2-Channel Temperature Monitor with Dual

Automatic PWM Fan-Speed Controller

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5

PIN

TQFN-EP

QSOP

NAME

FUNCTION

1, 15

3, 1

PWM2,

PWM1

Open-Drain Output to Power Transistor Driving Fan. Connect to the gate of a MOSFET or base of a

bipolar transistor. PWM_ requires a pullup resistor. The pullup resistor can be connected to a

supply voltage as high as 13.5V, regardless of the MAX6640’s supply voltage.

2, 16

4, 2

TACH2,

TACH1

Tachometer Inputs. Connect to the tachometer output of the fan. TACH_ requires a pullup resistor.

The pullup resistor can be connected to a supply voltage as high as 13.5V, regardless of the

MAX6640’s supply voltage.

35

46

THERM

Active-Low, Open-Drain Thermal Alarm Output. Typically used for clock throttling. Open circuit

57

OT

Active-Low, Open-Drain Overtemperature Output. Typically used for system shutdown or clock

68

7

10

GND

Ground. Connect to a clean ground reference.

8, 10

9, 12

DXP1,

DXP2

Combined Current Source and A/D Positive Input for Remote Diode. Connect to anode of remote-

diode-connected temperature-sensing transistor. Do not leave unconnected; connect to DXN if no

remote diode is used. Place a 2200pF capacitor between DXP_ and DXN for noise filtering.

911

DXN

Combined Current Sink and A/D Negative Input for Remote Diode. Connect cathode of the remote-

diode-connected transistor to DXN.

11

13

I.C.

12

14

ALERT

Active-Low, Open-Drain SMBus Alert Output

13

16

SCL

14

15

SDA

——

EP

Exposed Pad (TQFN package only). Internally connected to GND. Connect to a large ground

plane to maximize thermal performance. Not intended as an electrical connection point.

Pin Description

Typical Operating Characteristics (continued)

PWMOUT FREQUENCY

vs. DIE TEMPERATURE

TEMPERATURE (

°C)

85

60

35

10

-15

31

32

33

34

35

30

-40

110

PWMOUT FREQUENCY

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

5.0

4.5

4.0

3.5

31

32

33

34

35

30

3.0

5.5