19-3713; Rev 2; 10/08
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
General Description
The MAX6615/MAX6616 monitor two temperature chan-
nels, either the internal die temperature and the temper-
ature of an external thermistor, or the temperatures of
two external thermistors. The temperature data controls
a PWM output signal to adjust the speed of a cooling
fan, thereby minimizing noise when the system is run-
ning cool, but providing maximum cooling when power
dissipation increases. The fans’ tachometer output sig-
nals are monitored by the MAX6615/MAX6616 to detect
fan failure. If a fan failure is detected, the
FAN_FAIL
output is asserted.
The 2-wire serial interface accepts standard system
management bus (SMBus
TM
) write byte, read byte,
send byte, and receive byte commands to read the
temperature data and program the alarm thresholds.
The programmable alarm output can be used to gener-
ate interrupts, throttle signals, or overtemperature shut-
down signals.
The MAX6616 features six GPIOs to provide additional
flexibility. All of the GPIOs power-up as inputs, with the
exception of GPIO0, which powers up as either an input
or an output as determined by connecting the PRESET
pin to ground or V
CC
.
The MAX6616 is available in a 24-pin QSOP package,
while the MAX6615 is available in a 16-pin QSOP pack-
age. Both devices operate from a single-supply voltage
range of 3.0V to 5.5V, have operating temperature
ranges of -40°C to +125°C, and consume just 500µA of
supply current.
o
Two Thermistor Inputs
o
Two Open-Drain PWM Outputs for Fan-Speed
Control
o
Local Temperature Sensor
o
Six GPIOs (MAX6616)
o
Programmable Fan-Control Characteristics
o
Controlled PWM Rate-of-Change Ensures
Unobtrusive Fan-Speed Adjustments
o
Fail-Safe System Protection
o
OT
Output for Throttling or Shutdown
o
Nine Different Pin-Programmable SMBus
Addresses
o
16-Pin and 24-Pin QSOP Packages
Features
MAX6615/MAX6616
Ordering Information
PART
MAX6615AEE
MAX6616AEG
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
16 QSOP
24 QSOP
Functional Diagram
FAN_FAIL
V
CC
Applications
Desktop Computers
Servers
Power Supplies
Networking Equipment
Workstations
SCL
TH1
REF
TH2
THERMISTORS
AND LOCAL
TEMP SENSOR
PWM
GENERATOR
AND TACH
COUNTER
TACH1
PWM1
TACH2
PWM2
OT
SMBus is a trademark of Intel Corp.
SDA
SMBus
INTERFACE
AND
REGISTERS
LOGIC
GPIO0*
GPIO5*
Typical Application Circuits and Pin Configurations appear at
end of data sheet.
MAX6615
MAX6616
GND
ADD0
*MAX6616 ONLY
ADD1
PRESET*
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
MAX6615/MAX6616
ABSOLUTE MAXIMUM RATINGS
All Voltages Are Referenced to GND
Supply Voltage (V
CC
) ...............................................-0.3V to +6V
PWM_, TACH_,
OT, FAN_FAIL
............................-0.3V to +13.5V
ADD0, ADD1, SDA, SCL ..........................................-0.3V to +6V
All Other Pins..............................................-0.3V to (V
CC
+ 0.3V)
SDA,
OT, FAN_FAIL,
PWM_, GPIO_ Current....................±50mA
TH_ Current ........................................................................±1mA
REF Current ......................................................................±20mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derated at 8.3mW/°C
above +70°C)............................................................666.7mW
24-Pin QSOP (derated at 9.5mW/°C
above +70°C)...........................................................761.9 mW
ESD Protection (all pins, Human Body Model) ....................±2kV
Operating Temperature Range .........................-40°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 +5.5V, T
A
= 0°C to +125°C, unless otherwise noted. Typical values are at V
CC
= +3.3V, T
A
= +25°C.)
PARAMETER
Operating Supply Voltage
Standby Current
Operating Current
External Temperature Error
Internal Temperature Error
Temperature Resolution
Conversion Time
Conversion Rate Timing Error
PWM Frequency Error
INPUT/OUTPUT
Output Low Voltage
Output High Leakage Current
Logic Low Input Voltage
Logic High Input Voltage
Input Leakage Current
Input Capacitance
Serial Clock Frequency
Clock Low Period
Clock High Period
Bus Free Time Between STOP
and START Conditions
SMBus START Condition
Setup Time
C
IN
f
SCLK
t
LOW
t
HIGH
t
BUF
t
SU:STA
90% of SCL to 90% of SDA
10% to 10%
90% to 90%
10
4
4.7
4.7
4.7
5
400
SMBus TIMING (Figures 2, 3) (Note 2)
kHz
µs
µs
µs
µs
V
OL
I
OH
V
IL
V
IH
2.1
1
V
CC
= +3V, I
OUT
= 6mA
0.4
1
0.8
V
µA
V
V
µA
pF
-20
-20
I
S
SYMBOL
V
CC
Interface inactive, ADC in idle state
Interface inactive, ADC active
V
CC
= +3.3V, 0.15V
≤
V
TH_
≤
+0.71V (excludes
thermistor errors, thermistor nonlinearity) (Note1)
V
CC
= +3.3V, 0°C
≤
T
A
≤
+85°C,
V
CC
= +3.3V, 0°C
≤
T
A
≤
+125°C
0.125
250
+20
+20
0.5
CONDITIONS
MIN
3.0
TYP
MAX
5.5
10
1
±1
±2.5
±4
UNITS
V
µA
mA
°C
°C
°C
ms
%
%
2
_______________________________________________________________________________________
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, T
A
= 0°C to +125°C, unless otherwise noted. Typical values are at V
CC
= +3.3V, T
A
= +25°C.)
PARAMETER
START Condition Hold Time
STOP Condition Setup Time
Data Setup Time
Data Hold Time
SMBus Fall Time
SMBus Rise Time
SMBus Timeout
SYMBOL
t
HD:STO
t
SU:STO
t
SU:DAT
t
HD:DAT
t
F
t
R
(Note 3)
29
37
CONDITIONS
10% of SDA to 10% of SCL
90% of SCL to 10% of SDA
10% of SDA to 10% of SCL
10% of SCL to 10% of SDA
MIN
4
4
250
300
300
1000
55
TYP
MAX
UNITS
µs
µs
ns
ns
ns
ns
ms
MAX6615/MAX6616
Note 1:
1°C of error corresponds to an ADC error of 7.76mV when V
REF
= 1V.
Note 2:
Guaranteed by design and characterization.
Note 3:
Production tested.
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6615/6 toc01
THERMISTOR TEMPERATURE DATA
vs. THERMISTOR TEMPERATURE
MAX6615/6 toc02
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
MAX6615/6 toc03
1000
LOCAL
SUPPLY CURRENT (µA)
REMOTE
100
120
THERMISTOR TEMPERATURE DATA (°C)
100
80
60
40
20
0
2
TEMPERATURE ERROR (°C)
1
0
10
SHUTDOWN
-1
1
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
-2
0
20
40
60
80
100
120
0
25
50
75
100
THERMISTOR TEMPERATURE (°C)
DIE TEMPERATURE (°C)
_______________________________________________________________________________________
3
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
MAX6615/MAX6616
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
GPIO OUTPUT VOLTAGE
vs. GPIO SINK CURRENT
MAX6615/6 toc04
MAX6615/6 toc05
GPIO SINK CURRENT
vs. SUPPLY VOLTAGE
50
45
40
I
GPIO_
(mA)
35
30
25
20
15
3.0
3.5
4.0
4.5
5.0
5.5
V
CC
(V)
V
GPIO_
= 0.4V
V
GPIO_
(V)
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
PWM FREQUENCY
vs. DIE TEMPERATURE
4
3
FREQUENCY SHIFT (Hz)
2
1
0
-1
-2
-3
-4
NORMALIZED AT T
A
= +25°C
0
25
50
75
100
125
MAX6615/6 toc06
5
V
CC
= 3V
V
CC
= 5V
20
30
40
50
60
70
80
-5
DIE TEMPERATURE (°C)
I
GPIO_
(mA)
PWM FREQUENCY
vs. SUPPLY VOLTAGE
0.08
FREQUENCY SHIFT (Hz)
0.06
0.04
0.02
0
-0.02
NORMALIZED AT V
CC
= 5.0V
-0.04
3.0
3.5
4.0
4.5
5.0
5.5
V
CC
(V)
MAX6615/6 toc07
0.10
4
_______________________________________________________________________________________
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
Pin Description
PIN
MAX6616
1, 2, 5, 20,
23, 24
3
4
6
7
8
9
10, 15
11
12
13
14
16
17
18
19
21
22
MAX6615
—
1
2
3
4
5, 10
6
—
7
8
9
—
11
12
13
14
15
16
NAME
GPIO0–
GPIO5
PWM1
TACH1
ADD0
ADD1
GND
TH1
N.C.
REF
TH2
FAN_FAIL
PRESET
OT
V
CC
SDA
SCL
TACH2
PWM2
FUNCTION
Active-Low, Open-Drain GPIOs. Can be pulled up to 5.5V regardless of V
CC
.
Fan Driver Output 1. The pullup resistor can be connected to a supply voltage as high as
12V, regardless of the supply voltage. See the
PWM Output
section for configuration.
Fan Tachometer Input. Accepts logic-level signal from fan’s tachometer output. Can be
connected to a supply voltage as high as 12V, regardless of the supply voltage.
SMBus Slave Address Selection
SMBus Slave Address Selection
Ground. Must be connected together for MAX6615.
External Thermistor Input 1. Connect a thermistor in series with a fixed resistor between
REF and ground.
No Connection
Reference Voltage Output. Provides 1V during measurements. High impedance when not
measuring.
External Thermistor Input 2. Connect a thermistor in series with a fixed resistor between
REF and ground.
Fan-Failure Output. Asserts low when either fan fails. Can be pulled up as high as 5.5V
regardless of V
CC
. High impedance when V
CC
= 0V.
Connect to GND or V
CC
to set POR state of the GPIO0.
Overtemperature Output. Active low, open drain. Typically used for system shutdown or
clock throttling. Can be pulled up as high as 5.5V regardless of V
CC
. High impedance
when V
CC
= 0V.
Power Supply. 3.3V nominal. Bypass with a 0.1µF capacitor to GND.
SMBus Serial-Data Input/Output. Pull up with a 10kΩ resistor. Can be pulled up as high
as 5.5V regardless of V
CC
. High impedance when V
CC
= 0V.
SMBus Serial-Clock Input. Pull up with a 10kΩ resistor. Can be pulled up as high as 5.5V
regardless of V
CC
. High impedance when V
CC
= 0V.
Fan Tachometer Input. Accepts logic-level signal from fan’s tachometer output. Can be
connected to a supply voltage as high as 12V, regardless of the supply voltage.
Fan Driver Output 2. The pullup resistor can be connected to a supply voltage as high as
12V, regardless of the supply voltage. See the
PWM Output
section for configuration.
MAX6615/MAX6616
_______________________________________________________________________________________
5
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