MAX31740 Datasheet, PDF (1/11 Pages) Maxim Integrated Products – Ultra-Simple Fan-Speed Controller

MAX31740
Ultra-Simple Fan-Speed Controller
General Description
The MAX31740 is a sophisticated, yet easy-to-use fan-
speed controller. It monitors the temperature of an exter-
nal NTC thermistor and generates a PWM signal that can
be used to control the speed of a 2-, 3-, or 4-wire fan. The
fan control characteristics are set using external resistors,
thereby eliminating the need for an external microcon-
troller. Controllable characteristics include the starting
temperature for fan control, PWM frequency, fan speed
at low temperatures, and slope of the temperature-duty-
cycle transfer function.
Because the operating characteristics are selected by
hardwired passive components, a simple, low-cost fan-
speed controller can be implemented without the need
for firmware development. This can dramatically reduce
development time for the fan control function.
The MAX31740 is available in a 2mm x 3mm, 8-pin TDFN
package.
Typical Application Circuits
Features
● Self-Contained PWM Fan Control—No Micro Needed
● Controls Speed of 2-, 3-, or 4-Wire Fans
● Resistors Set Fan Control Characteristics
● Smooth, Linearly Varying PWM Duty Cycle Minimizes
Audibility of Fan Noise
● Accurately Monitors External Thermistor Temperature
● 3.0V to 5.5V Operating Voltage Range
● -40°C to +125°C Operating Temperature Range
Applications
● Consumer Equipment
● Communications Equipment
● Computing Equipment
● Industrial Equipment
Ordering Information appears at end of data sheet.
2-WIRE FAN-SPEED CONTROLLER
VDD
4-WIRE FAN-SPEED CONTROLLER
VDD
RST
RD1
C_B
RB
RD2
V_DD
SENSE
D0
FREQ
MAX31740
DMIN
PWM_OUT
GND SLOPE
CF
33Hz
VFAN
N
RSLOPE
RST
RD1
RD2
CB
RB
V_DD
SENSE
D0
FREQ
MAX31740
DMIN
PWM_OUT
GND SLOPE
CF
25kHz
VFAN
TACH OR
LOCKED
ROTOR
RSLOPE
For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX31740.related.
19-6697; Rev 0; 5/13