TC648VOA Microchip Technology, TC648VOA Datasheet - Page 11

• Manufacturer Part Number: TC648VOA
• Description: IC PWM FAN SPD CONTRLR SD 8-SOIC
• Manufacturer: Microchip Technology
• Type: Controller - PWM Fanr

Specifications of TC648VOA

• Applications: Fan Controller, Brushless (BLDC)
• Number Of Outputs: 1
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Motor Type: DC Brushless
• No. Of Outputs: 1
• Output Current: 5mA
• Supply Voltage Range: 3V To 5.5V
• Driver Case Style: SOIC
• No. Of Pins: 8
• Operating Temperature Range: 0°C To +85°C
• Product: Fan / Motor Controllers / Drivers
• Operating Supply Voltage: 3 V to 5.5 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

mistor resistance at T
deliver the desired speed at T
and RT
It may be necessary to adjust the values of R
after the initial calculation to obtain the desired results.
The design equations are:
EQUATION
EQUATION
EQUATION
Because the thermistor characteristics are fixed, it may
not be possible, in certain applications, to obtain the
desired values of V
equations. In this case, the circuit in Figure 5-4 can be
used. Diode D
sustain minimum speed.
R
equation on the previous page.
FIGURE 5-4:
2
2002 Microchip Technology Inc.
R
R
for the temperature sensor are identical to the
Where V
minimum fan speed. V
3
4
Where RT
V
fan speed.
MAX
Where: RT
1
are then checked at T
V
= the value of V
MAX
MIN
R
2
1MAX
1
= the value of V
=
=
clamps V
1
R
D
1
= Thermistor resistance at T
R
1
(RT
= thermistor resistance at T
= (0.1)(RT
2
MIN
RT
(RT
(R
(RT
Minimum Fan Speed Circuit.
1MIN
MIN
1
1
DD
1MIN
+ RT
and V
1MIN
IN
IN
V
. R
The calculations of R
= Power Supply Voltage
DD
+ R
required for maximum
to the voltage required to
)(R
MIN
1MIN
)(R
1MAX
2
IN
MAX
1
1
MAX
. The values for R
)(V
is then calculated to
)(V
required for
1
)(V
)
)(V
DD
MIN
for 2.65V nominal.
MIN
using the above
DD
- V
)
)
R
)
R
MIN
1
2
)
MIN
MAX
1
and R
V
1
,
IN
1
, R
and
2
2
5.3
A voltage divider on V
the part is automatically shut down if the sensed
temperature at V
V
As with the V
the temperature range of interest from T
respectively. Assuming that the temperature sensor
network designed previously is linearly related to
temperature, the shutdown temperature T
to T
EQUATION
For example, if 1.25V and 2.65V at V
a temperature range of T
auto-shutdown temperature desired is 25°C, then the
V
EQUATION
The V
divider, as shown in Figure 5-5.
FIGURE 5-5:
AS
AS
2
(i.e. V
voltage is:
and T
AS
V
voltage may be set using a simple resistor
Auto-Shutdown Temperature
Design
AS
IN
V
1
AS
=
< V
by:
2.65 - 1.25V
IN
=
(125 - 0)
I
DIV
AS
T
1.4V
input, 1.25V to 2.65V corresponds to
(
IN
2
).
- T
T
drops below the set temperature at
1.4V
GND
V
2
DD
1
AS
- T
V
R
AS
1
R
1
sets the temperature at which
(25 - 0) + 1.25 = 1.53V
2
)
1
= 0°C to T
(T
=
Circuit.
V
AS
AS
V
AS
- T
I
T
IN
- 1.25
AS
1
) + 1.25
2
- T
DS21448C-page 11
IN
TC648
= 125°C, and the
1
corresponds to
AS
is related
1
to T
2
,