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PDF ADM1025A Data sheet ( Hoja de datos )
| Número de pieza | ADM1025A | |
| Descripción | Low Cost PC Hardware Monitor ASIC | |
| Fabricantes | ON Semiconductor | |
| Logotipo |  |
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ADM1025, ADM1025A
Product Preview
Low Cost PC
Hardware Monitor ASIC
The ADM1025/ADM1025A1 is a complete system hardware
monitor for microprocessor-based systems, providing measurement
and limit comparison of various system parameters. Five voltage
measurement inputs are provided for monitoring 2.5 V, 3.3 V, 5 V, and
12 V power supplies and the processor core voltage. The
ADM1025/ADM1025A can monitor a sixth power supply voltage by
measuring its own VCC. One input (two pins) is dedicated to a remote
temperature-sensing diode, and an onchip temperature sensor allows
ambient temperature to be monitored. The ADM1025A has
open-drain VID inputs while the ADM1025 has on-chip 100 kW
pull-ups on the VID inputs.
Measured values and in/out of limit status can be read out via an I2C
compatible serial System Management Bus. The device can be
controlled and configured over the same serial bus. The device also
has a programmable INT output to indicate undervoltage, overvoltage,
and overtemperature conditions.
The ADM1025/ADM1025A’s 3.0 V to 5.5 V supply voltage range,
low supply current, and I2C compatible interface make it ideal for a
wide range of applications. These include hardware monitoring and
protection applications in personal computers, electronic test
equipment, and office electronics.
Features
Up to 8 Measurement Channels
5 Inputs to Measure Supply Voltages
VCC Monitored Internally
External Temperature Measurement with Remote Diode
On-chip Temperature Sensor
5 Digital Inputs for VID Bits
Integrated 100 kW Pull-ups on VID Pins (ADM1025 Only)
LDCM Support
I2C Compatible System Management Bus (SMBus)
Programmable RST Output Pin
Programmable INT Output Pin
Configurable Offset for Internal/External Channel
Shutdown 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
http://onsemi.com
QSOP−16
CASE 492
PIN ASSIGNMENT
SDA 1
SCL 2
16
ADD/RST/
INT/NTO
15 VCCPIN
GND 3
14 2.5VIN
VCC 4
ADM1025/
ADM1025A
13 3.3VIN
VID0 5
Top View 12 5VIN
VID1 6 (Not To Scale) 11 12VIN/VID4
VID2 7
10 D+
VID3 8
9 D−/NTI
MARKING DIAGRAM
1025A
RQZ
#YYWW
1025ARQZ
#
YY
WW
= Special Device Code
= Pb-Free Package
= Year
= Work Week
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 18 of this data sheet.
This document contains information on a product under development. ON Semiconductor
reserves the right to change or discontinue this product without notice.
Semiconductor Components Industries, LLC, 2012
August, 2012 − Rev. P6
1
Publication Order Number:
ADM1025/D
1 page  
SCL
SDA
tBUF
PS
t LOW
tR
tHD; STA
tHD; DAT
ADM1025, ADM1025A
tF
t HD; STA
tHIGH
tSU; DAT
tSU; STA
S
Figure 2. Serial Bus Timing Diagram
tSU; STO
P
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 3. Temperature Error vs. PC Board
Track Resistance
Figure 4. Temperature Error vs. Power Supply
Noise Frequency
Figure 5. Temperature Error vs. Common-mode
Noise Frequency
Figure 6. Pentium II) Temperature Measurement
vs. ADM1025/ADM1025A Reading
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5
5 Page 
ADM1025, ADM1025A
the absolute value of VBE, varies from device to device, and
individual calibration is required to null this out, so the
technique is unsuitable for mass production.
The technique used in the ADM1025/ADM1025A is to
measure the change in VBE when the device is operated at
two different currents.
This is given by:
DVBE + KTńq ln(N)
where:
K is Boltzmann’s constant
q is charge on the carrier
T is absolute temperature in Kelvins
N is ratio of the two currents
(eq. 1)
Figure 14 shows the input signal conditioning used to
measure the output of an external temperature sensor. This
figure shows the external sensor as a substrate transistor
provided for temperature monitoring on some
microprocessors, but it could equally well be a discrete
transistor.
If a discrete transistor is used, the collector will not be
grounded and should be linked to the base. If a PNP
transistor is used, the base is connected to the D− input and
the emitter to the D+ input. If an NPN transistor is used, the
emitter is connected to the D− input and the base to the D+
input.
I
NI
IBIAS
Bit 6 of Status Register 2 (42h) is set if a remote diode
fault is detected. The ADM1025/ADM1025A detects shorts
from D+ to GND or supply, as well as shorts/opens between
D+/D−.
Table 7. TEMPERATURE DATA FORMAT
Temperature
Digital Output
−128C
−125C
−100C
−75C
−50C
−25C
0C
+10C
+25C
+50C
+75C
+100C
+125C
+127C
1000 0000
1000 0011
1001 1100
1011 0101
1100 1110
1110 0111
0000 0000
0000 1010
0001 1001
0011 0010
0100 1011
0110 0100
0111 1101
0111 1111
VDD
REMOTE
SENSING
TRANSISTOR
D+
D−
BIAS
DIODE
LOW-PASS FILTER
fC = 65 kHz
VOUT+
To ADC
VOUT−
Figure 14. Signal Conditioning for External Diode Temperature Sensors
To prevent ground noise interfering with the
measurement, the more negative terminal of the sensor is not
referenced to ground but is biased above ground by an
internal diode at the D− input.
If the sensor is used in a very noisy environment, a
capacitor of value up to 1 nF may be placed between the D+
and D– inputs to filter the noise.
To measure DVBE, the sensor is switched between
operating currents of I and N I. The resulting waveform is
passed through a 65 kHz low-pass filter to remove noise,
then to a chopperstabilized amplifier that performs the
functions of amplification and rectification of the waveform
to produce a dc voltage proportional to DVBE. This voltage
is measured by the ADC to give a temperature output in 8-bit
twos complement format. To further reduce the effects of
noise, digital filtering is performed by averaging the results
of 16 measurement cycles. An external temperature
measurement takes nominally 34.8 ms.
http://onsemi.com
11
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet ADM1025A.PDF ] | |
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