MAX6650EUB+T Maxim Integrated Products, MAX6650EUB+T Datasheet - Page 14

• Manufacturer Part Number: MAX6650EUB+T
• Description: IC REG FAN SPEED 10-MSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6650EUB+T

• Applications: Fan Controller, Brushless (BLDC)
• Number Of Outputs: 1
• Voltage - Load: 0.3 V ~ 5.2 V
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Operating Supply Voltage: 3 V to 5.5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: MAX6650EUB+T; MAX6650EUB+TTR

impedance of the tachometer input (150kΩ max) or the
feedback input (150kΩ max).
A compensation capacitor is needed from the fan’s low
side to ground to stabilize the analog control loop.
Typically, this capacitor should be 10µF, but depend-
ing on the type of fan being used, a value between 1µF
and 100µF may be required. The proper value has
been selected when no ringing is present on the volt-
age at the fan’s low side.
Fan-Speed Regulators and Monitors
with SMBus/I
Table 10. Fan Manufacturers
Figure 7. Using the MAX6651 to Control Parallel Fans
14
Comair Rotron
EBM-Papst
NMB
Panasonic
Sunon
MANUFACTURER
______________________________________________________________________________________
INTERFACE
3V TO 5.5V
SMBus/I
V
CC
2
C
All DC brushless models can be
ordered with optional tachometer
output.
Tachometer output optional on some
models.
All DC brushless models can be
ordered with optional tachometer
output.
Panaflo and flat unidirectional
miniature fans can be ordered with
tachometer output.
Tachometer output optional on some
models.
Compensation Capacitor
FAN MODEL OPTION
2
C-Compatible Interface
FULL ON
ALERT
V
SCL
SDA
GPIO0
GPIO1
CC
MAX6651
TACH0
TACH1
TACH2
GND
ADD
OUT
FB
For closed-loop operation and fan monitoring, the
MAX6650/MAX6651 require fans with tachometer outputs.
A tachometer output is typically specified as an option on
many fan models from a variety of manufacturers. Verify
the nature of the tachometer output (open collector, totem-
pole) and the resultant levels, and configure the connec-
tion to the MAX6650/MAX6651 accordingly. Note how
many pulses per revolution are generated by the
tachometer output (this varies from model to model and
among manufacturers, though two pulses per revolution is
the most common).
Table 10 lists the representative fan manufacturers and
the models they make available with tachometer outputs.
Brushless DC fans increase reliability by replacing
mechanical commutation with electronic commutation. By
lowering the voltage across the fan to reduce its speed,
the MAX6650/MAX6651 are also lowering the supply volt-
age for the electronic commutation and tachometer elec-
tronics. If the voltage supplied to the fan is lowered too
far, the internal electronics may no longer function prop-
erly. Some of the following symptoms are possible:
• The fan may stop spinning.
• The tachometer output may stop generating a signal.
• The tachometer output may generate more than two
The problems that occur, and the supply voltages at
which they occur, depend on which fan is used. As a
pulses per revolution.
10kΩ
10kΩ
10kΩ
FAN
0
C
COMP
FAN
1
FAN
2
Low-Speed Operation
V
FAN
Fan Selection
5V OR 12V