MAX31785 MAXIM [Maxim Integrated Products], MAX31785 Datasheet - Page 11

• Manufacturer Part Number: MAX31785
• Description: 6-Channel Intelligent Fan Controller
• Manufacturer: MAXIM [Maxim Integrated Products]

Note: All pins except V
and reset. After device reset, the weak pullup is removed, and the pin is configured as input or output.
PIN
20
22
23
24
25
26
27
28
29
30
31
32
33
34
35
37
38
39
40
—
CONTROL
TACHSEL
REG18
TACH3
TACH2
TACH1
REG25
TACH0
FAULT
ALERT
NAME
PWM3
PWM2
PWM1
PWM0
RS+5
RS-5
SDA
SCL
A1/
A0
EP
DD
, V
SS
Fan PWM Output #3. CMOS push-pull output. Low when the fan is disabled. A 100% duty cycle
implies this pin is continuously high.
Regulator for Low-Voltage Digital Circuitry. Bypass REG18 to V
not connect other circuitry to this pin.
Fan Tachometer Input
Fan PWM Output #2. CMOS push-pull output. Low when the fan is disabled. A 100% duty cycle
implies this pin is continuously high.
Fan Tachometer Input
Fan PWM Output #1. CMOS push-pull output. Low when the fan is disabled. A 100% duty cycle
implies this pin is continuously high.
Fan Tachometer Input
Fan PWM Output #0. CMOS push-pull output. Low when the fan is disabled. A 100% duty cycle
implies this pin is continuously high.
Regulator for Analog Circuitry. Bypass REG25 to V
other circuitry to this pin.
Fan Tachometer Input
I
I
SMBus Address 0 Input. This pin is sampled on device power-up to determine the SMBus address;
connect a 100kI resistor from this pin to either V
Active-Low, Open-Drain Fault Input/Output. If enabled with the MFR_FAULT_RESPONSE command, this
pin is asserted during a fault condition (fan speed, overtemperature, overvoltage, or undervoltage). Also,
if enabled with the MFR_FAULT_RESPONSE command, this pin is monitored and when it is asserted the
fans can be configured to be forced to 100% PWM duty cycle. This pin is used to provide hardware fault
control across multiple devices. This output is unconditionally deasserted when RST is asserted or the
device is power cycled. This pin has a 50Fs deglitch filter.
Global Fan-Off Control. When this pin is connected low, all fans are forced off (other functionality
remains active). When this pin is connected high (or left open circuit), fans operate normally. This pin
has a 50Fs deglitch filter and contains a weak pullup.
SMBus Address 1 Input/Dual Tach-Select Output. This dual-function pin is sampled on device
power-up to determine the SMBus address; connect a 100kI resistor from this pin to either V
V
tachometers in dual-fan applications.
Active-Low, Open-Drain Alert Output
Ground Reference for Thermal Diode or Remote Voltage ADC Measurement
Thermal Diode or Remote Voltage ADC Input, Measurement Relative to RS-5
Exposed Pad (Bottom Side of Package). Connect EP to V
2
2
, REG18, REG25, ADC, and the EP are high impedance with a 50µA pullup during device power-up
DD
C/SMBus-Compatible Input/Output
C/SMBus-Compatible Clock Input
6-Channel Intelligent Fan Controller
to set the address. After device power-up, this pin becomes an output that selects between two
FUNCTION
SS
SS
or V
Pin Description (continued)
with 1FF and 10nF capacitors. Do not connect
DD
SS
to set the address.
.
SS
with 1FF and 10nF capacitors. Do
SS
or
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