MAX6660AEE+ Maxim Integrated Products, MAX6660AEE+ Datasheet - Page 14

• Manufacturer Part Number: MAX6660AEE+
• Description: IC REG FAN SPEED 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6660AEE+

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Control, Multiplexer, Register Bank
• Sensor Type: External
• Sensing Temperature: External Sensor
• Output Type: I²C™/SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Full Temp Accuracy: +/- 5 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 10 bit + Sign
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
Table 7. POR Slave Address Decoding
(ADD0 and ADD1)
Figure 6. MAX6660 Thermal Loop
14
High-impedance
High-impedance
High-impedance
______________________________________________________________________________________
ADD0
GND
GND
GND
V
V
V
CC
CC
CC
T
FAN
High-impedance
High-impedance
High-impedance
DRIVER CIRCUIT
FAN CONTROL
0.25s TO 16s
TEMPDATA
4/5/6 BITS
UPDATE
FCR
FSC
ADD1
FG
GND
GND
GND
V
V
V
CC
CC
CC
ADDRESS
0011 000
0011 001
0011 010
0101 001
0101 010
0101 011
1001 100
1001 101
1001 110
Power-up defaults include:
•
•
•
•
•
The fan-control function can be divided into the thermal
loop, the fan-speed-regulation loop (fan loop), and the
fan-failure sensor. The thermal loop sets the desired fan
speed based on temperature while the fan-speed-regu-
lation loop uses an internally divided down reference
oscillator to synchronize to and regulate the fan speed.
The fan-speed-regulation loop includes the fan driver
and the tachometer sensor. The fan-failure sensor pro-
vides a FAN FAIL alarm that signals when the fan
tachometer count is greater than the fan tachometer
value, which corresponds to a fan going slower than
the limit. The fan driver is an N-channel, 4Ω, 320mA
MOSFET with a 16V maximum V
nal connects to the low side of the fan. The tachometer
sensor (TACH IN) of the MAX6660 is driven from the
tachometer output of the fan and provides the feed-
back signal to the fan-speed-regulation loop for control-
ling the fan speed. For fans without tachometer outputs,
the MAX6660 can generate its own tachometer pulses
by monitoring the commutating current pulses (see
Commutating Current Pulses section).
The MAX6660 can be operated in a complete closed-
loop mode, with both the thermal and fan loops closed,
where the remote-diode sensor temperature directly
controls fan speed. Setting bit 3 of the Configuration
register to zero places the MAX6660 in thermal closed
loop (Figure 6). The remote-diode temperature sensor
is updated every 250ms. The value is stored in a tem-
porary register (TEMPDATA) and compared to the pro-
grammed temperature values in the T
T
outputs OVERT and ALERT.
The Fan Conversion Rate (FCR) register (Table 8) can
be programmed to update the TEMPDATA every 0.25s
HYST
Interrupt latch is cleared.
ADC begins autoconverting.
Command register is set to 00h to facilitate quick
internal Receive Byte queries.
T
-55°C, respectively.
T
respectively.
HIGH
HYST
, T
MAX
and T
and T
, and T
LOW
MAX
FAN
registers are set to +127°C and
are set to +95°C and +100°C,
registers to produce the error
Thermal Closed Loop
DS
whose drain termi-
Thermal Loop
Fan Control
HIGH
, T
LOW
,