MAX6670 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – Remote Temperature Switches with Integrated Fan Controller/Driver

19-2133; Rev 2; 11/02
Remote Temperature Switches with Integrated
Fan Controller/Driver
General Description
The MAX6668/MAX6670 remote-junction thermal
switches with an internal power transistor drive a cool-
ing 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 tran-
sistor) 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.
Applications
Notebook and Desktop Computers
Network Switches
PC Power Supplies
Laboratory Instruments
Card Racks
Temperature Alarms
Fan Controls
Features
o +12V, 250mA Integrated Fan Driver
o No Calibration Required
o Pin-Selectable 4°C, 8°C, or 12°C Hysteresis
(MAX6670)
o Factory-Programmed Temperature Thresholds
from +40°C to +75°C
o Overtemperature Warning Signals
o 110µA (typ) Supply Current
o Space-Saving 8-Pin and 10-Pin µMAX Packages
Ordering Information
PART
TEMP
RANGE
PI N -
PA C K A G E
THRESH-
OLD
(°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
C_S
2200pF
2N3904
+3.3V
V_DD
DXP
FANOUT
MAX6670
DXN
WARN
+12V
250mA
FAN
V_DD
10kΩ
V_DD
10kΩ
Pin Configuration appears at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
HYST
OT
GND PGND ^FORCEON
V_DD
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