TC651BEVUA Microchip Technology, TC651BEVUA Datasheet - Page 7

• Manufacturer Part Number: TC651BEVUA
• Description: IC TEMP SENSOR/DC FAN CTLR 8MSOP
• Manufacturer: Microchip Technology

Specifications of TC651BEVUA

• Function: Fan Control, Temp Monitor
• Topology: ADC
• Sensor Type: Internal
• Sensing Temperature: 30°C, 45°C Trip Points
• Output Type: Active Low
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 2.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Motor Type: DC Brushless
• No. Of Outputs: 1
• Output Current: 5mA
• Output Voltage: 2.3V
• Supply Voltage Range: 2.8V To 5.5V
• Driver Case Style: MSOP
• No. Of Pins: 8
• Temperature Threshold: + 45 C
• Full Temp Accuracy: +/- 2.5 C
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: - 25 C
• Supply Current: 90 uA
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

4.0
The TC650/TC651 acquire and convert their junction
temperature (T
state sensor with a typical accuracy of ±1°C. The tem-
perature data is digitally stored in an internal register.
The register is compared with pre-defined threshold val-
ues. The six threshold values are equally distributed
over a pre-defined range of temperatures (see Table 4-
1). The TC650/TC651 control the speed of a DC brush-
less fan using a fractional speed-control scheme. The
output stage requires only a 2N2222-type, small-signal
BJT for fans up to 300 mA. For larger current fans (up
to 1 amp), a logic-level N-channel MOSFET may be
used. In addition to controlling the speed of the fan, the
TC650/TC651 include an on-chip overtemperature
alarm (T
ature of the chip exceeds T
ture eliminates the need for a separate temperature
sensor for overtemperature monitoring. Figure 4-1
shows the block diagram of the device.
FIGURE 4-1:
4.1
The PWM pin is designed to drive a low-cost transistor
or MOSFET as the low-side, power-switching element
in the system. This output has an asymmetric
complementary drive and is optimized for driving NPN
transistors or N-channel MOSFETs. Since the system
relies on PWM rather than linear power control, the
dissipation in the power switch is kept to a minimum.
Generally, very small devices (TO-92 or SOT
packages) will suffice. The frequency of the PWM is
about 15 Hz. The PWM is also the time base for the
Start-up Timer (see Section 4.2 “Start-Up Timer”).
The PWM duty cycle has a range of 40% to 100% for
the TC650 and 50% to 100% for the TC651.
 2004 Microchip Technology Inc.
V
DD
Temperature Sensor
A/D Converter
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Set Point and
Temperature
DETAILED DESCRIPTION
Trim Range
PWM Output
) that gives a low signal when the temper-
J
) information from an on-chip, solid-
T
Functional Block Diagram.
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Duty Cycle
H
Control
Logic
Oscillator
by 10°C (typical). This fea-
SHDN
PWM
V+
4.2
To ensure reliable fan start-up, the Start-up Timer turns
PWM high for about 2 seconds whenever the fan is
started from the off state. This occurs at power-up and
when coming out of Shutdown mode.
4.3
This pin goes low when the T
10°C (typical). This indicates that the fan is at
maximum drive and the potential exists for system
overheating; either heat dissipation in the system has
gone beyond the cooling system's design limits or
some fault exists (such as fan bearing failure or an air-
flow obstruction). This output may be treated as a
“System Overheat” warning and be used to either
trigger system shutdown or bring other fans in the
system to full speed. The fan will continue to run at full
speed while T
prevents T
temperature is at or near the T
temperature falls through the T
teresis maintains the T
measured temperature is 5°C above the trip point
setting.
4.4
The fan can be unconditionally shut down by pulling
the SHDN pin low. During shutdown, the PWM output
is low; ideal for notebook computers and other portable
applications where you need to change batteries and
must not have the fan running at that time. Thermal
monitoring and T
shutdown. I
4.5
The TC651 features auto-shutdown. When the
temperature is below the factory set point at minimum
speed (T
shut off (Auto-shutdown mode). This feature is ideal for
notebook computers and other portable equipment that
need to conserve as much battery power as possible
and, thus, run a fan when it is only absolutely needed.
The TC651 will continue to be active in order to monitor
temperature for T
shutdown mode when the temperature rises above the
factory set point (T
Start-Up Timer
Overtemperature Alert (T
Shutdown (SHDN)
Auto-shutdown Mode
L
), PWM is low and the fan is automatically
OVER
DD
shutdown current is around 50 µA.
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from “chattering” when the measured
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1
TC650/TC651
).
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is asserted. Built-in hysteresis
are still in operation during
. The TC651 exits Auto-
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H
set point is exceeded by
H
H
output low until the
+ 10°C trip point, hys-
+ 10°C trip point. As
DS21450C-page 7
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)