THMC40 Datasheet, PDF (2/17 Pages) Texas Instruments – VARIABLE SPEED 12-VDC BRUSHLESS FAN MOTOR DRIVERS

THMC40, THMC41
VARIABLE SPEED 12-VDC BRUSHLESS FAN MOTOR DRIVERS
SLIS097 – MARCH 2000
description (continued)
The V_OUT duty cycle, and thus the motor speed, is proportional to the voltage present at the V_PWM input terminal.
This terminal allows controlling the fan speed via a DAC output from an external control IC or an RC-filtered
PWM output from a PC Super I/O chip.
The THMC40 and THMC41 have an internal Hall sensor amplifier and signal conditioner, global thermal
shutdown, locked rotor protection, and automatic restart after a locked rotor condition. The THMC40 provides
an open-drain tachometer output signal, while the THMC41 provides an open-drain locked rotor detection
output signal. These devices also provide a sleep-state mode to eliminate the need for an external power
component to disconnect the fan from the supply during a system sleep state or instantly available power down.
The THMC40 and THMC41 are primarily intended for cooling fan applications that require RPM speed control
and the availability of a tachometer or locked rotor detection signal.
functional block diagram
COSC
VPWM
PWM
Oscillator
23 kHz Nominal
PUC and VREF
OSC
SLEEP
PWM
Generator
PWM
High-Side Gate
Drive With
Synchronous
Rectification
Charge Pump
VSTART
VSLEEP
START and
SLEEP
Detection
SLEEP
Thermal
Shutdown
CP
VPWR
VOUT
TACH
(THMC40)
RD
(THMC41)
Tachometer
Output
OSC
Locked Rotor
Detection and
Auto Restart
Low-Side
Gate Drive
Control Logic
and Global
Thermal
Shutdown
Hall Sensor
Comparator
PHA
PHB
H+
H–
AGND
PGND
2
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