MAX6684ESA Maxim Integrated Products, MAX6684ESA Datasheet - Page 4

• Manufacturer Part Number: MAX6684ESA
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of MAX6684ESA

• Package / Case: SOIC-8 Narrow
• Digital Output - Bus Interface: Serial (2-Wire)
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Output Type: Analog
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The MAX6684 detects fan failure in brushless DC fans.
This device is especially well suited for critical systems
where no fan control is desired. No software is neces-
sary to control the MAX6684.
Fan-Failure Detector with Integrated
Power Switch
Figure 1. MAX6684 Functional Diagram
Figure 2. MAX6684 State Diagram
4
_______________________________________________________________________________________
C
FC+
FC-
F
SENSE
OFF
V
CC
UNDERCURRENT*
Detailed Description
70mV
CURRENT-SENSE AND
CURRENT-LIMITING
GND
CIRCUIT
CURRENT
UNDERCURRENT*
NORMAL
1s DELAY
FAIL LOW
FAN ON,
OVERCURRENT
*INVALID COMMUTATION CURRENT
NOTE: A THERMAL SHUTDOWN CONDITION OVERIDES ALL OTHER CONDITIONS,
IMMEDIATELY SHUTTING THE FAN OFF AND SIGNALING FAIL.
COMP
CURRENT
NORMAL
CURRENT
NORMAL
PGND
V FAN
2ms DELAY
OVERCURRENT
FAN OPERATION
FAIL HIGH
FAN ON,
THERMAL SHUTDOWN
NORMAL
BLANK
NOISE
2ms DELAY
OVERCURRENT
SHUTDOWN
THERMAL
Fan failure is determined based on the fan current
observed at SENSE. The current observed at SENSE is
converted to a voltage, V
the capacitor, C
OSCILLATOR
8.2kHz 8Hz
OVERCURRENT
60ms DELAY
S
NO THERMAL
SHUTDOWN
LATCH
FAIL LOW
FAN OFF,
R
F
, from FC+ to FC- (Figure 1).
Q
OVERCURRENT
THERMAL SHUTDOWN
DETECTION
FAN
FAULT-
MAX6684
DELAY
Fan-Failure Detection
, and highpass filtered by
FAIL