a
Preliminary Technical Data
FEATURES
On-Chip Temperature Sensor
External Temperature Measurement with Remote Diode
Interrupt and Overtemperature Outputs
Fault Tolerant Fan Control With Auto Hardware Trip Point
Remote Reset and Power Down Functions
LDCM Support
System Management Bus (SMBus) Communications
Standby Mode to Minimize Power Consumption
Limit Comparison of all Monitored Values
APPLICATIONS
Network Servers and Personal Computers
Microprocessor-Based Office Equipment
Test Equipment and Measuring Instruments
Low Cost PC Temperature
Monitor and Fan Control ASIC
ADM1028
GENERAL DESCRIPTION
The ADM1028 is a low-cost temperature monitor and fan
controller for microprocessor-based systems. The tem-
perature of a remote sensor diode may be measured, al-
lowing monitoring of processor temperature in single
processor systems. An on-chip temp sensor monitors
ambient system temperature.
Measured values can be read out via the System Manage-
ment Bus, and values for limit comparisons can be pro-
grammed in over the same serial bus.
The ADM1028 also contains a DAC for fan speed con-
trol. An automatic hardware temperature trip point is pro-
vided and the fan will be driven to full speed if it is
exceeded.
Finally, the chip has remote reset and power down
functionality, allowing it to be remotely shutdown via the
SMBus.
The ADM1028’s 3.0V to 5.5V supply voltage range, low
supply current, and SMBus make it ideal for a wide range
of applications. These include hardware monitoring
applications in PCs, electronic test equipment, and office
electronics.
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FUNCTIONAL BLOCK DIAGRAM
V
C C3 AUX
5
V
C C3AU X
10k
POWER ON
RESET
16
SDA
SERIAL BUS
INTERFACE
R_OFF
13
REMOTE
FUNCTION
REGISTER
15
SCL
R_RST
7
ADDRESS
POINTER
REGISTER
ANALOG
OUTPUT REGISTER
AND 8-BIT DAC
8
FAN_SPD/TEST_IN
AUXRST
3
RESET
ADM 1028
RST
6
FAN_SPD SHUTOFF &
R_OFF RESET
ALERT
STATUS
REGISTER
VALUE AND
LIMIT
REGISTERS
LIMIT
COMPARATORS
D+
10
ANALO G
SIGNAL
CONDITIONING
V
C C3AU X
10k
THERMA/TEST_OUT
11
MASK
GATING
2.5V
BANDGAP
REFERENCE
ADC
INTERRUPT
STATUS
REGISTERS
INT MASK
REGISTER
D-
9
14
INT
THERMB
12
CONFIGURATION
REGISTER
1
FAN_OFF
2
GPI
4
GND
REV. PrD 05/2000
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P Box 9106, Norwood, MA 02062-9106, U.S.A.
.O.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
Analog Devices, Inc., 1998
ADM1028–SPECIFICATIONS
PARAMETER
POWER SUPPLY
Supply Voltage, V
CC
Supply Current, I
CC
TEMP.-TO-DIGITAL CONVERTER
Internal Sensor Accuracy
Resolution
External Diode Sensor Accuracy
Resolution
Remote Sensor Source Current
Total Monitoring Cycle Time, t
c
1
90
5.5
1
Min
3.0
Typ
3.30
1.4
32
(T
A
= T
MIN
to T
MAX
, V
CC
= V
MIN
to V
MAX
, unless otherwise noted)
Max
5.5
2.0
<100
±3
±2
±5
±3
Units
V
mA
µA
C
°C
o
C
C
C
o
C
µA
µA
o
o
o
Test Conditions
Interface Inactive, ADC Active
Standby Mode
+60
O
C
T
A
+100
o
C
+60
O
C
T
A
+100
o
C
ANALOG OUTPUT
Output Voltage Range
Total Unadjusted Error, TUE
Full-Scale Error
Zero Error
Differential Non-Linearity, DNL
Integral Non-Linearity
Output Source Current
Output Sink Current
Reset Threshold, V
CC3AUX
Hysteresis
R_RST
OUTPUT
Reset Output Voltage, V
OL
VOLTAGE MONITOR THRESHOLDS
Reset Output Pulse Width, t
R_RST#
V
CC
to Reset Delay, t
D
THERMA
OUTPUT
THERMA
pull-up resistance
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1.0
1.4
s
0
±1
±2
±1
2
1
2.5
±3
±3
±1
V
%
%
LSB
LSB
LSB
mA
mA
V
mV
V
2.85
2.925
50
3.00
0.3
125
4000
20
7
10
13
µs
µs
k
Ω
60
3.5
130
7.5
High Level (D+ = D- +0.65V)
Low Level (D+ = D- +0.65V)
I
L
= 2mA
No Load
Monotonic by Design
Measured with Vcc falling.
I
SINK
= 1.2mA;
V
CC
= V
TH
(MAX)
–2–
REV. PrD
Preliminary Technical Data
Specifications (Continued)
PARAMETER
Min
Typ
Max
Units
ADM1028
Test Conditions/Comments
DIGITAL OUTPUT
THERMA
THERMA/TEST_OUT,
R_OFF
Output High Voltage, V
OH
2.4
Output Low Voltage, V
OL
OPEN-DRAIN DIGITAL OUTPUTS
(INT,
THERMB, FAN_OFF, R_RST)
Output Low Voltage, V
OL
High Level Output Leakage Current, I
OH
OPEN-DRAIN SERIAL DATA
BUS OUTPUT (SDA)
Output Low Voltage, V
OL
High Level Output Leakage Current, I
OH
SERIAL BUS DIGITAL INPUTS
(SCL, SDA)
Input High Voltage, V
IH
Input Low Voltage, V
IL
Input Leakage Current
Hysteresis
0.4
V
V
I
OUT
= 3.0mA
0.1
0.4
1
V
µA
I
OUT
= -3.0mA
V
OUT
= V
CC
DIGITAL INPUT LOGIC LEVELS
(FAN_SPD/TEST_IN, GPI)
Input High Voltage, V
IH
Input Low Voltage, V
IL
DIGITAL INPUT LEAKAGE CURRENT
(ALL DIGITAL INPUTS)
Input High Current, I
IH
Input Low Current, I
IL
Input Capacitance, C
IN
SERIAL BUS TIMING
Clock Frequency, f
SCLK
Bus Free Time, t
BUF
Start Setup Time, t
SU;STA
Start Hold Time, t
HD;STA
Stop Condition Setup Time, t
SU;STO
SCL Low Time, t
LOW
SCL High Time, t
HIGH
SCL, SDA Rise Time, t
r
SCL, SDA Fall Time, t
f
Data Setup Time, t
SU;DAT
Data Hold Time, t
HD;DAT
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0.1
2.1
0.8
±5
500
V (min)
V (max)
µA
mV
2.2
0.8
V
V
-1
-0.005
0.005
5
1
µA
µA
pF
100
4.7
4.0
4.0
4.0
4.7
4.0
1000
300
250
300
kHz
µs
µs
µs
µs
µs
µs
ns
ns
ns
ns
0.4
1
V
µA
I
OUT
= -3.0mA
V
OUT
= V
CC
V
IN
= V
CC
V
IN
= 0
See
See
See
See
See
See
See
See
See
See
See
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
1
1
1
1
1
1
1
1
1
1
1
NOTES
1
Typicals are at T
A
=25°C and represent most likely parametric norm. Standby current typ is measured with V
CC
= 3.3V.
3
Timing specifications are tested at logic levels of V
IL
= 0.8 V for a falling edge and V
IH
= 2.2 V for a rising edge.
REV. PrD
–3–
ADM1028
ABSOLUTE MAXIMUM RATINGS*
Preliminary Technical Data
THERMAL CHARACTERISTICS
Positive Supply Voltage (V
CC
)
6.5 V
Voltage on Digital Inputs except Therm
-0.3V to 6.5V
Voltage on Therm pin
-0.3V to Vcc +0.3V
Voltage on Any other Input
-0.3V to V
CC
+0.3V
or Output Pin
Input Current at any pin
±5mA
Package Input Current
±20mA
Maximum Junction Temperature (T
J
max)
150 °C
Storage Temperature Range
–65°C to +150°C
Lead Temperature
Soldering 10 sec
+300°C
IR Reflow Peak temperature
+220°C
ESD Rating (Human Body Model)
4000 V
*Stresses above those listed under “Absolute Maximum Ratings” may cause permanent
damage to the device. This is a stress rating only; functional. Operation of the device
at these or any other conditions above those indicated in the operational section of this
specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
16-Pin QSOP Package:
θ
JA
= 105°C/Watt,
θ
JC
= 39°C/Watt
ORDERING GUIDE
Model
ADM1028ARQ
Temperature
Range
0°C to +100°C
Package
Description
16-Pin QSOP
Package
Package
Option
RQ-16
tL O W
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FAN_OFF
1
2
GPI
AUXRST
3
GND
4
V
CC3AUX
5
RST
6
7
R_RST
FAN_SPD/NTEST_IN
8
tR
tF
t H D;S T A
t H IG H
t S U;D A T t S U;S T A
S
ADM1028 PINOUT
16 SDA
15 SCL
14 INT
13 R_OFF
12
THERMB
ADM1028
TOP VIEW
(Not to Scale)
11 THERMA/NTEST_OUT
10 D+
9
D-
t H D;S T A
tH D;D AT
t S U;S T O
S DA
P
tB UF
S
P
Figure 1. Diagram for Serial Bus Timing
–4–
REV. PrD
Preliminary Technical Data
PIN FUNCTION DESCRIPTION
PIN NO.
MNEMONIC
DESCRIPTION
ADM1028
1
FAN_OFF
Digital Output (Open Drain) Fan Off Request. When asserted low this indicates a
request to shut the fan off independent of the FAN_SPD output. When negated
(output FET off) it indicates that the fan may be turned on.
Digital Input (12V tolerant). This pin is a general purpose logic input with 12V
tolerance. It can be programmed as an active high or active low input that sets bit 4
of the Interrupt Status Register. A voltage >2.2V on this pin, represents a logic “1”
while a floating condition is interpreted as logic “0”.
Digital Input. This pin can be driven low as an input to reset the ADM1028.
2
GPI
3
4
5
6
AUXRST
GND
V
CC3AUX
RST
GROUND. Power and signal ground.
7
8
R_RST
FAN_SPD/TEST_IN
9
10
11
D-
D+
THERMA/TEST_OUT
Digital Output (Open Drain with integrated V
CC3AUX
pull-up). An active low thermal
overload output that indicates a violation of a temperature set point (over
-temperature). The fan is on full-speed whenever this pin is asserted low. Acts as the
output of the NAND Tree when the ADM1028 is in NAND Tree Test Mode.
THERMB
R_OFF
Digital Output (Open Drain). This pin is a second
THERM
signal. It can be used
to drive external circuitry with a different external pull-up supply rail.
Digital Output or Open Drain with integrated V
CC3AUX
pull-up. Remote off (power
down) output. This pin is driven high on receipt of a specific SMBus message. The
pin (and its associated register bit) remain high until the
RST
input is asserted low.
Digital Output (Open Drain), System Interrupt Output. This signal indicates a
violation of a set trip point. The output is enabled when Bit 1 of the Configuration
Register is set to 1. The default state is disabled.
Digital Input SMBus Clock
Digital I/O(Open Drain)
SMBus bi-directional Data
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POWER
+3.3Vaux. Power source and voltage monitor input for power on reset.
Digital Input. This pin can be pulled low externally to indicate to the ADM1028
that the main system power has been removed. The ADM1028 will shut off the
FAN_SPD output and reset its R_OFF output.
Digital Output (Open drain). This pin is a remote reset output which pulses low
on receipt of a specific SMBus message.
Analog Output/Test Input. An active-high input that enables NAND board-
level connectivity testing. Refer to section on NAND testing.
Used as an analog output for fan speed control when NAND test is not selected.
Remote Thermal Diode Negative Input. This is the negative input (current sink)
from the remote thermal diode. This also serves as the negative input into the A/D.
Remote Thermal Diode Positive Input. This is the positive input (current source)
from the remote thermal diode. This serves as the positive input into the A/D.
12
13
14
INT
15
16
SCL
SDA
REV. PrD
–5–
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