MAX6660AEE+ Maxim Integrated Products, MAX6660AEE+ Datasheet - Page 5

• 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

The MAX6660 is a remote temperature sensor and fan
controller with an SMBus interface. The MAX6660 con-
verts the temperature of a remote-junction temperature
sensor to a 10-bit + sign digital word. The remote tem-
perature sensor can be a diode-connected transistor,
such as a 2N3906, or the type normally found on the
substrate of many processors’ ICs. The temperature
information is provided to the fan-speed regulator and
is read over the SMBus interface. The temperature
data, through the SMBus, can be read as a 10-bit +
sign two’s complement word with a 0.125°C resolution
(LSB) and is updated every 0.25s.
The MAX6660 incorporates a closed-loop fan controller
that regulates fan speed with tachometer feedback. The
temperature information is compared to a threshold and
range setting, which enables the MAX6660 to automati-
cally set fan speed proportional to temperature. Full con-
trol of these modes is available, including being able to
open either the thermal control loop or the fan control
loop. Figure 1 shows a simplified block diagram.
The ADC is an averaging type that integrates over a
60ms period with excellent noise rejection. A bias cur-
PIN
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
Fan-Speed Regulator with SMBus Interface
SMBDATA
SMBCLK
TACH IN
OVERT
ALERT
NAME
AGND
PGND
ADD1
ADD0
Remote-Junction Temperature-Controlled
VFAN
GAIN
STBY
DXN
V
DXP
FAN
CC
_______________________________________________________________________________________
Detailed Description
Fan Drive Power-Supply Input. 4.5V to 13.5V.
Supply Voltage Input. +3V to +5.5V. Bypass V
Input: Remote-Junction Anode. Place a 2200pF capacitor between DXP and DXN for noise filtering.
Input: Remote-Junction Cathode. DXN is internally biased to a diode voltage above ground.
Open-Drain Output to Fan Low Side. Connect a minimum 1µF capacitor between FAN and VFAN.
SMBus Address Select Pin. ADD0 and ADD1 are sampled upon power-up.
Power Ground
Analog Ground
Overtemperature Shutdown Output. Active-low output (programmable for active high if desired). Open drain.
SMBus Slave Address Select Pin. ADD0 and ADD1 are sampled upon power-up.
SMBus Alert (Interrupt) Output. Open-drain, active-low output.
SMBus Serial Data Input/Output. Open drain.
Gain Control. Connect an external resistor from GAIN to V
SMBus Clock Line from Controller. This line tolerates inputs up to V
Hardware Standby Input. Drive STBY low to reduce supply current. Temperature and comparison
data are retained in standby mode.
Fan Tachometer Input. Tolerates voltages up to VFAN.
ADC
rent is steered through the remote diode, where the for-
ward voltage is measured, and the temperature is com-
puted. The DXN pin is the cathode of the remote diode
and is biased at 0.65V above ground by an internal
diode to set up the ADC inputs for a differential mea-
surement. The worst-case DXP-DXN differential input
voltage range is 0.25V to 0.95V. Excess resistance in
series with the remote diode causes about +1/2°C error
per ohm. Likewise, 200mV of offset voltage forced on
DXP-DXN causes approximately 1°C error.
A conversion sequence is initiated every 250ms in the
free-running autoconvert mode (bit 6 = 0 in the
Configuration register) or immediately by writing a One-
Shot command. The result of the new measurement is
available after the end of conversion. The results of the
previous conversion sequence are still available when
the ADC is converting.
Temperature accuracy depends on having a good-
quality, diode-connected small-signal transistor.
Accuracy has been experimentally verified for all
devices listed in Table 1. The MAX6660 can also direct-
CC
to ground with a 0.1µF capacitor.
FUNCTION
CC
to reduce the gain of the current-sense mode.
CC
even if MAX6660 is not powered.
A/D Conversion Sequence
Remote-Diode Selection
Pin Description
5