Rainbow Electronics MAX6670 - Manual

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
♦ +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
MAX6668/MAX6670
Remote Temperature Switches with Integrated
Fan Controller/Driver
________________________________________________________________ Maxim Integrated Products 1
DXP
GND PGND
HYST
V DD
MAX6670
FORCEON
FANOUT
WARN
OT
V
DD
DXN
V DD
C S
2200pF
2N3904
10k Ω
10k Ω
250mA
FAN
+3.3V
V DD
+12V
Typical Applications Circuit
Ordering Information
19-2133; Rev 0; 8/01
Pin Configuration appears at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
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.
*These parts are offered in eight standard temperature ver-
sions from +40°C through +75°C in 5°C increments. To com-
plete the suffix information, select an available temperature trip
point in degrees centigrade and fill in the blank. For example,
the MAX6670AUB065 describes a MAX6670 in a 10-pin µMAX
package with +65°C trip point.
PART* TEMP. RANGE PIN-PACKAGE
MAX6668AUA_ _ _ -40 °C to +125°C 8 µMAX
MAX6670AUB_ _ _ -40 °C to +125°C 10 µMAX