MAX6650EUB+T Maxim Integrated Products, MAX6650EUB+T Datasheet - Page 13

• 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

Figure 6. Fan Control with a Bipolar Transistor
tion, use DAC values between 08h and B0h (see
Typical Operating Characteristics ). When using the
closed-loop mode of operation, the contents of the
DAC Register are ignored. When writing to the DAC,
wait at least 500µs before attempting to read back.
The MAX6650/MAX6651 have volatile memory. To pre-
vent ambiguous power-supply conditions from corrupt-
ing the data in the memory and causing erratic
behavior, a POR voltage detector monitors V
clears the memory if V
is first applied and V
blocks begin operating (though reads and writes at
V
Power-up defaults include the following:
• All alarms are disabled.
• Prescale divider is set to 4.
• Fan speed is set in full-on mode.
See Table 2 for the default states of all registers.
The MAX6650/MAX6651 drive an external N-channel
MOSFET that requires five important parameters for
proper selection: gate-to-source conduction threshold,
maximum gate-to-source voltage, drain-to-source
CC
levels below 3V are not recommended).
MOSFET and Bipolar Transistor
Applications Information
______________________________________________________________________________________
INTERFACE
3V TO 5.5V
SMBus/I
CC
CC
with SMBus/I
falls below 1.6V. When power
V
rises above 1.6V, the logic
Power-on Reset (POR)
CC
2
C
Fan-Speed Regulators and Monitors
FULL ON
Selection
ALERT
CC
V
SCL
SDA
GPIO0
GPIO1
CC
and
MAX6650
2
C-Compatible Interface
breakdown voltage, current rating, and drain-to-source
on-resistance (R
threshold must be compatible with available V
maximum gate-to-source voltage and the drain-to-
source breakdown voltage rating should both be at
least a few volts higher than the fan supply voltage
(V
drain current rating higher than the maximum fan cur-
rent. R
mize the feedback voltage range. Maximum power
dissipation in the power transistor can be approximat-
ed by P = (V
tors are practical for driving small and midsize fans
(Figure 6). Very-high-current fans may require output
transistor base current greater than the MAX6650’s
50mA drive capability. Bipolar Darlington transistors
will work but have poor saturation characteristics and
could lose up to 2V to 3V of drive voltage.
The tachometer input voltages (V
voltage (V
Maximum Ratings ). When using a fan powered by a
13.2V or greater supply (V
from overvoltage conditions with series resistors. The
resistance required to protect these pins may be calcu-
lated from the following equation:
where V
voltage used to power the fan and R
FAN
TACH0
GND
OUT
ADD
FB
R
). Choose a MOSFET with a maximum continuous
PROTECT
DS(ON)
FAN(MAX)
FB
10kΩ
FAN X
) cannot exceed 13.2V (see Absolute
should be as low as practical to maxi-
= [(V
5V OR 12V
DS(ON)
I
is the worst-case maximum supply
FAN(MAX)
V
FAN
FAN(MAX)
FAN
C
10μF
COMP
). Gate-to-source conduction
FAN
) / 4. Bipolar power transis-
- 13.2V) x R
Resistor Selection
), protect these inputs
TACH_
) and feedback
IN
IN
is the input
] / 13.2V
CC
. The
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