MAXIM MAX6615, MAX6616 User Manual
General Description
The MAX6615/MAX6616 monitor two temperature channels, either the internal die temperature and the temperature 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 running cool, but providing maximum cooling when power
dissipation increases. The fans’ tachometer output signals 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 generate interrupts, throttle signals, or overtemperature shutdown 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 package. 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.
Applications
Desktop Computers
Servers
Power Supplies
Networking Equipment
Workstations
Features
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
MAX6615/MAX6616
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
________________________________________________________________
Maxim Integrated Products
1
19-3713; Rev 2; 10/08
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.
Ordering Information
SMBus is a trademark of Intel Corp.
Typical Application Circuits and Pin Configurations appear at
end of data sheet.
THERMISTORS
AND LOCAL
TEMP SENSOR
PWM
GENERATOR
AND TACH
COUNTER
SMBus
INTERFACE
AND
REGISTERS
LOGIC
ADD0 ADD1
*MAX6616 ONLY
FAN_FAIL
MAX6615
MAX6616
GND
V
CC
SDA
SCL
REF
TH1
TH2
PWM1
PWM2
TACH1
TACH2
OT
GPIO0*
GPIO5*
PRESET*
Functional Diagram
PART TEMP RANGE PIN-PACKAGE
MAX6615AEE -40°C to +125°C 16 QSOP
MAX6616AEG -40°C to +125°C 24 QSOP
MAX6615/MAX6616
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
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
ELECTRICAL CHARACTERISTICS
(VCC= +3.0V to +5.5V, TA= 0°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V, TA= +25°C.)
Operating Supply Voltage
Standby Current Interface inactive, ADC in idle state 10 µA
Operating Current I
External Temperature Error
Internal Temperature Error
Temperature Resolution 0.125 °C
Conversion Time 250 ms
Conversion Rate Timing Error -20 +20 %
PWM Frequency Error -20 +20 %
INPUT/OUTPUT
Output Low Voltage V
Output High Leakage Current I
Logic Low Input Voltage V
Logic High Input Voltage V
Input Leakage Current 1µA
Input Capacitance C
SMBus TIMING (Figures 2, 3) (Note 2)
Serial Clock Frequency f
Clock Low Period t
Clock High Period t
Bus Free Time Between STOP
and START Conditions
SMBus START Condition
Setup Time
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
V
CC
Interface inactive, ADC active 0.5 1 mA
S
V
OL
OH
IL
IH
IN
SCLK
LOW
HIGH
t
BUF
t
SU:STA
= +3.3V, 0.15V ≤ V
CC
thermistor errors, thermistor nonlinearity) (Note1)
VCC = +3.3V, 0°C ≤ TA ≤ +85°C, ±2.5
V
= +3.3V, 0°C ≤ TA ≤ +125°C ±4
CC
VCC = +3V, I
10% to 10% 4 µs
90% to 90% 4.7 µs
90% of SCL to 90% of SDA 4.7 µs
= 6mA 0.4 V
OUT
≤ +0.71V (excludes
TH_
3.0 5.5 V
±1 °C
1µA
0.8 V
2.1 V
5pF
10 400 kHz
4.7 µs
°C
MAX6615/MAX6616
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
_______________________________________________________________________________________ 3
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.
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +3.0V to +5.5V, TA= 0°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V, TA= +25°C.)
Typical Operating Characteristics
(V
CC
= +3.3V, TA= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6615/6 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
5.04.54.03.5
10
100
1000
1
3.0 5.5
LOCAL
REMOTE
SHUTDOWN
0
40
20
80
60
100
120
THERMISTOR TEMPERATURE DATA
vs. THERMISTOR TEMPERATURE
MAX6615/6 toc02
THERMISTOR TEMPERATURE (°C)
THERMISTOR TEMPERATURE DATA (°C)
0406020 80 100 120
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
MAX6615/6 toc03
DIE TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
755025
-1
0
1
2
-2
0100
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
START Condition Hold Time t
STOP Condition Setup Time t
Data Setup Time t
Data Hold Time t
HD:STO
SU:STO
SU:DAT
HD:DAT
SMBus Fall Time t
SMBus Rise Time t
10% of SDA to 10% of SCL 4 µs
90% of SCL to 10% of SDA 4 µs
10% of SDA to 10% of SCL 250 ns
10% of SCL to 10% of SDA 300 ns
F
R
300 ns
1000 ns
SMBus Timeout (Note 3) 29 37 55 ms
MAX6615/MAX6616
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, TA= +25°C, unless otherwise noted.)
GPIO SINK CURRENT
vs. SUPPLY VOLTAGE
MAX6615/6 toc04
VCC (V)
I
GPIO_
(mA)
5.04.54.03.5
20
25
30
35
40
45
50
15
3.0 5.5
V
GPIO_
= 0.4V
GPIO OUTPUT VOLTAGE
vs. GPIO SINK CURRENT
MAX6615/6 toc05
I
GPIO_
(mA)
V
GPIO_
(V)
706040 5020 3010
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0
080
VCC = 3V
VCC = 5V
-5
-2
-3
-4
-1
0
1
2
3
4
5
05025 75 100 125
PWM FREQUENCY
vs. DIE TEMPERATURE
MAX6615/6 toc06
DIE TEMPERATURE (°C)
FREQUENCY SHIFT (Hz)
NORMALIZED AT TA = +25°C
-0.04
0
-0.02
0.04
0.02
0.08
0.06
0.10
3.0 4.03.5 4.5 5.0 5.5
PWM FREQUENCY
vs. SUPPLY VOLTAGE
MAX6615/6 toc07
VCC (V)
FREQUENCY SHIFT (Hz)
NORMALIZED AT VCC = 5.0V
MAX6615/MAX6616
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
_______________________________________________________________________________________ 5
Pin Description
PIN
MAX6616 MAX6615
1, 2, 5, 20,
23, 24
3 1 PWM1
4 2 TACH1
6 3 ADD0 SMBus Slave Address Selection
7 4 ADD1 SMBus Slave Address Selection
8 5, 10 GND Ground. Must be connected together for MAX6615.
9 6 TH1
10, 15 — N.C. No Connection
11 7 REF
12 8 TH2
13 9 FAN_FAIL
14 — PRESET Connect to GND or VCC to set POR state of the GPIO0.
16 11 OT
17 12 V
18 13 SDA
19 14 SCL
21 15 TACH2
22 16 PWM2
—
NAME
GPIO0–
GPIO5
CC
FUNCTION
Active-Low, Open-Drain GPIOs. Can be pulled up to 5.5V regardless of V
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.
External Thermistor Input 1. Connect a thermistor in series with a fixed resistor between
REF and ground.
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
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
when V
CC
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
SMBus Serial-Clock Input. Pull up with a 10kΩ resistor. Can be pulled up as high as 5.5V
regardless of V
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.
. High impedance when VCC = 0V.
CC
= 0V.
. High impedance when VCC = 0V.
CC
. High impedance when VCC = 0V.
CC
.
CC
. High impedance
CC
MAX6615/MAX6616
Detailed Description
The MAX6615/MAX6616 accurately monitor two temperature channels, either the internal die temperature
and the temperature of an external thermistor, or the
temperatures of two external thermistors. They report
temperature values in digital form using a 2-wire
SMBus/I2C-compatible serial interface. The MAX6615/
MAX6616 operate from a supply voltage range of 3.0V
to 5.5V and consume 500µA (typ) of supply current.
The temperature data controls the duty cycles of two
PWM output signals that are used to adjust the speed
of a cooling fan. They also feature an overtemperature
alarm output to generate interrupts, throttle signals, or
shutdown signals.
The MAX6616 also includes six GPIO input/outputs to
provide additional flexibility. The GPIO0 power-up state
is set by connecting the GPIO PRESET input to ground
or VCC.
SMBus Digital Interface
From a software perspective, the MAX6615/MAX6616
appear as a set of byte-wide registers. Their devices use
a standard SMBus 2-wire/I2C-compatible serial interface
to access the internal registers. The MAX6615/MAX6616
have nine different slave addresses available; therefore, a
maximum of nine MAX6615/MAX6616 devices can share
the same bus.
The MAX6615/MAX6616 employ four standard SMBus
protocols: write byte, read byte, send byte, and receive
byte (Figures 1, 2, and 3). The shorter receive byte protocol allows quicker transfers, provided that the correct
data register was previously selected by a read byte
instruction. Use caution with the shorter protocols in multimaster systems, since a second master could overwrite
the command byte without informing the first master.
Temperature data can be read from registers 00h and
01h. The temperature data format for these registers is
8 bits, with the LSB representing 1°C (Table 1) and the
MSB representing 128°C. The MSB is transmitted first.
All values below 0°C clip to 00h.
Table 3 details the register address and function, whether
they can be read or written to, and the power-on reset
Dual-Channel Temperature Monitors and
Fan-Speed Controllers with Thermistor Inputs
6 _______________________________________________________________________________________
WRITE BYTE FORMAT
READ BYTE FORMAT
SEND BYTE FORMAT
RECEIVE BYTE FORMAT
SLAVE ADDRESS: EQUIVALENT TO CHIP-SELECT LINE
OF A 3-WIRE INTERFACE
COMMAND BYTE: SELECTS
WHICH REGISTER YOU ARE
WRITING TO
DATA BYTE: DATA GOES INTO THE REGISTER SET BY THE COMMAND BYTE (TO
SET THRESHOLDS, CONFIGURATION
MASKS, AND SAMPLING RATE)
SLAVE ADDRESS:
EQUIVALENT TO CHIPSELECT LINE
COMMAND BYTE:
SELECTS WHICH
REGISTER YOU ARE
READING FROM
SLAVE ADDRESS: REPEATED DUE TO CHANGE IN
DATA- FLOW DIRECTION
DATA BYTE: READS
FROM THE REGISTER
SET BY THE COMMAND
BYTE
COMMAND BYTE: SENDS COMMAND WITH NO DATA, USUALLY
USED FOR ONE-SHOT COMMAND
DATA BYTE: READS DATA FROM
THE REGISTER COMMANDED BY
THE LAST READ BYTE OR WRITE
BYTE TRANSMISSION; ALSO
USED FOR SMBUS ALERT
RESPONSE RETURN ADDRESS
S = START CONDITION SHADED = SLAVE TRANSMISSION
P = STOP CONDITION /// = NOT ACKNOWLEDGED
Figure 1. SMBus Protocols
S ADDRESS RD ACK DATA /// P
— 7 BITS — — 8 BITS — —
WRS ACK COMMAND ACK P
— — — 8 BITS — —
ADDRESS
7 BITS
P
1
ACK
—
DATA
8 BITS
ACK
—
COMMAND
8 BITS
ACK
—
WR
—
ADDRESS
7 BITS
S
—
S ADDRESS WR ACK COMMAND ACK S ADDRESS
7 BITS——8 BITS——7 BITS—
RD—ACK—DATA
8 BITS
///
—
P
—
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