Operating Temperature Range ......................... -55°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range ............................ -65°C to +150°C
Lead Temperature (soldering, 10s) ................................. +300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Electrical Characteristics
(V
CC
= +3.0V to +3.6V for MAX6656, V
CC
= +4.5V to +5.5V for MAX6655, T
A
= -55°C to +125°C, unless otherwise noted. Typical
values are at V
CC
= +3.3V for MAX6656, V
CC
= +5.0V for MAX6655, T
A
= +25°C.)
PARAMETER
Supply Range
Accuracy (Local Sensor)
Accuracy (Remote Sensor)
Temperature Measurement
Resolution
ADC Input Impedance
ADC Total Error
V
IN
ADC Resolution
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Power-On Reset (POR)
Threshold
POR Threshold Hysteresis
Standby Current
DXP and DXN Leakage Current
Average Operating Current
Conversion Time for Single
Temperature Measurement
Monitoring Cycle Time
t
CON
t
MONI
SMBus static, STBY = GND
In standby mode
Continuous temperature mode
From stop bit to conversion completed
Total of 3 temperature plus 4 voltage
measurements
95
550
125
625
V
CC
, falling edge
1
UVLO
V
CC
input, disables A/D conversion,
falling edge
2.50
Z
IN
V
IN1
, V
IN2
, V
IN3
input resistance
V
IN1
, V
IN2
, V
IN3
between 30% and 120% of
nominal
100
±1
8
2.70
90
1.7
90
3
10
2
1000
155
2.5
2.90
±1.5
SYMBOL
V
CC
+60°C ≤ T
A
≤ +100°C
0°C ≤ T
A
≤ +125°C
+60°C ≤ T
RJ
≤ +100°C
0°C ≤ T
RJ
≤ +120°C
0.125
11
CONDITIONS
MIN
3.0
TYP
MAX
5.5
±1.5
±3
±1
±3
UNITS
V
°C
°C
°C
Bits
kΩ
%
Bits
V
mV
V
mV
µA
µA
µA
ms
ms
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Maxim Integrated
│
2
MAX6655/MAX6656
Dual Remote/Local Temperature Sensors and
Four-Channel Voltage Monitors
Electrical Characteristics (continued)
(V
CC
= +3.0V to +3.6V for MAX6656, V
CC
= +4.5V to +5.5V for MAX6655, T
A
= -55°C to +125°C, unless otherwise noted. Typical
values are at V
CC
= +3.3V for MAX6656, V
CC
= +5.0V for MAX6655, T
A
= +25°C.)
PARAMETER
Remote Junction Current
(DXP, DXN)
Logic Input Low Voltage
Logic Input High Voltage
Input Leakage Current
Output Low Sink Current
Input Capacitance
SMBus Timeout
ALERT, OVERT
Output Low Sink Current
Output High Leakage Current
SMBus TIMING
Serial Clock Frequency
Bus Free Time Between STOP
and START Condition
START Condition Setup Time
Repeat START Condition Setup
Time
START Condition Hold Time
STOP Condition Setup Time
Clock Low Period
Clock High Period
Data Setup Time
Data Hold Time
Receive SMBCLK/SMBDATA
Rise Time
Receive SMBCLK/SMBDATA
Fall Time
Pulse Width of Spike Suppressed
t
SU:STA
t
HD:STA
t
SU:STO
t
LOW
t
HIGH
t
SU:DAT
t
HD:DAT
t
R
t
F
t
SP
0
90% to 90%
10% of SMBDATA to 90% of SMBCLK
90% of SMBCLK to 10% of SMBDATA
10% to 10%
90% to 90%
90% of SMBDATA to 10% of SMBCLK
(Note 1)
4
250
0
1
300
50
f
SCL
t
BUF
4.7
4.7
50
4
4
4.7
400
kHz
µs
µs
ns
µs
µs
µs
µs
ns
µs
µs
ns
ns
V
IL
VIH
I
LEAK
I
OL
C
IN
SMBCLK or SMBDATA time low for reset
V
OL
= +0.6V
V
OH
= +5.5V
30
SYMBOL
High level
Low level
V
CC
= +3.0V to +5.5V
V
CC
= +3.0V
V
CC
= +5.5V
V
IN
= GND or V
CC
V
OL
= +0.6V
5
35
60
6
1
2.1
2.6
±1
6
CONDITIONS
MIN
80
8
TYP
100
10
MAX
140
14
0.8
UNITS
µA
SMBus INTERFACE (SMBCLK, SMBDATA,
STBY)
V
V
µA
mA
pF
ms
mA
µA
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Maxim Integrated
│
3
MAX6655/MAX6656
Dual Remote/Local Temperature Sensors and
Four-Channel Voltage Monitors
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
REMOTE TEMPERATURE ERROR
vs. PC BOARD RESISTANCE
MAX6655/MAX6656 toc01
MAX6655/MAX6656 toc02
REMOTE TEMPERATURE ERROR (°C)
REMOTE TEMPERATURE ERROR (°C)
4
3
2
1
0
-1
-2
-3
-4
-5
-55
RANDOM SAMPLE
2N3906
10
PATH = DXP TO GND
TEMPERATURE ERROR (°C)
15
V
IN
= SQUARE WAVE
APPLIED TO V
CC
WITH
NO V
CC
BYPASS CAPACITOR
V
IN
= 250mVp-p
REMOTE DIODE
0
10
-10
PATH = DXP TO V
CC
(5V)
5
-20
1
10
LEAKAGE RESISTANCE (MΩ)
100
-5
45
95
0
0
10
20
30
40
50
TEMPERATURE (°C)
FREQUENCY (MHz)
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
REMOTE TEMPERATURE ERROR (°C)
REMOTE TEMPERATURE ERROR (°C)
14
12
10
8
6
4
2
0
0
10
20
V
IN
= 200mVp-p
MAX6655/MAX6656 toc04
REMOTE TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCE
MAX6655/MAX6656 toc05
V
IN
= SQUARE WAVE
AC-COUPLED TO DXN
14
12
10
8
6
4
2
0
0
V
CC
= +5V
45
SUPPLY CURRENT (µA)
40
35
30
25
20
15
10
5
0
SMBCLK IS DRIVEN
RAIL-TO-RAIL
V
IN
= 100mVp-p
30
40
50
50
100
150
200
1
10
100
1000
FREQUENCY (MHz)
DXP-DXN CAPACITANCE (nF)
SMBCLK FREQUENCY (kHz)
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6655/MAX6656 toc07
RESPONSE TO THERMAL SHOCK
MAX6655/MAX6656 toc08
VOLTAGE ACCURACY
vs. TEMPERATURE
12
OUTPUT VOLTAGE (V)
10
8
6
4
2
0
V
CC
V
IN2
V
IN3
INPUT VOLTAGES ARE NOMINAL
0
20
40
60
80
100
120
TEMPERATURE (°C)
V
IN1
MAX6655/MAX6656 toc09
140
SUPPLY CURRENT (µA)
120
100
80
60
40
20
0
0
1
2
ADD0, ADD1 = HIGH-Z
ADD0, ADD1 = GND
120
100
TEMPERATURE (°C)
80
60
40
20
0
REMOTE DIODE IMMERSED
IN +115°C FLUORINERT BATH
3
4
5
-1
0
1
2
TIME (s)
3
4
5
SUPPLY VOLTAGE (V)
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Maxim Integrated
│
4
MAX6655/MAX6656 toc06
50
STANDBY SUPPLY CURRENT
vs. CLOCK FREQUENCY
MAX6655/MAX6656 toc03
20
5
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
20
TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
MAX6655/MAX6656
Dual Remote/Local Temperature Sensors and
Four-Channel Voltage Monitors
Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
NAME
V
CC
DXP1
DXN1
ADD0
ADD1
DXP2
DXN2
GND
V
IN3
V
IN1
V
IN2
ALERT
SMBDATA
OVERT
SMBCLK
STBY
FUNCTION
Supply Voltage. +5V for MAX6655; +3.3V for MAX6656. Bypass V
CC
to GND with a 0.1µF capacitor.
External Diode 1 Positive Connection. DXP1 is the combined current source and ADC positive input for
remote-diode 1. If a remote-sensing junction is not used, connect DXP1 to DXN1.
External Diode 1 Negative Connection. DXN1 is the combined current sink and ADC negative input for
remote-diode 1. DXN1 is normally biased to a diode voltage above ground.
SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up. Table 5 is the truth
table.
SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.
External Diode 2 Positive Connection. DXP2 is the combined current source and ADC positive input for
remote-diode 2. If a remote-sensing junction is not used, connect DXP2 to DXN2.
External Diode 2 Negative Connection. DXN2 is the combined current sink and ADC negative input for
remote-diode 2. DXN2 is normally biased to a diode voltage above ground.
Ground
External Voltage Monitor 3. V
IN3
is typically used to monitor +2.5V supplies.
External Voltage Monitor 1. V
IN1
is typically used to monitor +12V supplies.
External Voltage Monitor 2. V
IN2
is typically used to monitor voltage supplies of +3.3V for MAX6655 and
+5.0V for MAX6656.
SMBus Alert (Interrupt) Output, Open-Drain
SMBus Serial-Data Input/Output, Open-Drain
Overtemperature Alarm Output, Open-Drain.
OVERT
is an unlatched alarm output that responds to the
programmed maximum temperature limit for all temperature channels.
SMBus Serial-Clock Input
Hardware Standby Input. Drive
STBY
low for low-power standby mode. Drive
STBY
high for normal
operating mode. Temperature and comparison threshold data are retained in standby mode.
Detailed Description
The MAX6655/MAX6656 are voltage and temperature
monitors that communicate through an SMBus-compatible
interface with a microprocessor or microcontroller in ther-
mal management applications.
Essentially an 11-bit serial ADC with a sophisticated front
end, the MAX6655/MAX6656 contain a switched-current
source, a multiplexer, an ADC, an SMBus interface, and
the associated control logic. Temperature data from the
ADC is loaded into a data register, where it is automati-
cally compared with data previously stored in over/under-
temperature alarm threshold registers. Temperature data
can be read at any time with 11 bits of resolution.
The MAX6655/MAX6656 can monitor external supply
voltages of typically 12V, 2.5V, and 3.3V for the MAX6655
and 5.0V for the MAX6656, as well as their own supply
voltage. All voltage inputs are converted to an 8-bit code
using an ADC. Each input voltage is scaled down by an
on-chip resistive-divider so that its output, at the nominal
input voltage, is approximately 3/4 of the ADC’s full-scale
range, or a decimal count of 198.
ADC
The averaging ADC integrates over a 40ms period (typ)
with excellent noise rejection. The ADC converts a tem-
perature measurement in 125ms (typ) and a voltage
measurement in 62.5ms (typ). For temperature measure-
ments, the multiplexer automatically steers bias currents
through the remote diode, then the forward voltage is
measured and the temperature is computed. The DXN
input is biased at one diode drop above ground by an
internal diode to set up the ADC inputs for a differential
measurement. The worst-case DXP-DXN differential input
voltage range is +0.25V to +0.95V.
Excess resistance in series with the remote diode causes
about +1/2°C error/Ω. A 200μV offset voltage at DXP-
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