TC642COA Microchip Technology, TC642COA Datasheet - Page 5

• Manufacturer Part Number: TC642COA
• Description: IC PWM FAN SPEED CONTRLR 8-SOIC
• Manufacturer: Microchip Technology
• Type: Controller - PWM Fanr

Specifications of TC642COA

• Package / Case: 8-SOIC (3.9mm Width)
• Operating Temperature: 0°C ~ 70°C
• Applications: Fan Controller, Brushless (BLDC)
• Number Of Outputs: 1
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Product: Fan / Motor Controllers / Drivers
• Operating Supply Voltage: 6 V
• Supply Current: 1 mA
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Load: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

3.0
3.1
The PWM circuit consists of a ramp generator and
threshold detector. The frequency of the PWM is deter-
mined by the value of the capacitor connected to the C
input. A frequency of 30 Hz is recommended
(C
Start-up Timer (see Section 3.4, “Start-Up Timer”). The
PWM voltage control range is 1.25V to 2.65V (typical)
for 0% to 100% output duty cycle.
3.2
The TC642 detects faults in two ways.
First, pulses appearing at SENSE due to the PWM
turning on are blanked, with the remaining pulses
filtered by a missing pulse detector. If consecutive
pulses are not detected for 32 PWM cycles ( 1 Sec if
C
is driven high continuously for three PWM cycles
( 100 msec if C
within this window, the Start-up Timer is triggered (see
Section 3.4). This should clear a transient fault condi-
tion. If the missing pulse detector times out again, the
PWM is stopped and FAULT goes low. When FAULT is
activated due to this condition, the device is latched in
shutdown mode and will remain off indefinitely.
FIGURE 3-1:
From
System
Shutdown
Controller
F
*The parallel combination of R
2002 Microchip Technology Inc.
F
= 1 µF), the Diagnostic Timer is activated, and V
= 1 µF). The PWM is also the time base for the
DETAILED DESCRIPTION
PWM
FAULT Output
(Optional)
F
R
1
= 1 µF). If a pulse is not detected
Fan Fault Output Circuit.
Q
2
3
and R
+5V
From
Temp
Sensor
R
R
4
4
3
must be >10 kΩ.
C
0.01 F
B
C
1 F
F
0.01 F
3
2
1
C
V
V
1
OUT
C
IN
MIN
F
F
+5V
8
V
DD
TC642
GND
The TC642 may be configured to continuously attempt
fan restarts, if so desired.
Continuous restart mode is enabled by connecting the
FAULT output to V
shown in Figure 3-1. When connected in this manner,
the TC642 automatically attempts to restart the fan
every time a fault condition occurs. When the FAULT
output is driven low, the V
pulled below V
fault condition. Normal fan start-up is then attempted as
previously described. The FAULT output may be
connected to external logic (or the interrupt input of a
microcontroller) to shut the TC642 down if multiple fault
pulses are detected at approximately one second
intervals. Diode D
R
a fan fault and not an over-temperature fault. A CMOS
logic OR gate may be substituted for these
components, if available.
6
Note:
4
are provided to ensure fan restarts are the result of
R
10kΩ
5
FAULT
SENSE
V
V
DD
OUT
At this point, action must be taken to restart
the fan by momentarily pulling V
V
case, the fan cannot remain disabled due
to a fault condition, as severe system dam-
age could result. If the fan cannot be
restarted, the system should be shut down.
SHDN
R
1kΩ
6
SHDN
6
7
5
D
, or cycling system power. In either
1
MIN
1
, capacitor C
, initiating a reset and clearing the
through a 0.01 µF capacitor, as
C
SENSE
MIN
1
0
Detected
TC642
Fault
1
RESET
input is momentarily
and resistors R
DS21444C-page 5
TC642
R
R
BASE
MIN
SENSE
below
+12V
5
Fan
and
Q
1