Maxim MAX6670AUB50 Remote temperature switches with integrated fan controller/driver Datasheet

19-2133; Rev 2; 11/02
Remote Temperature Switches with Integrated
Fan Controller/Driver
Features
♦ +12V, 250mA Integrated Fan Driver
♦ No Calibration Required
♦ Pin-Selectable 4°C, 8°C, or 12°C Hysteresis
(MAX6670)
♦ Factory-Programmed Temperature Thresholds
from +40°C to +75°C
♦ Overtemperature Warning Signals
♦ 110µA (typ) Supply Current
♦ Space-Saving 8-Pin and 10-Pin µMAX Packages
Ordering Information
TEMP
RANGE
PART
PI NPA CK AG E
THRESHOLD
( ° C)
MAX6668AUA40 -40°C to +125°C
8 µMAX
40
MAX6668AUA45 -40°C to +125°C
8 µMAX
45
MAX6668AUA50 -40°C to +125°C
8 µMAX
50
MAX6668AUA60 -40°C to +125°C
8 µMAX
60
MAX6668AUA70 -40°C to +125°C
8 µMAX
70
MAX6668AUA75 -40°C to +125°C
8 µMAX
75
Ordering Information continued at end of data sheet.
Typical Application Circuit
Applications
+12V
Notebook and Desktop Computers
Network Switches
PC Power Supplies
DXP
Laboratory Instruments
CS
2200pF
Card Racks
Temperature Alarms
250mA
FAN
+3.3V
2N3904
VDD
FANOUT
VDD
10kΩ
MAX6670
DXN
WARN
Fan Controls
VDD
10kΩ
HYST
GND
OT
PGND FORCEON
VDD
Pin Configuration appears at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX6668/MAX6670
General Description
The MAX6668/MAX6670 remote-junction thermal
switches with an internal power transistor drive a cooling fan rated for supply voltages up to +12V and
250mA. These devices measure the temperature of an
external P-N junction (typically a diode-connected transistor) and turn on the fan power switch when the
remote temperature rises above a factory-programmed
threshold. Self-contained and requiring no software
development, the MAX6668/MAX6670 are simple
“drop-in” fan-control solutions for a variety of systems.
The MAX6670 features an open-drain WARN output
that goes active when the remote temperature exceeds
the factory-programmed fan activation threshold by
+15°C. The MAX6670 features an open-drain OT output
that goes active when the remote temperature exceeds
the factory-programmed threshold by +30°C. The
MAX6668/MAX6670 provide a fan-control input,
FORCEON, that allows the fan to be driven externally,
regardless of temperature.
Available temperature thresholds range from +40°C to
+75°C in 5°C increments. Hysteresis is preset to 8°C on
the MAX6668 or pin selectable to 4°C, 8°C, or 12°C
using a three-level logic input on the MAX6670.
Temperature threshold accuracy is ±1°C (typ) and
±2.2°C (max) for remote-junction temperatures from
+40°C to +75°C.
The MAX6668/MAX6670 operate from a +3V to +3.6V
power supply, and are specified over the automotive
temperature range (-40°C to +125°C). The MAX6668 is
offered in an 8-pin µMAX package and the MAX6670 is
available in a space-saving 10-pin µMAX package.
MAX6668/MAX6670
Remote Temperature Switches with Integrated
Fan Controller/Driver
ABSOLUTE MAXIMUM RATINGS
VDD to GND ..............................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
FANOUT to GND ....................................................-0.3V to +15V
DXN to GND ..........................................................-0.3V to +0.8V
DXP, WARN, HYST, FORCEON, OT...........-0.3V to (VDD + 0.3V)
Current into VDD, GND, DXP, DXN, WARN, HYST,
FORCEON, OT..............................................................±20mA
Current into FANOUT, PGND ........................................ ±300mA
Continuous Power Dissipation (TA = +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............333mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-60°C to +150°C
Junction Temperature ......................................................+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
(VDD = +3V to +3.6V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = +3.3V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
3.6
V
110
200
µA
400
650
µA
1.5
2.0
POWER SUPPLY
Power-Supply Range
VDD
Average Supply Current
IDD
Operating Current
Power-On Reset (POR) Threshold
3
During sampling
POR
VDD falling edge
1
POR Threshold Hysteresis
50
V
mV
TEMPERATURE SENSOR
FANOUT Temperature
Threshold Accuracy
FANOUT Temperature
Threshold Hysteresis
∆TTH
THYST
TRJ = +40°C to +75°C (Note 1),
TA = 0°C to +85°C, VDD = +3.3V
±1
±2.2
TRJ = +40°C to +75°C (Note 1),
TA = -40°C to +125°C, VDD = +3.3V
±1
±4
MAX6670
°C
HYST = GND
4
HYST = float
8
HYST = VDD
12
MAX6668
°C
8
WARN Temperature Threshold
(MAX6670 Only)
Relative to FANOUT temperature threshold
+15
°C
OT Temperature Threshold
(MAX6670 Only)
Relative to FANOUT temperature threshold
+30
°C
Supply Sensitivity of Temperature
Threshold
1
Temperature Sample Frequency
3.3
1.6
4
°C/V
Hz
FAN DRIVE OUTPUT
FANOUT Output Voltage Low
VOL
ISINK = 250mA
0.5
1
V
Thermal Shutdown
170
°C
Thermal Shutdown Hysteresis
20
°C
LOGIC INPUT/OUTPUT
FORCEON Input High Voltage
2
VIH
0.8 x
VDD
_______________________________________________________________________________________
V
Remote Temperature Switches with Integrated
Fan Controller/Driver
(VDD = +3V to +3.6V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = +3.3V and TA = +25°C.)
PARAMETER
SYMBOL
FORCEON Input Low Voltage
CONDITIONS
MIN
TYP
VIL
FORCEON Input Bias Current
MAX
UNITS
0.2 x
VDD
V
1
µA
0.5
V
1
µA
V FORCEON = VDD or GND
WARN, OT Output Voltage Low
VOL
ISINK = 6mA
WARN, OT Output High Leakage
Current
IOH
V WARN or V OT = +5.5V
Note 1: TRJ is the temperature of the remote P-N junction.
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
0.6
IFANOUT = 250mA
1.8
1.6
100
0.3
1.2
IDD (µA)
VFANOUT (V)
0.4
TA = +105°C
1.0
TA = +65°C
0.8
0.6
0.2
0.1
0
0
150
200
250
300
2.0
IFANOUT (mA)
2.5
3.0
0
3.5
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
100
80
60
40
30
PERCENTAGE OF SAMPLES (%)
120
50
75
TEMPERATURE (°C)
100
TEMPERATURE THRESHOLD ERROR
MAX6668/70 toc04
140
IDD (µA)
25
VDD (V)
MAX6668/70 toc05
100
60
20
TA = +25°C
0.2
0
80
40
0.4
50
VDD = +3.3V, IFANOUT = 250mA
120
1.4
VDD = +3.3V
0
140
MAX6668/70 toc02
TA = +25°C
VFANOUT (V)
2.0
MAX6668/70 toc01
0.7
0.5
SUPPLY CURRENT
vs. TEMPERATURE
FANOUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX6668/70 toc03
FANOUT CURRENT
vs. FANOUT VOLTAGE
MAX6670AUB040
119 SAMPLES
25
20
15
10
5
20
FORCEON = VDD
0
3.0
3.3
VDD (V)
3.6
0
-1.00 -0.75 -0.50 -0.25
0
0.25 0.50 0.75
1.00
THRESHOLD ERROR (°C)
_______________________________________________________________________________________
3
MAX6668/MAX6670
ELECTRICAL CHARACTERISTICS (continued)
Remote Temperature Switches with Integrated
Fan Controller/Driver
MAX6668/MAX6670
Pin Description
PIN
NAME
MAX6668
MAX6670
1
1
FUNCTION
PGND
Power Ground. PGND is the power ground for the FANOUT power MOSFET switch.
Fan-Control Input. Drive FORCEON high for normal operation. Drive FORCEON low
to force fan on.
2
5
FORCEON
3
3
DXP
Current Source Positive Input. Connect to the anode of the external diodeconnected transistor. Do not leave DXP floating. Connect a 2200pF capacitor
between DXP and DXN for noise filtering.
4
4
DXN
Current Sink Negative Input. Connect to the cathode of the external diodeconnected transistor. DXN is internally biased to a diode voltage drop.
5, 7
7
GND
Ground
6
8
VDD
Positive Power Supply
8
10
FANOUT
—
2
WARN
—
6
OT
Overtemperature Output. OT is an open-drain output that goes low when the sensed
junction temperature is 30°C higher than the fan trip threshold.
—
9
HYST
Hysteresis Control Input. HYST is a three-level logic input for controlling the fandrive comparator’s hysteresis. Connect HYST to GND for 4°C hysteresis, to VDD for
12°C hysteresis, or leave floating for 8°C hysteresis.
Fan-Drive Output. FANOUT is an open-drain power MOSFET that sinks up to 250mA
current to turn on the fan when the sensed temperature exceeds the fan trip
threshold or the fan is forced on by driving FORCEON low.
Temperature Warning Output. WARN is an open-drain output that goes low when
the sensed junction temperature is 15°C higher than the fan trip threshold.
Detailed Description
Overtemperature Alarm Outputs
The MAX6668/MAX6670 are simple fan controllers/drivers that turn on an internal power transistor when the
sensed temperature of an external P-N junction
exceeds a factory-set threshold. By connecting a small
(up to +12V/250mA nominal) cooling fan to FANOUT, a
simple on/off fan-control system is created. Do not connect the fan to a power supply of higher than 12V nominal, 15V maximum.
WARN Output (MAX6670 Only)
WARN is an active-low, open-drain digital output that
indicates when the external P-N junction’s temperature
exceeds 15°C above the fan trip threshold. The WARN
output serves as a warning that the system temperature
has continued to rise well above the fan activation temperature.
FANOUT Driver and FORCEON Controller
FANOUT Fan-Driver Output
FANOUT is an open-drain output that sinks greater than
250mA of current to turn on the fan, either when the fan
trip threshold is exceeded or the fan is forced on by driving FORCEON low.
FORCEON Fan-Control Input
Drive FORCEON low to turn on the fan when the
MAX6670’s remote-sensing junction temperature is less
than the fan trip threshold temperature. This overrides
the internal control circuitry and allows for an external
device to activate the fan.
4
OT Output (MAX6670 Only)
OT is an active-low, open-drain digital output that indicates when the external P-N junction’s temperature
exceeds 30°C above the fan trip threshold. OT serves
as a thermal shutdown output to the system in case of
excessive temperature rise.
Hysteresis Input
The temperature comparator has hysteresis to prevent
small temperature changes near the threshold temperature from causing the fan to turn on and off repeatedly
over short periods of time. The FANOUT pin goes
active and powers the fan when the external P-N junction’s temperature exceeds the factory-programmed
_______________________________________________________________________________________
Remote Temperature Switches with Integrated
Fan Controller/Driver
Applications Information
Remote-Diode Selection
The MAX6668/MAX6670 directly measure the die temperature of CPUs and other ICs that have on-board temperature-sensing diodes (see Typical Operating Circuit)
or they can measure the temperature of a discrete
diode-connected transistor. For best accuracy, the discrete transistor should be a small-signal device with its
collector and base connected together. Several satisfactory discrete sensing transistors are shown in Table 1.
The sensing transistor must be a small-signal type with
a relatively high forward voltage. Otherwise, the DXP
input voltage range may be violated. The forward voltage at the highest expected temperature must be
greater than 0.25V at 10µA, and at the lowest expected
temperature, forward voltage must be less than 0.95V
at 100µA. Do not use large power transistors. Also,
ensure that the base resistance is less than 100Ω. Tight
specifications for forward current gain (50 < BF < 150,
for example) indicate that the manufacturer has good
process controls and that the transistors have consistent VBE characteristics.
Noise-Filtering Capacitor
In noisy environments, high-frequency noise can be
attenuated using an external 2200pF capacitor located
at the DXP and DXN pins. Larger capacitor values may
be used for additional filtering, but do not exceed
3300pF; excessive capacitance increases error. Figure
2 shows the recommended DXP/DXN PC traces.
Bypassing and Layout
The location of the remote-sensing junction in the system affects the MAX6668/MAX6670s’ operation. When
using a discrete temperature-sensing transistor, place
the sensing junction close to major heat-generating
components, such as a high-speed CPU or a power
device.
Table 1. Remote-Sensor Transistor
Manufacturers
MANUFACTURER
Central Semiconductor (USA)
MODEL NO.
CMPT3904
ON Semiconductor (USA)
2N3904, 2N3906
Rohm Semiconductor (USA)
SST3904
Samsung (Korea)
KST3904-TF
Siemens (Germany)
SMBT3904
Zetex (England)
FMMT3904CT-ND
To minimize noise and other errors, follow the guidelines below:
1) Place the MAX6668/MAX6670 as close as possible to
the remote diode. In a noisy environment, such as a
computer motherboard, this distance can be 10cm to
20cm (typ) or more as long as the worst noise
sources (such as CRTs, clock generators, memory
buses, and ISA/PCI buses) are avoided. In general,
minimize the distance to the remote-sensing junction.
2) Do not route the DXP/DXN traces next to the deflection coils of a CRT. Also, do not route the traces
across a fast memory bus, which can introduce
+30°C error or more, even with good filtering.
3) Route the DXP and DXN traces in parallel and in
close proximity to each other, away from any highvoltage traces, such as +12VDC. Avoid leakage currents from PC board contamination, since a 20MΩ
leakage path from DXP to GND causes about +1°C
error.
4) Connect guard traces to GND on either side of the
DXP/DXN traces (Figure 2). With guard traces in
place, routing near high-voltage traces is no longer
an issue.
5) Route through as few vias and crossunders as possible to minimize copper/solder thermocouple effects.
6) Use wide traces where possible. Narrow traces are
more inductive and tend to pick up radiated noise.
7) Do not use copper as an EMI shield. Only ferrous
materials such as steel work well. Placing a copper
ground plane between the DXP/DXN traces and
other traces carrying high-frequency noise signals
does not help reduce EMI.
The MAX6668/MAX6670s’ PGND is the ground return
for the fan driver. Bypass V DD to GND with a 1µF
capacitor located as close to VDD as possible. Add
additional bypass capacitors for long VDD and GND
lines.
_______________________________________________________________________________________
5
MAX6668/MAX6670
trip temperature. As the cooling fan operates, the circuit board temperature should decrease, which causes
the external P-N junction’s temperature to decrease.
When the P-N junction’s temperature is equal to the trip
threshold minus the hysteresis, the FANOUT pin turns
the fan off, removing power from the fan. For the
MAX6670, HYST is a three-level logic input for controlling the fan-drive comparator’s hysteresis. Connect
HYST to GND to select 4°C hysteresis, to VDD to select
12°C hysteresis, or leave floating to select 8°C hysteresis. The MAX6668 has a built-in hysteresis of 8°C. This
allows the amount of hysteresis to be matched to the
cooling and noise requirements of the system. Figure 1
shows the temperature trip threshold hysteresis.
MAX6668/MAX6670
Remote Temperature Switches with Integrated
Fan Controller/Driver
Pin Configurations
TRIP TEMPERATURE
TOP VIEW
TRIP TEMPERATURE
– HYSTERESIS
FANOUT
PGND
MAX6668
MAX6670
1
8
FANOUT
7
GND
3
6
VDD
DXN 4
5
GND
FORCEON 2
MAX6668
TIME
DXP
Figure 1. Temperature Trip Threshold Hysteresis
µMAX
PGND 1
GND
10MILS
DXP
10MILS
MINIMUM
WARN
2
DXP
3
DXN
FORCEON
10 FANOUT
9
HYST
8
VDD
4
7
GND
5
6
OT
MAX6670
DXN
10MILS
10MILS
GND
µMAX
Figure 2. Recommended DXP/DXN PC Traces
Chip Information
Typical Operating Circuit
+4.5V TO +12V
TRANSISTOR COUNT: 8113
PROCESS: BiCMOS
+3V TO +3.6V
CPU
DXP
VDD
Ordering Information
FANOUT
VDD
PART
MAX6670
DXN
WARN
VDD
HYST
GND
6
OT
PGND FORCEON
VDD
TEMP
RANGE
PI NPA CK AG E
THRESHOLD
( ° C)
MAX6670AUB40 -40°C to +125°C
10 µMAX
40
MAX6670AUB45 -40°C to +125°C
10 µMAX
45
MAX6670AUB50 -40°C to +125°C
10 µMAX
50
MAX6670AUB55 -40°C to +125°C
10 µMAX
55
MAX6670AUB60 -40°C to +125°C
10 µMAX
60
MAX6670AUB65 -40°C to +125°C
10 µMAX
65
MAX6670AUB70 -40°C to +125°C
10 µMAX
70
MAX6670AUB75 -40°C to +125°C
10 µMAX
75
_______________________________________________________________________________________
Remote Temperature Switches with Integrated
Fan Controller/Driver
VDD
DXP
FANOUT
TEMP
SENSOR
CS
TFAN
PGND
DXN
HYST
4°C, 8°C,
12°C
HYSTERESIS
WARN
FORCEON
TFAN
+15°C
OT
MAX6670
TFAN
+30°C
GND
VDD
DXP
FANOUT
TEMP
SENSOR
CS
TFAN
PGND
DXN
8°C
HYSTERESIS
MAX6668
FORCEON
GND
_______________________________________________________________________________________
7
MAX6668/MAX6670
Functional Diagrams
Package Information
4X S
8
E
ÿ 0.50±0.1
8
H
MIN
0.002
0.030
0.6±0.1
L
1
α
0.6±0.1
S
BOTTOM VIEW
D
MAX
0.043
0.006
0.037
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
4.78
5.03
0.41
0.66
0∞
6∞
0.5250 BSC
0.010
0.014
0.005
0.007
0.116
0.120
0.0256 BSC
0.116
0.120
0.188
0.198
0.016
0.026
6∞
0∞
0.0207 BSC
c
D
e
E
H
1
MILLIMETERS
MAX
MIN
INCHES
DIM
A
A1
A2
b
8LUMAXD.EPS
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
TOP VIEW
A1
A2
A
α
c
e
L
b
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0036
e
REV.
1
J
1
10LUMAX.EPS
MAX6668/MAX6670
Remote Temperature Switches with Integrated
Fan Controller/Driver
4X S
10
INCHES
10
H
ÿ 0.50±0.1
0.6±0.1
1
1
0.6±0.1
BOTTOM VIEW
TOP VIEW
D2
MILLIMETERS
MAX
DIM MIN
0.043
A
0.006
A1
0.002
A2
0.030
0.037
D1
0.116
0.120
0.114
0.118
D2
0.116
E1
0.120
0.118
E2
0.114
0.199
H
0.187
L
0.0157 0.0275
L1
0.037 REF
b
0.007
0.0106
e
0.0197 BSC
c
0.0035 0.0078
0.0196 REF
S
α
0∞
6∞
MAX
MIN
1.10
0.15
0.05
0.75
0.95
3.05
2.95
3.00
2.89
3.05
2.95
2.89
3.00
4.75
5.05
0.40
0.70
0.940 REF
0.177
0.270
0.500 BSC
0.090
0.200
0.498 REF
0∞
6∞
E2
GAGE PLANE
A2
c
A
b
A1
D1
FRONT VIEW
α
E1
L
L1
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0061
REV.
I
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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