0).................................................................................36

7.22 PWMOUT1 Control Register -- Index 5Ah (Bank 0)......................................................................36-A

7.23 PWMOUT2 Control Register -- Index 5Bh (Bank 0)..........................................................................37

7.24 PWMOUT1/2 Clock Select Register -- Index 5Ch (Bank 0)................................................................ 37

7.25 VBAT Monitor Control Register -- Index 5Dh (Bank 0).....................................................................38

7.26 Reserved Register -- Index 5Eh (Bank 0)............................................................................................39

7.27 Reserved Register -- Index 5Fh (Bank 0)........................................................................................... 39

7.28 Temperature Sensor 1 Temperature (High Byte) Register - Index 00h................................................39

7.29 Temperature Sensor 1 Temperature (Low Byte) Register - Index 00h................................................. 39

7.30 Temperature Sensor 1 Configuration Register - Index 01h .................................................................40

7.31 Temperature Sensor 1 Hysteresis (High Byte) Register - Index 02h....................................................41

Publication Release Date: April 1999

- II - Version

0.55

W83783S

Preliminary

7.32 Temperature Sensor 1 Hysteresis (Low Byte) Register - Index 02h.....................................................41

7.33 Temperature Sensor 1 Over-temperature (High Byte) Register - Index 03h.........................................42

7.34 Temperature Sensor 1 Over-temperature (Low Byte) Register - Index 03h .........................................42

7.35 Reserved Register -- Index 50h--52h (BANK4).................................................................................43

7.36 BEEP Control Register 3 -- Index 53h (Bank 4).................................................................................43

7.37 Reserved Register -- Index 54h--58h (Bank 4)....................................................................................43

7.38 Real Time Hardware Status Register I -- Index 59h (Bank 4) .............................................................43

7.39 Real Time Hardware Status Register II -- Index 5Ah (Bank 4) ........................................................... 44

8. SPECIFICATIONS...................................................................................................................................46

8.1 Absolute Maximum Ratings .................................................................................................................46

8.2 DC Characteristics...............................................................................................................................46

8.3 AC Characteristics...............................................................................................................................48

8.3.1 Serial Bus Timing Diagram...........................................................................................................48

9. HOW TO READ THE TOP MARKING.................................................................................................49

10. PACKAGE DIMENTIONS.....................................................................................................................50

11. APPLICATION CIRCUIT OF WINBOND W83783S ...........................................................................52

Publication Release Date: April 1999

- III - Version

0.55

W83783S

WINBOND H/W MONITORING IC

1. GENERAL DESCRIPTION

W83783S is an evolving version of W83782D --- Winbond's most popular hardware status
monitoring IC. The W83783S 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 stable and properly. W83783S provides I2CTM serial bus
interface.

An 8-bit analog-to-digital converter (ADC) was built inside W83783S. The W83783S can monitor 6
analog voltage inputs, 3 fan tachometer inputs, and 3 remote temperature. The remote temperature
sensing can be performed by thermistors, or 2N3904 NPN-type transistors, or directly from Intel
Deschutes CPU thermal diode output. Also the W83783S provides: 2 PWM (pulse width modulation)
outputs for the fan speed control; beep tone output for warning; SMI#, OVT#, GPO# signals for
system protection events.

Through the application software or BIOS, the users can read all the monitored parameters of system
from time to time. And a pop-up warning can be also activated when the monitored item was out of
the proper/preset range. The application software could be Winbond's Hardware DoctorTM, or Intel
LDCM (LanDesk Client Management), or other management application software. Also the users can
set up the upper and lower limits (alarm thresholds) of these monitored parameters and to activate
one programmable and maskable interrupts. An optional beep tone could be used as warning signal
when the monitored parameters is out of the preset range.

TM

TM

Additionally, 5 VID inputs are provided to read the VID of CPU (i.e. PentiumTM II) if applicable. This is
to provide the Vcore voltage correction automatically. Also W83783S uniquely provides an optional
feature: early stage (before BIOS was loaded) beep warning. This is to detect if the fatal elements
present --- Vcore or +3.3V voltage fail, and the system can not be boomed up.

Publication Release Date: April 1999

- 1 - Revision 0.55

W83783S

Preliminary

2. FEATURES

2.1 Monitoring Items

• 3 thermal inputs from remote thermistors or 2N3904 NPN-type transistors or PentiumTM II
(Deschutes) thermal diode output

• 6 voltage inputs

• --- typical for Vcore, +3.3V, +12V, -12V, +5V, -5V

• 3 fan speed monitoring inputs

• Case open detection input

• WATCHDOG comparison of all monitored values

• Programmable hysteresis and setting points (alarm thresholds) for all monitored items

2.2 Actions Enabling

• Beep tone warning

•

2 PWM (pulse width modulation) outputs for fan speed control (MUX optional)

--- Total up to 2 sets of fan speed monitoring and controlling

• Issue SMI#, OVT#, GPO# signals to activate system protection

• Warning signal pop-up in application software

2.3 General

• I2CTM serial bus interface

• 5 VID input pins for CUP Vcore identification (for PentiumTM II)

• Initial power fault beep (for +3.3V, Vcore)

• IntelTM LDCM (DMI driver 2.0) support

• AcerTM ADM (DMI driver 2.0) support

• Winbond hardware monitoring application software (Hardware Doctor

Windows 95/98 and Windows NT 4.0/5.0

• Input clock rate optional for 24, 48, 14.318 Mhz

• 5V Vcc operation

2.4 Package

• 24-pin SOP

TM

) support, for both

Publication Release Date: April 1999

- 2 - Revision 0.55

3. KEY SPECIFICATIONS

• Voltage monitoring accuracy ±1% (Max)

• Monitoring Temperature Range and Accuracy

- 40°C to +120°C ± 3°C(Max)

• Supply Voltage 5V

• Operating Supply Current 5 mA typ.

• ADC Resolution 8 Bits

4. PIN CONFIGURATION

W83783S

Preliminary

VID4
FANIN1
FANIN2

FANIN3/PWMOUT1

OVT#

BEEP/GPO#

VID3

CLKIN

SMI#/PWMOUT2

GNDD

SCL

SDA

1
2

3
4

5
6
7
8

9
10

11
12

24
23
22
21

20
19

18
17
16
15
14
13

VCC

VT1/PII1
VREF

VCORE
+3.3VIN
+12VIN

-12VIN

-5VIN/VT2/PII2
GNDA

VID0
VID1
VID2

Publication Release Date: April 1999

- 3 - Revision 0.55

5. PIN DESCRIPTION

I/O

- TTL level bi-directional pin with 12 mA source-sink capability

12t

I/O

- TTL level and schmitt trigger

12ts

OUT12 - Output pin with 12 mA source-sink capability
AOUT - Output pin(Analog)
OD12 - Open-drain output pin with 12 mA sink capability
INt - TTL level input pin
INts - TTL level input pin and schmitt trigger
AIN - Input pin(Analog)

Pin Name Pin No. Type Description

W83783S

Preliminary

VID4 1 IN
FANIN1 2 IN
FANIN2 3 IN
FANIN3/

PWMOUT1

4 INts /

OUT

t

ts

ts

12t

Voltage Supply readouts from Pentium IITM.
0V to 5V amplitude fan tachometer input.
0V to 5V amplitude fan tachometer input.
0V to 5V amplitude fan tachometer input. /
Fan speed control (PWM) output.

This multi-functional pin is programmable.
OVT# 5 OD
BEEP/GPO# 6 OD

12

12

Over temperature Shutdown Output.

Beep (Default) / General purpose output

This multi-functional pin is programmable.
VID3 7 IN
CLKIN 8 IN

t

t

Voltage Supply readouts from Pentium IITM.

System clock input. Can select 48MHz or 24MHz

or 14.318MHz. The default is 24MHz.
SMI# /

9 OD12 /

System Management Interrupt (open drain). The

default state is disabled.
PWMOUT2

OUT

12t

Fan speed control (PWM) output.

This multi-functional pin is programmable.
GNDD 10 DGROUND Internally connected to all digital circuitry.
SCL 11 IN
SDA 12

OD

VID2 13 IN

ts

12

t

Serial Bus Clock.

Serial Bus bi-directional Data.

Voltage Supply readouts from Pentium IITM.

Publication Release Date: April 1999

- 4 - Revision 0.55

Pin Discription, continued

Pin Name Pin No. Type Description

W83783S

Preliminary

VID1 14 IN
VID0 15 IN

t

t

Voltage Supply readouts from Pentium IITM.

Voltage Supply readouts from Pentium IITM.
GNDA 16 AGROUND Internally connected to all analog circuitry. The

ground reference for all analog inputs.

-5VIN /
VT2 /
PII2

17 AIN 0V to 4.096V FSR Analog Inputs (Default). /

Thermistor 2 terminal input. /

Pentium II

TM

thermal 2 diode input.

This multi-functional pin is programmable.

-12VIN 18 AIN 0V to 4.096V FSR Analog Inputs.
+12VIN 19 AIN 0V to 4.096V FSR Analog Inputs.
+3.3VIN 20 AIN 0V to 4.096V FSR Analog Inputs.
VCOREA 21 AIN 0V to 4.096V FSR Analog Inputs.
VREF 22 AOUT Reference Voltage.
VT1 /
PII1

23 AIN Thermistor 1 terminal input. /

Pentium II

TM

thermal diode 1 input.

VCC (+5V) 24 POWER +5V VCC power. Bypass with the parallel

combination of 10µF (electrolytic or tantalum) and

0.1µF (ceramic) bypass capacitors.

Publication Release Date: April 1999

- 5 - Revision 0.55

W83783S

Preliminary

6. FUNCTIONAL DESCRIPTION

6.1 General Description

The W83783S provides at most 6 analog positive inputs, 3 fan speed monitors, 2 sets for fan PWM
(Pulse Width Modulation) control, 2 thermal inputs from remote thermistors or 2N3904 transistors or
Pentium
exceed the set limit value including voltage, temperature, or fan counter. When start the monitor
function on the chip, the watch dog machine monitor every function and store the value to registers. If
the monitor value exceeds the limit value, the interrupt status will be set to 1.

6.2 Access Interface

The W83783S provides I2C Serial Bus to read/write internal reigsters. In the W83783S there are two
serial bus address. The first address defined at CR[48h] can read/write all registers excluding Bank 1
temperature sensor registers and the address default value is 0101101. The second address defined
at CR[4Ah] bit2-0 only read/write temperature sensor 1 registers and the address default value is

1001001.

TM

II (Deschutes) thermal diode outputs and beep function output when the monitor value

6.2.1 The first serial bus access timing are shown as follow:

(a) Serial bus write to internal address register followed by the data byte

SCL

SDA

0

0 1 0 1 1 0 1 D7 D6 D5 D4 D3 D2 D1 D0

Start By
Master

Figure 1. Serial Bus Write to Internal Address Register followed by the Data Byte

Frame 1

Serial Bus Address Byte

SCL

(Continued)

SDA (Continued)

7 8 0 7 8

R/W

Ack

by

781D

0

D7 D6 D5 D4 D3 D2 D1 D0

Frame 2

Internal Index Register Byte

Frame 3
Data Byte

7 8

Ack

by

781D

Stop

by

Master

Ack

by

781D

Publication Release Date: April 1999

- 6 - Revision 0.55

(b) Serial bus write to internal address register only

W83783S

Preliminary

SCL

SDA

0

0 1 0 1 1 0 1 D7 D6 D5 D4 D3 D2 D1 D0

Start By
Master

Frame 1

Serial Bus Address Byte

7 8 0 7 8

R/W

Ack

by

781D

0

Frame 2

Internal Index Register Byte

Ack
781D

Stop by

by

Master

Figure 2. Serial Bus Write to Internal Address Register Only

(c) Serial bus read from a register with the internal address register prefer to desired location

SCL

SDA

0

0 1 0 1 1 0 1 D7 D6 D5 D4 D3 D2 D1 D0

Start By
Master

Frame 1

Serial Bus Address Byte

Figure 3. Serial Bus Write to Internal Address Register Only

7 8 0 7 8

R/W

Ack

by

781D

0

Frame 2

Internal Index Register Byte

Ack

by

Master

Stop by
Master

6.2.2 The serial bus timing of the temperature 2 and 3 is shown as follow:

(a) Typical 2-byte read from preset pointer location (Temp, TOS, T

SCL

SDA

0

0 1 0 1 1 0 1 D7 D1 D0

Start By
Master

Frame 1

Serial Bus Address Byte

Figure 4. Typical 2-Byte Read From Preset Pointer Location

7 8 0 7 8

... ...

R/W

Ack

by

782D

...

Frame 2

MSB Data Byte

Ack

by

Master

Publication Release Date: April 1999

- 7 - Revision 0.55

)

HYST

0 7

D7 D1 D0

...

Frame 3

LSB Data Byte

Ack

by

Master

Stop by
Master

W83783S

Preliminary

(b) Typical pointer set followed by immediate read for 2-byte register (Temp, TOS, T

Frame 2

Pointer Byte

Ack

by

Master

4

D1 D0

0 7

D7 D1 D0

...

Frame 5

LSB Data Byte

Ack

by

782D

SCL

SDA

SCL

SDA

0

1 0 0 1 A2 A1 A0 R/W

Start By
Master

0

Frame 1

Serial Bus Address Byte

7 8 0

0 0 0 0 0 0

Ack

by

782D

7 8 0 7 8

... ...

D7 D1 D0

1 0 0 1 A2 A1 A0 R/W

Start By
Master

Frame 3

Serial Bus Address Byte

Ack

by

782D

0

Figure 5. Typical Pointer Set Followed by Immediate Read for 2-Byte Register

...

Frame 4

MSB Data Byte

(c) Typical read 1-byte from configuration register with preset pointer

SCL

SDA

0

1 0 0 1 A2 A1 A0 R/W D1D5 D4 D3D6

Start By
Master

Frame 1

Serial Bus Address Byte

7 8 0

D7 D2

Ack

by

782D

Frame 2

Data Byte

8

7

D0

No Ack

by

Master

HYST

No Ack

by

Master

Stop by
Master

)

Stop by
Master

Figure 6. Typical 1-Byte Read From Configuration With Preset Pointer

Publication Release Date: April 1999

- 8 - Revision 0.55

(d) Typical pointer set followed by immediate read from configuration register

W83783S

Preliminary

SCL

0

SDA

1 0 0 1 A2 A1 A0 R/W

Start By
Master

Frame 1

Serial Bus Address Byte

0

7 8 0

SCL (Cont..)

SDA (Cont..)

1 0 0 1 A2 A1 A0 R/W

Repea

Start

By

Master

Frame 3

Serial Bus Address Byte

Figure 7. Typical Pointor Set Followed by Immediate Read from Temp 2/3
Configuration Register

(e) Temperature 2/3 configuration register Write

SCL

SDA

0

1 0 0 1 A2 A1 A0 R/W

Start By

Master

Frame 1

Serial Bus Address Byte

7 8 0

7 8 0

0 0 0 0 00

Ack

by

782D

D7 D5 D4

Ack

by

782D

D6 D3

Frame 4

MSB Data Byte

Frame 2

Pointer Byte

4

0 0 0 0 0 0 0

Ack
782D

by

Frame 2

Pointer Byte

4

D2 D1 D0

D1 D0

D1 D0

7

No Ack
Master

7 8

7 8

8

by

Ack

by

782D

Ack

by

782D

Stop by
Master

...

...

SCL (Cont...)

0

SDA (Cont...)

0 0 D4 D3 D2 D10 D0

Frame 3

Configuration Data Byte

Figure 8. Configuration Register Write

- 9 - Revision 0.55

7 8

Ack

Stop

by

by

782D

Master

Publication Release Date: April 1999

W83783S

Preliminary

(f) Temperature 2/3 TOS and T

SCL

SDA

SCL (Cont...)

SDA (Cont...)

0

1 0 0 1 A2 A1 A0 R/W

Start By
Master

0

Frame 1

Serial Bus Address Byte

D6 D5 D4 D3 D2 D1D7 D0

Frame 3

MSB Data Byte

HYST

write

7 8 0

Ack

by

782D

7 8

Ack

by

781D

4

0

0

0 0 0 0

Frame 2

Pointer Byte

0 7 8

D6 D5 D4 D3 D2 D1D7 D0

Frame 4

LSB Data Byte

7 8

D1 D0

Ack

by

782D

Ack
782D

Stop

by

by

Master

Figure 9. Configuration Register Write

6.3 Analog Inputs

The maximum input voltage of the analog pin is 4.096V because the 8-bit ADC has a 16mv LSB.
Really, the application of the PC monitoring would most often be connected to power suppliers. The
CPU V-core voltage ,+3.3V and battery voltage can directly connected to these analog inputs. The
5VSB and +12V inputs should be reduced a factor with external resistors so as to obtain the input
range. As Figure 11 shows.

Publication Release Date: April 1999

- 10 - Revision 0.55

W83783S

Ω

Preliminary

VCORE

+3.3VIN

VDD(+5V)

R

10K, 1%

VREF Pin 22
VT1 Pin 23

**The connections of VT2

is same as VT1

N12VIN Pin 18

N5VIN

R8

V1

Positive Input

Negative Input

Typical Thermister Connection

V3

V4

Positive Inputs

R1

R7

R2

12VIN

R5

R

THM

10K, 25 C

Figure 11.

6.3.1 Monitor over 4.096V voltage:

The input voltage +12VIN can be expressed as following equation.

Pin 21
Pin 20
Pin 24

Pin 19

8-bit ADC

with

16mV LSB

Pin 17

R6

R

12

VIN V

= ×

1

2

R R

+

1 2

The value of R1 and R2 can be selected to 28K Ohms and 10K Ohms, respectively, when the input
voltage V1 is 12V. The node voltage of +12VIN can be subject to less than 4.096V for the maximun
input range of the 8-bit ADC. The Pin 24 is connected to the power supply VCC with +5V. There are
two functions in this pin with 5V. The first function is to supply internal analog power in the W83783S
and the second function is that this voltage with 5V is connected to internal serial resistors to monitor
the +5V voltage. The value of two serial resistors are 34K ohms and 50K ohms so that input voltage
to ADC is 2.98V which is less than 4.096V of ADC maximum input voltage. The express equation can
represent as follows.

K

V VCC

= ×

in

50

K K

50 34

+

Ω Ω

≅

2 98

.

V

where VCC is set to 5V.

Publication Release Date: April 1999

- 11 - Revision 0.55

W83783S

Ω

−

×−β

−

×−γ

Preliminary

6.3.2 Monitor negative voltage:

The negative voltage should be connected two series resistors and a positive voltage VREF (is equal
to 3.6V). In the Figure 11, the voltage V3 and V4 are two negative voltage which they are -12V and ­5V respectively. The voltage V3 is connected to two serial resistors then is connected to another
terminal VREF which is positive voltage. So as that the voltage node N12VIN can be obtain a
posedge voltage if the scales of the two serial resirtors are carefully selected. It is recommanded from
Winbond that the scale of two serial resistors are R5=232K ohms and R6=56K ohm. the The input
voltage of node -12VIN can be calculated by following equation.

K

N VIN VREF V

If the V5 is equal to -12V then the voltage is equal to 0.567V and the converted hexdecimal data is set
to 35h by the 8-bit ADC with 16mV-LSB.This monitored value should be converted to the real
negative votage and the express equation is shown as follows.

= + ×

where VREF is equal 3.6V.

5 5

232

K K

232 56

+

Ω Ω

V12

+( ) ( )

N VIN VREF

V

Where β is 232K/(232K+56K). If the N2VIN is 0.567 then the V5 is approximately equal to -12V.
The another negative voltage input V6 (approximate -5V) also can be evaluated by the similar

method and the serial resistors can be selected with R7=120K ohms and R8=56K ohms by the
Winbond recommended. The expression equation of V6 With -5V voltage is shown as follows.

V

Where the β is set to 120K/(120K+56K). If the monitored ADC value in the N5VIN channel is 0.8635,
VREF=3.6V and the parameter β is 0.6818 then the negative voltage of V6 can be evalated to be -

5V.

12

=

5

N VIN VREF

5

=

6

1

β

1

γ

Publication Release Date: April 1999

- 12 - Revision 0.55

W83783S

Preliminary

6.3.3 Monitor temperature from thermistor:

The W83783S can connect three thermistors to measure three different envirment temperature. The
specification of thermistor should be considered to (1) β value is 3435K, (2) resistor value is 10K
ohms at 25°C. In the Figure 11, the themistor is connected by a serial resistor with 10K Ohms, then
connect to VREF (Pin 37).

6.3.4 Monitor temperature from Pentium IITM thermal diode or bipolar transistor 2N3904

The W83783S can alternate the thermistor to Pentium IITM (Deschutes) thermal diode interface or
transistor 2N3904 and the circuit connection is shown as Figure 12. The pin of Pentium IITM D- is
connected to power supply ground (GND) and the pin D+ is connected to pin PIIx in the W83783S.
The resistor R=30K ohms should be connected to VREF to supply the diode bias current and the
bypass capacitor C=3300pF should be added to filter the high frequency noise. The transistor 2N3904
should be connected to a form with a diode, that is, the Base (B) and Collector (C) in the 2N3904
should be tied togeter to act as a thermal diode.

Bipolar Transistor

Temperature Sensor

C

B

2N3904

E

OR

Pentium II

CPU D+

Therminal

Diode

VREF

R=30K, 1%

PIITDx

C=3300pF

W83783S

R=30K, 1%

PIITDx

C=3300pF

D-

Figure 12.

Publication Release Date: April 1999

- 13 - Revision 0.55